76
|
Silhár P, Eubanks LM, Seki H, Pellett S, Javor S, Tepp WH, Johnson EA, Janda KD. Targeting botulinum A cellular toxicity: a prodrug approach. J Med Chem 2013; 56:7870-9. [PMID: 24127873 DOI: 10.1021/jm400873n] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The botulinum neurotoxin light chain (LC) protease has become an important therapeutic target for postexposure treatment of botulism. Hydroxamic acid based small molecules have proven to be potent inhibitors of LC/A with nanomolar Ki values, yet they lack cellular activity conceivably due to low membrane permeability. To overcome this potential liability, we investigated two prodrug strategies, 1,4,2-dioxazole and carbamate, based on our 1-adamantylacetohydroxamic acid scaffold. The 1,4,2-dioxazole prodrug did not demonstrate cellular activity, however, carbamates exhibited cellular potency with the most active compound displaying an EC50 value of 20 μM. Cellular trafficking studies were conducted using a "fluorescently silent" prodrug that remained in this state until cellular uptake was complete, which allowed for visualization of the drug's release inside neuronal cells. In sum, this research sets the stage for future studies leveraging the specific targeting and delivery of these prodrugs, as well as other antibotulinum agents, into neuronal cells.
Collapse
|
77
|
Liss DT, Fishman PA, Rutter CM, Grembowski D, Ross TR, Johnson EA, Reid RJ. Outcomes among chronically ill adults in a medical home prototype. THE AMERICAN JOURNAL OF MANAGED CARE 2013; 19:e348-e358. [PMID: 24304182 PMCID: PMC4074014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
OBJECTIVES To compare quality, utilization, and cost outcomes for patients with selected chronic illnesses at a patient-centered medical home (PCMH) prototype site with outcomes for patients with the same chronic illnesses at 19 nonintervention control sites. STUDY DESIGN Nonequivalent pretest-posttest control group design. METHODS PCMH redesign results were investigated for patients with preexisting diabetes, hypertension, and/or coronary heart disease. Data from automated databases were collected for eligible enrollees in an integrated healthcare delivery system. Multivariable regression models tested for adjusted differences between PCMH patients and controls during the baseline and follow-up periods. Dependent measures under study included clinical processes and, outcomes, monthly healthcare utilization, and costs. RESULTS Compared with controls over 2 years, patients at the PCMH prototype clinic had slightly better clinical outcome control in coronary heart disease (2.20 mg/dL lower mean low-density lipoprotein cholesterol; P <.001). PCMH patients changed their patterns of primary care utilization, as reflected by 86% more secure electronic message contacts (P <.001), 10% more telephone contacts (P = .003), and 6% fewer in-person primary care visits (P <.001). PCMH patients had 21% fewer ambulatory care-sensitive hospitalizations (P <.001) and 7% fewer total inpatient admissions (P = .002) than controls. During the 2-year redesign, we observed 17% lower inpatient costs (P <.001) and 7% lower total healthcare costs (P <.001) among patients at the PCMH prototype clinic. CONCLUSIONS A clinic-level population-based PCMH redesign can decrease downstream utilization and reduce total healthcare costs in a subpopulation of patients with common chronic illnesses.
Collapse
|
78
|
Johnson EA. Biotechnology of non-Saccharomyces yeasts—the basidiomycetes. Appl Microbiol Biotechnol 2013; 97:7563-77. [DOI: 10.1007/s00253-013-5046-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 06/05/2013] [Accepted: 06/07/2013] [Indexed: 12/24/2022]
|
79
|
Peng L, Liu H, Ruan H, Tepp WH, Stoothoff WH, Brown RH, Johnson EA, Yao WD, Zhang SC, Dong M. Cytotoxicity of botulinum neurotoxins reveals a direct role of syntaxin 1 and SNAP-25 in neuron survival. Nat Commun 2013; 4:1472. [PMID: 23403573 PMCID: PMC4052923 DOI: 10.1038/ncomms2462] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 01/09/2013] [Indexed: 12/05/2022] Open
Abstract
Botulinum neurotoxins (BoNT/A-G) are well-known to act by blocking synaptic vesicle exocytosis. Whether BoNTs disrupt additional neuronal functions has not been addressed. Here we report that cleavage of syntaxin 1 (Syx 1) by BoNT/C and cleavage of SNAP-25 by BoNT/E both induce degeneration of cultured rodent and human neurons. Furthermore, although SNAP-25 cleaved by BoNT/A can still support neuron survival, it has reduced capacity to tolerate additional mutations and also fails to pair with syntaxin isoforms other than Syx 1. Syx 1 and SNAP-25 are well-known for mediating synaptic vesicle exocytosis, but we found that neuronal death is due to blockage of plasma membrane recycling processes that share Syx 1/SNAP-25 for exocytosis, independent of blockage of synaptic vesicle exocytosis. These findings reveal neuronal cytotoxicity for a subset of BoNTs and directly link Syx 1/SNAP-25 to neuron survival as the prevalent SNARE proteins mediating multiple fusion events on neuronal plasma membranes.
Collapse
|
80
|
Reid RJ, Johnson EA, Hsu C, Ehrlich K, Coleman K, Trescott C, Erikson M, Ross TR, Liss DT, Cromp D, Fishman PA. Spreading a medical home redesign: effects on emergency department use and hospital admissions. Ann Fam Med 2013; 11 Suppl 1:S19-26. [PMID: 23690382 PMCID: PMC3707243 DOI: 10.1370/afm.1476] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The patient-centered medical home (PCMH) is being rapidly deployed in many settings to strengthen US primary care, improve quality, and control costs; however, evidence supporting this transformation is still lacking. We describe the Group Health experience in attempting to replicate the effects on health care use seen in a PCMH prototype clinic via a systemwide spread using Lean as the change strategy. METHODS We used an interrupted time series analysis with a patient-month unit of analysis over a 4-year period that included baseline, implementation, and stabilization periods for 412,943 patients. To account for secular trends across these periods, we compared changes in use of face-to-face primary care visits, emergency department visits, and inpatient admissions with those of a nonequivalent comparison group of patients served by community network practices. RESULTS After accounting for secular trends among network patients, patients empaneled to the PCMH clinics had 5.1% and 6.7% declines in primary care office visits in early and later stabilization years, respectively, after the implementation year. This trend was accompanied by a 123% increase in the use of secure electronic message threads and a 20% increase in telephone encounters. Declines were also seen in emergency department visits at 1 and 2 years (13.7% and 18.5%) compared with what would be expected based on secular trends in network practices. No statistically significant changes were found for hospital admissions. CONCLUSIONS The Group Health experience shows it is possible to reduce emergency department use with PCMH transformation across a diverse set of clinics using a clear change strategy (Lean) and sufficient resources and supports.
Collapse
|
81
|
Johnson EA. Monitoring foreign gene incorporation into the plastome of Chlamydomonas reinhardtii by multiplex qPCR. PHOTOSYNTHESIS RESEARCH 2013; 115:81-87. [PMID: 23649166 DOI: 10.1007/s11120-013-9835-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 04/23/2013] [Indexed: 06/02/2023]
Abstract
The genetic material of the Chlamydomonas reinhardtii chloroplast can be easily manipulated and creation of transgenic plastomes is of interest for both photosynthetic research and for biofuel and biomass production. Because multiple copies of the chloroplast genome are present, it is important to understand whether, following the introduction of a foreign gene, the resulting transgenic plastome is homoplasmic or heteroplasmic. By quantitative PCR together with a simple DNA extraction procedure and a series of DNA oligonucleotides the following protocol will determine the extent of foreign gene incorporation into a host chloroplast plastome. This approach is used to follow the degree of heteroplasmy following biolistic transformation of several transgenic strains. The approach used is quick, simple to set up, and gives an accurate quantitation of foreign genes within of the chloroplast plastome. Possible future uses of the technique are discussed.
Collapse
|
82
|
Chubak J, Rutter CM, Kamineni A, Johnson EA, Stout NK, Weiss NS, Doria-Rose VP, Doubeni CA, Buist DSM. Measurement in comparative effectiveness research. Am J Prev Med 2013; 44:513-9. [PMID: 23597816 PMCID: PMC3631525 DOI: 10.1016/j.amepre.2013.01.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 10/09/2012] [Accepted: 01/08/2013] [Indexed: 01/11/2023]
Abstract
Comparative effectiveness research (CER) on preventive services can shape policy and help patients, their providers, and public health practitioners select regimens and programs for disease prevention. Patients and providers need information about the relative effectiveness of various regimens they may choose. Decision makers need information about the relative effectiveness of various programs to offer or recommend. The goal of this paper is to define and differentiate measures of relative effectiveness of regimens and programs for disease prevention. Cancer screening is used to demonstrate how these measures differ in an example of two hypothetical screening regimens and programs. Conceptually and algebraically defined measures of relative regimen and program effectiveness also are presented. The measures evaluate preventive services that range from individual tests through organized, population-wide prevention programs. Examples illustrate how effective screening regimens may not result in effective screening programs and how measures can vary across subgroups and settings. Both regimen and program relative effectiveness measures assess benefits of prevention services in real-world settings, but each addresses different scientific and policy questions. As the body of CER grows, a common lexicon for various measures of relative effectiveness becomes increasingly important to facilitate communication and shared understanding among researchers, healthcare providers, patients, and policymakers.
Collapse
|
83
|
Kamps-Hughes N, Quimby A, Zhu Z, Johnson EA. Massively parallel characterization of restriction endonucleases. Nucleic Acids Res 2013; 41:e119. [PMID: 23605040 PMCID: PMC3675476 DOI: 10.1093/nar/gkt257] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Restriction endonucleases are highly specific in recognizing the particular DNA sequence they act on. However, their activity is affected by sequence context, enzyme concentration and buffer composition. Changes in these factors may lead to either ineffective cleavage at the cognate restriction site or relaxed specificity allowing cleavage of degenerate ‘star’ sites. Additionally, uncharacterized restriction endonucleases and engineered variants present novel activities. Traditionally, restriction endonuclease activity is assayed on simple substrates such as plasmids and synthesized oligonucleotides. We present and use high-throughput Illumina sequencing-based strategies to assay the sequence specificity and flanking sequence preference of restriction endonucleases. The techniques use fragmented DNA from sequenced genomes to quantify restriction endonuclease cleavage on a complex genomic DNA substrate in a single reaction. By mapping millions of restriction site–flanking reads back to the Escherichia coli and Drosophila melanogaster genomes we were able to quantitatively characterize the cognate and star site activity of EcoRI and MfeI and demonstrate genome-wide decreases in star activity with engineered high-fidelity variants EcoRI-HF and MfeI-HF, as well as quantify the influence on MfeI cleavage conferred by flanking nucleotides. The methods presented are readily applicable to all type II restriction endonucleases that cleave both strands of double-stranded DNA.
Collapse
|
84
|
Hong WS, Young EWK, Tepp WH, Johnson EA, Beebe DJ. A Microscale Neuron and Schwann Cell Coculture Model for Increasing Detection Sensitivity of Botulinum Neurotoxin Type A. Toxicol Sci 2013; 134:64-72. [DOI: 10.1093/toxsci/kft082] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
|
85
|
Chun CL, Ochsner U, Byappanahalli MN, Whitman RL, Tepp WH, Lin G, Johnson EA, Peller J, Sadowsky MJ. Association of toxin-producing Clostridium botulinum with the macroalga Cladophora in the Great Lakes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:2587-2594. [PMID: 23421373 DOI: 10.1021/es304743m] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Avian botulism, a paralytic disease of birds, often occurs on a yearly cycle and is increasingly becoming more common in the Great Lakes. Outbreaks are caused by bird ingestion of neurotoxins produced by Clostridium botulinum, a spore-forming, gram-positive, anaerobe. The nuisance, macrophytic, green alga Cladophora (Chlorophyta; mostly Cladophora glomerata L.) is a potential habitat for the growth of C. botulinum. A high incidence of botulism in shoreline birds at Sleeping Bear Dunes National Lakeshore (SLBE) in Lake Michigan coincides with increasingly massive accumulations of Cladophora in nearshore waters. In this study, free-floating algal mats were collected from SLBE and other shorelines of the Great Lakes between June and October 2011. The abundance of C. botulinum in algal mats was quantified and the type of botulism neurotoxin (bont) genes associated with this organism were determined by using most-probable-number PCR (MPN-PCR) and five distinct bont gene-specific primers (A, B, C, E, and F). The MPN-PCR results showed that 16 of 22 (73%) algal mats from the SLBE and 23 of 31(74%) algal mats from other shorelines of the Great Lakes contained the bont type E (bont/E) gene. C. botulinum was present up to 15000 MPN per gram dried algae based on gene copies of bont/E. In addition, genes for bont/A and bont/B, which are commonly associated with human diseases, were detected in a few algal samples. Moreover, C. botulinum was present as vegetative cells rather than as dormant spores in Cladophora mats. Mouse toxin assays done using supernatants from enrichment of Cladophora containing high densities of C. botulinum (>1000 MPN/g dried algae) showed that Cladophora-borne C. botulinum were toxin-producing species (BoNT/E). Our results indicate that Cladophora provides a habitat for C. botulinum, warranting additional studies to better understand the relationship between this bacterium and the alga, and how this interaction potentially contributes to botulism outbreaks in birds.
Collapse
|
86
|
Hohenlohe PA, Day MD, Amish SJ, Miller MR, Kamps-Hughes N, Boyer MC, Muhlfeld CC, Allendorf FW, Johnson EA, Luikart G. Genomic patterns of introgression in rainbow and westslope cutthroat trout illuminated by overlapping paired-end RAD sequencing. Mol Ecol 2013; 22:3002-13. [PMID: 23432212 DOI: 10.1111/mec.12239] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 12/05/2012] [Accepted: 12/11/2012] [Indexed: 12/14/2022]
Abstract
Rapid and inexpensive methods for genomewide single nucleotide polymorphism (SNP) discovery and genotyping are urgently needed for population management and conservation. In hybridized populations, genomic techniques that can identify and genotype thousands of species-diagnostic markers would allow precise estimates of population- and individual-level admixture as well as identification of 'super invasive' alleles, which show elevated rates of introgression above the genomewide background (likely due to natural selection). Techniques like restriction-site-associated DNA (RAD) sequencing can discover and genotype large numbers of SNPs, but they have been limited by the length of continuous sequence data they produce with Illumina short-read sequencing. We present a novel approach, overlapping paired-end RAD sequencing, to generate RAD contigs of >300-400 bp. These contigs provide sufficient flanking sequence for design of high-throughput SNP genotyping arrays and strict filtering to identify duplicate paralogous loci. We applied this approach in five populations of native westslope cutthroat trout that previously showed varying (low) levels of admixture from introduced rainbow trout (RBT). We produced 77 141 RAD contigs and used these data to filter and genotype 3180 previously identified species-diagnostic SNP loci. Our population-level and individual-level estimates of admixture were generally consistent with previous microsatellite-based estimates from the same individuals. However, we observed slightly lower admixture estimates from genomewide markers, which might result from natural selection against certain genome regions, different genomic locations for microsatellites vs. RAD-derived SNPs and/or sampling error from the small number of microsatellite loci (n = 7). We also identified candidate adaptive super invasive alleles from RBT that had excessively high admixture proportions in hybridized cutthroat trout populations.
Collapse
|
87
|
Reid RJ, Coleman K, Johnson EA, Fishman PA, Hsu C, Soman MP, Trescott CE, Erikson M, Larson EB. The Group Health medical home at year two: cost savings, higher patient satisfaction, and less burnout for providers. Health Aff (Millwood) 2013; 29:835-43. [PMID: 20439869 DOI: 10.1377/hlthaff.2010.0158] [Citation(s) in RCA: 362] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
As the patient-centered medical home model emerges as a key vehicle to improve the quality of health care and to control costs, the experience of Seattle-based Group Health Cooperative with its medical home pilot takes on added importance. This paper examines the effects of the medical home prototype on patients' experiences, quality, burnout of clinicians, and total costs at twenty-one to twenty-four months after implementation. The results show improvements in patients' experiences, quality, and clinician burnout through two years. Compared to other Group Health clinics, patients in the medical home experienced 29 percent fewer emergency visits and 6 percent fewer hospitalizations. We estimate total savings of $10.3 per patient per month twenty-one months into the pilot. We offer an operational blueprint and policy recommendations for adoption in other health care settings.
Collapse
|
88
|
Hernández-Barrera A, Quinto C, Johnson EA, Wu HM, Cheung AY, Cárdenas L. Using hyper as a molecular probe to visualize hydrogen peroxide in living plant cells: a method with virtually unlimited potential in plant biology. Methods Enzymol 2013; 527:275-90. [PMID: 23830637 DOI: 10.1016/b978-0-12-405882-8.00015-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Reactive oxygen species (ROS) are highly reactive reduced oxygen molecules that play a myriad of roles in animal and plant cells. In plant cells, the production of ROS occurs as a result of aerobic metabolism during respiration and photosynthesis. Therefore mitochondria, chloroplasts, and peroxisomes constitute an important source of ROS. However, they can be produced in response to many physiological stimuli such as pathogen attack, hormone signaling, abiotic stresses, or during cell wall organization and plant morphogenesis. Monitoring ROS in plant cells has been limited to biochemical assays and use of fluorescent probes, however, the irreversible oxidation of the fluorescent dyes make it impossible to visualize dynamic changes of ROS. Hyper is a recently developed live cell probe for H2O2 and consists of a circularly permutated YFP (cpYFP) inserted into the regulatory domain of the Escherichia coli hydrogen peroxide (H2O2) sensor OxyR rendering it a H2O2 specific ratiometric, and therefore quantitative probe. Herein, we describe a protocol for using Hyper as a dynamic probe for H2O2 in Arabidopsis with virtually unlimited potential to detect H2O2 throughout the plant and under a broad range of developmental and environmental conditions.
Collapse
|
89
|
Abstract
Approximately, 20 years ago, a haemoglobin gene was identified within the genome of the cyanobacterium Nostoc commune. Haemoglobins have now been confirmed in multiple species of photosynthetic microbes beyond N. commune, and the diversity of these proteins has recently come under increased scrutiny. This chapter summarizes the state of knowledge concerning the phylogeny, physiology and chemistry of globins in cyanobacteria and green algae. Sequence information is by far the best developed and the most rapidly expanding aspect of the field. Structural and ligand-binding properties have been described for just a few proteins. Physiological data are available for even fewer. Although activities such as nitric oxide dioxygenation and oxygen scavenging are strong candidates for cellular function, dedicated studies will be required to complete the story on this intriguing and ancient group of proteins.
Collapse
|
90
|
Šilhár P, Silvaggi NR, Pellett S, Čapková K, Johnson EA, Allen KN, Janda KD. Evaluation of adamantane hydroxamates as botulinum neurotoxin inhibitors: synthesis, crystallography, modeling, kinetic and cellular based studies. Bioorg Med Chem 2012; 21:1344-8. [PMID: 23340139 DOI: 10.1016/j.bmc.2012.12.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 12/01/2012] [Accepted: 12/03/2012] [Indexed: 10/27/2022]
Abstract
Botulinum neurotoxins (BoNTs) are the most lethal biotoxins known to mankind and are responsible for the neuroparalytic disease botulism. Current treatments for botulinum poisoning are all protein based and thus have a limited window of treatment opportunity. Inhibition of the BoNT light chain protease (LC) has emerged as a therapeutic strategy for the treatment of botulism as it may provide an effective post exposure remedy. Using a combination of crystallographic and modeling studies a series of hydroxamates derived from 1-adamantylacetohydroxamic acid (3a) were prepared. From this group of compounds, an improved potency of about 17-fold was observed for two derivatives. Detailed mechanistic studies on these structures revealed a competitive inhibition model, with a K(i)=27 nM, which makes these compounds some of the most potent small molecule, non-peptidic BoNT/A LC inhibitors reported to date.
Collapse
|
91
|
|
92
|
DeRosa DC, Lim RB, Lin-Hurtubise K, Johnson EA. Symptomatic hibernoma: a rare soft tissue tumor. HAWAI'I JOURNAL OF MEDICINE & PUBLIC HEALTH : A JOURNAL OF ASIA PACIFIC MEDICINE & PUBLIC HEALTH 2012; 71:342-345. [PMID: 23251871 PMCID: PMC3525332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Hibernomas are benign soft tissue tumors containing prominent brown adipocytes that resemble normal brown fat. Hibernomas have not been associated with malignant potential; however, they are similar in clinical presentation to malignant tumors like liposarcomas. This article describes the clinical, radiographic, and histologic features of a patient with a hibernoma arising from the left superior flank.
Collapse
|
93
|
Whitemarsh RCM, Pier CL, Tepp WH, Pellett S, Johnson EA. Model for studying Clostridium botulinum neurotoxin using differentiated motor neuron-like NG108-15 cells. Biochem Biophys Res Commun 2012; 427:426-30. [PMID: 23000406 DOI: 10.1016/j.bbrc.2012.09.082] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Accepted: 09/13/2012] [Indexed: 11/16/2022]
Abstract
Cancerous cell lines have traditionally shown low sensitivity to laboratory or pharmaceutical preparations of botulinum neurotoxin. The work presented here demonstrates that the mouse neuroblastoma/rat glioma hybrid cell line NG108-15 is capable of more sensitively detecting BoNT/A1 than any cell line previously described. This cell line has previously been described to have motor neuron like characteristics, therefore making it a good model to study BoNTs. Differentiation of NG108-15 cells in serum-free medium containing retinoic acid and purmorphamine dramatically increased sensitivity of the neurons to BoNT/A (EC(50) = ~16 LD(50) U). Additional pre-treatment with triasialoganglioside GT1B prior to toxin exposure reduced the EC(50) further to ~11 LD(50) U. Co-culture of the neurons with C2C12 myotubes also significantly increased BoNT/A sensitivity of NG108-15 cells (EC(50) = 26 U) in the absence of differentiation factors.
Collapse
|
94
|
Johnson EA, Pellett S, Whitemarsh R, Tepp WH. 128. Human iPS Neuronal Platform for Botulinum Neurotoxins. Toxicon 2012. [DOI: 10.1016/j.toxicon.2012.04.129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
95
|
Guan Z, Johnston NC, Raetz CRH, Johnson EA, Goldfine H. Lipid diversity among botulinum neurotoxin-producing clostridia. MICROBIOLOGY-SGM 2012; 158:2577-2584. [PMID: 22837302 DOI: 10.1099/mic.0.060707-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Clostridium botulinum has been classified into four groupings (groups I to IV) based on physiological characteristics and 16S rRNA sequencing. We have examined the lipid compositions of 11 representative strains of C. botulinum and a strain of Clostridium sporogenes by 2D-TLC and by MS. All strains contained phosphatidylglycerol (PG), cardiolipin (CL) and phosphatidylethanolamine (PE) in both the all-acyl and the alk-1'-enyl (plasmalogen) forms. Five strains in proteolytic group I, which are related to C. sporogenes, contained varying amounts of an ethanolamine-phosphate derivative of N-acetylglucosaminyl-diradylglycerol, which is also present in C. sporogenes. Three strains in group II, which are related to Clostridium butyricum, Clostridium beijerinckii and Clostridium acetobutylicum, contained lipids characteristic of these saccharolytic species: a glycerol acetal and a PG acetal of the plasmalogen form of PE. Two group III strains, which are related to Clostridium novyi, contained amino-acyl derivatives of PG, which are also found in C. novyi. A strain in group IV had PE, PG and CL, but none of the distinguishing lipids. This work shows that the lipidome of C. botulinum is consistent with its classification by other methods.
Collapse
|
96
|
Strotman LN, Lin G, Berry SM, Johnson EA, Beebe DJ. Facile and rapid DNA extraction and purification from food matrices using IFAST (immiscible filtration assisted by surface tension). Analyst 2012; 137:4023-8. [PMID: 22814365 DOI: 10.1039/c2an35506j] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Extraction and purification of DNA is a prerequisite to detection and analytical techniques. While DNA sample preparation methods have improved over the last few decades, current methods are still time consuming and labor intensive. Here we demonstrate a technology termed IFAST (Immiscible Filtration Assisted by Surface Tension), that relies on immiscible phase filtration to reduce the time and effort required to purify DNA. IFAST replaces the multiple wash and centrifugation steps required by traditional DNA sample preparation methods with a single step. To operate, DNA from lysed cells is bound to paramagnetic particles (PMPs) and drawn through an immiscible fluid phase barrier (i.e. oil) by an external handheld magnet. Purified DNA is then eluted from the PMPs. Here, detection of Clostridium botulinum type A (BoNT/A) in food matrices (milk, orange juice), a bioterrorism concern, was used as a model system to establish IFAST's utility in detection assays. Data validated that the DNA purified by IFAST was functional as a qPCR template to amplify the bont/A gene. The sensitivity limit of IFAST was comparable to the commercially available Invitrogen ChargeSwitch® method. Notably, pathogen detection via IFAST required only 8.5 μL of sample and was accomplished in five-fold less time. The simplicity, rapidity and portability of IFAST offer significant advantages when compared to existing DNA sample preparation methods.
Collapse
|
97
|
Sun S, Tepp WH, Johnson EA, Chapman ER. Botulinum neurotoxins B and E translocate at different rates and exhibit divergent responses to GT1b and low pH. Biochemistry 2012; 51:5655-62. [PMID: 22720883 PMCID: PMC3398548 DOI: 10.1021/bi3004928] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
![]()
Botulinum neurotoxins (BoNTs, serotypes A–G) are
the most
deadly substances known. Here, we investigated how BoNT/E, a serotype
that causes human botulism, translocates into the cytosol of neurons.
Analogous to BoNT/B, BoNT/E required binding of the coreceptor, GT1b,
to undergo significant secondary structural changes and transform
into a hydrophobic protein at low pH. These data indicate that both
serotypes act as coincidence detectors for both GT1b and low pH, to
undergo translocation. However, BoNT/E translocated much more rapidly
than BoNT/B. Also, BoNT/E required only GT1b, and not low pH, to oligomerize,
whereas BoNT/B required both. In further contrast to the case of BoNT/B,
low pH alone altered the secondary structure of BoNT/E to some degree
and resulted in its premature inactivation. Hence, comparison of two
BoNT serotypes revealed that these agents exhibit both convergent
and divergent responses to receptor interactions, and pH, in the translocation
pathway.
Collapse
|
98
|
Johnson EA, De Lee R, Agni R, Pfau P, Reichelderfer M, Gopal DV. Probe-Based Confocal Laser Endomicroscopy to Guide Real-Time Endoscopic Therapy in Barrett's Esophagus with Dysplasia. Case Rep Gastroenterol 2012; 6:285-92. [PMID: 22754488 PMCID: PMC3376345 DOI: 10.1159/000338835] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Probe-based confocal laser endomicroscopy (pCLE) is a novel imaging technique which utilizes a low-power laser light passed through a fiber-optic bundle, within a miniprobe that is advanced into the working channel, to obtain microscopic images of the mucosa. This allows the endoscopist to evaluate the microarchitecture of the gastrointestinal epithelium in real time. At this time pCLE cannot replace histopathology, but it can provide diagnostic information as well as guide therapeutic management in patients with Barrett's esophagus (BE) with high-grade dysplasia (HGD). We describe a retrospective case series in which four patients with BE and biopsy-proven HGD underwent endoscopy with pCLE to direct real-time endoscopic ablation therapy and/or endoscopic mucosal resection (EMR), which was performed in conjunction with pCLE. All four patients had pCLE showing features of HGD. After either EMR or radiofrequency ablation (RFA), pCLE was again used to evaluate the margins after therapy to assure accuracy. In one case, pCLE had features of dysplasia at the margin and further repeat EMR was immediately performed. Another case had a normal-appearing esophagus, but pCLE found features of BE in discrete areas and targeted biopsies were performed, which confirmed BE. This patient subsequently underwent RFA therapy of the residual areas of BE. In conclusion, in patients with BE and dysplasia, pCLE is an effective tool used to target biopsies, guide endoscopic therapy and assess the accuracy of EMR or RFA.
Collapse
|
99
|
Michaletz ST, Johnson EA, Tyree MT. Moving beyond the cambium necrosis hypothesis of post-fire tree mortality: cavitation and deformation of xylem in forest fires. THE NEW PHYTOLOGIST 2012; 194:254-263. [PMID: 22276783 DOI: 10.1111/j.1469-8137.2011.04021.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
• It is widely assumed that post-fire tree mortality results from necrosis of phloem and vascular cambium in stems, despite strong evidence that reduced xylem conductivity also plays an important role. • In this study, experiments with Populus balsamifera were used to demonstrate two mechanisms by which heat reduces the hydraulic conductivity of xylem: air seed cavitation and conduit wall deformation. Heat effects on air seed cavitation were quantified using air injection experiments that isolate potential temperature-dependent changes in sap surface tension and pit membrane pore diameters. Heat effects on conduit wall structure were demonstrated using air conductivity measurements and light microscopy. • Heating increased vulnerability to cavitation because sap surface tension varies inversely with temperature. Heating did not affect cavitation via changes in pit membrane pore diameters, but did cause significant reductions in xylem air conductivity that were associated with deformation of conduit walls (probably resulting from thermal softening of viscoelastic cell wall polymers). • Additional work is required to understand the relative roles of cavitation and deformation in the reduction of xylem conductivity, and how reduced xylem conductivity in roots, stems, and branches correlates and interacts with foliage and root necroses to cause tree mortality. Future research should also examine how heat necrosis of ray parenchyma cells affects refilling of embolisms that occur during and after the fire event.
Collapse
|
100
|
Peng L, Berntsson RPA, Tepp WH, Pitkin RM, Johnson EA, Stenmark P, Dong M. Botulinum neurotoxin D-C uses synaptotagmin I and II as receptors, and human synaptotagmin II is not an effective receptor for type B, D-C and G toxins. J Cell Sci 2012; 125:3233-42. [PMID: 22454523 DOI: 10.1242/jcs.103564] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are classified into seven types (A-G), but multiple subtype and mosaic toxins exist. These subtype and mosaic toxins share a high sequence identity, and presumably the same receptors and substrates with their parental toxins. Here, we report that a mosaic toxin, type D-C (BoNT/D-C), uses different receptors from its parental toxin BoNT/C. BoNT/D-C, but not BoNT/C, binds directly to the luminal domains of synaptic vesicle proteins synaptotagmin (Syt) I and II, and requires expression of SytI/II to enter neurons. The SytII luminal fragment containing the toxin-binding site can block the entry of BoNT/D-C into neurons and reduce its toxicity in vivo in mice. We also found that gangliosides increase binding of BoNT/D-C to SytI/II and enhance the ability of the SytII luminal fragment to block BoNT/D-C entry into neurons. These data establish SytI/II, in conjunction with gangliosides, as the receptors for BoNT/D-C, and indicate that BoNT/D-C is functionally distinct from BoNT/C. We further found that BoNT/D-C recognizes the same binding site on SytI/II where BoNT/B and G also bind, but utilizes a receptor-binding interface that is distinct from BoNT/B and G. Finally, we also report that human and chimpanzee SytII has diminished binding and function as the receptor for BoNT/B, D-C and G owing to a single residue change from rodent SytII within the toxin binding site, potentially reducing the potency of these BoNTs in humans and chimpanzees.
Collapse
|