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Walker KD, Evans JS, MacIntosh D. Use of expert judgment in exposure assessment. Part I. Characterization of personal exposure to benzene. JOURNAL OF EXPOSURE ANALYSIS AND ENVIRONMENTAL EPIDEMIOLOGY 2001; 11:308-22. [PMID: 11571610 DOI: 10.1038/sj.jea.7500171] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/1998] [Accepted: 04/25/2001] [Indexed: 04/14/2023]
Abstract
This paper presents the results of the first phase of a study, conducted as an element of the National Human Exposure Assessment Survey (NHEXAS), to demonstrate the use of expert subjective judgment elicitation techniques to characterize the magnitude of and uncertainty in environmental exposure to benzene. In decisions about the value of exposure research or of regulatory controls, the characterization of uncertainty can play an influential role. Classical methods for characterizing uncertainty may be sufficient when adequate amounts of relevant data are available. Frequently, however, data are neither abundant nor directly relevant, making it necessary to rely to varying degrees on subjective judgment. Since the 1950s, methods to elicit and quantify subjective judgments have been explored but have rarely been applied to the field of environmental exposure assessment. In this phase of the project, seven experts in benzene exposure assessment were selected through a peer nomination process, participated in a 2-day workshop, and were interviewed individually to elicit their judgments about the distributions of residential ambient, residential indoor, and personal air benzene concentrations (6-day integrated average) experienced by both the non-smoking, non-occupationally exposed target and study populations of the US EPA Region V pilot study. Specifically, each expert was asked to characterize, in probabilistic form, the arithmetic means and the 90th percentiles of these distributions. This paper presents the experts' judgments about the concentrations of benzene encountered by the target population. The experts' judgments about levels of benzene in personal air were demonstrative of patterns observed in the judgments about the other distributions. They were in closest agreement about their predictions of the mean; with one exception, their best estimates of the mean fell within 7-11 microg/m(3) although they exhibited striking differences in the degree of uncertainty expressed. Their estimates of the 90th percentile were more varied with the best estimates ranging from 12 to 26 microg/m(3) for all but one expert. However, their predictions of the 90th percentile were far more uncertain. The paper demonstrates that coherent subjective judgments can be elicited from exposure assessment scientists and critically examines the challenges and potential benefits of a subjective judgment approach. The results of the second phase of the project, in which measurements from the NHEXAS field study in Region V are used to calibrate the experts' judgments about the benzene exposures in the study population, will be presented in a second paper.
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Sharma P, Patchell VB, Gao Y, Evans JS, Levine BA. Cytoplasmic interactions between phospholamban residues 1-20 and the calcium-activated ATPase of the sarcoplasmic reticulum. Biochem J 2001; 355:699-706. [PMID: 11311132 PMCID: PMC1221785 DOI: 10.1042/bj3550699] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Phospholamban regulates the activity of the calcium-activated ATPase (CaATPase) of cardiac sarcoplasmic reticulum. Equilibrium fluorescence studies have shown that the N-terminal cytoplasmic region of phospholamban (residues 1-20, domain 1) causes a decrease in the intrinsic tryptophan fluorescence of the CaATPase. The interaction of phospholamban residues 1-20 with the CaATPase also results in spectral changes for the extrinsic chromophore FITC covalently attached to the cytoplasmic region of the calcium pump. The fluorescence changes for both reporter groups correlate with a dissociation constant of approximately 40 microM for the complex between phospholamban residues 1-20 and the CaATPase. Complex formation is notably weaker when phospholamban 1-20 is titrated into the CaATPase in the presence of calcium, with altered conformational effects resulting from binding. The interaction of domain 1 of phospholamban with the CaATPase is also reduced upon phosphorylation of phospholamban 1-20 at Ser-16. This region of phospholamban 1-20 is shown by isotope-edited NMR study to be involved in interaction with the CaATPase. Binding of the phosphorylated peptide is not abolished, however, indicating that phospholamban 1-20 remains associated with the CaATPase even after phosphorylation. The data provide direct evidence for the interaction between the cytoplasmic regions of phospholamban and the pump, and are discussed in the context of the mechanism for inhibition of cardiac CaATPase activity by phospholamban.
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Zhang B, Evans JS. Modeling AFM-induced PEVK extension and the reversible unfolding of Ig/FNIII domains in single and multiple titin molecules. Biophys J 2001; 80:597-605. [PMID: 11159428 PMCID: PMC1301259 DOI: 10.1016/s0006-3495(01)76040-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Molecular elasticity is associated with a select number of polypeptides and proteins, such as titin, Lustrin A, silk fibroin, and spider silk dragline protein. In the case of titin, the globular (Ig) and non-globular (PEVK) regions act as extensible springs under stretch; however, their unfolding behavior and force extension characteristics are different. Using our time-dependent macroscopic method for simulating AFM-induced titin Ig domain unfolding and refolding, we simulate the extension and relaxation of hypothetical titin chains containing Ig domains and a PEVK region. Two different models are explored: 1) a series-linked WLC expression that treats the PEVK region as a distinct entropic spring, and 2) a summation of N single WLC expressions that simulates the extension and release of a discrete number of parallel titin chains containing constant or variable amounts of PEVK. In addition to these simulations, we also modeled the extension of a hypothetical PEVK domain using a linear Hooke's spring model to account for "enthalpic" contributions to PEVK elasticity. We find that the modified WLC simulations feature chain length compensation, Ig domain unfolding/refolding, and force-extension behavior that more closely approximate AFM, laser tweezer, and immunolocalization experimental data. In addition, our simulations reveal the following: 1) PEVK extension overlaps with the onset of Ig domain unfolding, and 2) variations in PEVK content within a titin chain ensemble lead to elastic diversity within that ensemble.
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Strickland DJ, Bishop J, Evans JS, Majeed T, Cox RJ, Morrison D, Romick GJ, Carbary JF, Paxton LJ, Meng CI. Midcourse Space Experiment/Ultraviolet and Visible Imaging and Spectrographic Imaging limb observations of combined proton/hydrogen/electron aurora. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000ja002007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Evans JS, Handley SJ, Perham N, Over DE, Thompson VA. Frequency versus probability formats in statistical word problems. Cognition 2000; 77:197-213. [PMID: 11018509 DOI: 10.1016/s0010-0277(00)00098-6] [Citation(s) in RCA: 154] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Three experiments examined people's ability to incorporate base rate information when judging posterior probabilities. Specifically, we tested the (Cosmides, L., & Tooby, J. (1996). Are humans good intuitive statisticians after all? Rethinking some conclusions from the literature on judgement under uncertainty. Cognition, 58, 1-73) conclusion that people's reasoning appears to follow Bayesian principles when they are presented with information in a frequency format, but not when information is presented as one case probabilities. First, we found that frequency formats were not generally associated with better performance than probability formats unless they were presented in a manner which facilitated construction of a set inclusion mental model. Second, we demonstrated that the use of frequency information may promote biases in the weighting of information. When participants are asked to express their judgements in frequency rather than probability format, they were more likely to produce the base rate as their answer, ignoring diagnostic evidence.
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Zhang B, Xu G, Evans JS. Model peptide studies of sequence repeats derived from the intracrystalline biomineralization protein, SM50. II. Pro,Asn-rich tandem repeats. Biopolymers 2000; 54:464-75. [PMID: 10951331 DOI: 10.1002/1097-0282(200011)54:6<464::aid-bip90>3.0.co;2-n] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the biomineralization process, a number of Pro-rich proteins participate in the formation of three-dimensional supramolecular structures. One such protein superfamily, the Pro,Gly-rich sea urchin intracrystalline spicule matrix proteins, form protein-protein supramolecular assemblies that modify the microstructure of the inorganic mineral phase (calcite) within embryonic sea urchin spicules and adult sea urchin spines. These proteins represent a useful model for understanding Pro sequence usage and the resulting generation of extended or "open" structures for protein-protein and/or protein-crystal recognition. In the sea urchin spicule matrix protein, SM50 (Strongylocentrotus purpuratus), there exists an unusual 20-residue Pro,Asn-containing repeat, &bond;PNNPNNPNPNNPNNPNNPNPbond which links the upstream 15-residue C-terminal domain and the downstream 211-residue beta-spiral repeat domain. To define the structural preferences of this 20-residue repeat, we created a 20-residue N- and C-terminal "capped" peptidomimetic of this sequence. Using far-uv CD dichroism, CH(alpha) and alpha-(15)N conformational shifts, (3)J(NH-CHalpha) coupling constants, sequential d(NN(i, i + 1)) rotating frame nuclear Overhauser effect connectivities, d(alphaN(i, i + 1))/d(NN(i, i + 1)) intensity ratios, amide temperature shift coefficients, amide solvent exchange, and simulated annealing refinement protocols, we have determined that this 20-residue repeat motif adopts an extended "twist" structure consisting of turn- and coil-like regions. These findings are consistent with previous studies, which have shown that Pro-rich tandem repeats adopt extended, flexible structures in solution. We hypothesize that this 20-residue repeat may fulfill the role of a mineral-binding domain, a protein-protein docking domain, or as an internal "molecular spacer" for the SM50 protein during spicule biocomposite formation.
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Evans JS, Thompson KM, Hattis D. Exposure efficiency: concept and application to perchloroethylene exposure from dry cleaners. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION (1995) 2000; 50:1700-1703. [PMID: 11055167 DOI: 10.1080/10473289.2000.10464199] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Standard approaches for computing population exposures due to specific sources of air pollutants are relatively complex. In many cases, more simple and approximate methods would be useful. This paper develops an approach, based on the concept of exposure efficiency, that may be used for estimating the impact of a source (or source class) on the integrated population exposure. The approach is illustrated by an example, which uses the concept of exposure efficiency to examine the impact of perchloroethylene emissions from dry cleaners in the United States. The paper explores the geographic variability of exposure efficiency by evaluating it for each of 100 randomly selected dry cleaners. For perchloroethylene, which has a long atmospheric residence time, the site-to-site variability in exposure efficiency is found to be relatively small. This suggests that simple exposure assessments, based on generic distributional characterizations of exposure efficiency, may be used in risk assessments without introducing appreciable uncertainty. For many compounds, like perchloroethylene, the uncertainty inherent in the estimation of cancer potency or source emissions would dominate these small errors.
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Carrothers TJ, Evans JS. Assessing the impact of differential measurement error on estimates of fine particle mortality. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION (1995) 2000; 50:65-74. [PMID: 10680366 DOI: 10.1080/10473289.2000.10463988] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In air pollution epidemiology, error in measurements of correlated pollutants has been advanced as a reason to distrust regressions that find statistically significant weak associations. Much of the related debate in the literature and elsewhere has been qualitative. To promote quantitative evaluation of such errors, this paper develops an air pollution time-series model based on correlations among unit-normal variables. Assuming there are no other sources of bias present, the model shows the expected amount of relative bias in the regression coefficients of a bivariate regression of coarse and fine particulate matter measurements on daily mortality. The model only requires information on instrumental error and spatial variability, along with the observed regression coefficients and information on the true fine-course correlation. Analytical results show that if one pollutant is truly more harmful than the other, then it must be measured more precisely than the other in order not to bias the ratio of the fine and course regression coefficients. Utilizing published data, a case study of the Harvard Six-Cities study illustrates use of the model and emphasizes the need for data on spatial variability across the study area. Current epidemiology time-series regressions can use this model to address the general concern of correlated pollutants with differing measurement errors.
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Evans JS, Oram MP. Neurological recovery after prolonged verapamil-induced cardiac arrest. Anaesth Intensive Care 1999; 27:653-5. [PMID: 10631424 DOI: 10.1177/0310057x9902700617] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A 15-year-old female survived a total of 65 minutes cardiac arrest following ingestion of verapamil and selective serotonin re-uptake inhibitors. We consider that the lack of neurological damage, despite evidence of significant renal and myocardial injury, may be related to the possible neuroprotective effect of a large dose of verapamil.
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Gonzalez E, Bamshad M, Sato N, Mummidi S, Dhanda R, Catano G, Cabrera S, McBride M, Cao XH, Merrill G, O'Connell P, Bowden DW, Freedman BI, Anderson SA, Walter EA, Evans JS, Stephan KT, Clark RA, Tyagi S, Ahuja SS, Dolan MJ, Ahuja SK. Race-specific HIV-1 disease-modifying effects associated with CCR5 haplotypes. Proc Natl Acad Sci U S A 1999; 96:12004-9. [PMID: 10518566 PMCID: PMC18402 DOI: 10.1073/pnas.96.21.12004] [Citation(s) in RCA: 206] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/1999] [Indexed: 11/18/2022] Open
Abstract
Genetic variation in CC chemokine receptor 5 (CCR5), the major HIV-1 coreceptor, has been shown to influence HIV-1 transmission and disease progression. However, it is generally assumed that the same CCR5 genotype (or haplotype) has similar phenotypic effects in different populations. To test this assumption, we used an evolutionary-based classification of CCR5 haplotypes to determine their associated HIV-1 disease-modifying effects in a large well-characterized racially mixed cohort of HIV-1-seropositive individuals. We demonstrate that the spectrum of CCR5 haplotypes associated with disease acceleration or retardation differs between African Americans and Caucasians. Also, we show that there is a strong interactive effect between CCR5 haplotypes with different evolutionary histories. The striking population-specific phenotypic effects associated with CCR5 haplotypes emphasize the importance of understanding the evolutionary context in which disease susceptibility genes are expressed.
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Abstract
Progress in the pharmacotherapy of pediatric gastrointestinal diseases continued during 1998 despite ongoing obstacles encountered by clinicians and researchers. The major change involved warnings that cisapride, a widely used prokinetic agent, could cause potentially fatal arrythmias in susceptible people. The risk for children is unclear and a consensus of prescribing guidelines is needed. Excellent pediatric-oriented reviews have been published that summarize our knowledge of proton pump inhibitors, probiotics, 5-hydroxtryptamine-3 (5-HT3) antagonists, and the treatment of gastrointestinal infections and chronic abdominal pain. Triple medication therapy for the eradication of Helicobacter pylori is now the standard of care, but the optimal combination and duration of therapy needs to be determined. Also described are interesting developments requiring further confirmation: the treatments of infectious diarrhea with zinc; achalasia and Hirschsprung's disease with botulinum toxin; weight loss with megestrol acetate; and sialorrhea with glycopyrollate.
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Zhang B, Xu G, Evans JS. A kinetic molecular model of the reversible unfolding and refolding of titin under force extension. Biophys J 1999; 77:1306-15. [PMID: 10465743 PMCID: PMC1300420 DOI: 10.1016/s0006-3495(99)76980-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Molecular elasticity is a physicomechanical property that is associated with a select number of polypeptides and proteins, such as the giant muscle protein, titin, and the extracellular matrix protein, tenascin. Both proteins have been the subject of atomic force microscopy (AFM), laser tweezer, and other in vitro methods for examining the effects of force extension on the globular (FNIII/Ig-like) domains that comprise each protein. In this report we present a time-dependent method for simulating AFM force extension and its effect on FNIII/Ig domain unfolding and refolding. This method treats the unfolding and refolding process as a standard three-state protein folding model (U right arrow over left arrow T right arrow over left arrow F, where U is the unfolded state, T is the transition or intermediate state, and F is the fully folded state), and integrates this approach within the wormlike chain (WLC) concept. We simulated the effect of AFM tip extension on a hypothetical titin molecule comprised of 30 globular domains (Ig or FNIII) and 25% Pro-Glu-Val-Lys (PEVK) content, and analyzed the unfolding and refolding processes as a function of AFM tip extension, extension rate, and variation in PEVK content. In general, we find that the use of a three-state protein-folding kinetic-based model and the implicit inclusion of PEVK domains can accurately reproduce the experimental force-extension curves observed for both titin and tenascin proteins. Furthermore, our simulation data indicate that PEVK domains exhibit extensibility behavior, assist in the unfolding and refolding of FNIII/Ig domains in the titin molecule, and act as a force "buffer" for the FNIII/Ig domains, particularly at low and moderate extension forces.
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Xu G, Zhang B, Evans JS. PFG-omega1-filtered TOCSY experiments for the determination of long-range heteronuclear and homonuclear coupling constants and estimation of J-coupling "crosstalk" artifacts in 2-D omega1-filtered "E. COSY-style" spectra. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 1999; 138:127-134. [PMID: 10329235 DOI: 10.1006/jmre.1999.1720] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We present novel one- and two-dimensional versions of the omega1-filtered TOCSY experiment. These experiments utilize pulsed-field gradient techniques and INEPT-reverse INEPT magnetization transfer to generate heteronuclear filtering by means of coherence pathway selection. The major advantages of this approach are twofold: first, each experiment requires a reasonable number of transmitter pulses, gradient pulses, and delays to implement. Second, the use of z-axis gradients at the beginning and termination of the pulse sequences prevents the recovery of dephased magnetization prior to FID detection. This technique was incorporated into 1-D and 2-D omega1-filtered JXH- and JHH-TOCSY-style experiments. As demonstrated on 15N-enriched peptide samples, the use of the pulsed-field-gradient coherence selection scheme effectively filters out unwanted magnetization components, thereby improving the overall sensitivity of the experiments. In addition to this suite of pulse sequences, we also present a method for correcting the reduction in J-coupling that results from crosspeak shifting in 2-D omega1-filtered E. COSY-style spectra. This correction is applicable to both Lorentzian and Gaussian 2-D crosspeak lineshapes.
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Brand KP, Rhomberg L, Evans JS. Estimating noncancer uncertainty factors: are ratios NOAELs informative? RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 1999; 19:295-308. [PMID: 10765406 DOI: 10.1023/a:1006981829124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The prominent role of animal bioassay evidence in environmental regulatory decisions compels a careful characterization of extrapolation uncertainties. In noncancer risk assessment, uncertainty factors are incorporated to account for each of several extrapolations required to convert a bioassay outcome into a putative subthreshold dose for humans. Measures of relative toxicity taken between different dosing regimens, different endpoints, or different species serve as a reference for establishing the uncertainty factors. Ratios of no observed adverse effect levels (NOAELs) have been used for this purpose; statistical summaries of such ratios across sets of chemicals are widely used to guide the setting of uncertainty factors. Given the poor statistical properties of NOAELs, the informativeness of these summary statistics is open to question. To evaluate this, we develop an approach to "calibrate" the ability of NOAEL ratios to reveal true properties of a specified distribution for relative toxicity. A priority of this analysis is to account for dependencies of NOAEL ratios on experimental design and other exogenous factors. Our analysis of NOAEL ratio summary statistics finds (1) that such dependencies are complex and produce pronounced systematic errors and (2) that sampling error associated with typical sample sizes (50 chemicals) is nonnegligible. These uncertainties strongly suggest that NOAEL ratio summary statistics cannot be taken at face value; conclusions based on such ratios reported in well over a dozen published papers should be reconsidered.
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Xu G, Evans JS. Model peptide studies of sequence repeats derived from the intracrystalline biomineralization protein, SM50. I. GVGGR and GMGGQ repeats. Biopolymers 1999; 49:303-12. [PMID: 10079769 DOI: 10.1002/(sici)1097-0282(19990405)49:4<303::aid-bip5>3.0.co;2-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We report solution-state pulsed field gradient nmr studies of a native sequence-derived 23-residue peptidomimetic, N alpha-acetyl-QPGVGGRQPGMGGQPGVGGRQPG-C alpha-amid, that incorporates the prevalent GVGGR and GMGGQ repeats found in the sea urchin embryo intracrystalline spicule matrix protein, SM50 (Strongylocentrotus purpuratus). These repeats are sequence homologues of elastin protein repeats (VPGVG, VGGVG, and APGVGV) and spider dragline silk protein repeats (GPGG, GQGG, and QPGYG). Using rotating frame nuclear Overhauser effect (ROE) connectivities, CH alpha proton conformational shifts, 3JNH-CH alpha coupling constants, amide temperature shift coefficients, and pulsed field gradient ROE spectroscopy solvent exchange measurements, we find that the 23-mer peptidomimetic possesses a multiple beta-turn structure in aqueous solution, in equilibria with an extended or coil structure (60% beta-turn: 40% random coil). The GVGGR sequence adopts a double beta-turn conformation that is stabilized by two hydrogen bonds (R7-->V4, R20-->V17; G6-->G3, G19-->G16). The GMGGQ region adopts a single beta-turn conformation that is stabilized by a hydrogen bond involving residues Q14 and M11. Repeating beta-turn structures, or beta-spirals, may play an important role with regard to matrix assembly, protein stability, molecular elasticity, and/or protein-crystal recognition within the spicule mineralized matrix.
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Evans JS, Lock KP, Levine BA, Champness JN, Sanderson MR, Summers WC, McLeish PJ, Buchan A. Herpesviral thymidine kinases: laxity and resistance by design. J Gen Virol 1998; 79 ( Pt 9):2083-92. [PMID: 9747715 DOI: 10.1099/0022-1317-79-9-2083] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Patel JC, Tepas JJ, Huffman SD, Evans JS. Neonatal necrotizing enterocolitis: the long-term perspective. Am Surg 1998; 64:575-9; discussion 579-80. [PMID: 9619181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ten years' experience with neonatal necrotizing enterocolitis (NNEC) was reviewed retrospectively to determine long-term survival and quality of life and to analyze risk factors associated with in-hospital mortality. Institutional records were queried to identify all neonates who required emergent surgical intervention for NNEC. These records were then reviewed and survivors' families interviewed by phone to determine patient status, persistent gastrointestinal problems, and overall quality of life. Once identified, long-term survivors (LTSs) were compared to in-hospital deaths by the analysis of birth weight, gestational age, time interval from birth to diagnosis, indications for laparotomy, and extent of intestinal involvement. Between 1986 and 1996, 69 patients required surgical intervention for NNEC. Eleven patients were lost to follow-up. Of the remaining 58 patients, 31 were ultimately discharged home, with 28 patients having survived an average of 4.18 years. The acute, or in-hospital, mortality rate was 39.1 per cent. Infants who died did so within an average of 23 days postoperatively, and those who were discharged home required an average of 121 days of inpatient convalescence. Twenty-one of the 28 LTSs achieved a normal quality of life with no persistent health problems. One patient required a hepatic-intestinal transplant, and another six had minor problems with frequent diarrhea. Average birth weight, age at NNEC diagnosis, and gestational age were not significantly different between LTSs and those with acute deaths. Aggressive in-hospital care is warranted for infants with NNEC. The excellent quality of life achieved in 75 per cent of survivors implies that the expense of heroic surgical care for these seriously ill premature infants is a worthwhile investment.
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Ricci RM, Evans JS, Meffert JJ, Kaufman L, Sadkowski LC. Primary cutaneous Aspergillus ustus infection: second reported case. J Am Acad Dermatol 1998; 38:797-8. [PMID: 9591788 DOI: 10.1016/s0190-9622(98)70460-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We describe the second case of primary cutaneous Aspergillus ustus infection in an immunocompromised patient. Cutaneous aspergillosis was confirmed both by culture and positive fluorescent antibody staining. Few species of Aspergillus are pathogenic in human beings, and fewer still cause primary cutaneous disease. The only other reported case of aspergillosis from Aspergillus ustus occurred in an immunosuppressed patient who was temporally and geographically separated from ours.
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Mollitt DL, Dokler ML, Evans JS, Jeiven SD, George DE. Complications of retained internal bolster after pediatric percutaneous endoscopic gastrostomy. J Pediatr Surg 1998; 33:271-3. [PMID: 9498400 DOI: 10.1016/s0022-3468(98)90445-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE Percutaneous endoscopic gastrostomy (PEG) has been widely accepted as an efficacious means of nutritional support in the infant and child. A well-described technique uses the Gauderer-Ponsky tube (CR Bard Incorporated, Tewksbury, MA) drawn antegrade through the gastric wall and secured by an internal and external SILASTIC (Dow Corning; Midland, MI) bolster. The majority of reported complications attendant to its use occur secondary to insertion. This report details a less well-described complication of tube removal. METHODS Since 1992, 234 pediatric PEGs have been performed using a Gauderer-Ponsky tube. Approximately 6 weeks after the procedure, all catheters were removed and replaced with gastric buttons. The internal bolster was left within the stomach to pass spontaneously. RESULTS Five children (2.1%), ages 6 months to 5 years, failed to pass this crossbar. Three subsequently presented with dysphagia and drooling with the internal bolster wedged in the proximal esophagus. All were left with significant residual stricture after endoscopic removal of the crossbar. Two required dilatation and the third underwent operative stricturoplasty. A fourth child returned with intermittent gastric outlet obstruction. The internal bolster was retained in the stomach 4 months after catheter removal. Endoscopic retrieval resulted in resolution of the symptomatology. The final case was found to have an asymptomatic bolster in the stomach approximately 18 months after catheter removal. CONCLUSIONS These cases highlight a potential sequelae of pediatric percutaneous endoscopic gastrostomy not previously acknowledged. The significant complications associated with the retained bolster in four of these five children suggests that follow-up should be altered to monitor prompt passage of the crossbar after tube removal.
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Evans JS, Lock KP, Levine BA, Champness JN, Sanderson MR, Summers WC, Buchan A. Structure-specificity features of HSV-1 thymidine kinases. Biochem Soc Trans 1997; 25:S621. [PMID: 9450049 DOI: 10.1042/bst025s621] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Baird SJ, Catalano PJ, Ryan LM, Evans JS. Evaluation of effect profiles: Functional Observational Battery outcomes. FUNDAMENTAL AND APPLIED TOXICOLOGY : OFFICIAL JOURNAL OF THE SOCIETY OF TOXICOLOGY 1997; 40:37-51. [PMID: 9398486 DOI: 10.1006/faat.1997.2357] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The Functional Observational Battery (FOB) is a neurotoxicity screening assay composed of 25-30 descriptive, scalar, binary, and continuous endpoints. These outcomes have been grouped into six biologically logical domains as a means to interpret the neuroactive properties of tested chemicals (V. C. Moser, 1992, J. Am. Coll. Toxicol. 10(6), 661-669). However, no data-based exploration of these functional domains has been done. We investigated the degree to which experimental data correspond to the domain groupings by examining severity scores from 10 chemicals tested using a standardized protocol for acute exposure (V. C. Moser et al., 1995, J. Toxicol. Environ. Health 45, 173-210) and identifying endpoint groupings (factors) that best describe the interrelationships in the data, allowing a statistical assessment of whether the FOB endpoints break into domains. We also used a standard measure of bivariate association to confirm the results of the factor analysis. Our results show that while there are clear relationships among variables that compose some domains, there is often substantial correlation among endpoints in different domains. In addition, we investigated a related issue concerning the relative power of the chosen endpoint groupings for identifying significant domain effects. Results from a randomization analysis of the 10 chemicals suggest that the neurophysiologic domain structuring may provide some degree of statistical efficiency for identifying effects.
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Evans JS, Nims T, Cooley J, Bradley W, Jagodzinski L, Zhou S, Melcher GP, Burke DS, Vahey M. Serum levels of virus burden in early-stage human immunodeficiency virus type 1 disease in women. J Infect Dis 1997; 175:795-800. [PMID: 9086132 DOI: 10.1086/513973] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The fundamental clinical, viral, and immunologic features of early-stage human immunodeficiency virus type 1 (HIV-1) disease were examined in a seroprevalent cohort of 28 men and 14 women assessed longitudinally at three equally dispersed time points over a mean of 43 months. There were no gender differences in the relative risk of developing AIDS-defining end points or death. The median serum RNA levels assessed at the three study time points were 3.3-, 4.9-, and 1.5-fold lower, respectively, in women than in men. This suggests that while serum virus load may be as powerful a correlate of disease status in women as it is in men, the absolute values of the virus levels may be different in the 2 populations. These observations may have implications for the interpretation of levels of virus burden in women for the assessment of disease progression, transmission, and treatment.
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Xu G, Evans JS. Determination of Long-Range JXH Couplings Using "Excitation-Sculpting" Gradient-Enhanced Heteronuclear Correlation Experiments. JOURNAL OF MAGNETIC RESONANCE. SERIES A 1996; 123:105-10. [PMID: 8980069 DOI: 10.1006/jmra.1996.0219] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Evans JS, Ellis CE, Newstead SE. On the mental representation of conditional sentences. THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY. A, HUMAN EXPERIMENTAL PSYCHOLOGY 1996; 49:1086-114. [PMID: 8962546 DOI: 10.1080/713755667] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Four experiments are reported which attempt to externalize subjects' mental representation of conditional sentences, using novel research methods. In Experiment 1, subjects were shown arrays of coloured shapes and asked to rate the degree to which they appeared to be true of conditional statements such as "If the figure is green then it is a triangle". The arrays contained different distributions of the four logically possible cases in which the antecedent or consequent is true or false: TT, TF, FT, and FF. For example, a blue triangle would be FT for the conditional quoted above. In Experiments 2 to 4, subjects were able to construct their own arrays to make conditional either true or false with any distribution of the four cases they wished to choose. The presence and absence of negative components was varied, as was the form of the conditional, being either "if then" as above or "only if": "The figure is green only if it is a triangle". The first findings was that subjects represent conditional in fuzzy way: conditional that include some counter-example TF cases (Experiment 1) may be rated as true, and such cases are often included when subjects construct an array to make the rule true (Experiments 2 to 4). Other findings included a strong tendency to include psychologically irrelevant FT and FF cases in constructed arrays, presumably to show that conditional statements only apply some of the time. A tendency to construct cases in line with the "matching bias" reported on analogous tasks in the literature was found, but only in Experiment 4, where the number of symbols available to construct each case was controlled. The findings are discussed in relation to the major contemporary theories of conditional reasoning based upon inference rules and mental models, neither of which can account for all the results.
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Milton DK, Walters MD, Hammond K, Evans JS. Worker exposure to endotoxin, phenolic compounds, and formaldehyde in a fiberglass insulation manufacturing plant. AMERICAN INDUSTRIAL HYGIENE ASSOCIATION JOURNAL 1996; 57:889-96. [PMID: 8865598 DOI: 10.1080/15428119691014396] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Worker exposures in a fiberglass wool insulation manufacturing plant were studied. The plant used a continuous process and operated at full production during a six-week study. Area samples were used to characterize spatial variability of contaminant levels. Repeated personal samples were used to characterize the distribution and to explore within- and between-worker variability of exposures. The greatest potential for exposure to each of the contaminants was restricted to specific areas of the plant. Area geometric mean concentrations were 1 to 390 ng/m3 for endotoxin and 22 to 414 micrograms/m3 for formaldehyde. There was considerable within-area variation of endotoxin (geometric standard deviation [GSD] 2.6 to 5.5) and formaldehyde (GSD 2.0 to 4.5). Concentrations of phenolic compounds were correlated with endotoxin and were influenced by a relatively high limit of detection. The ranges of personal GM exposures across homogeneous groupings were smaller than the range for the corresponding areas (endotoxin 5.8 to 36.4 ng/m3; formaldehyde 18.1 to 67.4 micrograms/m3). Variability in personal exposure was high. Individual GSDs ranged up to 10, with the mean individual GSD of 3.4 for endotoxin, and up to 12 with mean 3.7 for formaldehyde. Suggested thresholds for acute respiratory effects of endotoxin exposure were frequently exceeded (46% of 8-hr personal samples > 10 ng/m3, 7% > 100 ng/m3). No personal samples exceeded the Occupational Safety and Health Administration permissible exposure level or the American Conference of Government Industrial Hygienists' threshold limit value for formaldehyde; however, 34% were greater than 60 micrograms/m3 and 11% were greater than 120 micrograms/m3. Thus, exposures fell in a range where important exposure-response relationship could be examined.
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