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PubMed2006

[What is the methodological quality of articles on therapeutic procedures published in Cirugía Española?].

INTRODUCTION: The aim of this study was to determine the methodological quality of articles on therapeutic procedures published in Cirugía Española and to study its association with the publication year, center, and subject-matter. MATERIAL AND METHOD: A bibliometric study that included all articles on therapeutic procedures published in Cirugía Española between 2001 and 2004 was performed. All kinds of clinical designs were considered, excluding editorials, review articles, letters to editor, and experimental studies. The variables analyzed were: year of publication, center, design, and methodological quality. Methodological quality was determined by a valid and reliable scale. Descriptive statistics (calculation of means, standard deviation and medians) and analytical statistics (Pearson's chi2, nonparametric, ANOVA and Bonferroni tests) were used. RESULTS: A total of 244 articles were studied (197 case series [81%], 28 cohort studies [12%], 17 clinical trials [7%], 1 cross sectional study and 1 case-control study [0.8%]). The studies were performed mainly in Catalonia and Murcia (22% and 16%, respectively). The most frequent subject areas were soft tissue and hepatobiliopancreatic surgery (23% and 19%, respectively). The mean and median of the methodological quality score calculated for the entire series was 10.2 +/- 3.9 points and 9.5 points, respectively. Methodological quality significantly increased by publication year (p < 0.001). An association between methodological quality and subject area was observed but no association was detected with the center performing the study. CONCLUSIONS: The methodological quality of articles on therapeutic procedures published in Cirugía Española between 2001 and 2004 is low. However, a statistically significant trend toward improvement was observed.

Bibliometrics↗

PubMed1999

A study of PROforma, a development methodology for clinical procedures.

Knowledge engineering has shown that besides the general methodologies from software engineering it is useful to develop special purpose methodologies for knowledge based systems (KBS). PROforma is a newly developed methodology for a specific type of knowledge based systems. PROforma is intended for decision support systems and in particular for clinical procedures in the medical domain. This paper reports on an evaluation study of PROforma, and on the trade-off that is involved between general purpose and special purpose development methods in Knowledge Engineering and Medical AI. Our method for evaluating PROforma is based on re-engineering a realistic system in two methodologies: the new and special purpose KBS methodology PROforma and the widely accepted, and more general KBS methodology CommonKADS. The four most important results from our study are as follows. Firstly, PROforma has some strong points which are also strong related to requirements of medical reasoning. Secondly, PROforma has some weak points, but none of them are in any way related to the special purpose nature of PROforma. Thirdly, a more general method like CommonKADS works better in the analysis phase than the more special purpose method PROforma. Finally, to support a complementary use of the methodologies, we propose a mapping between their respective languages.

Artificial Intelligence↗

PubMed2003

[The German guideline clearing-project on bronchial asthma-part 1: Methodology and results of formal appraisal].

BACKGROUND: In order to promote quality of asthma management in Germany, a national asthma guidelines clearing project was initiated in 2000 by the German Guidelines Clearinghouse (Sponsors: German Medical Association (GMA), National Association of the Statutory Health Insurance Physicians (NASHIP), German Hospital Federation, Federal Association of the Statutory Sickness Funds. Part 1 of this article shows the methodology and the results of the appraisal, part 2 (to be published) shows the key topics which should be dealt with in a german guideline on bronchial asthma. OBJECTIVES: To identify and compare evidence-based, high-quality German- and English language asthma guidelines as benchmarks for ongoing guideline development and implementation programmes. To disseminate information about asthma guidelines developed in accordance with current methodological know-how. To identify and consent key topics for a national evidence-based guideline for Germany. METHODS: Search procedure, formal appraisal: Systematic search using literature databases (XMED, incl. Medline and Embase) and English-/German-language guideline databases (via www. leitlinien.de), published between January 1990 and March 2000. Abstract screening of the search results according to the inclusion criteria (n = 54 of a total of 502 hits). Methodological guideline evaluation of 16 guidelines using the German checklist for methodological guideline appraisal. Appraisal of guidelines' contents: Peer review of guidelines with the following inclusion criteria: Bronchial Asthma-general, German and English language, based in references published later than 1994, new guideline or actual update. Peer review was performed by a multidisciplinary focus group of EBM experts (clinical and ambulatory settings). No expert was involved in guideline production during the review period. RESULTS: Methodological appraisal: 16 out of guidelines were in accordance with the formal minimal standard with a wide range within the following domains: "description of the development process", "declaration of authors' independence", "explicit link between recommendations and the supporting evidence", "management options", "tools for implementation". The focus group recommended for future national asthma guidelines to rely on the following procedures: (1) to formulate the recommendations using standardized, clearly described consensus methods basing on evidence retrieved and selected in a systematic way (2) to prove links between recommendations and supporting evidence (3) to develop guideline versions for health care professionals as well as for consumer/patients (4) to develop guideline-based education tools (5) to ensure periodical updates of the asthma guideline (6) to consider the methodological recommendations and to give reasons for deviations from the methodological recommendations. APPRAISAL OF GUIDELINES CONTENT: None of the guidelines identified comprised information about all of the following key topics considered to be relevant for a German national guideline by the focus group: (1) intended guideline users/goals, (2) definition (3) cause of disease, (4) form of disease, (5) severity, (6) diagnosis, (7) therapeutic goals, (8) prevention, (9) pharmacotherapy, (10) non-pharmacotherapy, (11) therapy control and compliance, (12) emergency treatment, (13) rehabilitation, (14) comorbidity, (15) special aspects, (16) coordination of care, (17) quality assurance/quality management, (18) implementation. SUMMARY POINTS: For quality promotion of bronchial asthma management in Germany, the development of a national evidence-based guideline, using the internationally accepted quality criteria for clinical practice guidelines, was recommended by an expert group of the German Guideline Clearinghouse. The experts identified and peer-reviewed 16 out of 54 guidelines, which might be useful as benchmarks and examples for a German asthma guideline. From the peer review results, the expert group identified 18 key topics for a national asthma guideline.

Asthma↗

PubMed2004

Exploring attitudes: the case for Q methodology.

Attitudes are often referred to, researched and considered in the discipline of health education and health promotion. This paper highlights Q methodology as an appropriate and relevant means of exploring and studying attitudes within this field. It begins by discussing the difficulties in defining attitude and the problems inherent in attitude measurement. A brief history of Q methodology is given, followed by an explanation of what Q methodology is and the processes involved. This paper argues the case for the use of Q methodology when studying attitudes and justifies why Q methodology should particularly be selected in the study of attitudes within the health field. There are many reasons for this assertion which are explored throughout the paper. The principle one is that Q methodology is a more robust technique, than alternative methods, for the measurement of attitudes and subjective opinion. This paper concludes by proposing that Q methodology is taken up by researchers within health education and health promotion who are concerned with exploring attitudes and subjective opinion.

Attitude to Health↗

PubMed1990

Methodological guidelines for impedance cardiography.

Impedance cardiography was introduced over 20 years ago as a noninvasive and unobtrusive technique for measuring systolic time intervals and cardiac output. Although our understanding of the physiological events reflected in the impedance cardiogram has become more refined, the technique's theoretical basis remains somewhat controversial and acceptance of its validity has relied heavily upon empirical validation. Largely as a consequence of this status, there have been inadequate grounds on which to develop sound methodological standardization. Currently, the methodological approaches that have been most frequently adopted may be viewed as representing the standard. The various aspects of impedance methodology are discussed, and alternative approaches described, with the objective of providing an informed basis for choosing among these methodological alternatives. It is recommended that studies utilizing impedance cardiography should be reported with clear and detailed methodological description. This should help clarify the extent to which methodological differences may underlie any discrepant research observations, as well as facilitate the emergence of improved methodological standards.

Cardiac Output↗

PubMed2005

Association between compliance with methodological standards of diagnostic research and reported test accuracy: meta-analysis of focused assessment of US for trauma.

PURPOSE: To study whether compliance with methodological standards affected the reported accuracy of screening ultrasonography (US) for trauma. MATERIALS AND METHODS: Meta-analysis was conducted of prospective investigations in which US was compared with any diagnostic reference test in patients with suspected abdominal injury. Reports were retrieved from electronic databases without language restrictions; added information was gained with manual search. Two reviewers independently assessed methodological rigor by using 27 items contained in the Standards for Reporting of Diagnostic Accuracy (STARD) checklist and the Quality Assessment of Studies of Diagnostic Accuracy included in Systematic Reviews (QUADAS) instrument. Inconsistencies were resolved by means of consensus. Summary receiver operating characteristics and random-effects meta-regression were used to model the effect of methodological standards and other study features on US accuracy. RESULTS: A total of 62 trials, which included a total of 18,167 participants, were eligible for meta-analysis. The average proportion of men or boys was 71.7%, the mean age was 30.6 years +/- 10.8 (standard deviation), and the mean injury severity score was 16.7 +/- 8.3. The prevalence of abdominal trauma was 25.1% (95% confidence interval [CI]: 21.1%, 29.1%). Pooled overall sensitivity and specificity of US were 78.9% (95% CI: 74.9%, 82.9%) and 99.2% (95% CI: 99.0%, 99.4%), respectively. Varying end points (hemoperitoneum or organ damage) did not change these results. US accuracy was much lower in children (sensitivity, 57.9%; specificity, 94.3%). Strong heterogeneity was observed in sensitivity, whereas specificity remained constant across trials. There was evidence of publication bias. Initial interobserver agreement with methodological standards ranged from poor (kappa = 0.03, independent verification of US findings) to perfect (kappa = 1.00, sufficiently short interval between US and reference test). By consensus, studies fulfilled a median of 13 methodological criteria (range, five to 20 criteria). In investigations that lacked individual methodological standards, researchers overestimated pooled sensitivity, with predicted differences of 9%-18%. The use of a single reference test, specification of the number of excluded patients, and calculation of CIs independently contributed to predicted sensitivity in a multivariate model. In 16 investigations (1309 subjects), a single reference test was used, which provided a combined sensitivity of 66.0% (95% CI: 56.2%, 75.8%). CONCLUSION: Bias-adjusted sensitivity of screening US for trauma is low. Adherence to methodological standards included in appraisal instruments like STARD and QUADAS is crucial to obtain valid estimates of test accuracy.

Abdominal Injuries↗

PubMed2006

Conflict between guideline methodologic quality and recommendation validity: a potential problem for practitioners.

BACKGROUND: It is not clear if good methodologic quality in current practice guidelines necessarily leads to more valid recommendations, i.e., those that are supported with consistent research evidence or, when evidence is conflicting or lacking, with sufficient consensus among the guideline development team. To help clarify this issue, we assessed whether there is a link between methodologic quality and recommendation validity in practice guidelines for the use of laboratory tests in the management of patients with non-small cell lung cancer (NSCLC). METHODS: We conducted a systematic review of data on laboratory tests in NSCLC published in English or in French within the last 10 years and retrieved 11 practice guidelines for the use of these tests. The guidelines were critically appraised and scored for methodologic quality and recommendation validity based on the Appraisal of Guidelines Research and Evaluation (AGREE) criteria and on the systematic review. RESULTS: Overall, these 11 guidelines had considerable shortcomings in methodologic quality and, to a lesser extent, in recommendation validity. Practice guidelines with the best methodologic quality were not necessarily the most valid in their recommendations, and conversely. CONCLUSIONS: Poor methodologic quality and lack of recommendation validity in laboratory medicine call for methodologic standards of guideline development and for international collaboration of guideline development agencies. We advise readers of guidelines to critically evaluate the methods used as well as the content of the recommendations before adopting them for use in practice.

Carcinoma, Non-Small-Cell Lung↗

PubMed1993

Methodological aspects of international drug price comparisons.

Drug prices have become an important issue in the last few years as concerns about constrained healthcare resources have increased. Healthcare authorities in all industrialised countries are questioning whether their country is carrying a heavier burden than others in paying for drugs. In view of this discussion, several price comparison studies have been conducted. However, there is no generally accepted methodology on how to conduct price comparisons, and many methodological issues remain unresolved. The results of most published studies are affected by moderately serious methodological flaws, which are never properly addressed. The purpose of this study is to discuss the methodological issue of international drug price comparison, in terms of 6 points that appear to this author to be necessary to conduct a methodologically sound study. A previous review of a large number of drug price comparisons revealed that they all fail to take into account some or all of these 6 basic methodological points. Studies that fulfil the methodological criteria outlined in this paper are therefore urgently needed before drug pricing studies can be fully utilised as a basis for important policy decisions in the healthcare arena.

Drug Costs↗

PubMed2003

Validation methodology in publications describing epidemiological registration methods of dental caries: a systematic review.

OBJECTIVE: The aim was to describe and systematically review the methodology and reporting of validation in publications describing epidemiological registration methods for dental caries. BASIC RESEARCH METHODOLOGY: Literature searches were conducted in six scientific databases. All publications fulfilling the predetermined inclusion criteria were assessed for methodology and reporting of validation using a checklist including items described previously as well as new items. The frequency of endorsement of the assessed items was analysed. Moreover, the type and strength of evidence, was evaluated. MAIN OUTCOME MEASURES: Reporting of predetermined items relating to methodology of validation and the frequency of endorsement of the assessed items were of primary interest. RESULTS: Initially 588 publications were located. 74 eligible publications were obtained, 23 of which fulfilled the inclusion criteria and remained throughout the analyses. A majority of the studies reported the methodology of validation. The reported methodology of validation was generally inadequate, according to the recommendations of evidence-based medicine. The frequencies of reporting the assessed items (frequencies of endorsement) ranged from four to 84 per cent. A majority of the publications contributed to a low strength of evidence. CONCLUSION: There seems to be a need to improve the methodology and the reporting of validation in publications describing professionally registered caries epidemiology. Four of the items assessed in this study are potentially discriminative for quality assessments of reported validation.

Dental Caries↗

PubMed1994

Methodologic quality and relevance of references in pharmaceutical advertisements in a Canadian medical journal.

OBJECTIVE: To evaluate the methodologic quality and relevance of references in pharmaceutical advertisements in the Canadian Medical Association Journal (CMAJ). DESIGN: Analytic study. DATA SOURCE: All 114 references cited in the first 22 distinct pharmaceutical advertisements in volume 146 of CMAJ. MAIN OUTCOME MEASURES: Mean methodologic quality score (modified from the 6-point scale used to assess articles in the American College of Physicians' Journal Club) and mean relevance score (based on a new 5-point scale) for all references in each advertisement. MAIN RESULTS: Twenty of the 22 companies responded, sending 78 (90%) of the 87 references requested. The mean methodologic quality score was 58% (95% confidence limits [CL] 51% and 65%) and the mean relevance score 76% (95% CL 72% and 80%). The two mean scores were statistically lower than the acceptable score of 80% (p < 0.05), and the methodologic quality score was outside the preset clinically significant difference of 15%. The poor rating for methodologic quality was primarily because of the citation of references to low-quality review articles and "other" sources (i.e., other than reports of clinical trials). Half of the advertisements had a methodologic quality score of less than 65%, but only five had a relevance score of less than 65%. CONCLUSIONS: Although the relevance of most of the references was within minimal acceptable limits, the methodologic quality was often unacceptable. Because advertisements are an important part of pharmaceutical marketing and education, we suggest that companies develop written standards for their advertisements and monitor their advertisements for adherence to these standards. We also suggest that the Pharmaceutical Advertising Advisory Board develop more stringent guidelines for advertising and that it enforce these guidelines in a consistent, rigorous fashion.

Advertising↗

PubMed1998

HIV seroprevalence, risk behaviors, and cognitive factors among Asian and Pacific Islander American men who have sex with men: a summary and critique of empirical studies and methodological issues.

The goals of this article are to (a) summarize and discuss published empirical studies addressing HIV seroprevalence rates and HIV-related behaviors and cognitive factors among Asian and Pacific Islander American (API) men who have sex with men (MSM) in the United States, (b) examine existing population-based research methodologies for studying HIV and AIDS prevention, (c) describe a conceptual framework to facilitate the identification of ecologically sound or culturally appropriate and competent methodologies for studying HIV prevention among API MSM, and (d) discuss methodological issues and recommend alternative methodologies to better understand this population in HIV prevention. A total of eight published empirical studies reported the HIV seroprevalence rates, HIV-risk behaviors, and attitudes toward HIV and AIDS among API MSM. Specifically, seven studies reported HIV seroprevalence rates that were based on either self-disclosure of HIV status or HIV test results among the study participants. Four studies also reported findings about the relationships between HIV-related behaviors and cognitive factors. There are five population-based databases on HIV and AIDS epidemiology and surveillance which have been managed by the Centers for Disease Control and Prevention. Findings from the seven studies indicate that API MSM are as likely to engage in HIV-risk behaviors as other groups. The present analysis reveals that conventional surveillance or epidemiological techniques (e.g., random digit telephone dialing), based on a singular model of populations, are not appropriate to address culturally, linguistically and racially/ethnically diverse groups of API MSM. To address the diversity of this group, ecologically sound or culturally appropriate and competent research methodologies are needed. Thus, a conceptual framework for such methodologies with examples was reviewed. Two alternative methodologies, network analysis and venue-based sampling, were briefly discussed.

Asian↗

PubMed1982

Methodologic issues in the evaluation of vaccine effectiveness: measles vaccine at 12 vs. 15 months.

Initial studies of vaccine effectiveness are usually controlled clinical trials. Subsequent serologic and epidemiologic investigations cannot be as carefully controlled, and methodologic rigor must be considered when evaluating their results. The authors reviewed the methodologic features of greatest importance in the design of field investigations of vaccine efficacy and examined how different methodologic approaches may have influenced the results of studies of measles vaccine efficacy at 12 vs. 15 months of age. Among the serologic studies, time since vaccination was not controlled, so that children vaccinated several years ago at 12 months of age may have been compared with children vaccinated much more recently at later ages. Most studies included children vaccinated at several years of age as controls rather than children vaccinated only at the pivotal ages of 13-15 months. Finally, studies using a single clinic as their vaccine source found smaller differences in efficacy than studies using multiple vaccine sources, suggesting that variation in handling and storage may affect the results. Among the epidemiologic studies, no single methodologic feature clearly influenced whether there was significantly improved vaccine efficacy with increasing age at vaccination. However, studies differed with respect to intensity of effort to detect cases unreported through the usual channels; definition of what constituted a case of measles; whether the effect of midoutbreak clinics on overall estimates of vaccine efficacy was considered; and inclusion of revaccinated children in the analysis. These methodologic variations can make it extremely difficult to evaluate the size and clinical importance of relatively small differences in vaccine efficacy. Greater attention to the methodologic features discussed here will be needed in future studies of vaccine efficacy.

Epidemiologic Methods↗

PubMed2003

Methodologic assessment of studies on endoscopic sinus surgery.

BACKGROUND: Functional endoscopic sinus surgery (ESS) has become the procedure of choice for surgical treatment of chronic rhinosinusitis. Does the published literature support the claims of greater efficacy than medical treatment alone or older sinus procedures? OBJECTIVE: To analyze the methodology of the published literature regarding the efficacy of ESS. DATA SOURCES: MEDLINE search for primary studies published in 1987 through 2001, written in the English language, reporting results on more than 100 patients, using the MeSH (medical subject headings) terms sinusitis [subheadings surgery or therapy] and endoscopy. STUDY SELECTION: Of 512 studies initially identified, 29 studies met the inclusion and exclusion criteria for further assessment of methodologic criteria. An additional 6 studies were found when the reference lists of reviews or included studies were searched. DATA EXTRACTION: Articles were evaluated for 4 core (inclusion/exclusion criteria, control group, intervention, and clear outcome measure) methodologic criteria essential to the determination of efficacy of ESS. Eight additional methodologic criteria were also used to rate the articles. DATA SYNTHESIS: Three studies met all 4 core methodologic criteria. Only 4 of 35 studies used a control group to evaluate efficacy of ESS to treat chronic sinusitis. Mean number of criteria met was 7.2, with a range of 2 to 11. CONCLUSIONS: Absence of a control group is the most important reason that studies are unable to scientifically assess the comparative efficacy of ESS to medical therapy or other sinus procedures. The methodologic criteria described here can be used to evaluate studies of interventions for other disorders.

Comorbidity↗

PubMed2001

Relationship between methodological trial quality and the effects of selective digestive decontamination on pneumonia and mortality in critically ill patients.

CONTEXT: Although meta-analyses of randomized trials have shown that selective digestive decontamination (SDD) prevents nosocomial pneumonia in critically ill patients, the influence of trial quality on the effectiveness of SDD has not been rigorously evaluated. OBJECTIVE: To assess the methodological quality of individual studies of SDD and its relation to the reported effects on pneumonia and mortality. DESIGN: Thirty-two studies were identified in a MEDLINE and reference list search and their methodological quality was assessed using a scoring system (range, 0-13 points) based on allocation and concealment, patient selection, patient characteristics, blinding of the intervention, and the definition of pneumonia. MAIN OUTCOME MEASURE: Methodological quality of the primary trials and its effect on the relative risk reductions (RRRs) of SDD on pneumonia and mortality. RESULTS: The mean (SD) methodological quality score was 7.8 (2.9) (range, 1-11). The RRRs ranged from -0.1 to 1.0 for pneumonia and from -0.1 to 0.6 for mortality. The methodological quality score was associated with the RRR for pneumonia so that for each quality-point added, the RRR decreased by 5.8% (95% confidence interval, 2.4%-9.3%). No association between trial quality and the impact of SDD was found on mortality. Of the individual trial quality characteristics, patient selection, allocation of intervention, and blinding most strongly influenced the treatment effect. CONCLUSIONS: The inverse relationship between methodological quality score and the benefit of SDD on the incidence of pneumonia may have resulted in overly optimistic estimates of SDD in prior meta-analyses. This emphasizes the importance of rigorous trial design in evaluating preventive interventions in the intensive care unit.

Antibiotic Prophylaxis↗

PubMed1998

Prevalence of Parkinson's disease in Northwestern Italy: comparison of tracer methodology and clinical ascertainment of cases.

The prevalence of idiopathic Parkinson's disease (PD) in an area of Northwestern Italy (Socio-Sanitary District of Cossato, 61,830 inhabitants) was analyzed and the reliability of "drug tracer methodology" evaluated. The patients were identified by both conventional epidemiological methodology (general practitioners, consultant neurologist, computerized archives) and drug tracer methodology (registered levodopa prescriptions). The diagnosis of PD was clinically verified by examining all patients. Of 146 patients examined, 104 were affected by PD; the remaining by other types of parkinsonism. The crude point prevalence rate (October 20, 1991) was 168 per 100,000 population (95% confidence interval [95% CI] 138-204), with a progressive increase up to the 80-89 age group. Using "tracer" methodology, the estimated crude point prevalence rate was 196 (95% CI 163-235), with an overestimation of the prevalence in older patients and women and an underestimation in younger and less seriously affected cases. The uneven distribution of PD in Italy appears to be the result of, at least in part, methodological factors. "Tracer" methodology may cause biases in the evaluation of the epidemiological characteristics of PD, especially if the clinical diagnosis of cases identified by this method is not carefully verified. Nevertheless, it appears useful as an additional source of cases for descriptive surveys.

Aged↗

PubMed2005

Methodological quality of animal studies on neuroprotection in focal cerebral ischaemia.

BACKGROUND: The recurrent failure of apparently promising neuroprotective drugs to improve outcome in trials of patients with acute ischaemic stroke may partially be explained by over-optimistic conclusions about efficacy as a result of methodological shortcomings in preclinical studies. We assessed the methodological quality of animal studies of five different neuroprotective agents that have been tested in 21 clinical trials including a total of more than 12,000 patients with acute ischaemic stroke. METHODS: We performed a literature search restricted to full publications on the effects of clomethiazole, gavestinel, lubeluzole, selfotel, or tirilazad mesylate on infarct volume or functional outcome in animal models of acute focal cerebral ischaemia. We used a rating scale to assess the methodological quality of the included studies. One point was attributed to each of 10 items. A score of 4 to 6 points was considered "medium" and a score above 7 "high." RESULTS: A total of 45 articles were included. The median score on the methodological quality index was 3; 18 studies had a medium score and one a high score. Randomised treatment allocation was mentioned in 19 studies (42 %), blinded administration of study medication in 10 (22 %), and blinded outcome assessment in 18 (40 %). The study drug was administered at a median of 10 min (range, -60 to 360 min) after the onset of ischaemia. CONCLUSION: The evidence for neuroprotective efficacy that formed the basis for initiating the 21 trials was obtained in animal studies with a methodological quality that would, in retrospect, not justify such a decision. More rigorous preclinical study methodology may lead to more reliable and reproducible results.

Animals↗

PubMed2006

Critical sampling points methodology: case studies of geographically diverse watersheds.

Only with a properly designed water quality monitoring network can data be collected that can lead to accurate information extraction. One of the main components of water quality monitoring network design is the allocation of sampling locations. For this purpose, a design methodology, called critical sampling points (CSP), has been developed for the determination of the critical sampling locations in small, rural watersheds with regard to total phosphorus (TP) load pollution. It considers hydrologic, topographic, soil, vegetative, and land use factors. The objective of the monitoring network design in this methodology is to identify the stream locations which receive the greatest TP loads from the upstream portions of a watershed. The CSP methodology has been translated into a model, called water quality monitoring station analysis (WQMSA), which integrates a geographic information system (GIS) for the handling of the spatial aspect of the data, a hydrologic/water quality simulation model for TP load estimation, and fuzzy logic for improved input data representation. In addition, the methodology was purposely designed to be useful in diverse rural watersheds, independent of geographic location. Three watershed case studies in Pennsylvania, Amazonian Ecuador, and central Chile were examined. Each case study offered a different degree of data availability. It was demonstrated that the developed methodology could be successfully used in all three case studies. The case studies suggest that the CSP methodology, in form of the WQMSA model, has potential in applications world-wide.

Ecosystem↗

PubMed2004

Integration of hydrogen/deuterium exchange and cyanylation-based methodology for conformational studies of cystinyl proteins.

This report documents the feasibility and advantages of integrating hydrogen/deuterium exchange (HDX) methodology with cyanylation (CN)-based methodology to determine the conformation of cystinyl proteins and intermediates during refolding. The CN-based methodology can be used to trap, identify, and preserve the disulfide structure of a given cystinyl protein folding intermediate, while the HDX methodology can be used to assess other conformational features of the intermediate. Specifically, in this study, CN-based methodology was used to trap a 1-disulfide bond and a 2-disulfide intermediate of long Arg(3) insulin-like growth factor-I (LR(3)IGF-I), which was then exposed to HDX using D(2)O at pD 6.8 and subsequently digested with pepsin before analysis by matrix-assisted laser desorption/ionization mass spectrometry. The HDX results show an increasing degree of secondary and tertiary structure as a function of disulfide bond formation. In addition, the HDX results for two overlapping peptic fragments suggest that a segment of the polypeptide exists in two conformations, which can be distinguished by HDX and pepsin. These results from HDX mass spectrometry are in reasonably good agreement with those from nuclear magnetic resonance studies of native LR(3)IGF-I and IGF-I, in which approximately 5000 times more material was used than in our study. Indications are that the integrated use of HDX and CN-based methodologies will be effective in studying the refolding of cystinyl proteins at the subnanomole level.

Cyanides↗