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PubMed1995

Prenatal development of the integument in Delphinidae (Cetacea: Odontoceti).

The prenatal development of epidermis, dermis, and hypodermis was studied in embryos of different age of two delphinid species (Stenella attenuata, Delphinus delphis), using light and transmission electron microscopical methods. The delphinid embryo is covered by a multilayered tissue formed by four different epidermal generations (periderm, stratum intermedium-I, str. intermedium-II, str. spinosum) produced by the str. basale. The first layer appears at about 40-50 mm of body length, the second type (s.i.-I) about 60-160 mm, and the third type (s.i.-II) is present at 160-500 mm. The first spinosal cells are produced at 225-260 mm body length; thenceforth, the epidermis increases continuously in thickness. Epidermal ridge formation begins about 400-mm body length. The development of the dermis is characterized by the early production of thin connective tissue fibers (40-70-mm body length) and simultaneously the cutaneous muscle matures in structure. Vascular development intensifies between embryos of 150-225 mm, and collagen production increases markedly in fetuses of 225-260-mm length. These events are paralleled by an increase in dermal thickness. The first elastic fibers can be recognized in the skin from the abdomen at about 600-mm body length. The development of the hypodermis is marked by very rapid and constantly progressing growth, beginning about 60-mm body length. The first typical fat cells appear in animals of 360-400 mm. Regional differences are obvious for all skin layers with regard to the flippers, where structural maturation proceeds more rapidly than in dorsal or abdominal regions.

Animals↗

PubMed2004

Development of quality of care indicators for Parkinson's disease.

Parkinson's disease (PD) is a major cause of disability. To date, there have been no large-scale efforts to measure the quality of PD care because of a lack of quality indicators for conducting an explicit review of PD care processes. We present a set of quality indicators for PD care. Based on a structured review of the medical literature, 79 potential indicators were drafted. Through a two-round modified Delphi process, an expert panel of seven movement disorders specialists rated each indicator on criteria of validity, feasibility, impact on outcomes, room for improvement, and overall utility. Seventy-one quality indicators met validity and feasibility thresholds. Applying thresholds for impact on outcomes, room for improvement, and overall utility, a subset of 29 indicators was identified, spanning dopaminergic therapy, assessment of functional status, assessment and treatment of depression, coordination of care, and medication use. Multivariable analysis showed that overall utility ratings were driven by validity and impact on outcomes (P < 0.01). An expert panel can reach consensus on a set of highly rated quality indicators for PD care, which can be used to assess quality of PD care and guide the design of quality improvement projects.

Activities of Daily Living↗

PubMed1986

Testing a classification instrument for the ambulatory care setting.

The purpose of this study was to evaluate the construct validity, generalizability, and interrater reliability of an instrument designed to measure the complexity of nursing care in the ambulatory care setting. The conceptual framework for the development of the classification instrument was adapted from a theory of organizations and is based upon knowledge technology. Previous research using the Delphi methodology delineated 44 activity categories for the classification instrument. These categories were organized under six literature-based responsibility areas. The instrument was tested in seven areas of one hospital-based ambulatory care setting. A total of 641 valid patient ratings were used for the analysis. Results indicate the instrument has beginning construct validity and high interrater reliability with training. It is not generalizable across services unless the effect of clinic type on nursing care complexity is considered.

Ambulatory Care↗

PubMed2004

Identifying and predicting behaviour outcomes in cancer patients undergoing curative treatment.

A lot of emphasis is now being placed in early identification of 'distress', a state that lies between the feelings of sadness and apprehension, and clinically defined syndromes. It is assumed that an intervention at this stage will check the progression along the continuum in cancer patients. We have been working in global distress in cancer patients undergoing multimodality treatment with curative intent, for over 5 years. It all started with the generation of a hypothesis which led to the development of the 'Distress Inventory for Cancer', its refinement, and finally to modelling distress. This article gives a brief overview of our work on distress as conceptualised by the National Comprehensive Cancer Network in 1998, adopted and modified by us using informal patient interviews, expert Delphi exercise and structured patient interviews.

Humans↗

PubMed1992

Thermodynamics of melittin tetramerization determined by circular dichroism and implications for protein folding.

The tetramerization of melittin, a 26-amino acid peptide from Apis mellifera bee venom, has been studied as a model for protein folding. Melittin converts from a monomeric random coil to an alpha-helical tetramer as the pH is raised from 4.0 to 9.5, as ionic strength is increased, as temperature is raised or lowered from about 37 degrees C, or as phosphate is added. The thermodynamics of this tetramerization (termed "folding") are explored using circular dichroism. The melittin tetramer has two pKa values of 7.5 and 8.5 corresponding to protonation of the N-terminus and Lys 23, respectively. pKa values calculated with the program DelPhi (Gilson, M.K., Sharp, K.A., & Honig, B.H., 1987, J. Comp. Chem. 9, 327-335; Gilson, M.K. & Honig, B.H., 1988a, Proteins 3, 32-52; Gilson, M.K. & Honig, B.H., 1988b, Proteins 4, 7-18) agree with experimental titration data. Greater electrostatic repulsion of these protonated groups destabilizes the tetramer by 3.6 kcal/mol at pH 4.0 compared to pH 9.5. Increasing the concentration of NaCl in the solution from 0 to 0.5 M stabilizes the tetramer by 5-6 kcal/mol at pH 4.0. The effect of NaCl is modeled with a ligand-binding approach. The melittin tetramer is found to have a temperature of maximum stability ranging from 35.5 to 43 degrees C depending on the pH, unfolding above and below that temperature. delta Cp0 for folding ranges from -0.085 to -0.102 cal g-1 K-1, comparable to that of other small globular proteins (Privalov, P.L., 1979, Adv. Protein Chem. 33, 167-241). delta H0 and delta S0 are found to decrease with temperature, presumably due to the hydrophobic effect (Kauzmann, W., 1959, Adv. Protein Chem. 14, 1-63). Phosphate is found to perturb the equilibrium substantially with a maximal effect at 150 mM, stabilizing the tetramer at pH 7.4 and 25 degrees C by 4.6 kcal/mol. The enthalpy change due to addition of phosphate (-7.5 kcal/mol at 25 degrees C) can be accounted for by simple dielectric screening. Both circular dichroism and crystallographic results suggest that phosphate may bind Lys 23 at the ends of the elongated tetramer. These detailed measurements give insight into the relative importance of various forces for the stability of melittin in the folded form and may provide an experimental standard for future tests of computational energetics on this simple protein system.

Amino Acid Sequence↗

PubMed1994

Do salt bridges stabilize proteins? A continuum electrostatic analysis.

The electrostatic contribution to the free energy of folding was calculated for 21 salt bridges in 9 protein X-ray crystal structures using a continuum electrostatic approach with the DELPHI computer-program package. The majority (17) were found to be electrostatically destabilizing; the average free energy change, which is analogous to mutation of salt bridging side chains to hydrophobic isosteres, was calculated to be 3.5 kcal/mol. This is fundamentally different from stability measurements using pKa shifts, which effectively measure the strength of a salt bridge relative to 1 or more charged hydrogen bonds. The calculated effect was due to a large, unfavorable desolvation contribution that was not fully compensated by favorable interactions within the salt bridge and between salt-bridge partners and other polar and charged groups in the folded protein. Some of the salt bridges were studied in further detail to determine the effect of the choice of values for atomic radii, internal protein dielectric constant, and ionic strength used in the calculations. Increased ionic strength resulted in little or no change in calculated stability for 3 of 4 salt bridges over a range of 0.1-0.9 M. The results suggest that mutation of salt bridges, particularly those that are buried, to "hydrophobic bridges" (that pack at least as well as wild type) can result in proteins with increased stability. Due to the large penalty for burying uncompensated ionizable groups, salt bridges could help to limit the number of low free energy conformations of a molecule or complex and thus play a role in determining specificity (i.e., the uniqueness of a protein fold or protein-ligand binding geometry).

Crystallography, X-Ray↗

PubMed2003

The role of electrostatic interaction in the molecular recognition of selective agonists to metabotropic glutamate receptors.

The influence of electrostatic interactions in determining selectivity for individual subtypes of metabotropic glutamate receptors (mGluRs) is evaluated for a small set of agonists by using the program Delphi and the information thus obtained is compared with docking experiments carried out with AutoDock. The evaluation of the electrostatic component of the free energy of binding for L-Glu, L-AP4, or S-PPG to mGluR1, mGluR2, and mGluR4 subtypes allowed for the detection of subtle differences in the electronic properties of the three subtypes, differences that can account for the observed agonist selectivity.

Amino Acid Sequence↗

PubMed2006

Limited validity of group additivity for the folding energetics of the peptide group.

The principle of group additivity is a standard feature of analyses of the energetics of protein folding, but it is known that it may not always be valid for the polar peptide group. The neighboring residue effect shows that group additivity is not strictly valid for a heteropeptide. We show here that group additivity fails seriously for peptide groups close to either peptide end, even for a homopeptide that has blocked end groups with no formal charges involved. The failure of group additivity is caused by the electrostatic character of the solvation of peptide polar groups and is illustrated with values of the electrostatic solvation free energy (ESF) calculated by DelPhi. Solvation free energies and enthalpies are known experimentally for monoamides and are often used to model the solvation of peptide groups, but ESF results show that monoamide values are very different from those of peptide groups. A main cause of the difference is that peptide solvation depends on the dipole-dipole interactions made between adjacent peptide groups, which vary with peptide conformation. Ligands that interact with the peptide backbone by an electrostatic mechanism could show a similar peptide end effect, and hydrogen exchange results from the literature confirm that exchange rates are position-dependent close to peptide ends.

Hydrogen Bonding↗

PubMed1995

A strategy for theoretical binding constant, Ki, calculations for neuraminidase aromatic inhibitors designed on the basis of the active site structure of influenza virus neuraminidase.

Neuraminidase (NA) is one of the two major surface antigens of influenza virus. It plays an indispensable role in the release and spread of progeny virus particles during infection. NA inhibitors reduce virus infection in animals. To improve the clinical efficacy of NA inhibitors, we have begun the design of non-carbohydrate inhibitors based on the active site structure of NA. The approach is an iterative process of ligand modeling and electrostatic calculations followed by chemical synthesis of compounds, biological testing, and NA-inhibitor complex structure determination by X-ray crystallography. A strategy has been developed to calculate Ki for newly designed inhibitors. The calculations using the DelPhi program were performed for carbohydrate inhibitors and three preliminary benzoic acid inhibitors of neuraminidase (BANA) that have been synthesized and shown to bind to the active site of NA in the crystal structure. The calculated Kis of these inhibitors have an enlightening agreement with their in vitro biological activities. This demonstrates that the calculations produce informative results on the affinity of modeled inhibitors. GRID maps were also calculated and several pockets were identified for accepting possible new ligands. The calculated Kis for newly designed ligands suggest that these potential compounds will have high inhibitory activities.

Aminobenzoates↗

PubMed1993

Electrostatic recognition in redox copper proteins: a 1H NMR study of the protonation behavior of His 19 in oxidized and reduced Cu,Zn superoxide dismutase.

The pK shift of the His 19 residue in bovine Cu,Zn superoxide dismutase was carefully measured by nuclear magnetic resonance spectroscopy as a function of the change of the copper oxidation state. The measured pK values were identical within experimental error, at variance with results obtained with other copper proteins under similar conditions. The DelPhi program, based on a macroscopic dielectric model for the electrostatic interactions in proteins, was used to calculate pK shifts, as a function of charge perturbation introduced by metal oxidation, between the oxidized and the reduced enzyme, which are assumed to have the same structure on the basis of previous spectroscopic data. A nice fit with the experimental pK values was obtained protonating the imidazole of the copper-zinc bridging His 61, which is known to release the copper in the reduced enzyme. Protonation of His 61 in the reduced state gives rise to an electrostatic potential distribution around the protein almost identical to that observed in the oxidized one. These results suggest that a major role for the bridging histidine in Cu,Zn superoxide dismutase is to provide identical electrostatic steering of the substrate in the two oxidation states of the enzyme by redox-linked protonation-deprotonation processes. This property is discussed in comparison with the effect of copper reduction on the distribution of the electric field in small blue copper proteins.

Acids↗

PubMed2002

Effect of interactions between the adsorbed species on the properties of single and mixed-surfactant monolayers at the air/water interface.

Experimental data on surface tension available from the literature and generated in the present study are analyzed to estimate the applicability of adsorption models, based on the Frumkin equation, to nonionic and ionic surfactants and their mixtures. Optimization programs based on the least-squares method in media of Delphi V and Pascal VII are used. The effect of interactions between the adsorbed species on surface tension is considered in all cases. The results are compared to those obtained with the simpler Szyszkowski equation, employed in numerous studies of nonionic surfactants, when interactions are neglected. Cases where the Frumkin model can be successfully employed with ionic surfactants and mixtures are presented and the conditions of its applicability are analyzed. Related characteristic quantities (maximum adsorption, standard free energy of surfactant adsorption, energy of interaction between adsorbed species, standard free energy of counterion adsorption, degree of coverage by surfactant/counterion associates) are established as a function of: The properties of an adsorption layer from a mixture of nonionic and ionic surface-active species are compared to those of the single surfactants.

Adsorption↗

PubMed1993

Long-range surface charge-charge interactions in proteins. Comparison of experimental results with calculations from a theoretical method.

Long-range coulombic interaction energies between surface-charges in barnase and subtilisin have been determined to provide data for calibrating theoretical methods. The pKa of His18 in barnase can be measured accurately by titrating the fluorescence of Trp94 that is significantly quenched on protonation of His18. The pKa of His64, the active site base of subtilisin, has previously been shown to be measured accurately from the pH dependence of kcat/Km for the hydrolysis of substrates. The titration curves of both histidine residues fit the theoretical equations for the ionization of single groups with great precision; the Hill constants for wild-type and mutant enzymes are all close to 1.0. The coulombic interaction energies of distant charged side-chains with the protonated form of His18 and His64 have been measured from changes in pKa of these residues on mutation of those charged side-chains. The interaction energies between single charges on the surfaces of the proteins at low ionic strength are small, some 0.3-0.5 kcal mol-1 at a distance of 12 A, and fall gradually with distance to 0.05-0.3 kcal mol-1 at 20 A. Multiple mutations are frequently additive. Effects are larger in subtilisin than in barnase, possibly related to the degree of solvent exposure of the charge. These data have been used to benchmark the finite-difference method of calculating electrostatic interactions as implemented in the program DelPhi. There is reasonable agreement between the calculated and measured results as a function of both position and ionic strength.

Bacterial Proteins↗

PubMed1999

Predicting the rate enhancement of protein complex formation from the electrostatic energy of interaction.

The rate of association of proteins is dictated by diffusion, but can be enhanced by favorable electrostatic forces. Here the relationship between the electrostatic energy of interaction, and the kinetics of protein-complex formation was analyzed for the protein pairs of: hirudin-thrombin, acetylcholinesterase-fasciculin and barnase-barstar, and for a panel of point mutants of these proteins. Electrostatic energies of interaction were calculated as the difference between the electrostatic energy of the complex and the sum of the energies of the two individual proteins, using the computer simulation package DelPhi. Calculated electrostatic energies of interaction were compared to experimentally determined rates of association. One kcal/mol of Coulombic interaction energy increased the rate of association by a factor of 2.8, independent of the protein-complex or mutant analyzed. Electrostatic energies of interaction were also determined from the salt dependence of the association rate constant, using the same basic equation as for the theoretical calculation. A Brönsted analysis of the electrostatic energies of interactions plotted versus experimentally determined ln(rate)s of association shows a linear relation between the two, with a beta value close to 1. This is interpreted as the energy of the transition state varies according to the electrostatic interaction energy, fitting a two state model for the association reaction. Calculating electrostatic rate enhancement from the electrostatic interaction energy can be used as a powerful tool to design protein complexes with altered rates of association and affinities.

Acetylcholinesterase↗

PubMed2002

Costs and cost-effectiveness of a clinical intervention to increase mammography utilization in an inner city public health hospital.

BACKGROUND: Studies have demonstrated the cost-effectiveness of screening women for breast cancer; however, the cost-effectiveness of strategies to motivate women to receive breast cancer screening has been less well studied. METHODS: A total of 196 women, aged 50 to 74, who were enrolled in a public health hospital clinic, were noncompliant with mammography screening, and had at least one routine clinic appointment during the study period (15 months) were entered into a randomized, controlled trial of a motivational intervention to increase mammography rates. Costs were captured via a modified Delphi technique, accounting records, sampling of staff time logs, and an estimation of miscellaneous and overhead costs. Summary costs were calculated using Excel spread sheets. RESULTS: Overall, 49% of women who received the intervention had a mammogram within 8 weeks of an index visit compared with 22% of control women. Calculation of the cost-effectiveness of the project showed an additional cost of $151 (1996 U.S.$) for each woman receiving the intervention and $559 for each additional woman motivated to receive a mammogram. CONCLUSIONS: Cost tracking and cost-effectiveness analysis can be done when intervening in a clinical setting, thereby allowing clinics to make informed decisions about implementing programs to increase motivation of their patients to receive screening.

Aged↗

PubMed1986

A performance-based management system to reduce prematurity and low birth weight.

A performance system is a management tool for ensuring that programs accomplish their objectives. Using Delphi and nominal group process techniques, the authors established objectives for a system to reduce prematurity and low birth weight. A task force consisting of state, regional, and local public health personnel, consultants from the Centers for Disease Control, and faculty from the School of Public Health then developed the activities, standards, and guidelines of the performance system. Finally, an assessment tool for evaluation of the system was designed. The system, which is intended to complement initiatives to improve the medical care of maternity patients, should be useful to maternity clinic managers and supervisors who wish to develop performance standards specifically targeted to the achievement of objectives for reducing prematurity and low birth weight.

Centers for Disease Control and Prevention, U.S.↗

PubMed1976

IMP: a new method for health problem assessment.

This paper presents a new method for health problem assessment, called IMP. It is based upon the premise that the critical step in the development of policy decisions isthe definition of health problems at the community level. The method is an extension of the Delphi technique but has been significantly improved by the determination of the critical variables in the problem set and by the incroporation of a structured logic system and of professional judgment. The study compares the IMP method with data gathered by traditional, epidemiological prevalence surveys and also with data from a computer simulation. The conclusion is unavoidable: the IMP method is an accurate as the other methods, at far less cost. The problem of preventable bureaucratic blindness has been used as an illustration of the application of this technique.

Epidemiologic Methods↗

PubMed2001

Quality of life in children and adolescents: a European public health perspective.

OBJECTIVES: The measurement of health-related quality of life (HRQOL) is increasingly important as a means of monitoring population health status over time, of detecting sub-groups within the general population with poor HRQOL, and of assessing the impact of public health interventions within a given population. At present, no standardised instrument exists which can be applied with equal relevance in pediatric populations in different European populations. The collaborative European KIDSCREEN project aims to develop a standardised screening instrument for children's quality of life which will be used in representative national and European health surveys. Participants of the project are centres from Austria, France, Germany, Netherlands, Spain, Switzerland, and United Kingdom. By including the instrument in health services research and health reporting, it also aims at identifying children at risk in terms of their subjective health, thereby allowing the possibility of early intervention. METHODS: Instrument development will be based on constructing a psychometrically sound HRQOL instrument taking into account the existing state of the art. Development will centre on literature searches, expert consultation (Delphi Methods) and focus groups with children and adolescents (8-17 years). According to international guidelines, items will be translated into the languages of the seven participating countries for a pilot test with 2,100 children and their parents in Europe. The final instrument will be used in representative mail and telephone surveys of HRQOL in 1,800 children and their parents per country (total n = 25,200) and normative data will be produced. The potential for implementing the measurement tool in health services and health reporting will also be evaluated in several different research and public health settings. The final analysis will involve national and cross cultural-analysis of the instrument. RESULTS: The international, collaborative nature of the KIDSCREEN project means it is likely to provide many challenges in terms of producing an instrument which is conceptually and linguistically appropriate for use in many different countries, but it will also provide the opportunity to develop, test and implement the first truly cross-national HRQOL instrument developed for use in children and adolescents. This will help to contribute to a better understanding of perceived health in children and adolescents and to identify populations at risk.

Adolescent↗

PubMed1987

[Need for professional expertise in institutions and public health services in 4 cantons and Tessin. Hypothesis--objectives--implementation].

This survey consists in a process of "collaborative reflection" between consultants from a university department of public health and health authorities in five cantons. The goal of this effort is to identify, within a common framework, known and suspected health problems, risk factors, preventive measures as well as priority research needs in these areas. This information is used to determine the need for an increased access to public health experts at the level of the cantons and gives some indication as to the characteristics required of such experts. Since participants in the survey are also responsible for promotion and implementation of concrete actions for prevention, it is anticipated that this project will result in a number of initiatives focused on the problem which have been identified. The methodology used was inspired by methods previously described for problem identification and program planning, such as the Delphi technique, but was adapted in an original way to the particular needs of this survey. In the first phase, interviews with persons responsible for key health administrations and institutions in each canton are conducted in order to identify the maximum number of salient facts, problems and unresolved questions. In a second phase results and problem statements are consolidated, fed back to all participants and, through repeated contacts, completed, redefined and ranked in order of importance. Although the survey is still ongoing, it has already led to the identification of a number of health problems, possible risk factors and research priorities which had hitherto not been formally identified, and to one concrete program aimed at improving preventive intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Health Planning↗