The dynamic impact of CpG methylation in DNA.

Solid-state deuterium NMR is used to investigate perturbations of the local, internal dynamics in the EcoRI restriction binding site, -GAATTC- induced by cytidine methylation. Methylation of the cytidine base in this sequence is known to suppress hydrolysis by the EcoRI restriction enzyme. Previous solid-state deuterium NMR studies have detected large amplitude motions of the phosphate-sugar backbone at the AT-CG junction of the unmethylated DNA sequence. This study shows that methylation of the cytidine base in a CpG dinucleotide reduces the amplitudes of motions of the phosphate-sugar backbone. These observations suggest a direct link between suppression of the amplitudes of localized, internal motions of the sugar-phosphate backbone of the DNA and inhibition of restriction enzyme cleavage.

Early and late M intermediates in the bacteriorhodopsin photocycle: a solid-state NMR study.

To enforce vectorial proton transport in bacteriorhodopsin (bR), it is necessary that there be a change in molecular structure between deprotonation and reprotonation of the chromophore-i.e., there must be at least two different M intermediates in the functional photocycle. We present here the first detection of multiple M intermediates in native wild-type bacteriorhodopsin by solid-state NMR. Illumination of light-adapted [zeta-15N-Lys]-bR at low temperatures shifts the 15N signal of the retinal Schiff base (SB) downfield by about 150 ppm, indicating a deprotonated chromophore. In 0.3 M Gdn-HCl at pH 10.0, two different M states are obtained, depending on the temperature during illumination. The M state routinely prepared at the lower temperature, Mo, decays to the newly observed M state, Mn, and the N intermediate, as the temperature is increased. Both relax to bR568 at 0 degreesC. A unique reaction sequence is derived: bR568-->Mo-->(Mn+N)-->bR568. Mo and Mn have similar chemical shifts at [12-13C]ret, [14-13C]ret, and [epsilon-13C]Lys216, indicating that Mn, like Mo, has a 13-cis and C=N anti chromophore. However, a small splitting in the [14-13C]ret signal of Mo reveals that it has at least two substates. The 7 ppm greater shielding of the SB nitrogen in Mn compared to Mo suggests an increase in basicity and/or hydrogen bonding. Probing the peptide backbone of the protein, via [1-13C]Val labeling, reveals a substantial structural change between Mo and Mn including the relaxation of perturbations at some sites and the development of new perturbations at other sites. The combination of the change in the protein structure and the increase in the pKa of the SB suggests that the demonstrated Mo-->Mn transition may function as the "reprotonation switch" required for vectorial proton transport.

Uncertainty considerations in group decisions: staffing and ratesetting in a health promotion center.

There are a variety of methods for including risk or uncertainty in Group Decision Support Systems (GDSS). Monte Carlo simulation is one method. An application of Monte Carlo simulation in Group Decisions and GDSS for diversification of services is presented in this paper. Specifically, the uncertainty associated with the finances of a Health Promotion Center are evaluated for staffing and rate setting. The distributions of outcome variables are used in decision rules.

Distance measurements in nucleic acids using windowless dipolar recoupling solid state NMR.

A windowless, homonuclear dipolar recoupling pulse sequence (DRAWS) is described and a theoretical basis for describing its recoupling performance is developed using numerical techniques. It is demonstrated that DRAWS recouples weak dipolar interactions over a broad range of experimental and molecular conditions. We discuss two spectroscopic control experiments, which help to take into account effects due to insufficient proton decoupling, relaxation, and static dipolar couplings to nearby 13C spins at natural abundance. Finally DRAWS is used in combination with selective 13C labeling to measure 13C-13C distances in five doubly labeled DNA dodecamers, [d(CGCGAAT*T*CGCG)]2, which contain the binding site for the restriction enzyme EcoRI. The longest distance reported is 4.8 A. In most cases the distances agree well with those derived from X-ray crystallographic data, although small changes in hydration level can result in relatively large changes in internuclear distances.

Dioxygen diffusion in the stratum corneum: an EPR spin label study.

The stratum corneum, the outer 10 microns of the skin, serves as a permeability barrier regulating the transport of molecules between the body and the environment. The purpose of this study is to understand this permeability barrier function as it pertains to the diffusion of molecular oxygen. The stratum corneum was investigated with EPR spectroscopy following inoculation with a stearic acid spin probe. The presence of paramagnetic molecular oxygen results in the broadening of the EPR spectral lines of the spin probe. The rate of oxygen diffusion across the stratum corneum, and then the oxygen diffusion coefficient, D(O2), was determined by studying this line-broadening as a function of time. D(O2) in human stratum corneum was found to be 3 x 10(-7) cm2/s at 37 degrees C with an activation energy of approx. 44 kJ/mol. The application of the permeation-enhancing chemicals, DeMSO and DMSO, to the stratum corneum increased D(O2) two- to three-fold.

A case mix simulation decision support system model for negotiating hospital rates.

The institution of prospective payment systems by many health care insurers has drawn increased attention to case-based financial planning in hospitals. When hospital revenues are directly linked to patient diagnoses rather than to the types and quantities of services supplied to patients, managers must be aware of the financial implications of different case mixes and must be prepared to influence insurers' price structures. A case-based financial planning model is presented here for the purpose of assisting managerial decision making in the strategic areas of case mix planning and pricing. The computerized model characterizes hospitals as product manufacturers, the product being discharged patients. Diagnosis serves to differentiate the "products"; however, diagnoses are grouped by payor and similar treatment cost experiences to create a limited set of managerially meaningful case types. Diagnostic and treatment costs are also aggregated to facilitate the modeling of the hospital production process. The computerized model projects the number of patients of each case-type and total patient volume, based on estimated patient volume growth rates. The model also projects prices and contribution margins for each case-type, as well as total contribution to hospital overhead. Testing the model with a hypothetical example of a hospital strategic planning problem demonstrates the model's potential as a decision-making aid in case mix planning and case-type pricing. It also reveals several model shortcomings that require further developmental effort.

How to create a marketing strategy based on hospital characteristics that attract physicians.

Through use of multivariate statistical and research techniques, the authors analyzed 30 hospital features that contribute to a physician's image of a hospital as being a good or a poor place for patient admission and in which to practice. Use of the data obtained in this study can enable a hospital administrator to monitor changes in physicians' attitudes, plan strategies to encourage quality physicians to admit their patients, improve aspects perceived to be weak or unresponsive, and capitalize on strengths.

Validation of a decision model for triaging hypertensive patients to alternate health education interventions.

The ability to assign patients to the most appropriate program of intervention would improve patient outcomes and reduce health care costs. This paper evaluates specific potentials of triaging patients into various combinations of health education treatments. Blood pressure improvement among hypertensive patients was measured and the associated treatment cost and savings were compared. Triaging rules were formed empirically from the relationship between patient characteristics selected before the study was conducted and their achieved blood pressure control within each combination of interventions. Patients randomly assigned to seven combinations of three interventions were studied in contrast to patients in a randomized control group. A combination of all three interventions was the most effective program for the undifferentiated (random) patient population, achieving a 49% increase over 18 months in patients with blood pressure under control. By triaging, 51-91% increases in patients with controlled blood pressure were achieved. Educational history of the patients which is a fairly reliable measure was the most efficient triaging variable, showing a 91% increase in patients with blood pressure under control and a relative cost saving of about 400%.

Factors influencing consumer receptivity to the nurse practitioner. A systems analysis.

This paper describes a methodology to delineate factors associated with consumer acceptance of the medical nurse practitioner (MNP). The MNP is a category of new health practitioners with proficiency in medical/health care functions traditionally performed only by physicians. A process model approach was developed to study the significance of selected sociodemographic cognitive, attitudinal, and clinical/medical factors that are expected to predispose consumer acceptance of the MNP. The survey population consists of predominantly elderly and indigent ambulatory patients to an inner-city primary care clinic. The data were collected from 156 primary care patients before and after the introduction of the MNP program. The results clearly demonstrate consumer support for the new health practitioner concept. This finding is further substantiated in the "after" study. From an analysis of symptoms experience, symptom severity, and type of symptoms, symptoms experience emerged as the strongest indicator of consumer receptivity to MNP concept. Additionally, exposure to MNP caused the consumer to become more aware of proper consumption and increased the demand for physician care and specialty care where appropriate.

Improving compliance among hypertensives: a triage criterion with cost-benefit implications.

Triage method based upon individual patient characteristics is developed to determine the most effective health education interventions for hypertensive patients. The sample included 402 patients randomly assigned to experimental and control groups. The efficacy of a triage process, whereby patients are subdivided into groups that are more predisposed to benefit from a given health education approach, is discussed. From a limited cost-benefit evaluation, it appears that the benefits of the triage method for achieving medication compliance clearly outweigh its costs only in the case of the highly depressed patients (24 per cent of the sample). Different levels of depression were found to be differentially responsive to different health education treatments for achieving adherence to medication. The most depressed patients were more responsive to family member reinforcement, a 156 per cent increase in the number of high compliers as compared to no intervention.