A review of cost-effectiveness, cost-containment and economics curricula in graduate medical education.

OBJECTIVE: Numerous studies performed over the last 30 years suggest that doctors have poor knowledge of the costs of medical care. In most graduate medical education programmes, trainees do not receive formal training in cost-effective medical practice. METHODS: Comprehensive literature search of electronic bibliographic databases for articles that describe health economics, cost-containment and cost-effectiveness curricula in graduate medical education. Critical appraisal of the literature and qualitative description is presented. Heterogeneity of curricula precluded quantitative summary of data. RESULTS: We identified 40 articles that met the inclusion criteria for this review. Internal medicine residents were the targeted learners in 27 studies (68%); Family Medicine and Surgery residents were each targeted in five studies (13%); Rehabilitation, Paediatrics and Emergency Medicine residents were each targeted in one study. In general, the methodological quality of the included studies was poor to moderate and mostly targeted knowledge of health economics or cost-containment as opposed to targeting cost-effectiveness. In terms of describing the standard curricular components, studies sufficiently described the different educational strategies (e.g. didactics, interactive, experiential, self-directed) and the component of learner assessment, but lacked the description of other elements such as needs assessment and curriculum evaluation. CONCLUSION: Cost-effectiveness curricula in graduate medical education are lacking and clearly needed.

Stabilizing formulations for inhalable powders of live-attenuated measles virus vaccine.

Carbon dioxide Assisted Nebulization with a Bubble Dryer((R)) (CAN-BD) processing allows particles to be made in the 3-5 mum size range, which is desirable for lung delivery, without destroying biological activity. In response to the Grand Challenge in Global Health Initiative #3, we have been developing an inhalable needle-free live-attenuated measles virus vaccine for use in developing countries. Measles was chosen because it is the number one vaccine preventable killer of children worldwide. Powders were processed by CAN-BD, where a solution containing excipients and live-attenuated measles virus in water was mixed intimately with supercritical or near superctitical carbon dioxide to form an emulsion. The emulsion was expanded to atmospheric pressure through a flow restrictor. The resulting plume was dried by heated nitrogen and the powders collected on a filter at the bottom of the drying chamber. Powders were analyzed using varying techniques including X-ray diffraction, scanning electron microscopy, Andersen cascade impaction, differential scanning calorimetery, Karl Fischer titration, and viral plaque assay. CAN-BD has been used to produce powders of live-attenuated measles virus vaccine with characteristics desirable for lung delivery. The powders retain viral activity through forming and drying the microparticles by CAN-BD, and have passed the WHO stability test for 1 week at 37 degrees C. The powders have an amorphous character and a glass transition temperature of around 60 degrees C. Lyophilization, the present standard commercial method of processing measles vaccine makes solids with a water content of less than 1%. By substituting myo-inositol for sorbitol and using the CAN-BD drying technique the water content can be lowered to 0.5%. The most successful formulations to date have been based conceptually on the current lyophilized formulation, but with modifications to the type and amounts of sugar. Of current interest are formulations containing myo-inositol, as they retain high viral activity and have low initial water content.

Stabilization of measles virus for vaccine formulation.

An attenuated live measles virus (MV) was characterized by several biophysical methods as a function of temperature and pH. Following a method developed previously, the resultant light scattering and spectroscopic data were synthesized into an empirical phase diagram that visually and simultaneously represents the entire data set. Using this empirically-based phase diagram, screening assays were developed to identify potential vaccine stabilizers. Various compounds are shown by these assays to inhibit the temperature-induced aggregation of viral particles, and also to protect the integrity of the viral envelope. Accelerated stability assays show that, upon thermal challenge, MV formulated with these excipients retains its infectivity to a significant extent. Thus, the enhanced physical stability produced by this method is shown to protect the biological activity of this important but labile vaccine.

Biophysical characterization of polymeric and liposomal gene delivery systems using empirical phase diagrams.

A major problem with the pharmaceutical use of nonviral gene delivery systems arises from their limited characterization due to their size and heterogeneity. In this study, we provide a more intuitive view of their structure and behavior employing an empirically based phase diagram approach. Complexes formed between plasmid DNA and four cationic carriers (a monovalent lipid, the same monovalent lipid combined with a helper lipid, polylysine, and a branched form of polyethyleneimine), at both positive and negative nitrogen/phosphorous ratios, are characterized employing dynamic light scattering, circular dichroism, and extrinsic dye fluorescence as methods sensitive to various aspects of the structure of the complexes. These measurements were performed as a function of pH and ionic strength to perturb the electrostatic contacts that are key to complex formation. Using a multidimensional eigenvalue approach, the data are presented in the form of a colored, five dimensional diagram. The resultant eight empirical phase diagrams display three to five variably resolved phases. In contrast, the phase diagram of the plasmid alone showed only two to three such phases. Each state is assigned to a particular form of the complex in terms of their size, extent of collapse and conformation of the associated DNA component. The utility of this approach is then briefly discussed.

A stopped-flow kinetic study of the assembly of nonviral gene delivery complexes.

Stopped-flow circular dichroism and fluorescence spectroscopy are used to characterize the assembly of complexes consisting of plasmid DNA bound to the cationic lipids dimethyldioctadecylammonium bromide and 1, 2-dioleoyl- 3-trimethylammonium-propane and a series of polyamidoamine dendrimers. The kinetics of complexation determined from the stopped-flow circular dichroism measurements suggests complexation occurs within 50 ms. Further analysis, however, was precluded by the presence of mixing (shear) artifacts. Stopped-flow fluorescence employing the high-affinity DNA dyes Hoechst 33258 and YOYO-1 was able to resolve two sequential steps in the assembly of complexes that are assigned to binding/dehydration and condensation events. The rates of each process were determined over the temperature range of 10-50 degrees C and activation energies were determined from the slope of Arrhenius plots. The behavior of polyamidoamine dendrimers can be separated into two classes based on their differing binding modes: generation 2 and the larger generations (G4, G7, and G9). The larger generations have activation energies for binding that follow the trend G4 > G7 > G9. The activation energies for condensation (compaction) of complexes composed of these same dendrimers have the opposite trend G9 > G7 > G4. It is postulated that a balance between a more energetically favorable condensation and less favorable binding may prove beneficial in enhancing gene delivery.

Structure/function relationships of polyamidoamine/DNA dendrimers as gene delivery vehicles.

PAMAM dendrimers are members of a class of polyamine polymers that demonstrate significant gene delivery ability. In this study, a selection of PAMAM dendrimers, spanning a range of sizes (generations 2, 4, 7, and 9) and transfection efficiencies, are characterized by various biophysical methods to search for structural properties that correlate with transfection. Measurements of colloidal properties (size and zeta potential) as a function of charge ratio reveal that highly transfecting dendrimer/DNA complexes have size/zeta potential values between 4 and 8. Circular dichroism (CD) and FTIR spectroscopy of complexes confirm the DNA component remains in B form when associated with all dendrimer generations up to a 5:1 charge ratio (+/-). Isothermal titration calorimetry and differential scanning calorimetry detect changes that are related to polymer structure and charge ratio but do not directly correlate with transfection efficiency. Despite DNA structural and stability changes detected by CD, FTIR, DSC, and ITC that are similar to those seen with other cationic delivery vehicles [e.g., cationic lipids, peptoids/lipitoids, peptides, polyethyleneimines (PEIs), etc.], clear correlations with transfection activity are not readily apparent. This may be due, at least in part, to the heterogeneity of the complexes.

The structure of DNA within cationic lipid/DNA complexes.

The structure of DNA within CLDCs used for gene delivery is controversial. Previous studies using CD have been interpreted to indicate that the DNA is converted from normal B to C form in complexes. This investigation reexamines this interpretation using CD of model complexes, FTIR as well as Raman spectroscopy and molecular dynamics simulations to address this issue. CD spectra of supercoiled plasmid DNA undergo a significant loss of rotational strength in the signal near 275 nm upon interaction with either the cationic lipid dimethyldioctadecylammonium bromide or 1,2-dioleoyltrimethylammonium propane. This loss of rotational strength is shown, however, by both FTIR and Raman spectroscopy to occur within the parameters of the B-type conformation. Contributions of absorption flattening and differential scattering to the CD spectra of complexes are unable to account for the observed spectra. Model studies of the CD of complexes prepared from synthetic oligonucleotides of varying length suggest that significant reductions in rotational strength can occur within short stretches of DNA. Furthermore, some alteration in the hydrogen bonding of bases within CLDCs is indicated in the FTIR and Raman spectroscopy results. In addition, alterations in base stacking interactions as well as hydrogen bonding are suggested by molecular dynamics simulations. A global interpretation of all of the data suggests the DNA component of CLDCs remains in a variant B form in which base/base interactions are perturbed.

Diagnosis and management of acute bronchitis.

Acute bronchitis is one of the top 10 conditions for which patients seek medical care. Physicians show considerable variability in describing the signs and symptoms necessary to its diagnosis. Because acute bronchitis most often has a viral cause, symptomatic treatment with protussives, antitussives, or bronchodilators is appropriate. However, studies indicate that many physicians treat bronchitis with antibiotics. These drugs have generally been shown to be ineffective in patients with uncomplicated acute bronchitis. Furthermore, antibiotics often have detrimental side effects, and their overuse contributes to the increasing problem of antibiotic resistance. Patient satisfaction with the treatment of acute bronchitis is related to the quality of the physician-patient interaction rather than to prescription of an antibiotic.

Enhancements in gene expression by the choice of plasmid DNA formulations containing neutral polymeric excipients.

Formulations containing maltodextrin (2% w/v) were identified to facilitate intramuscular (im) delivery of plasmid DNA in mice using the reporter genes luciferase and chloramphenicol acetyltransferase (CAT) and the therapeutic gene of erythropoietin (EPO) as monitors of transfection efficiency. Even though considerable variability in gene expression was observed in animals, a 5-8-fold enhancement of reporter gene expression was observed with this excipient compared with saline formulations of DNA. In a therapeutically significant experiment, a single im injection of an EPO plasmid formulation containing 2% (w/v) maltodextrin resulted in a significant and prolonged elevation of the hematocrit levels of mice compared with control DNA in saline. Biophysical studies with Fourier transform infrared (FTIR) spectroscopy, isothermal titration, and differential scanning calorimetry (DSC) suggested a weak interaction between DNA and maltodextrin as well as a thermal stabilizing effect on the DNA. These in vivo and biophysical results with maltodextrin are comparable to those reported previously with other nonionic polymers, such as poly(vinyl pyrrolidone) and poloxamers, and indicate that maltodextrin is an additional nonionic excipient that displays the property of gene expression enhancement.