Clinical decision making in acute medicine.

Clinical decision-making is a core skill for the practice of medicine and yet during training there is often little formal analysis of the process of clinical reasoning or instruction about how to do it better. This paper reviews the process of clinical decision-making with a particular focus on diagnostic reasoning. Aspects of psychology and philosophy are applied to the process along with consideration of potential sources of error and the steps that can be taken to minimize this.

Quantum nature of a strongly coupled single quantum dot-cavity system.

Cavity quantum electrodynamics (QED) studies the interaction between a quantum emitter and a single radiation-field mode. When an atom is strongly coupled to a cavity mode, it is possible to realize important quantum information processing tasks, such as controlled coherent coupling and entanglement of distinguishable quantum systems. Realizing these tasks in the solid state is clearly desirable, and coupling semiconductor self-assembled quantum dots to monolithic optical cavities is a promising route to this end. However, validating the efficacy of quantum dots in quantum information applications requires confirmation of the quantum nature of the quantum-dot-cavity system in the strong-coupling regime. Here we find such confirmation by observing quantum correlations in photoluminescence from a photonic crystal nanocavity interacting with one, and only one, quantum dot located precisely at the cavity electric field maximum. When off-resonance, photon emission from the cavity mode and quantum-dot excitons is anticorrelated at the level of single quanta, proving that the mode is driven solely by the quantum dot despite an energy mismatch between cavity and excitons. When tuned to resonance, the exciton and cavity enter the strong-coupling regime of cavity QED and the quantum-dot exciton lifetime reduces by a factor of 145. The generated photon stream becomes antibunched, proving that the strongly coupled exciton/photon system is in the quantum regime. Our observations unequivocally show that quantum information tasks are achievable in solid-state cavity QED.

Self-tuned quantum dot gain in photonic crystal lasers.

We demonstrate that very few (2-4) quantum dots as a gain medium are sufficient to realize a photonic-crystal laser based on a high-quality nanocavity. Photon correlation measurements show a transition from a thermal to a coherent light state proving that lasing action occurs at ultralow thresholds. Observation of lasing is unexpected since the cavity mode is in general not resonant with the discrete quantum dot states and emission at those frequencies is suppressed. In this situation, the quasicontinuous quantum dot states become crucial since they provide an energy-transfer channel into the lasing mode, effectively leading to a self-tuned resonance for the gain medium.

piggyBac internal sequences are necessary for efficient transformation of target genomes.

A previously reported piggyBac minimal sequence cartridge, which is capable of efficient transposition in embryo interplasmid transposition assays, failed to produce transformants at a significant frequency in Drosophila melanogaster compared with full-length or less extensive internal deletion constructs. We have re-examined the importance of these internal domain (ID) sequences for germline transformation using a PCR strategy that effectively adds increasing lengths of ID sequences to each terminus. A series of these piggyBac ID synthetic deletion plasmids containing the 3xP3-ECFP marker gene are compared for germline transformation of D. melanogaster. Our analyses identify a minimal sequence configuration that is sufficient for movement of piggyBac vectored sequences from plasmids into the insect genome. Southern hybridizations confirm the presence of the piggyBac transposon sequences, and insertion site analyses confirm these integrations target TTAA sites. The results verify that ID sequences adjacent to the 5' and 3' terminal repeat domains are crucial for effective germline transformation with piggyBac even though they are not required for excision or interplasmid transposition. Using this information we reconstructed an inverted repeat cartridge, ITR1.1k, and a minimal piggyBac transposon vector, pXL-BacII-ECFP, each of which contains these identified ID sequences in addition to the terminal repeat configuration previously described as essential for mobility. We confirm in independent experiments that these new minimal constructs yield transformation frequencies similar to the control piggyBac vector. Sequencing analyses of our constructs verify the position and the source of a point mutation within the 3' internal repeat sequence of our vectors that has no apparent effect on transformation efficiency.

Regulation of mesenchymal stem cell attachment and spreading on hydroxyapatite by RGD peptides and adsorbed serum proteins.

The successful development of biomaterials must take into consideration how those surfaces will interact with in vivo processes such as adsorption of endogenous proteins. In this study, we examined whether modifying highly adsorbent materials like hydroxyapatite (HA) with RGD peptides would improve mesenchymal stem cell (MSC) adhesion. We found that RGD, alone, was not sufficient to promote full cell spreading. However, given that RGD-modified HA will likely adsorb osteogenic serum proteins in vivo, we evaluated MSC behavior on HA pre-coated with RGD, then over-coated with serum (RGD/FBS). Interestingly, RGD/FBS coatings additively stimulated MSC attachment and spreading compared to either coating alone, but only at low RGD coating concentrations. High RGD concentrations inhibited cell attachment, and completely eliminated cell spreading on RGD/FBS surfaces. To better understand the mechanism by which RGD and adsorbed serum proteins interactively regulate cell behavior, we monitored the deposition of fibronectin (FN) from serum onto HA pre-coated with increasing RGD concentrations. These studies showed that high RGD concentrations did not inhibit FN adsorption, therefore cell spreading is attenuated by mechanisms other than lack of FN availability. Collectively, our results suggest a potential therapeutic benefit for functionalizing HA with RGD, however such a benefit will likely depend upon the RGD density.

Utility and accuracy of template-directed dye-terminator incorporation with fluorescence-polarization detection for genotyping single nucleotide polymorphisms.

There are little independent data available about how well single nucleotide polymorphism (SNP) genotyping technologies perform in the typical molecular genetics laboratory. We evaluated the utility and accuracy of a widely used technology, template-directed dye-terminator incorporation with fluorescence-polarization detection (FP-TDI), in a sample of 177 SNPs selected solely on the basis of map location. Genotypes were generated without optimization using standard protocols. Overall, 81% of the SNPs we studied generated readable genotypes by FP-TDI. Thirty-two SNPs were genotyped in duplicate by PCR-RFLP orfluorescent dye-terminator sequencing. Out of a total of 631 duplicate genotypes, no true discrepancies were detected. The true error rate has a 95% chance of lying between 0 and 6 out of 1000 genotypes. We also tested for deviations from Hardy-Weinberg Equilibrium in 33 SNPs genotyped in 50 unrelated individuals, and no significant deviations were detected. Our FP-TDI data were readily adaptable to automated genotype calling using our own method of cluster analysis, which assigns a probability score to each genotype call. We conclude that FP-TDI is both efficient and accurate. The method can easily fill the needs of SNP genotyping projects at the scale typically used for regional or candidate-gene association studies.

Simultaneous flow cytometric analysis of phagocytosis and oxidative burst activity in equine leukocytes.

This paper describes a method for simultaneously measuring phagocytosis and oxidative burst activity in equine peripheral blood leukocytes by flow cytometry. Opsonized propidium iodide-labelled Staphylococcus aureus (PI-Sa) was used to measure the uptake of bacteria by equine phacocytes and the oxidative burst activity by oxidation of dihydrorhodamine 123. The requirements to achieve optimal activity of phagocytosis and oxidative burst are described. The advantage of the simultaneous technique is that it provides both independent and comparative values for phagocytosis and the oxidative burst, for the detection of impaired mechanisms of microbial destruction. Furthermore, the technique allows evaluation of opsonization activity in this context.

Full parity: steps toward treatment equity for mental and addictive disorders.

The 1996 Mental Health Parity Act requiring equal annual and lifetime dollar limits for mental health benefits is to sunset 30 September 2001. This paper reviews the impact and limitations of both this law and existing state provisions and describes recent research on the actual and projected costs associated with such laws. We contend that full parity provided within the context of managed care not only is possible, but represents a "sequential" rather than a final step toward the broader goal of achieving equity in the treatment of persons with mental and addictive disorders.

Role of phosphorylation of the cytoplasmic domain of the alpha(2)-macroglobulin receptor (LRP).

The low density lipoprotein receptor-related protein (alpha(2)MR/LRP) is a cell surface receptor which is present on most cells and tissues. We show that the 85 kDa subunit, containing the transmembrane region and cytoplasmic domain is phosphorylated in vivo. Comparison of the phosphorylation of the low density lipoprotein receptor (LDLR) with a chimeric receptor containing the cytoplasmic domain of the alpha(2)MR/LRP (LDLR/LRP) showed that phosphorylation is exclusive to the cytoplasmic domain. Staurosporine, a general kinase inhibitor, resulted in a 40% lowering of phosphorylation of LDLR/LRP, but did not give rise to measurable changes in its membrane traffic in MDCK cells. The role of phosphorylation on degradation of the receptor was studied using inhibitors of lysosomal and proteasomal degradation. These studies showed that LDLR/LRP was rapidly turned over by proteasomal degradation but that this turnover was also not a consequence of phosphorylation.

Characterization of peripheral blood and pulmonary leukocyte function in healthy foals.

Studies in infants and foals indicate an age-dependent maturation of peripheral lymphocyte subsets. The age-dependent relationship for maturation of cellular immune responses, such as phagocytosis and lymphocyte responses of the peripheral and pulmonary-derived leukocytes, has not been characterized in foals. Lymphocyte subpopulations, mitogen stimulation response of lymphocytes, lymphokine-activated killing cell activity, phagocytosis and oxidative burst activity, and serum immunoglobulin (Ig) classes G and M concentrations were determined in developing foals. This study illustrates age-dependent changes in immunoglobulin class concentrations, lymphocyte subsets, and EqMHC Class II expression in cells of the peripheral blood and lungs of developing neonatal-to-weanling foals. The increase in peripheral blood and BAL B-lymphocytes and serum immunoglobulins in developing foals suggests expansion of immune cell populations during a time in which environmental pathogen exposure is great. General immune function, mitogenic responses, LAK cell activity, opsonized phagocytosis, and oxidative burst activity of newborns was similar to the adult horse. Total immune-cell numbers, rather than function, seemed to be the limiting factor in the development of the equine neonatal immune system. There was an age-related percent increase in the appearance of pulmonary lymphocytes, but a percent decrease in macrophages. Although development of the respiratory immune system follows changes in the peripheral blood, cellular expansion, activation, and migration may occur at a slower pace, making the respiratory environment susceptible to pathogens prior to optimal immune system maturity.

Demographic differences in medication use among individuals with self-reported major depression.

In a nationally representative household-based sample, more than one-third of those who identified themselves as having major depression reported not taking any medications in the last year. Male gender, minority status, excellent health, and being at either end of the age continuum were associated with nonuse of medication. Lower-income, widowed, and never-married individuals showed a trend toward being less likely to use medication. The results suggest the need to further assess the role of potential factors in the limited use of medication among various demographic subgroups of individuals who identify themselves as being depressed.

Clinical pathways in home nutrition support.

In home-care settings, physicians with various medical specialties may order home enteral and/or parenteral nutrition support. Clinical pathways may be used to provide a clear, concise, standardized method for ordering and monitoring home nutrition support. The clinical pathways should be appropriate for 80% of the patients placed on the pathways, allowing for a 20% variance, or deviation, from the pathway. In one home-care facility, disease-specific clinical pathways have been used for longer than 1 year for patients with a variety of diseases requiring home nutrition support. To determine the usefulness of the home nutrition support clinical pathways, data obtained from 20 patients were analyzed. Patients were followed up while being treated using home nutrition support clinical pathways designed for oncology (9 patients), human immunodeficiency virus/acquired immunodeficiency syndrome (2 patients), short bowel syndrome (6 patients), and hyperemesis (3 patients) for 191 weeks. Overall, an average variance (deviation from the pathway) of 22% (the number of variances divided by the total weeks of therapy) was observed. The use of the pathways to provide enteral or parenteral nutrition facilitated more cost-effective care by following pathway guidelines for obtaining laboratory values and patient visits. Communication between the home-care staff and the physician was also improved. Clinical pathways can enable standardization of care for patients receiving nutrition support at home.

An economic and clinical rationale for changing utilization review practices for outpatient psychotherapy.

The growth of managed care has led to greater cost consciousness in the financing and delivery of mental health and substance abuse services. The authors examine whether pressures to reduce the costs associated with mental health and substance abuse treatment have led to the overapplication of a popular managed care strategy, utilization review (UR), to the management of outpatient psychotherapy benefits. Several arguments are presented highlighting why changing outpatient psychotherapy UR practices would be in the best economic and clinical interests of all involved parties, including payers, managed care organizations (MCOs), mental health consumers, and providers. A number of alternatives to the aggressive management of outpatient psychotherapy benefits are outlined and discussed.

The nucleotide sequence of Saccharomyces cerevisiae chromosome V.

Here we report the sequence of 569,202 base pairs of Saccharomyces cerevisiae chromosome V. Analysis of the sequence revealed a centromere, two telomeres and 271 open reading frames (ORFs) plus 13 tRNAs and four small nuclear RNAs. There are two Tyl transposable elements, each of which contains an ORF (included in the count of 271). Of the ORFs, 78 (29%) are new, 81 (30%) have potential homologues in the public databases, and 112 (41%) are previously characterized yeast genes.

Medicare Part A utilization and expenditures for psychiatric services: 1995.

This study provides an overview of Medicare's current coverage and payment policies regarding hospitalization for psychiatric disorders, and presents new information on demographic, diagnostic, utilization, and expenditure characteristics associated with inpatient psychiatric care among 1995 Medicare beneficiaries. Results suggest that utilization and expenditure patterns for Medicare beneficiaries hospitalized for psychiatric illness in 1995 differ across demographic (e.g., age, sex, race) and diagnostic categories. The implications of these findings for current management of the Medicare program as well as the evolution of Medicare managed care systems for behavioral health services are discussed.