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Biomedical subjects

B Davis

Publications and source records attributed to B Davis.

At least 127 records · Page 7Linked to original sources
PubMed1995

Factors affecting ED length-of-stay in surgical critical care patients.

To determine what patient characteristics are associated with prolonged emergency department (ED) length-of-stay (LOS) for surgical critical care patients, the charts of 169 patients admitted from the ED directly to the operating room (OR) or intensive care unit (ICU) during a 6-week period in 1993 were reviewed. The ED record was reviewed for documentation of factors that might be associated with prolonged ED LOS, such as use of computed tomographic (CT), radiology special procedures, and the number of plain radiographs and consultants. ED LOS was considered to be the time from triage until a decision was made to admit the patient. Using a Cox proportional hazards model, use of CT and special procedures were the strongest independent predictors of prolonged ED length-of-stay. The number of plain radiographs and consultants had only a minimal effect. Use of a protocol-driven trauma evaluation system was associated with a shorter ED LOS. In addition to external factors that affect ED overcrowding, ED patient management decisions may also be associated with prolonged ED length-of-stay. Such ED-based factors may be more important in surgical critical care patients, whose overall ED LOS is affected more by the length of the ED work-up rather than the time spent waiting for a ICU bed or operating suite.

Adolescent↗
PubMed1995

Risk assessment of environmental chemicals.

Risk assessment is an evolving process, based not only upon toxicology but also upon a broad background of knowledge in fields ranging from chemistry to physiology and molecular biology and from environmental transport processes to applied statistics. Risk assessment procedures must be continually updated to reflect advances in these basic sciences. This review addresses several areas of risk assessment that are receiving heightened attention, including neurotoxicity, immunotoxicity, reproductive and developmental toxicity, genotoxicity, carcinogenicity, and toxicokinetics and modeling. Risk assessors must work with the scientific community at large to incorporate advances in the basic sciences into their extrapolations. A concerted attempt to better define the variability and decrease the uncertainty of hazard estimates will result in more efficient protection of the public and the environment against toxic hazards.

Animals↗
PubMed1995

Microfluctuations of steady-state accommodation and the cardiopulmonary system.

The relationship between variations in steady-state accommodation (microfluctuations) and rhythmic cycles in cardiopulmonary system was investigated. As previously reported, vascular pulse frequency was consistently correlated with the high frequency component of steady-state accommodation microfluctuations. In a new finding, respiration rate and an associated cycle in the instantaneous pulse rate also showed a correlation with a low frequency component of the accommodation power spectra. This apparent coherence between respiration frequency and an accommodation low frequency component was maintained during rapid breathing and was evident at the expected frequency during regulated breathing patterns. This association may reflect the direct influence of the autonomic nervous system upon the ciliary muscle or may be caused by the modulation of intraocular pulse by the autonomic nervous system.

Accommodation, Ocular↗
PubMed1994

The structure of the transition state for the association of two fragments of the barley chymotrypsin inhibitor 2 to generate native-like protein: implications for mechanisms of protein folding.

Possible early events in protein folding may be studied by dissecting proteins into complementary fragments. Two fragments of chymotrypsin inhibitor 2 [CI2-(20-59) and CI2-(60-83)] associate to form a native-like structure in a second-order reaction that combines collision and rearrangement. The transition state of the reaction, analyzed by the protein engineering method on 17 mutants, is remarkably similar to that for the folding of the intact protein--a structure that resembles an expanded version of the folded structure with most interactions significantly weakened. The exception is that the N-terminal region of the single alpha-helix (the N-capping box) is completely formed in the transition state for association of the fragments, whereas it is reasonably well formed for the intact protein. Preliminary evidence on the structures of the individual fragments indicates that both are mainly nonnative, lacking native secondary structure and having regions of nonnative buried hydrophobic clusters. The association reaction does not result from the collision of a subpopulation of two fully native-like fragments but involves a considerable rearrangement of structure.

Amino Acid Sequence↗
PubMed1994

Detection of an intermediate in the folding of the (beta alpha)8-barrel N-(5'-phosphoribosyl)anthranilate isomerase from Escherichia coli.

We have used thermodynamic and kinetic techniques to monitor the guanidinium chloride induced (GdmCl-induced) denaturation of N-(5'-phosphoribosyl)anthranilate isomerase from Escherichia coli (ePRAI). Although CD-monitored equilibrium denaturation curves are consistent with cooperative unfolding of the protein centered at 1.45 M GdmCl, fluorescence readings drop by over 25% in the region preceding the CD-monitored transition, suggesting non-two-state behavior. Kinetics experiments measure a slow relaxation rate with negative fluorescence amplitude when protein is diluted from 0 to 0.5 M GdmCl, corroborating results from equilibrium conditions. Detection of several unfolding and refolding rates in final GdmCl concentrations from 0 to 5.0 M indicates the presence of at least one intermediate along unfolding and refolding pathways. GdmCl dependence of the relaxation rates can be explained most easily by a nonsequential mechanism for ePRAI unfolding, though a sequential mechanism cannot be ruled out. The data corroborate the fragment complementation studies of Eder and Kirschner [Eder, J., & Kischner, K. (1992) Biochemistry 31, 3617-3625], which are consistent with unfolding of the C-terminal portion of a yeast-derived PRAI in its folding intermediate. In ePRAI, such partial unfolding would expose W391 to quenching by solvent molecules; W356, ePRAI's other tryptophan, is buried in the hydrophobic core and is unlikely to be affected by local changes in structure. A C-terminally unfolded folding intermediate has been demonstrated in the folding of tryptophan synthase (alpha-subunit), a related beta alpha-barrel enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldose-Ketose Isomerases↗
PubMed1994

Stereoselective epoxidation of 2,2-dimethyl-2H-1-benzopyran-6-carbonitrile.

The chiral intermediate (3S,4R)-trans-3,4-dihydro-3,4-dihydroxy-2,2-dimethyl- 2H-1-benzopyran-6-carbonitrile [(+)-trans diol 3] was made by the stereoselective microbial epoxidation of 2,2-dimethyl-2H-1-benzopyran-6-carbonitrile 1. This compound is a potential intermediate for the total synthesis of potassium-channel openers. Several microbial cultures were found which catalyzed the transformation of 1 to the corresponding (3S,4S)-epoxide 2 and (+)-trans diol 3. The two best cultures, Corynebacterium sp. SC 13876 and Mortierella ramanniana SC 13840 gave reaction yields of 32 M% and 67.5 M% and optical purities of 88 and 96%, respectively, for (+)-trans diol 3. A single-stage process (fermentation-epoxidation) for the biotransformation of 1 was developed using Corynebacterium sp. SC 13876 and M. ramanniana SC 13840. In a 25-L fermentor, the (+)-trans diol 3 was obtained in 38.6 M% yield with an optical purity of 90% using Corynebacterium SC 13876. The reaction yield of 60.7 M% and optical purity of 92.5% were obtained for (+)-trans diol 3 using M. ramanniana SC 13840. A two-stage process for the preparation of (+)-trans diol 3 was also developed using a 3 L cell-suspension (10% w/v, wet cells) of M. ramanniana SC 13840. The reaction was carried out in a 5-L Bioflo fermentor. The concentration of substrate 1 was 2 g L-1 with glucose present at 10 g L-1. After 48 h, (+)-trans diol 3 was obtained in 76 M% yield with an optical purity of 96%.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteria↗
PubMed1994

Appointment access: planning to benchmark a complex issue.

BACKGROUND: Kaiser Permanente-Southern California Region carried out an external benchmarking project to improve appointment access. This article provides practical guidelines for planning a benchmark project around a complex issue such as appointment access. METHOD: Before conducting external site visits, team members determined the goals of the project, defined internal processes, and identified 16 key elements of access (or those factors important to member satisfaction with appointment access). Once a questionnaire was finalized, external benchmark partners were identified and on-site visits conducted. CONCLUSION: On the basis of the on-site visits, team members identified innovative and best practices for each of the 16 key elements of access. Based on these recommendations, some improvements were made across the Southern California region, such as the elimination of provisional booking. Reports of the results have also been sent to Kaiser Permanente medical centers in the region and across the country. Each medical center is encouraged to use these results to internally improve its own appointment access.

Appointments and Schedules↗
PubMed1994

Anti-inflammatory active polyacetylenes from Bidens campylotheca.

The n-hexane extract of Bidens campylotheca Schultz Bip. ssp campylotheca (Compositae) showed significant in vitro inhibition of cyclooxygenase (CO) and 5-lipoxygenase (5-LO). Five polyacetylenes, heptadeca-2E,8E,10E,16-tetraene-4,6-diyne (1), heptadeca-2E,8Z,10E,16-tetraene-4,6-diyne (2), heptadeca-2E,8E,16-triene-4,6-diyne-10-ol (3), safynol (5) and, as a new compound, safynol-2-O-isobutyrate (4) could be isolated and their structures elucidated mainly by UV, MS, NMR, and COSY-NMR. The isolated compounds exhibited a significant inhibitory effect on cyclooxygenase and 5-lipoxygenase.

Acetylene↗
PubMed1994

Effective utilization of a scarce resource: RNs.

Nursing costs make up nearly half of a hospital's total budget, a situation exacerbated by the RN shortage. To maximize effectiveness, hospital administrators must ensure that RNs do only those tasks which require an RN. A nurse "extender" program is described which utilizes nursing students to provide care that does not require the expertise of a RN. This system has increased RN productivity and direct patient care opportunities while simultaneously providing an effective avenue for recruiting RN graduates at decreased orientation costs.

Costs and Cost Analysis↗
PubMed1994

VDT screen reflections and accommodation response.

Reflections in computer screens are imaged behind the screen and therefore potentially create a conflicting cue to appropriate accommodation response to the plane of screen. We investigated the effect of screen reflections on accommodation response by producing reflections (1.33 D accommodation demand) surrounding and overlying the fixation point (2 D accommodation demand) in the screen. We have found little evidence that reflections in visual display terminal screens can influence the accuracy of the users' accommodation responses under normal binocular viewing conditions. The accuracy of the accommodation response was not significantly influenced by the position of the reflections, the presence of surrounding text (peripheral cues), or the subjects' dark focus level. The variability of accommodation response did not significantly change under the various test conditions. However, accommodation errors were apparent to a small degree (< 0.25 D) under some monocular viewing conditions in the presence of screen reflections.

Accommodation, Ocular↗
PubMed1993

Glutamate stimulates dopamine release from cortical and limbic rat brain in vitro.

In vitro superfusion studies were performed to compare the glutamatergic control of dopamine release from minislices of rat striatum, olfactory tubercle and frontal cortex. In the absence of Mg2+, release of endogenous dopamine from olfactory tubercle and striatum, and [3H]dopamine from frontal cortex, was stimulated by glutamate (at concentrations of 0.3, 3 and 1 mM respectively). In all three areas the response to N-methyl-D-aspartate (NMDA) was greater than that to kainate, implying mediation largely by NMDA receptors, with non-NMDA receptors contributing to a smaller extent. This was confirmed by antagonist studies in the frontal cortex, where the response to glutamate was largely (70%) blocked by 2-amino-5-phosphonopentanoic acid (AP5), and further blocked by AP5 + 6,7-dinitroquinoxaline-2,3-dione (DNQX). In the olfactory tubercle and striatum, glutamate was as effective as NMDA, but in the frontal cortex the response to NMDA was significantly larger than that to glutamate.

Animals↗