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Biomedical subjects

B Davis

Publications and source records attributed to B Davis.

At least 145 records · Page 8Linked to original sources
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↗
PubMed1993

Quality audit of megavoltage radiotherapy units: intercomparison of dose at a reference point using a mailed TL-dosimetry system.

A dosimetry intercomparison based on mailed TL-dosimeters and the well proven IAEA/EORTC phantom is described. Its aim is to identify discrepancies in dosimetry larger than +/- 3%. Dosimeters were mailed to all radiotherapy centres in Switzerland for irradiation with 2 Gy at a reference point in a water container, using photons and electrons. Thirty-six beams were monitored. The results show an agreement of within 2% for the majority of the beams monitored. Two electron beams were at 6% of the reference value.

Cobalt Radioisotopes↗
PubMed1993

Preliminary, dermatologic first step criteria for lupus erythematosus and second step criteria for systemic lupus erythematosus.

BACKGROUND: Comparisons of cases of systemic lupus erythematosus (SLE) with cases of rheumatoid arthritis and other rheumatologic disorders affords the basis of the 1982 revised criteria of the American Rheumatism Association (ARA) for classifying SLE cases. We address three questions: Do comparisons of LE cases with non-LE cases that have suggestive skin lesions yield criteria for use in dermatology clinics for primary classification of cases with photo distributions of skin lesions? Do comparisons of SLE with cutaneous LE cases yield the same or similar criteria to the revised ARA criteria for SLE? How should subacute cutaneous LE cases be evaluated for signs of significant systemic involvement? METHODS: Discriminant analyses on 168 cases with skin lesions suggestive of LE were performed using data based on the ARA criteria for SLE and study factors for cutaneous LE suggested by the European Academy of Dermatology and Venereology. RESULTS: These yielded two sets of criteria: (1) The 11 preliminary, dermatologic first step criteria (10 plus 1 for discoid lesions and histology) serve to classify cases as LE or non-LE. (2) The 11 preliminary, dermatologic second step criteria classify LE cases as cutaneous LE or systemic LE. Interestingly, 5 of 11 of these second step criteria differ from the 11 ARA criteria for systemic LE. These second step criteria afford a useful means of distinguishing between subacute cutaneous LE cases with or without significant systemic involvement. CONCLUSIONS: The study factors included in both the first and the second step criteria fall into three groups, notably clinical criteria, laboratory criteria, and "added study factors." The latter factors distinguish between the groups compared (LE vs. non-LE and cutaneous vs. systemic LE) but not as well as the study factors included as "criteria."

Humans↗
PubMed1993

Calibration of the Canon Autoref R-1 for continuous measurement of accommodation.

The Canon Autoref R-1 is an infrared optometer which allows free-space viewing. Pugh and Winn described hardware modifications necessary to convert the Autoref R-1 from an instrument capable of taking single static measurements of the eye's accommodative (refractive) status to an instrument capable of continuous measurement of the accommodative status of the eye. We describe two methods of calibrating the Autoref R-1 for continuous measurement of accommodation for any individual eye. The assumptions and sources of error underlying these calibration techniques are discussed. We also describe further hardware modifications to simplify signal acquisition from the Autoref R-1.

Accommodation, Ocular↗
PubMed1993

Rational behavior training effectiveness for white and nonwhite incarcerated felons.

45 incarcerated male felons in a medium-security state correctional institution participated in a Rational Behavior Training treatment outcome study. 58% of the subjects were white, 18% were African-American, 17% were Hispanic, and 7% were classified as other. Subjects were selected from an institutional group-therapy waiting list and randomly assigned to one of four group facilitators. The Novaco Provocation Inventory, Buss-Durkee Hostility Inventory, and Rational Behavior Training Concepts Test were administered before and after the 10-wk. treatment period. No differences in gain scores (pretest minus posttest) were observed although the slightly greater improvement on the concepts test by subjects of ethnic minority encourages further study.

Adult↗
PubMed1992

Impaired in vitro growth of purified (CD34+) hematopoietic progenitors in human immunodeficiency virus-1 seropositive thrombocytopenic individuals.

In this report the role played by human immunodeficiency virus type-1 (HIV-1) in the pathogenesis of HIV-1-related thrombocytopenia was investigated. CD34+ hematopoietic stem/progenitor cells were purified from the bone marrow (BM) of HIV-1(+) thrombocytopenic patients, HIV-1(+) nonthrombocytopenic individuals, HIV-1(-) patients with immune thrombocytopenic purpura, and HIV-1(-) normal donors. CD34+ cells from HIV-1(+) thrombocytopenic individuals alone showed a reduced capacity to give rise to megakaryocytic colonies (CFU-Meg) and also a progressive and significant decline in cell number when placed in liquid culture containing recombinant human interleukin-3 (rIL-3). This decline involved not only megakaryocyte but also erythroid and granulocyte/macrophage progenitors. The defects in megakaryocyte colony formation and CD34+ cell growth did not result from a productive HIV-1 infection of CD34+ cells. Moreover, HIV-1 DNA was absent from CD34+ cells in 10 of 12 thrombocytopenic patients examined. On the other hand, the decreased survival/proliferation of CD34+ cells in liquid culture, within the HIV-1(+) thrombocytopenic patients, was correlated with the presence of HIV-1 p24 antigen in BM plasma. These results demonstrate an impairment of CD34+ cells in HIV-1(+) individuals presenting thrombocytopenia as the only hematologic manifestation. Furthermore, these findings suggest that increased viral replication in the BM microenvironment may cause this impairment and possibly contributes to HIV-induced thrombocytopenia.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Renin predicts diastolic blood pressure response to nonpharmacologic and pharmacologic therapy.

OBJECTIVE: Plasma renin activity was measured at baseline and 6 months in a trial of nonpharmacologic therapy of mild hypertension to determine whether plasma renin activity predicts the diastolic blood pressure (DBP) response to nonpharmacologic therapy. DESIGN, SETTING, AND PARTICIPANTS: Randomized controlled trial of volunteers from the general community with mild hypertension (DBP between 90 and 100 mm Hg), off all antihypertensive therapy at baseline, treated in special research clinics (n = 593). INTERVENTIONS: Subjects were randomly assigned to usual, weight loss, or low sodium/high potassium diet and then randomly assigned to receive placebo, chlorthalidone, or atenolol. MAIN OUTCOME MEASURES: Renin was analyzed as plasma renin activity and as a renin index (logarithm of 24-hour urinary sodium excretion times logarithm of plasma renin activity) (593 patients at baseline and 6 months) to correct for varied sodium intakes. The DBP was measured using the random zero device. RESULTS: Change in DBP at 6 months could be predicted from baseline plasma renin activity or renin index. The DBP was decreased after 6 months of therapy by 2 mm Hg for each unit increase in baseline plasma renin activity and by 0.16 mm Hg for each unit increase in baseline renin index. Patients in the highest renin index quartile had a greater DBP response to atenolol therapy, and patients in the lowest renin index quartile had a greater DBP response to chlorthalidone therapy. Weight loss diet achieved a greater reduction in DBP in patients with higher baseline renin index and had an additive effect on DBP response in both of the drug groups. Patients on a weight loss diet receiving placebo in the highest baseline renin index quartile had a reduction in DBP of 12.4 mm Hg, compared with 4.4 mm Hg in the lowest baseline renin index quartile (P = .009). A low sodium/high potassium diet had a lesser effect than a weight loss diet on pharmacologic therapy. As with the weight loss diet, patients on a low sodium/high potassium diet in the highest baseline renin index quartile had a greater reduction in DBP than patients in the lowest baseline renin index quartile. CONCLUSIONS: These data suggest a significant relationship between baseline levels of plasma renin index and the likelihood of success of nonpharmacologic treatment of hypertension.

Adult↗
PubMed1992

Development of myopia in infants with birth weights less than 1251 grams. The Cryotherapy for Retinopathy of Prematurity Cooperative Group.

The authors report on the incidence of myopia in a large group of premature infants with birth weights of less than 1251 g followed as part of the multicenter study of Cryotherapy for Retinopathy of Prematurity. None of the eyes reported here underwent cryotherapy. Eyes were refracted using cycloplegic retinoscopy at 3 months (n = 2916), 12 months (n = 2626), and 24 months (n = 961 at 5 of the 23 centers) after term. Myopia was observed in approximately 20% of the children at each test age. The percentage of high myopia (greater than or equal to 5 diopters) doubled from 2% to 4.6% between 3 and 12 months and remained stable thereafter. Lower birth weight and increasing severity of retinopathy of prematurity (ROP) were strong predictors of myopia and high myopia. In addition, anisometropia, astigmatism, and the presence of posterior pole residua from ROP also were associated with a higher incidence of myopia and high myopia.

Anisometropia↗