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Biomedical subjects

P D Davis

Publications and source records attributed to P D Davis.

At least 19 recordsLinked to original sources
PubMed1995

Enhancing multicultural harmony: ten actions for managers.

Health-care managers have a responsibility to create harmony within the workforce, increasingly a culturally diverse group. Suggestions offered by the literature for actions a manager can take to deal effectively with cultural diversity may not agree with employee perspectives on this issue. This article introduces a quasi-experimental evaluation method that may be used as introductory work for research in multicultural-workfoce management. This major challenge for health care in the next decade is second in importance only to health-care reform.

Cooperative Behavior↗
PubMed1995

The national jockey injury study: an analysis of injuries to professional horse-racing jockeys.

While there have been numerous reports in the literature of accidents in equestrian sports, no comprehensive study has been conducted to ascertain the nature and incidence of injuries incurred by professional horse-racing jockeys. A survey was conducted to determine the types of injuries to jockeys and racing-related health concerns, including weight reduction methods. The questionnaire was completed by 706 professional jockeys actively competing at United States racetracks between July and October 1990 about injuries they had sustained in their careers. More than 1,700 injuries were reported. Fractures (n = 1,113) accounted for 64% of the total. The most common cause of injury was becoming unseated, followed by the horse falling. Relationships between characteristics of jockeys and injuries were evaluated. There were significant numbers of serious injuries with prolonged periods of not riding. Recommendations for improving jockey safety are made.

Absenteeism↗
PubMed1993

Inhibitors of protein kinase C. 3. Potent and highly selective bisindolylmaleimides by conformational restriction.

The protein kinase inhibitor staurosporine has been used to design a series of selective bisindolylmaleimide inhibitors of protein kinase C (PKC). Guided by molecular graphics, conformational restriction of the cationic side chain has led to ATP competitive inhibitors of improved potency and selectivity. Two compounds have been further evaluated and were shown to inhibit PKC of human origin and prevent T-cell activation in a human allogeneic mixed lymphocyte reaction. One of these compounds was orally absorbed in mice and antagonized a phorbol ester induced paw edema in a dose-dependent manner. This compound also selectively inhibited the secondary T-cell mediated response in a developing adjuvant arthritis model in rats and provides evidence for the potential use of PKC inhibitors as therapeutic immunomodulators.

Alkaloids↗
PubMed1993

Relations between children's playground and classroom behaviour.

In this within-subjects design field experiment children's behaviour in the playground was charted as a function of gender and time in the classroom immediately preceding playtime. Playground behaviour was also related to post-recess classroom behaviour. Twenty-three 9-year-old children were observed for 14 weeks. Classroom behaviour (i.e., task relevant behaviour on standardised seat work immediately before and after playtime) and playground behaviour (i.e., social and non-social exercise and sedentary behaviour) were observed. Time in classroom before playtime was manipulated so that there was a shorter and a longer confinement period. Results indicated that children were less attentive to seat work as a function of time and that longer confinement resulted in more exercise for boys and more social sedentary behaviour for girls. Social behaviour at playtime and post-playtime attention to seat work were significantly related. Results are discussed in terms of Novelty Theory.

Attention↗
PubMed1992

Inhibitors of protein kinase C. 2. Substituted bisindolylmaleimides with improved potency and selectivity.

A hypothetical mode of inhibition of protein kinase C (PKC) by the natural product staurosporine has been used as a basis for the design of substituted bisindolylmaleimides with improved potency over the parent compound. Structure-activity relationships were consistent with the interaction of a cationic group in the inhibitor with a carboxylate group in the enzyme, and the most potent compound had a Ki of 3 nM. The inhibitors were competitive with ATP but inhibited cAMP-dependent protein kinase (PKA) only at much higher concentrations despite the extensive sequence homology between the ATP-binding regions of PKA and PKC. Three compounds were evaluated further and found to inhibit a human allogeneic mixed lymphocyte reaction pointing to the potential utility of PKC inhibitors in immunosuppressive therapy. One of these compounds was orally absorbed in the rat and represents an attractive lead in the development of PKC inhibitors as drugs.

Animals↗
PubMed1992

Oral, anti-inflammatory activity of a potent, selective, protein kinase C inhibitor.

The protein kinase C family of enzymes is thought to be important in mediating signal transduction. Ro 31-8830 is a novel, potent inhibitor of protein kinase C, derived from the non-selective protein kinase inhibitor staurosporine. In this paper we demonstrate the selectivity of Ro 31-8830 for protein kinase C over other protein kinases and its ability to inhibit protein kinase-C-mediated events in platelets and lymphocytes. In addition, we describe a novel system for the in vivo evaluation of inhibitors of protein kinase C, and we demonstrate the oral anti-inflammatory activity of Ro 31-8830. This finding has implications for the treatment of inflammatory disorders in the clinic.

Administration, Oral↗
PubMed1992

Inhibitors of protein kinase C. 1. 2,3-Bisarylmaleimides.

The design and synthesis of a series of novel inhibitors of protein kinase C (PKC) is described. These 2,3-bisarylmaleimides were derived from the structural lead provided by the indolocarbazoles, staurosporine and K252a. Optimum activity required the imide NH, both carbonyl groups, and the olefinic bond of the maleimide ring. 2,3-Bisindolylmaleimides were the most active, and the potency of these was improved by a chloro substituent at the 5-position of one indole ring (compound 28, IC50 0.11 microM). In a series of (phenylindolyl)maleimides, nitro compound 74 was most active (IC50 0.67 microM). Naphthalene 19 and benzothiophene 21 showed greater than 100-fold selectivity for inhibition of PKC over the closely related cAMP-dependent protein kinase (PKA).

Animals↗
PubMed1991

A novel conformationally restricted protein kinase C inhibitor, Ro 31-8425, inhibits human neutrophil superoxide generation by soluble, particulate and post-receptor stimuli.

A novel, bis-indolylmaleimide, Ro 31-8425, bearing a conformationally restricted side chain, inhibits protein kinase C isolated from rat brain and human neutrophils with a high degree of selectivity over cAMP-dependent kinase and Ca2+/calmodulin-dependent kinase. It also inhibits phorbol ester-induced intracellular events known to be mediated by protein kinase C (p47 phosphorylation in intact platelets, CD3 and CD4 down-regulation in T-cells). Ro 31-8425 inhibited superoxide generation in human neutrophils activated by both receptor stimuli (formyl-methionyl-leucylphenylalanine, opsonized zymosan, IgG and heat aggregated IgG) and post-receptor stimuli (1,2-dioctanoylglycerol and fluoride). The compound also blocked antigen driven, but not IL-2 induced, T-cell proliferation. These results support a central role for protein kinase C in the activation of the respiratory burst and antigen-driven T-cell proliferation.

Animals↗
PubMed1991

Modulation of cellular processes by H7, a non-selective inhibitor of protein kinases.

H7 has been described as a potent inhibitor of protein kinase C (PKC) and has been widely used to investigate the regulatory role of this enzyme in intact cell systems. In this comparative study between H7 and the microbial alkaloid, staurosporine, we found that the former inhibited rat brain PKC and cAMP dependent protein kinase with IC50 values of 18 and 16 microM respectively whereas the latter was a much more potent inhibitor of both kinases with IC50 values of 9.5 nM and 42 nM respectively. H7, at concentrations up to 100 microM, failed to block cellular events induced by phorbol esters, agents which specifically stimulate PKC, yet was a potent inhibitor of IL-2 induced T cell proliferation with an IC50 value of 19 microM. In contrast, staurosporine was a potent inhibitor of both phorbol ester induced p47 phosphorylation in platelet (I50 value = 540 nM) and also CD3 and CD4 down-regulation in T cells (I50 values 200 nM and 50 nM respectively). Staurosporine was also a potent inhibitor of IL-2 induced T cell proliferation I50 value = 9 nM). These results provide a strong argument against the use of H7 to probe for PKC involvement in cellular processes.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1991

Novel, potent and selective inhibitors of protein kinase C show oral anti-inflammatory activity.

Clarification of the precise role of protein kinase C (PKC) in cellular functional responses has been hampered by a lack of potent, selective inhibitors. The structural lead provided by staurosporine, a potent but non-selective protein kinase (PK) inhibitor, was used to derive a series of bis(indolyl)maleimides of which the most potent, Ro 31-8425 (I50: PKC = 8 nM) showed 350-fold selectivity for PKC over cAMP-dependent protein kinase. Ro 31-8425 antagonised cellular processes triggered by phorbol esters (potent, specific PKC activators) and inhibited the allogeneic mixed lymphocyte reaction, suggesting a role for PKC in T-cell activation. Methylation of the primary amine in Ro 31-8425 produced an analogue. Ro 31-8830 which, when administered orally, produced a dose-dependent inhibition of a phorbol ester-induced paw oedema in mice (minimum effective dose = 15 mg/kg). Ro 31-8830 also selectively inhibited the secondary inflammation in a developing adjuvant arthritis model in the rat. The results presented here suggest that these selective inhibitors of PKC may have therapeutic value in the treatment of T-cell-mediated autoimmune diseases.

Administration, Oral↗
PubMed1990

K252a is a potent and selective inhibitor of phosphorylase kinase.

The inhibition of phosphorylase kinase by a number of protein kinase inhibitors was examined. Both K252a and staurosporine are potent inhibitors of phosphorylase kinase with IC50 values of 1.7 nM and 0.5 nM respectively. K252a shows a 300-fold selectivity for this enzyme over protein kinase C whereas staurosporine shows only a 20-fold selectivity for phosphorylase kinase. In contrast, the Roche bis-indolyl maleimides inhibit phosphorylase kinase with IC50 values of approximately 1 microM and are highly selective for protein kinase C.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1989

Potent selective inhibitors of protein kinase C.

A series of potent, selective inhibitors of protein kinase C has been derived from the structural lead provided by the microbial broth products, staurosporine and K252a. Our inhibitors block PCK in intact cells (platelets and T cells), and prevent the proliferation of mononuclear cells in response to interleukin 2 (IL2).

Alkaloids↗
PubMed1989

1H-NMR and protection studies of interactions between ligands and bovine pancreatic phospholipase A2.

A number of long-chain amines and naphthylamine sulfonates have been studied for their ability to inhibit bovine pancreatic phospholipase A2 (PLA2) and to protect PLA2 against alkylation of the active site histidine by p-bromophenacyl bromide. Their areas of interaction on the enzyme were further delineated using observations of chemical shift changes of assigned aromatic signals in the 1H-NMR spectrum of PLA2, while the bound conformations of two amine inhibitors were revealed using transferred nuclear Overhauser effects. The alkyl amines bind rather non-specifically on the surface of the enzyme, over the active site cleft and the interface recognition site.

Amines↗
PubMed1985

Data entry by light pen.

Collection of data is often difficult in medical and nursing applications of computers. A system has been developed using an inexpensive light pen to enter most of the required information. This method of data entry has proved to be acceptable to medical and nursing staff in clinical situations. The software places light blocks adjacent to a list of items available for selection. When the pen is applied to a light block, the item is selected with visual and audible confirmation being given. Corrections may be made by re-applying the pen to the light block.

Computers↗
PubMed1982

Tapered connectors in patient breathing systems.

Investigations using recommended gauging tools have shown that many tapered connectors on breathing systems do not meet the relevant standard. It would be important to improve dimensional tolerances so that better interchangeability is achieved. This improvement may make it unnecessary to employ 'anti-disconnexion' fittings.

Adult↗
PubMed1981

The microcomputer in self-assessment for examinations in anaesthesia.

A series of 30 multiple choice questions were modified for presentation on a microcomputer which was programmed to present them to the user and mark them. In a preliminary study, 15 trainee anaesthetists all agreed the system was satisfactory as an aid to preparation for the FFARCS.

Anesthesiology↗