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Biomedical subjects

P Lloyd

Publications and source records attributed to P Lloyd.

At least 37 records · Page 2Linked to original sources
PubMed1997

The effect of valsartan on the angiotensin II pressor response in healthy normotensive male subjects.

OBJECTIVE: Valsartan is an oral antagonist of angiotensin II that competes with angiotensin II for the AT1-receptor and is being developed as an antihypertensive agent. This study assessed the ability of 80 mg valsartan to inhibit the pressor effect of exogenous angiotensin II in healthy normotensive men, first after a single dose and then after multiple doses once daily for 7 days. METHODS: This was a single-center, double-blind, placebo-controlled, randomized crossover study. Six healthy men underwent angiotensin II challenges to determine a suitable dose required to increase their systolic blood pressure by approximately 30 mm Hg. Each subject then received an 80 mg dose of valsartan or matching placebo. The inhibition of the angiotensin II pressor effect was determined by the systolic blood pressure response to repeated angiotensin II challenges at multiple time points. RESULTS: Systolic blood pressure responses to angiotensin II challenges after single and multiple doses of valsartan were significantly lower than placebo, indicating that valsartan blocked the blood pressure response to angiotensin II. The maximum blocking effect was observed within 2 to 3 hours. Mean data suggested that differences in effect between valsartan and placebo were similar after both single and multiple doses and persisted up to 24 hours after administration. The angiotensin II blocking effect was maintained up to this time, despite low plasma valsartan levels and minimal accumulation after multiple doses. CONCLUSION: Valsartan, 80 mg, is a potent angiotensin II antagonist with a rapid onset of action and persistent angiotensin II inhibition up to 24 hours. There is no attenuation of this effect after multiple doses.

Adult↗
PubMed1997

The AERX aerosol delivery system.

PURPOSE: We describe the AERX aerosol delivery system, a new, bolus inhalation device that is actuated at preprogrammed values of inspiratory flow rate and inhaled volume. We report on its in vitro characterization using a particular set of conditions used in pharmacokinetic and scintigraphic studies. METHODS: Multiple doses of aerosol were delivered from single use collapsible plastic containers containing liquid formulation. The aerosol was generated by forcing the formulation under pressure through an array of 2.5 micron holes. Air was drawn through the device at 70 LPM, and the aerosol was collected onto a filter or Andersen cascade impactor. The emitted dose was quantified from the filter collection data, and the particle size distribution was obtained from the best fit log-normal distribution to the impactor data. RESULTS: 57.0 +/- 5.9% of the dose of drug placed as an aqueous solution in the 45 microL collapsible container was delivered as an aerosol (n = 40). The best fit size distribution had an MMAD = (2.95 +/- 0.06) microns and a geometric standard deviation sigma g = 1.24 +/- 0.01 (n = 6). CONCLUSIONS: The AERX aerosol delivery system generates a nearly monodisperse aerosol with the properties required for efficient and repeatable drug delivery to the lung.

Administration, Inhalation↗
PubMed1997

Does drawing attention to the referent constrain the way in which children construct verbal messages?

Tasks which assess children's speaker skills in the referential communication paradigm frequently mark the target item in some way to indicate which picture should be described. It was hypothesized that this procedure would interfere with effective scanning of the visual array (comparison processing) assumed to be necessary for the production of accurate messages. It was also predicted that, when one item was highlighted, more redundant features would be included in messages. An experiment which compared a marked with an unmarked target condition across three age ranges (6, 8, 10 years) found that message accuracy was not affected by highlighting. But significantly more redundant features were reported in the marked condition, indicating that, where redundancy is the focus of interest, a highlighting procedure should be avoided. Two age effects were also found: Message accuracy improved with age, while redundancy reduced with age.

Attention↗
PubMed1997

Effect of a 15-minute infusion of DDAVP on the pharmacokinetics and pharmacodynamics of REVASC during a four-hour intravenous infusion in healthy male volunteers.

Plasma pharmacokinetics, effect on coagulation parameters, and safety and tolerability of an intravenous infusion of REVASC before, during and after a DDAVP infusion were investigated. Twelve healthy volunteers were given an intravenous bolus dose followed by a constant rate four-hour infusion of REVASC. Fifteen-minute infusions of 0.9% saline and DDAVP were started two and three hours respectively after the start of the REVASC infusion. Plasma REVASC concentrations were not affected by either the saline or DDAVP infusion. REVASC infusion produced an increase in APTT which plateaued between 0.5 and 3 hours. After the DDAVP infusion there was a tendency towards a new lower plateau whilst the REVASC infusion continued. There were no serious adverse events or bleeding episodes throughout the study. In conclusion, the co-administration of intravenous DDAVP has no effect on the plasma pharmacokinetics of REVASC and partially reverses the REVASC-induced increase in APTT. This may represent a role for DDAVP in the partial reversal of anticoagulation induced by REVASC.

Adult↗
PubMed1997

Moving patients.

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Back Injuries↗
PubMed1995

Validation of the MMPI-2 Low Self-Esteem Content Scale.

We explored the concurrent validity of the MMPI-2 Low Self-Esteem (LSE) Content scale by asking 216 undergraduate students to complete the Minnesota Multiphasic Personality Inventory-2 (Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1991), Harter Adult Self-Perception Profile (Harter, 1986a) and Rosenberg Self-Esteem Scale (Rosenberg, 1965). Results suggest the LSE renders a good assessment of global self-esteem as well as being a measure of three distinct components of self-esteem. These specific subscales, identified by factor analysis, were labeled Ineptitude, Negative Self-Value, and Negative Comparison with Others. The LSE and its subscales produced good internal consistency (alpha and Gutman Split Half) coefficients.

Adolescent↗
PubMed1994

Clinical pharmacology and pharmacokinetics of oxcarbazepine.

Oxcarbazepine (OCBZ) is a new antiepileptic drug (AED) structurally related to carbamazepine (CBZ) but differing in several important aspects, notably metabolism and induction of metabolic pathways. Consequently, OXCB has fewer drug-drug interactions compared with CBZ. Absorption of OCBZ is rapid and complete. In animals it is responsible for the pharmacological effect. In humans, however, the parent compound is rapidly and extensively metabolized to a monohydroxy derivative (MHD), which is responsible for the therapeutic effect. Exposure to the MHD increases dose proportionally, and steady state is achieved after only three or four doses in a twice-daily regimen. When given with food, systemic exposure to MHD increases by about 17%. MHD is eliminated with a half-life of about 8-10 h. About 27% of the dose is recovered in the urine as unchanged MHD and a further 49% as a glucuronide conjugate of MHD. Results suggest that the kinetics of OCBZ should not be affected by impaired liver function. Impaired kidney function does not affect the kinetics of MHD; the glucuronide conjugate will, however, accumulate in these patients. The conversion of OCBZ to MHD is catalyzed by reductase enzymes, which are not subject to induction. Furthermore, OCBZ itself does not appear to induce the cytochrome P-450 family in general, although it does induce the P-450 IIIA subfamily, which is responsible for the metabolism of estrogens and the dihydropyridine calcium-channel blockers (e.g., nifedipine, felodipine). In patients, linear and dose-proportional kinetics with no autoinduction of metabolism simplify OCBZ dosage adjustment.

Adolescent↗
PubMed1994

Management competencies in health for all/new public health settings.

Competency-based health management research, commonly undertaken by educationalists, has tended to draw upon the attitudes and beliefs of managers from the curative, institutional/bureaucratic health care sector. With traditional health care priorities being questioned in many industrialized countries, and in particular with greater attention being paid to the concepts underlying the "Health for All" (or what is known in Australia perhaps more commonly as the "New Public Health") movement, there would seem to be a need to broaden competency-based research to incorporate the attitudes of practitioners managing non-curative health services and programs. To this end an exploratory qualitative research project involving New Public Health managers in a series of semi-structured focus sessions was undertaken. The discussions were transcribed and analyzed to identify and isolate the features perceived to be essential for effective New Public Health practice and its management. While consensus was not apparent even on definitional issues, certain qualities were seen as necessary in the effective public health manager. In particular "key figure" attributes--charisma, commitment, and drive--were rated highly, as were the abilities to function in a loosely regulated environment while at the same time dealing with bureaucratic processes.

Administrative Personnel↗
PubMed1994

v-raf suppresses apoptosis and promotes growth of interleukin-3-dependent myeloid cells.

Interleukin-3 (IL-3) is required for the proliferation, survival and differentiation of myeloid progenitors. In the absence of IL-3, murine myeloid 32D.3 cells accumulate in the G1 phase of the cell cycle and subsequently undergo programmed cell death, or apoptosis. Here we demonstrate that enforced expression of the v-raf oncogene suppresses apoptosis of myeloid 32D.3 cells following the withdrawal of IL-3. Surprisingly, steady state levels of Bcl-2, an oncogene known to suppress apoptosis, were not dependent upon IL-3 in 32D.3 cells and its levels were not augmented in v-raf clones. This suggests that ability of v-raf to suppress apoptosis in the absence of ligand is either Bcl-2 independent or that v-raf kinase promotes Bcl-2 function. v-raf also promoted growth of these cells in the presence of IL-3. v-raf clones proliferated at an increased rate due to a shortened G1 phase and had decreased requirements for IL-3 for growth. Therefore, transformation of myeloid cells by v-raf involves signaling pathways which promote both cell cycle progression and cell survival.

Animals↗
PubMed1993

After Allitt.

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Occupational Health↗
PubMed1993

Choosing alternative therapy: an exploratory study of sociodemographic characteristics and motives of patients resident in Sydney.

Disenchantment with allopathic medicine has coincided with an upsurge in recent years in Australians consulting alternative therapists about their health care needs. Two major government studies have provided valuable independent evidence about the sociodemographic characteristics of users of alternative therapies and about their attitudes to health and medical care. However, the focus of these inquiries was predominantly on the users of chiropractic and osteopathy, just two of the modalities which make up this diverse field. To investigate, among other things, who consults alternative practitioners, how they come to choose a particular therapist, and whether, and on what basis, they have abandoned cosmopolitan medical care or use a combination of alternative and allopathic medicine, we conducted a cross-sectional survey of 289 patients of eight Sydney practices providing a range of alternative modalities. Findings indicate that far from being representative of the Australian community, the majority of our sample population came from a very select group, with a narrow range of socioeconomic backgrounds. The health risk behaviour of those surveyed was also significantly different from that exhibited by the population in general.

Attitude to Health↗