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Biomedical subjects

A Byrne

Publications and source records attributed to A Byrne.

At least 37 records · Page 2Linked to original sources
PubMed1998

Efficacy of salmeterol xinafoate powder in children with chronic persistent asthma.

BACKGROUND: The efficacy and safety of salmeterol powder have not previously been evaluated in children with asthma in the United States. OBJECTIVE: The efficacy and safety of salmeterol powder versus placebo were compared in children between the ages of 4 and 11 years with chronic persistent asthma. METHODS: A randomized, double-blind, placebo-controlled, parallel group trial was performed at 11 clinical centers. Two hundred seven patients were randomly assigned to receive 50 microg salmeterol powder or placebo (and albuterol as needed) twice daily via a breath-actuated device for 12 weeks. Twelve-hour serial pulmonary function assessments were conducted on day 1 and at week 12. Daily recordings of morning and evening peak expiratory flow (PEF), supplemental albuterol use, asthma symptoms, and nocturnal awakenings were assessed. RESULTS: On day 1 and at week 12, weighted mean percent of predicted PEF (P < .001, day 1 and P=.008, week 12) and weighted mean forced expiratory volume in one second (P < .001, day 1 and week 12) were significantly higher at all timepoints evaluated over the 12-hour postdosing period in patients treated with salmeterol powder compared with placebo. Overall reductions in supplemental albuterol use and mean asthma symptom scores were also significantly greater in children administered salmeterol compared with placebo (P=.004 and P=.006, respectively). The frequency of adverse events was similar in the two treatment groups. CONCLUSION: Salmeterol powder (50 microg twice daily) is effective and safe in producing bronchodilation and relieving symptoms in children with chronic persistent asthma during 12 weeks of treatment.

Albuterol↗
PubMed1998

Platelet activation, epinephrine, and blood pressure in obstructive sleep apnea syndrome.

OBJECTIVE: There is an increased risk of patients with obstructive sleep apnea syndrome (OSAS) to have stroke or cardiac infarcts. Besides hypertension, epinephrine-induced platelet activation could be a further reason for the increased cardiovascular morbidity and mortality in OSAS. METHODS: During a 4-month period (August 1994 to December 1994) we recruited prospectively 76 patients referred for polysomnograms because of a suspected sleep disorder such as OSAS. RESULTS: Fifty patients had no respiratory events during sleep (non-OSAS), 19 patients had more than five but less than 50 obstructive apneas or hypopneas per hour of total sleep time (mild-to-moderate OSAS group), and seven patients had an apnea hypopnea index of more than 50 per hour of total sleep time (severe OSAS group). Blood pressure, plasma epinephrine levels, and P-selectin expression (as a marker for platelet activation) were measured in every patient at 9 PM and 6 AM (before and after the polysomnogram). There was a significant correlation of the apnea hypopnea index with 9 PM and 6 AM systolic and diastolic blood pressure, with 9 PM platelet activation, and with 6 AM epinephrine levels mainly due to high values in the severe OSAS group. CONCLUSIONS: Our results suggest that platelet activation, epinephrine, and high blood pressure play a role in the high prevalence of cerebrovascular and cardiovascular events in patients with OSAS.

Adult↗
PubMed1997

Attributions and accessibility of explanations for future events in anxiety and depression.

OBJECTIVES: The research examined qualitative and quantitative aspects of future thinking in mood-disturbed participants. DESIGN: A cross-sectional, mixed design compared three groups of participants on measures of future thinking using an adapted fluency paradigm. METHODS: Participants who were either anxious (N = 25), anxious and depressed (mixed; N = 25), or neither anxious nor depressed (control; N = 25) were presented with a range of future positive and negative events and asked to provide explanations as to why those events would (pro reasons) or would not (con reasons) happen to them. Number of reasons given of each type was measured. The reasons were further analysed in terms of a number of attributional dimensions. RESULTS: Mood-disturbed participants (anxious and mixed) provided more pro relative to con reasons for negative events and more con relative to pro reasons for positive events. Compared to the control group, mood-disturbed participants also provided more internal and more global reasons for why negative events would happen and for why positive events would not happen. CONCLUSION: Mood-disturbed participants differ from controls on qualitative as well as quantitative aspects of future thinking.

Adult↗
PubMed1997

Continued thromboxane A2 formation despite administration of a platelet glycoprotein IIb/IIIa antagonist in patients undergoing coronary angioplasty.

Experimental data suggest that formation of thromboxane A2 may be suppressed during administration of a glycoprotein IIb/IIIa antagonist. We determined the dose of one such compound, fradafiban, required to provide > 80% occupancy of the platelet glycoprotein IIb/IIIa and examined its effects on thromboxane A2 formation in patients undergoing PTCA. The dose response to fradafiban and additional effects of aspirin were explored initially in patients with stable coronary artery disease. Fradafiban induced a dose-dependent inhibition of platelet aggregation that correlated with fibrinogen receptor occupancy and plasma drug concentration. Addition of aspirin 300 mg had no effect on these parameters. At the highest dose, mean fibrinogen receptor occupancy was 89.7 +/- 1.2% (n = 3) at 4 hours and platelet aggregation had decreased by 93.4 +/- 2.7%. Eighteen patients undergoing coronary angioplasty were randomized to receive either aspirin 330 mg or that dose of fradafiban producing > 80% fibrinogen receptor occupancy. Platelet aggregation was suppressed throughout the infusion of fradafiban to a greater extent than with aspirin. However, there was a marked increase in urinary excretion of 11-dehydrothromboxane B2 in patients treated with fradafiban: from 1973 +/- 889 to a peak of 9760 +/- 3509 pg/mg creatinine (P = .0046). Despite this evidence of continued platelet activation in vivo, there were no cases of coronary thrombosis. In conclusion, fradafiban suppresses platelet aggregation and may be a useful alternative to aspirin in the prevention of thrombotic events in patients undergoing PTCA. However, there is continued formation of thromboxane A2, which may continue to exert its effects as a potent vasoconstrictor and vascular smooth muscle mitogen.

Administration, Oral↗
PubMed1996

Anxiety, depression, and the anticipation of future positive and negative experiences.

An experiment is reported that attempts to distinguish between anxious and depressive future thinking in terms of anticipation of future positive and future negative experiences. Anxious, mixed (anxious-depressed), and control participants were given an adapted verbal fluency paradigm to examine the ease with which they could think of future positive and negative personal experiences. Anxious participants differed from controls only in anticipating more future negative experiences; mixed participants showed both greater anticipation of negative experiences and reduced anticipation of positive experiences. Self-report measures of hopelessness and worry followed a similar pattern to future positive and future negative anticipation, respectively. The results are discussed in terms of the distinction between positive affect and negative affect (D. Watson, L. A. Clark, & G. Carey, 1988).

Adult↗
PubMed1996

Harm minimization approaches to drug misuse: current challenges in evaluation.

Harm minimization approaches to drug misuse have become popular in recent years, particularly as a response to reducing the transmission of HIV among intravenous drug users. Harm minimization rests on the principle that many individuals will misuse drugs and that managing that misuse is more appropriate than attempting to stop use altogether. Such approaches are considered to be cost effective in comparison to treatment models which have abstinence as a goal, although the evidence is not available to make an assessment of this claim. This paper attempts to address the current challenges in relation to evaluating the efficacy of harm minimization approaches. It is argued that there is a need to more closely monitor the outcomes of harm minimization approaches to drug use and suggests ways in which this might be possible.

Australia↗
PubMed1995

Conditioned place preferences, conditioned locomotion, and behavioral sensitization occur in rats treated with diethylpropion.

Diethylpropion is a centrally acting appetite-suppressing drug thought to act primarily through catecholamine pathways in the brain. In the present study, four doses of diethylpropion (0, 10, 20, and 40 mg/kg, intraperitoneally) were administered to rats to examine the hypothesis that the drug has psychomotor stimulant properties such as the ability to induce conditioned behaviors and behavioural sensitization. The rats were administered drug and then vehicle on alternating days, and confined to a "drug" or vehicle-paired side of a two-compartment box for 16 pairings. Only the 10-mg/kg dose of diethylpropion increased spontaneous locomotor activity in comparison to vehicle; the 20- and 40-mg/kg doses significantly decreased spontaneous locomotion. All doses of diethylpropion decreased spontaneous rearing, and the 20-and 40-mg/kg doses produced significantly less rearing than the 10-mg/kg one. At the 10-mg/kg dose, conditioned place preferences, conditioned locomotion, and conditioned rearing were observed. The 40-mg/kg dose produced conditioned rearing and conditioned defecation. In response to a 5-mg/kg challenge injection of diethylpropion, behavioural sensitization in locomotion and rearing occurred in rats that had previously received any one of the three doses of diethylpropion. Over 36 days, decreased weight gain was observed only in the 20- and 40-mg/kg groups. The rats were killed 48 h after the last drug injection, and whole brain was analyzed for levels of the catecholamines, homovanillic acid (HVA), 3,4-dihydroxyphenylacetic acid (DOPAC), 5-HT (not a catecholamine), and 5-hydroxyindoleacetic acid (5-HIAA) by HPLC with electrochemical detection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗