PubMed Health⌕ Search

Biomedical subjects

L M Isaac

Publications and source records attributed to L M Isaac.

5 recordsLinked to original sources
PubMed1997

Effects of SCA40 on bovine trachealis muscle and on cyclic nucleotide phosphodiesterases.

While UK-93,928 (1-[[3-(6,9-dihydro-6-oxo-9-propyl-1H-purin-2-yl)-4-ethoxyphenyl] sulfonyl]-4-methylpiperazine; 5 nM-5 microM) was devoid of relaxant activity, benzafentrine, isoprenaline, levcromakalim and SCA40 (6-bromo-8-methylaminoimidazo[1,2-a]pyrazine-2-carbonitrile) each relaxed histamine (460 microM)-precontracted bovine isolated trachealis. Each of these relaxants was antagonised by a K+-rich (80 mM) medium. Except in the case of levcromakalim, nifedipine (1 microM) offset this antagonism. Charybdotoxin (100 nM) antagonised isoprenaline in a nifedipine-sensitive manner but did not antagonise SCA40 or benzafentrine. Iberiotoxin (100 nM) did not antagonise SCA40. Acting on tissue precontracted with carbachol, SCA40 potentiated isoprenaline but did not potentiate sodium nitroprusside. While levcromakalim (1 and 10 microM) induced hyperpolarisation, SCA40 (1 and 10 microM) induced little change in the membrane potential of bovine trachealis. In trachealis preloaded with 86Rb+, levcromakalim (1 and 10 microM) promoted efflux of the radiotracer while SCA40 (1 and 10 microM) had no effect. Tested as an inhibitor of isoenzymes of cyclic nucleotide phosphodiesterase, SCA40 was most potent against the type III, less potent against the type IV and least potent against the type I isoenzyme. It is concluded that neither inhibition of phosphodiesterase type V nor the promotion of BKCa channel opening explains the tracheal smooth muscle relaxant activity of SCA40. This compound relaxes bovine tracheal smooth muscle mainly by inhibiting phosphodiesterase isoenzyme types III and IV.

Animals↗
PubMed1994

Questionable prescribing for elderly patients in Quebec.

OBJECTIVE: To estimate the prevalence of questionable and rational high-risk prescribing among elderly people of the three drug groups most commonly implicated in drug-related illness: cardiovascular drugs, psychotropic drugs and nonsteroidal anti-inflammatory drugs (NSAIDs). DESIGN: Retrospective prevalence study; all prescription and billing records for the period Jan. 1 to Dec. 31, 1990, for the study sample were retrieved from the relevant provincial databases of the Régie de l'assurance-maladie du Québec. SETTING: Quebec. PARTICIPANTS: Regionally stratified random sample of 63,268 elderly medicare registrants who made at least one visit to physician in 1990 and were not living in a health care institution for the entire year. MAIN OUTCOME MEASURE: Prescription information was examined for three types of high-risk prescribing: rational and questionable drug combinations, excessive treatment duration and drugs relatively contraindicated for use in elderly people. RESULTS: Overall, 52.6% of the patients experienced one or more events of high-risk prescribing, and 45.6% experienced at least one that was questionable. High-risk prescribing was most prevalent for psychotropic drugs, and questionable prescribing was more frequent than rational prescribing in this drug group. An estimated 30.8% of the total elderly population in Quebec received benzodiazepines for more than 30 consecutive days, 12.9% received a long-acting benzodiazepine, and 13.0% received a questionable high-risk psychotropic drug combination. The prevalence of high-risk prescribing was higher among the women than among the men and increased with age until 75 to 84 years. There were significant unexplained differences between regions in the regional prevalence of high-risk prescribing, particularly of psychotropic drugs. CONCLUSION: The prevalence of questionable high-risk prescribing, especially of psychotropic drugs, is substantial among elderly people. This may be a potentially important and avoidable risk factor for drug-related illness in elderly people.

Age Factors↗
PubMed1993

Compliance and cognitive function: a methodological approach to measuring unintentional errors in medication compliance in the elderly. McGill-Calgary Drug Research Team.

This study describes the development of a method for assessing the relationship between cognitive function, comprehension, and compliance with medication. We assessed multiple aspects of cognitive performance, medication planning ability, and medication compliance in a convenience sample of 20 outpatients. Using a test battery that measured mental status, attention/concentration, memory function, and motor strength and dexterity, we found that: (1) standard mental status assessment was poorly correlated with memory function; (2) attention/concentration and memory were related to medication planning accuracy; (3) motor dexterity and strength were related to the ability to access medications; and (4) visual perception and memory were the skills most strongly correlated with medication compliance. Findings suggest that aspects of attention/concentration, visual and verbal memory, and motor function which are untapped by simple mental status assessment are related to medication access, planning, and compliance in elderly patients.

Aged↗
PubMed1990

Endorsement and strength of alcohol expectancies.

It has been suggested that the strength of alcohol-related expectancies can be ascertained from the number of items endorsed on subscales consisting of multiple items. In the present study, subjects were asked to rate the strength of their beliefs in addition to indicating whether or not they endorsed the items on a measure of alcohol-related expectancies. Three issues were addressed: (1) Do strength ratings and endorsements predict the perceived likelihood of drinking when their correlated effects are taken into consideration and do these responses interact? (2) Do the endorsements and strength ratings form higher order factors? and (3) Do men and women with various drinking habits rate the strength of their beliefs for a moderate and a large dose of alcohol in a way that mirrors their endorsements? The results suggest that the strength of an alcohol-related expectancy must be measured in its own right and cannot be inferred from the pattern of endorsements. Interactions of endorsements and strength ratings produce unique information that is not deducible from either measure alone.

Adolescent↗