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D M Murray

Publications and source records attributed to D M Murray.

At least 145 records · Page 8Linked to original sources
PubMed1984

The shunt pathway of mevalonate metabolism in the isolated perfused rat liver.

The shunt pathway of mevalonate metabolism (Edmond, J., and Popják, G. (1974) J. Biol. Chem. 249, 66-71) has been studied in isolated livers from fed rats perfused with physiological concentrations of variously labeled [14C]mevalonates. The measured rates of 14CO2 production were converted to rates of mitochondrial acetyl-CoA production from mevalonate by methods which take into account underestimations of metabolic rates derived from 14CO2 production. Our data confirm that the shunt pathway leads to mitochondrial acetyl-CoA. The apparent negligible rate of mevalonate shunting in liver, previously reported by others, stems from the very low contribution (congruent to 0.1%) of plasma mevalonate to total mevalonate metabolism in the liver. This contribution was assessed from the relative incorporations of 3H2O and [5-14C]mevalonate into sterols. In livers from fed rats, the shunt diverts about 5% of the production of mevalonate. The total rate of mevalonate shunting in the liver is about 200 times greater than in two kidneys. The liver is therefore the main site of mevalonate shunting in the rat.

Acetyl Coenzyme A↗
PubMed1984

The shunt pathway of mevalonate metabolism in the isolated perfused rat kidney.

The shunt pathway of mevalonate metabolism (Edmond, J., and Popják, G. (1974) J. Biol. Chem. 249, 66-71) has been studied in isolated kidneys from rats perfused with physiological concentrations of variously labeled [14C]- and [3H]mevalonates. The rate of operation of the shunt pathway was quantified by the production of either 14CO2 or 3H2O from the tracers. The measured rates of 14CO2 production from [14C] mevalonate were converted to rates of mitochondrial acetyl-CoA production by methods which take into account underestimations of metabolic rates derived from 14CO2 production. We have shown that the sex difference in renal shunting of mevalonate (Wiley, M. H., Howton, M. M., and Siperstein, M. D. (1979) J. Biol. Chem. 254, 837-842) occurs at physiological levels of substrate. The shunt pathway diverts up to 17% of the flux of mevalonate entering the cholesterol synthesis pathway in the kidney. It may, therefore, play a role in the long term regulation of cholesterol synthesis in this organ, as had been hypothesized by Edmond and Popják.

Acetyl Coenzyme A↗
PubMed1984

Measurement of adolescent smoking behavior: rationale and methods.

The initiation of cigarette smoking among adolescents is a health problem which has been the subject of discussion and study for many years. The evaluation of strategies to deter the adoption of smoking has long been hampered by the problems of measuring adolescent smoking behavior. Recently, interest has increased in biochemical measures of smoking under the assumption that they are more objective measures. The validity of this assumption is addressed for several ages of adolescents. This paper presents saliva thiocyanate levels, expired air carbon monoxide levels, and smoking self-reports from a sample of 2200 junior and senior high-school students. Interrelationships among the biochemical and behavioral measures are strong among the total population, ranging from 0.48 to 0.95 (Pearson r) but are much weaker at the younger age levels. Normative levels of carbon monoxide and saliva thiocyanate are presented by age (11-13, 14-15, and 16-17 years old). These data indicate that habitual smoking appears to develop in a gradual fashion and that several years may pass between initial experimentation and adult levels of smoking. Younger students consistently display lower levels of thiocyanate and carbon monoxide than older students of the same self-reported levels of smoking, suggesting that inhalation patterns may vary as a function of age or years smoking.

Adolescent↗
PubMed1984

Response to O'Malley: cigarette smoking among high school seniors.

P. M. O'Malley (Prev. Med. 13, 421-426, 1984) has stimulated discussion on the issues of self-reported smoking, the use of validation procedures to enhance self-report of smoking behavior, and the question of trends toward increases in underreporting of adolescent smoking. O'Malley's analysis was prompted by an earlier report of data from the Childhood Antecedents of Smoking Study. In response to O'Malley, further analysis comparing data from the Childhood Antecedents of Smoking Study with data from the Monitoring the Future study is presented, and recent evidence on the "bogus pipeline" methodology is reviewed.

Adolescent↗
PubMed1983

Prevention of cigarette smoking: three-year follow-up of an education program for youth.

We reported previously on the success of an innovative approach to cigarette smoking prevention in seventh-grade students. The present report describes a 3-year follow-up of three schools and 1081 students initially involved in the research program. The curriculum emphasizes the short-term influences which affect smoking in youth, particularly social and peer influences. In the school which received this curriculum from like-aged peer leaders, the incidence of smoking remained low compared to that in a control school. Those who did smoke in this school consumed significantly fewer cigarettes. In the school where the curriculum was adult taught, smoking rates were initially lower but rose in the later years, ultimately differing little from those in the control school. Reported smoking behavior was confirmed by saliva thiocyanate measurement in all students. Cigarette smoking behavior appears significantly inhibited by a peer-taught curriculum and that effect is retained for several years after the education program.

Adolescent↗
PubMed1983

Nonverbal behavior of the type A individual.

Forty-one health professional students were videotaped during three consecutive conditions: a 5-min wait for a tardy interviewer, the structured interview for determining the Type A behavior pattern, and a 5-min relaxation period. Afterward, subjects were classified as Type A or B based on audiotapes of the interview. The total amount of activity and the frequency or duration of Type A behaviors were compared between Type A and Type B subjects. In all three experimental conditions, Type A subjects moved their arms more than Type B subjects. During both the waiting and the relaxation periods, Type A subjects sat still less and spent more time exploring than did Type B subjects. During the interview, Type A subjects gestured more frequently than Type B subjects. Nonverbal behaviors correctly identified behavior pattern in 71% of the subjects. The addition of nonverbal behaviors improved the discrimination of behavior pattern above that obtained from verbal behavior alone. The greater activity, restlessness, exploratory behavior, and gestures of Type A persons are consistent with the two major etiologies proposed for the Type A behavior pattern.

Adult↗
PubMed1982

Nutrition education in supermarkets: an unsuccessful attempt to influence knowledge and product sales.

Although much evidence links dietary patterns with coronary heart disease, effective and economical methods for inducing dietary change in nonclinical populations are needed to influence public health. This study was designed as a preliminary investigation of the feasibility of conducting effective nutrition education campaigns in supermarket settings. Eight supermarkets from a supermarket chain in the Twin Cities area participated. Four were assigned to an experimental condition in which educational materials consisting of posters, recipes, and brochures were placed in the dairy section during a 6-month period. Four other stores were assigned to a control condition and received no educational materials. Shoppers in experimental and control stores completed a nutrition survey pre- and post-intervention. In addition, sales data for 25 dairy products were collected during a 10-month period. A significant increase in knowledge on the nutrition survey between pre- and posttests occurred among shoppers in all stores. There was no significant knowledge or product sales effect due to the education campaign. Study results suggest that, overall, shopper knowledge of food selections for cardiovascular disease risk reduction is high and improving. Unfortunately, knowledge is often not reflected in food purchase patterns.

Adult↗
PubMed1982

Metabolism of plasma mevalonate in rats and humans.

A circadian rhythm in plasma mevalonate was identified in human subjects. This variation, over a 5-fold range, is paralleled by a rhythm in urinary excretion. No such diurnal change in plasma mevalonate was observed in schedule-fed, light-cycled rats, despite the presence of a pronounced rhythm in liver HMG-Coa reductase and sterol synthesis. A linear correlation was found between liver HMG-CoA reductase activity and the rate of hepatic sterol synthesis. Sterol synthesis accounted for 59% of the HMG-CoA reductase activity. A 4-fold increase in plasma mevalonate following bilateral nephrectomy did not feed back on liver HMG-CoA reductase. Turnover rates for circulating R- and S-mevalonate were determined by the kinetics of tritiated tracers. S-Mevalonate exhibited first-order kinetics with a T 1/2 of 19 to 23 min, while R-mevalonate kinetics could be resolved into two phases with half-lives of 9 and 42 min. The renal uptake of circulating mevalonate was measured by the initial rate of increase in plasma mevalonate immediately following bilateral nephrectomy; this was confirmed by determination of the renal arterio-venous difference. This value ranges between 500 and 600 pmol/min for a 250-g rat.

Adult↗
PubMed1981

The Minnesota smoking prevention program: a seventh-grade health curriculum supplement.

A seventh-grade program based on social psychological theories attempted to prevent non-smokers from starting to smoke. Two competing strategies, a Short-Term Influences Curriculum and a Long-Term Influences Curriculum were compared. Within these broad strategies, several other variables were also tested: the use of same age peer opinion leaders or health educators as teachers, the use of media supplements and the elicitation of a public commitment not to become a regular smoker. Program effectiveness was evaluated using self-report measures confirmed by saliva thiocyanate analyses. The treatment groups were compared to a standard curriculum comparison group.

Adolescent↗
PubMed1981

Saliva thiocyanate: a chemical indicator of cigarette smoking in adolescents.

Denial and minimization in self-reports of cigarette smoking are probable common among youth and other groups where smoking is discouraged. Chemical measures may obtain more accurate measurement of smoking habits in those groups. One such measure, saliva thiocyanate (SCN), was evaluated in 1,419 eighth grade students. In that group, 54.9% of students admitted to regular smoking of greater than one pack/week had thiocyanates greater than or equal to 100 m g/ml compared to 2.3% nonsmokers at those levels. Of students who smoked greater than or equal to 10 cigarettes in the prior 24 hours, 66.7% were at or above 100 microgram/ml. Elevated SCN in nonsmokers was uncommon. Saliva SCN is a safe, inexpensive, and acceptable prevalence measurement for cigarette smoking. It can be used in place of self-reports to document smoking of greater than on pack/week in populations of youth.

Adolescent↗
PubMed1978

The cat's response to stimulus difference as attention focus and cue.

The cat's response to visual difference targets in figure-ground and figure-figure arrays (a unique target figure in a field of contrasting identical figures) was studied. Subjects approached the targets of the figure-ground arrays readily when they were presented in a training series, learning to use them as cues to the location of a food reward, and showing no disturbance when stimulus aspects of the arrays were reversed. Response to the figure-figure targets during training was more variable. Some were approached promptly, but others, especially those involving interchanging of target and background elements, required considerable training before consistent approach was achieved. Subjects selected the target with significant frequency in test series with novel figure-ground arrays, even after only brief training; they did not, however, select the target in novel figure-figure arrays until they had extended experience with training stimuli.

Animals↗
PubMedDate not supplied

Statistical models appropriate for designs often used in group-randomized trials.

Group-randomized trials are characterised by the allocation of identifiable groups rather than individuals to study conditions; members within those groups are then observed to assess the effect of the intervention. It is convenient to categorize the designs employed in group-randomized trials along two dimensions, each with two levels. The first distinguishes between designs having just one or two time intervals and those having three or more intervals. The second distinguishes between nested cohort and nested cross-sectional designs. Following a brief review of the design and analytic issues common to group-randomized trials, and their general solutions, this paper presents the adaptations of the mixed-model analysis of covariance and random coefficients models that are required for the four combinations that result from this categorization scheme. The assumptions, strengths and weaknesses of each model are discussed.

Cohort Studies↗
PubMedDate not supplied

Three approaches to adolescent smoking detection: a comparison of "expert" assessment, anonymous self-report, and co measurement.

A new method designed to assess adolescent smoking was recently developed and applied by researchers in the former Soviet Union. As originally applied in Lithuania and Russia, two official student leaders from each class were chosen to estimate smoking prevalence rates for their class, and so the method became labeled as the "expert assessment." Their findings suggested that this "expert assessment" method agreed quite well with school-wide prevalence estimates based on a survey of the entire school population. The purpose of the present study was to determine whether student representatives, selected at random and coached to accurately summarize the smoking habits of their classmates, could provide accurate estimates of the smoking prevalence rate in their school. To accomplish this purpose, estimates from the student representatives were compared to those from an anonymous survey and from measurement of carbon monoxide in expired air. The results indicated that the self-report and carbon monoxide data were in close agreement, while the student representatives substantially overestimated the prevalence of smoking in their school, in spite of the coaching provided according to the "expert assessment" protocol. Additional research on alternative methods to select student representatives, such as those based on a sociometric analysis, may yet result in a low-cost method to assess schoolwide levels of smoking in adolescent populations.

Adolescent↗