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Biomedical subjects

B Johnstone

Publications and source records attributed to B Johnstone.

At least 73 records · Page 4Linked to original sources
PubMed1990

The relationship between the pediatric neurological examination and neuropsychological assessment measures for young children.

Children with some degree of neurological dysfunction have traditionally been assessed by means of pediatric neurological examinations and/or neuropsychological test batteries. The present study investigated the relationship between these two different assessment methods in a normal population of 129 kindergarten and second grade students. Results indicated that of the 396 correlations conducted for each grade, 18% of the kindergarten and 15% of the second grade sample correlations were significant at the .01 level. Given the relatively few positive correlations, and the fact that there were few consistent patterns within and across grade levels, it was concluded that these two assessment procedures measure different areas of functioning and constitute two separate components of a broad evaluation of the relationship between behavior and the adequacy of brain functions.

Age Factors↗
PubMed1990

Chemoprevention for lung cancer--evidence for a high degree of compliance.

Studies of treatment efficacy are important for the development of cancer chemoprevention strategies. Recruitment aims for motivated, compliant subjects. The Concerned Smoker Study targets smokers with at least a 15-pack-year history and bronchial atypia on sputum sampling. Subjects receive etretinate 25 mg daily or identical placebo and are followed for 6 months. Compliance was monitored by assessing timely return for follow-up visits, return of monthly sputum samples, pill counts, and serum etretinate levels. Contamination, in the control group, was assessed by measuring etretinate levels. With half of the subjects having completed the study, this report assesses compliance: 88% follow-up visits occurred on schedule with only 9 missed visits of a possible total of 380; 443 (97.1%) of 456 possible sputum samples were returned. Pill counts indicated a high degree of compliance which was supported by the serum etretinate levels. Contamination was insignificant. The results suggest a very high degree of compliance. Only minor protocol changes will be required.

Etretinate↗
PubMed1989

Etretinate blood levels in monitoring of compliance and contamination in a chemoprevention trial.

We measured serum etretinate to monitor compliance in an ongoing chemoprevention trial in which heavy smokers are randomized to either etretinate or placebo orally for 6 months. Blood is collected for determination of etretinate levels before treatment and then at 2, 4, 8, 16, and 24 weeks after randomization. The monitoring strategy was assessed by interim evaluation. There were 276 posttreatment samples available from 75 randomized subjects of whom 36 received etretinate and 39 placebo. The mean coefficient of variation for the internal standard retinyl acetate in serum was 4.16% for the high-pressure liquid chromatography method used. Among positive samples, the mean etretinate concentration was 25.7 ng/mL (SD, 23.4). Of the 131 samples obtained from subjects randomized to etretinate, 120 or 91.6% had detectable levels compared with 4 of 145 or 2.8% placebo samples. Among the 36 subjects given etretinate, at least one positive test occurred. In 27 of these 36 participants, etretinate was detected in every sample obtained. In the other nine, the absence of drug could be explained by pill counts or a history of discontinuation of treatment for six. Among the 39 subjects given placebo, the four positive samples were from four individuals, all of whom were negative on three other occasions. These data confirm the usefulness of the monitoring system we used and indicate that compliance and/or contamination will not be major problems in this trial.

Chromatography, High Pressure Liquid↗
PubMed1989

Recruitment for an efficacy study in chemoprevention--the Concerned Smoker Study.

Efficacy studies are important for the development of long-term cancer prevention strategies. Recruitment aims for a highly motivated group of participants. The Concerned Smoker Study is aimed at smokers with at least a 15 pack-year history and bronchial atypia on sputum sampling Recruitment has been primarily through use of the media. During the first year of randomization 905 potential participants expressed interest. Of these, 80 were eventually randomized. With over 60 participants having completed the study only one has defaulted and compliance with the study protocol has been high. Participants became aware of the study through the following sources: daily newspaper 36.6%, weekly newspaper 16.2%, television 14.9%, radio 13.8%, community television 1.3%, other sources 13.3%. Over 90% of potential participants who initially express interest in such a chemoprevention project may not ultimately be suitable. The population chosen for such studies may not be very representative of the more general population; however, a high degree of compliance can be obtained which will provide valuable information on treatment efficacy.

Advertising↗
PubMed1988

1988 Volvo award in basic science. Proteoglycan synthesis in the human intervertebral disc. Variation with age, region and pathology.

Slices of human annulus fibrosus were cultured under conditions that controlled their hydration and prevented loss of proteoglycans from the extracellular matrix. A quantitative analysis of proteoglycan synthesis was carried out. Both the absolute rate of synthesis and the topographical variation in chondrocyte activity changed with age; the most active cells in the adult were found in the mid-annulus region, whereas in the fetal disc the cells in the inner annulus were the most active. The conditions under which the tissue was stored, and changes in hydration during culture, had considerable effects on synthesis. Pathological discs had a wide range of biological activity that reflected the heterogeneous properties of these specimens. It is suggested that this culture method provides a means of investigating the way in which the synthesis of the macromolecular components of the intervertebral disc are coordinated and subsequently incorporated into the extracellular matrix.

Adolescent↗
PubMed1988

Test-retest reliability of the Reitan-Indiana Neuropsychological Test Battery for Children Aged 5 Through 8.

The present study attempted to assess the test-retest reliability of the Reitan-Indiana Neuropsychological Test Battery for Children aged 5 through 8 and to establish the magnitude of practice effects for a normal sample of school aged children. The sample population included 191 kindergarten and 193 second grade students who were administered the entire Reitan-Indiana Battery during the first year of the study and again at one year follow-up. Correlation analyses of random half samples of the population revealed 35 of the 39 test indices measured were stable for at least one of the half samples for the younger (kindergarten-first grade) sample with the same being true for 31 of the 39 variables assessed for the older (second-third grade) sample.

Child↗
PubMed1986

In vitro method for measuring synthesis rates in the intervertebral disc.

A method for culturing intervertebral disc tissue in vitro under conditions that control changes in hydration and minimize loss of proteoglycans has been developed. Disc slices were enclosed in small-pore dialysis tubing and incubated in medium containing polyethylene glycol (PEG). By varying the PEG concentration, different external swelling pressures could be applied to the tissue. The rate of glycosaminoglycan synthesis in rabbit and dog disc was then measured using [35S]sulphate as a precursor. Synthesis rates varied with final hydration of the tissue, and the highest rates were found at hydrations close to those found in vivo. Under conditions of controlled hydration, rabbit nucleus has a higher rate of glycosaminoglycan synthesis than annulus. However, the rates measured in sagittal slices of dog disc decreased from the outer to the inner regions of the anterior annulus, reaching a minimum value in the nucleus and then increasing again in the posterior part of the annulus. The results show that in the intervertebral disc, measured rates depend on culture conditions.

Animals↗