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Biomedical subjects

D L Johnson

Publications and source records attributed to D L Johnson.

At least 361 records · Page 20Linked to original sources
PubMed1967

Honey bees: do they use the direction information contained in their dance maneuver?

Direction communication experiments, when controlled against unilateral visitation of trained foragers at the experimental site, exhibited no evidence supporting the precision of communication suggested in the dance "language" hypothesis. Results compare well with those which might be expected on the basis of the geometric arrangement of the feeding dishes.

Animals↗
PubMedDate not supplied

Antitumor agents from bohemic acid complex, III. The isolation of marcellomycin, musettamycin, rudolphomycin, mimimycin, collinemycin, alcindoromycin, and bohemamine.

Six anthracycline antitumor agents, marcellomycin, musettamycin, rudolphomycin, alcindoromycin, collinemycin, and mimimycin, have now been isolated from bohemic acid complex. This has been achieved by classical column chromatography with Sephadex LH-20 and ammonia-neutralized silica and by analytical and prepatative hplc techniques with normal phase systems containing aqueous ammonia.

Animals↗
PubMedDate not supplied

Use of global positioning system technology to track subject's location during environmental exposure sampling.

Global positioning system (GPS) data recorders were worn by subjects in the Oklahoma Urban Air Toxics Study (OUATS) for automatic logging of their location as they went about their normal daily activities. The location information obtained by the GPS units had an uncertainty of about 10-20 m, which was sufficiently precise to track subjects' movements on trips outside the immediate vicinity of their homes. Due to instrument problems, primarily related to reduced battery life, the units operated for only about 30% of the total monitoring time attempted in 25 trials. The GPS data were compared to time-activity diaries kept by the subjects. In almost all cases, the GPS data confirmed all travel events reported in the subjects' diaries. Additionally, in five out of five trials in which the logging period covered most or all of the subjects' daytime activities, at least one travel event that was not recorded in the diary was detected by GPS. Notwithstanding the limitations of present technology, GPS was found to be a promising means for tracking of research subjects in community-based exposure assessment studies.

Adult↗
PubMedDate not supplied

Effects of early middle ear effusion on child intelligence at three, five, and seven years of age.

OBJECTIVE: This study tested the hypothesis that children with prolonged middle ear effusion (MEE) during the first 3 years of life are at risk for cognitive delays or deficits. METHOD: A prospective study enrolled 698 children from diverse backgrounds and controlled for eight demographic and environmental factors. Participants were recruited at birth and monitored for ear status frequently in the home; 379 children were assessed for cognition with the Stanford-Binet, 4th ed., at 3 years of age, 294 at 5 years, and 198 at 7 years. RESULTS: Using the SAS General Linear Models (GLM) procedure, we found a significant direct relation between duration of bilateral MEE and Stanford-Binet Composite and Nonverbal Reasoning/Visualization Factor scores at age 3, but not at age 5 or age 7. Statistical clustering analysis revealed four groups with different temporal patterns of MEE: Low MEE, Early MEE (peaking at 0-6 months), Later MEE (peaking at 6-12 months), and High MEE. GLM analyses revealed no direct effects, but several moderated effects, of MEE cluster on cognitive development at 3 years, but none at 5 or 7 years. In general, children in the Later MEE and High MEE groups appeared to be more adversely affected by bilateral MEE at 3 years, but effects were moderated in complex ways by socioeconomic status or home stimulation. Growth curve modeling across the three assessment periods showed no effects of total duration of MEE but did indicate that children in the Later MEE cluster had low scores at age 3 but caught up at ages 5 and 7. CONCLUSIONS: Prolonged MEE, especially between 6 and 12 months, may put children at risk for cognitive delays at 3 years, but the risk effect is not strong and effects are no longer detectable at 5 or 7 years.

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