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Biomedical subjects

D A Allen

Publications and source records attributed to D A Allen.

At least 55 records · Page 3Linked to original sources
PubMed1981

Effect of temperature on growth and activity of Aeromonas spp. and mixed bacterial populations in the Anacostia River.

During the winter months, total bacterial counts in the water column and in the sediment in the Anacostia River were two- to eightfold higher than at other times of the year, whereas Aeromonas spp. decreased in number of several orders of magnitude. This significant decrease in number in the Anacostia River during the cold months of the year can be explained by the low metabolic activity of Aeromonas at low temperatures.

Aeromonas↗
PubMed1980

Language disorders in preschool children: predictors of outcome -- a preliminary report --.

Child neurologists are often asked to evaluate young children who have failed to develop speech despite adequate hearing and skills for non-verbal tasks. At our center, in addition to a standard neurologic evaluation, hearing test, and EEG, we obtain videotape recordings of the child and his mother in play interaction. These observations enable us to assess the child's non-verbal communicative abilities, his affect, his ability to utilize toys symbolically and creatively, and his attention span. Approximately 20 preschool children who were non-verbal or had very limited speech at entry into our study are being followed longitudinally. Readily observable aspects of language and behavior were scored by reviewed the serial videotapes obtained over a 2-year period. Predictors of outcome that do not require detailed linguistic analysis of the child's utterances are tentatively identified and discussed.

Brain Damage, Chronic↗
PubMed1980

Isolation, enumeration, and characterization of Aeromonas from polluted waters encountered in diving operations.

Counts of total viable, aerobic, heterotrophic bacteria, indicator organisms, and Aeromonas spp. were made at a diver training site on the Anacostia River in Washington, D.C. The numbers of Aeromonas cells in Anacostia River sediment and water increased during periods of elevated water temperature, to maxima of 4 x 10(5) cells per g of sediment and 300 cells per ml of water. Correspondingly, Aeromonas counts dropped 2 to 4 logs as the water temperature decreased to 0 to 0.5 degrees C. Cultures taken by sterile swabs from the ears and face masks of divers after a 30-min swim in the Anacostia River yielded bacterial types and numbers similar to those found in the river. The nasal passages of the divers apparently did not become contaminated by swimming, possibly because of the protective effect of the face masks used by the divers. Properties associated with virulence in Aeromonas hydrophila and Aeromonas sobria strains isolated from the river, sediment, and divers were investigated. Nearly 40% of the strains of both species collected during the study produced cytotoxic activity for mouse Y-1 adrenal cells, as well as elastase. Enterotoxin activity, as detected by the Y-1 assay, was observed in 3% (1 of 35) of the strains of A. sobria and in 6% (19 of 330) of the A. hydrophila strains. Fluid accumulation in rabbit ileal loops induced by both species of Aeromonas varied greatly among the 17 strains examined. Fluid accumulation of at least 0.4 ml/cm was correlated with positive cytotoxin- or enterotoxin-like response in the Y-1 tissue culture assay.

Aeromonas↗
PubMed1980

Biochemical characteristics and virulence of environmental group F bacteria isolated in the United States.

Bacteria phenotypically resembling Aeromonas hydrophila, but requiring NaCl for growth, have been isolated form the New York Bight. The bacteria proved to be identical to group F organisms isolated from cases of human diarrhea in Indonesia and Bangladesh. Anaerogenic strains initiated responses in Y-1 tissue culture and rabbit ileal loop, consistent with those associated with cytotoxin- and enterotoxin-producing Aeromonas spp. strains. Separation on the basis of production of gas from glucose by group F strains was correlated with differences in mean guanine-plus-cytosine deoxyribonucleic acid base composition and in deoxyribonucleic acid relative reassociation. Both aerogenic and anaerogenic strains reassociated to a significantly greater extent with Vibrio spp. than with Aeromonas spp. and indeed should be considered a new species of the genus Vibrio.

Base Composition↗
PubMed1980

Filling time versus affective response to the activity that fills the time: independent effects on time judgment?

Previous time perception research has confounded manipulations intended to evoke different affective reactions to the task with different levels of nontemporal processing demands. An attempt was made to separate these dimensions by a social comparison procedure aimed at making the same concurrent task (card sorting) appear differentially interesting to two groups of college students. Response uncertainty varied within the task to that processing demands could be compared while reported interest in the task varied between groups. Magnitude of time estimates related inversely to response uncertainty, but reported interest in the task made no independent contribution to the variance of estimates.

Affect↗
PubMed1979

Aeromonas primary wound infection of a diver in polluted waters.

Two separate species of Aeromonas, A. sobria (not listed as a species in Bergey's Manual of Determinative Bacteriology, 8th ed.) and A. hydrophila, were primary pathogens isolated from the leg wound of a diver conducting operations in polluted waters. This is the first recorded instance of a primary infection of soft tissue in a human caused by two species of Aeromonas, one of which was resistant to tetracycline. Because of the very rapid development of this wound infection, cytotoxicity of these organisms was examined in several biological systems. A. sobria was hemolytic for sheep erythrocytes, cytotoxic for Y-1 adrenal cells, and enterotoxic in rabbit ligated intestinal loops, whereas A. hydrophila was hemolytic and cytotoxic. Pertinent clinical, bacteriological, and environmental features of the case are presented.

Adult↗
PubMed1979

Ecology and taxonomy of bacteria attaching to wood surfaces in a tropical harbor.

Water, sediment, and wooden pilings, samples of which were collected from a harbor in Puerto Rico during the course of a long-term study of biofouling of wood treated with creosote and related compounds, were found to support growth of microbial populations, the dominant taxa of which included Hyphomicrobium, Hyphomonas, Pseudomonas, Vibrio, and Bacillus. New wood exposed to the harbor water was rapidly colonized by Hyphomicrobium vulgare. Old pilings in an advanced stage of biodeterioration maintained a diverse bacterial microflora, representatives of which were also found widely distributed in the water column and sediment. Evidence for bacterial species succession was obtained, indicating that microbial interactions are important for attachment to, and subsequent colonization of, wood surfaces in the marine environment.

Bacteria↗
PubMed1979

Effect of information feedback on temporal discrimination in concurrent and post-feedback measures.

College students estimated time intervals (5, 6, 7, 8, and 9 sec.) where one group (N = 20) received information feedback in terms of actual interval durations and a second group (N = 18) received no information. Theshold measures were then taken for all subjects using the method of constant stimuli (comparison stimuli of 5, 6, 7, 8, and 9 sec. and a 7-sec. standard). In addition to increased accuracy and consistency of judgments, the feedback group showed a decreasing Weber fraction during the estimation phase, while the Weber fraction for the no-feedback group increased. The feedback group retained only a slight advantage in subsequent threshold measures; group differences in difference thresholds and derived nonparametric estimates of d' were nonsignificant.

Differential Threshold↗
PubMed1979

Ototoxicity in neonates treated with gentamicin and kanamycin: results of a four-year controlled follow-up study.

This article reports the results of a four-year follow-up study initiated in 1970 on the long-term effects of gentamicin and kanamycin use in newborn infants. Audiometric, vestibular, and psychometric evaluations were performed on gentamicin-treated, kanamycin-treated, and untreated, matched control infants and children. No substantial sensorineural hearing loss or vestibular dysfunction was identified in these patients that could be attributed to aminoglycoside therapy. Performances on the Illinois Test of Psycholinguistic Abilities, Beery Test of Visual Motor Integration, the Peabody Picture Vocabulary Test, and on fine and gross motor examinations were comparable for the three study groups.

Audiometry↗
PubMed1979

The repetition effect in judgments of temporal duration across minutes, days, and months.

Three experiments assessed the stability of the repetition effect in time judgment. In Experiment 1, subjects (N = 18) produced intervals ranging from 8 to 31 sec in a two-phase procedure with a five min rest between phases. In Experiment 2, subjects (N = 20) made verbal estimates of intervals ranging from 8 to 20 sec with a 48-hour delay between phases. Experiment 3 involved daily productions by three subjects of intervals ranging from 8 to 54 sec over several months. The slope of the psychophysical function increased across phases in Experimental 1, declined (as expected for estimation) across days in Experiment 2, and increased across months in Experiment 3. It was concluded that the repetition effect is relatively permanent and thus more similar to habituation than to sensory adaptation.

Adult↗