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Biomedical subjects

D J Hansen

Publications and source records attributed to D J Hansen.

At least 37 records · Page 2Linked to original sources
PubMed1989

Group conversational-skills training with inpatient children and adolescents. Social validation, generalization, and maintenance.

Two groups of inpatient youths (n = 4 and n = 5) received group conversational-skills training. Conversational component behaviors of both groups at baseline were compared to the behaviors of normal youth from the community. For each inpatient group, component behaviors on which they were most discrepant from normal youths were selected for training. Multiple-baseline designs across component behaviors were used and patients were trained to socially-validated criterion levels. Effectiveness of training was demonstrated through (a) behavioral ratings during dyadic, unstructured conversations with other members of their group, (b) behavioral ratings during conversations with unfamiliar nonpsychiatric persons, (c) global ratings of conversational effectiveness by nonpatient peers, (d) generalization to in vivo conversations, and (e) maintenance of improvement at 1- and 3-month follow-up assessments. Results were replicated across both groups and indicated that training effects were socially validated, generalized to conversations with unfamiliar persons and to in vivo conversations, and maintained over time.

Adolescent↗
PubMed1989

A peer-mediated intervention with clinic-referred socially isolated girls. Generalization, maintenance, and social validation.

Peer-mediated interventions have been widely employed with seriously impaired autistic and handicapped children to modify social withdrawal. This study extends the literature by examining the impact of a peer intervention on the interactions of developmentally normal, socially isolated girls. Two to three actual classroom peers were trained to serve as helpers to initiate and maintain interactions with the subjects. The intervention was introduced sequentially across 2 girls in a multiple-baseline design, and a within-subject ABA withdrawal design was used to assess maintenance. Behavioral observations during recess periods indicated that both children's positive social interactions with peer helpers and other classmates were increased significantly during intervention and were maintained in return-to-baseline conditions and at 4-month follow-up. Increases in positive social interactions of both subjects generalized to a second recess setting, in which intervention was not introduced. Subjects' interactions in both recess settings reached levels comparable to those of social-comparison groups of peers. Teacher and self-report ratings suggested that both girls had fewer social problems and experienced less loneliness and dysphoria as a result of the intervention.

Behavior Therapy↗
PubMed1988

The influence of task and location on solvent exposures in a printing plant.

A work measurement technique was used to monitor the activities of seven printing press operators. Repeated observations were made to learn workers' tasks and workers' locations in the plant, and a photoionization detector was used to measure the instantaneous solvent concentration in each worker's breathing zone. Location data, analyzed using a computer aided design system, did not show any indication that there were high or low exposure areas. Regression, however, showed that a significant amount of variability in a worker's exposures was accounted for by the number of times the worker performed a certain "hazardous task" (r2 = 0.57). The results indicate that it may be possible to simplify industrial hygiene sampling strategies by using work measurement data, such as time study or work sampling, to identify maximum risk employees.

Air Pollutants, Occupational↗
PubMed1987

Distribution and ultrastructure of neurons in opossum piriform cortex displaying immunoreactivity to GABA and GAD and high-affinity tritiated GABA uptake.

GABAergic neurons have been identified in the piriform cortex of the opossum at light and electron microscopic levels by immunocytochemical localization of GABA and the GABA-synthesizing enzyme glutamic acid decarboxylase and by autoradiographic visualization of high-affinity 3H-GABA uptake. Four major neuron populations have been distinguished on the basis of soma size, shape, and segregation at specific depths and locations: large horizontal cells in layer Ia of the anterior piriform cortex, small globular cells with thin dendrites concentrated in layers Ib and II of the posterior piriform cortex, and multipolar and fusiform cells concentrated in the deep part of layer III in anterior and posterior parts of the piriform cortex and the subjacent endopiriform nucleus. All four populations were well visualized with both antisera, but the large layer Ia horizontal cells displayed only very light 3H-GABA uptake, thus suggesting a lack of local axon collaterals or lack of high-affinity GABA uptake sites. The large, ultrastructurally distinctive somata of layer Ia horizontal cells receive a very small number of symmetrical synapses; the thin, axonlike dendrites of small globular cells are exclusively postsynaptic and receive large numbers of both symmetrical and asymmetrical synapses, in contrast to somata which receive a small number of both types; and the deep multipolar and fusiform cells receive a highly variable number of symmetrical and asymmetrical synapses on somata and proximal dendrites. Labeled puncta of axon terminal dimensions were found in large numbers in the neuropil surrounding pyramidal cell somata in layer II and in the endopiriform nucleus. Moderately large numbers of labeled puncta were found in layer I at the depth of pyramidal cell apical dendrites with greater numbers in layer Ia at the depth of distal apical segments than in layer Ib. High-affinity GABA uptake was demonstrated in the termination zone of the projection from the anterior olfactory nucleus to the anterior piriform cortex. Cell bodies of origin of this projection displayed heavy retrograde labeling with 3H-GABA. Matching neuropil and cellular labeling was demonstrated with the GABA-BSA antiserum but not with the GAD antiserum, thus suggesting that GABA is normally present in these cells but is taken up from the neuropil rather than synthesized. No comparable high-affinity GABA uptake was demonstrated in the association fiber systems that originate in the piriform cortex.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Respiratory symptoms associated with the use of azodicarbonamide foaming agent in a plastics injection molding facility.

Respiratory health variables were studied cross-sectionally in 227 employees of a plastics molding facility where numerous complaints had been apparently associated with the use of azodicarbonamide foaming agent in injection molding. Pre- and postshift respiratory status measures and azodicarbonamide concentrations were also obtained for 17 employees. Cross-sectional pulmonary function differences by injection molding status were not observed. Modest decrements in pulmonary function measures were observed between start and end of shift but with no dose-effect relationship. A strong association was observed for injection molding workers for eye/nose/throat irritation, cough, and wheezing. Additionally, wheezing, chest tightness, and symptoms of chronic bronchitis were strongly associated with work in injection molding during periods in which azodicarbonamide was in use. These results suggest respiratory symptom causation by some combination of azodicarbonamide itself, reaction products of azodicarbonamide formed during injection molding, or other unidentified agents uniquely associated with the process of injection molding with azodicarbonamide foaming agent.

Adult↗
PubMed1986

Early life-stage toxicity test methods for gulf toadfish (Opsanus beta) and results using chlorpyrifos.

Gulf toadfish (Opsanus beta) were continuously exposed as embryos, sac fry, and juveniles to technical chlorpyrifos in two 49-day early life-stage toxicity tests. Survival was significantly (alpha = 0.05) reduced only in 150 micrograms/liter. However, toadfish exposed to chlorpyrifos concentrations from 3.7 to 150 micrograms/liter weighted significantly less than control fish: 9% lower in 3.7 micrograms/liter to 62% lower in 150 micrograms/liter. The 96-hr LC50 for juvenile fish was 520 micrograms/liter. Concentrations of chlorpyrifos in toadfish and bioconcentration factors increased with increasing exposure concentration, a condition not generally observed with other marine fishes and other test chemicals. These results demonstrated the procedures for, and the practicality of, early life-stage tests with this marine species. We recommend the use of the gulf toadfish for comparative toxicity testing and for evaluating the toxicity of substances in conjunction with ontogenetical, physiological, and histological investigations of this considerably studied genus. We do not recommend it for routine effects testing.

Animals↗
PubMed1985

An inventory to measure staff knowledge of behavioral methods with inpatient children and adolescents.

A 35-item multiple choice inventory to assess inpatient staff's knowledge of behavioral methods with children and adolescents is described. The instrument appears to possess satisfactory content validity for basic behavioral principles and good internal consistency and reliability. It appears useful for research and staff inservice educational assessment in inpatient treatment settings where a measure of this type in needed. The inventory may also be useful in identifying newly employed staff who may benefit from behavioral training before assuming direct services roles on inpatient wards.

Adolescent↗
PubMed1985

A new early life-stage toxicity test using the California grunion (Leuresthes tenuis) and results with chlorpyrifos.

California grunion were continuously exposed as embryos and fry to technical chlorpyrifos in two toxicity tests conducted in the same exposure apparatus. The first test, a 35-day early life-stage (ELS) test, began with approximately 2.5-day-old embryos that were exposed in flow-through aquaria in darkness until hatching was stimulated on Day 9 of exposure. The second toxicity test, a fry test, began with newly hatched fry and lasted 26 days. Test water temperature ranged from 23 to 26 degrees C and salinity from 24.5 to 34.0%. Results of the two tests were similar, indicating that exposure of embryos added little to the overall toxicity of chlorpyrifos to grunions. Percentage hatch of embryos was unaffected by the chlorpyrifos concentrations tested. Fry survival was apparently reduced in nominal concentrations greater than or equal to 1.0 micrograms/liter in both tests, but significantly so in concentrations greater than or equal to 1.0 micrograms/liter in the ELS test and greater than or equal to 2.0 micrograms/liter in the fry test. When compared with carrier controls, mean fish weights were significantly reduced in nominal chlorpyrifos concentrations greater than or equal to 0.5 micrograms/liter in the ELS test and greater than or equal to 1.0 micrograms/liter in the fry exposure. Mean bioconcentration factors were 770X for fish that survived the ELS test and 190X for those that survived the fry test. Results demonstrate the practicality of conducting ELS tests for the first time with a marine fish from the Pacific coastal waters of the United States.

Animals↗
PubMed1985

Computerized spirometry using a portable microcomputer.

The reliable conduct of pulmonary function studies, while in the field, is increasingly important as various standards mandate this activity. Versatile, portable and accurate equipment is required. A lightweight and computerized portable spirometer system is discussed, PSPIRO, which uses a standard volumetric spirometer and a briefcase-sized microcomputer. The system, compact enough to be easily moveable by one person, performs tests for FVC, FEV(1), FEV(3), the percentage of predicted pulmonary function for each, and the ratio of FEV(1)/FVC. Back extrapolation is used to establish the start of each forced expiratory maneuver, reproducibility checks are performed, and accuracy is within acceptable epidemiologic standards. A small, portable analog to digital interface (PLAD) was developed for performing A/D conversions through the RS-232C port of the portable microcomputer.

Humans↗
PubMed1984

Earplugs--a computer program for simulation of personal hearing protection devices.

Earplugs is a program to allow predictive evaluation of earplugs and earmuffs. Written in Basic for the Apple II+, it is translatable into all other versions of Basic. The program allows the user to compare the attenuation capabilities of any earplug versus the environmental octave band analysis for the workplace in question. This version of the program provides a plot of the results.

Ear Protective Devices↗
PubMed1984

Stress management training for dental students.

Dental school and professional practice are well-documented sources of stress. Although students and dentists risk developing stress-related disorders, no empirically evaluated method for helping dental students cope with stress has been reported. A group of 17 dental students participated in a six-session program that included instruction in self-relaxation and time management; exercise and leisure planning; and cognitive modification techniques. From pre- to post-training, subjects showed improvement on a variety of self-report and physiological measures relative to a waiting-list control group. A three-month follow-up assessment revealed continued reductions in stress-related behavior. The importance of stress-management training for dental students is discussed as well as suggestions for future research.

Adaptation, Psychological↗
PubMed1983

Computer assisted spirometry.

Three of the most popular microcomputers, the TRS-80 Model I, the APPLE II+, and the IBM Personal Computer were connected to a spirometer for data acquisition and analysis. Simple programs were written which allow the collection, analysis and storage of the data produced during spirometry. Three examples demonstrate the relative ease for automating spirometers.

Computers↗
PubMed1977

Endrin: effects on the entire life cycle of a saltwater fish, Cyprinodon variegatus.

The sheepshead minnow (Cyprinodon variegatus) was continuously exposed for 23 wk to the organochlorine insecticide endrin, from the embryonic state through hatching until adulthood and spawing. The resultant progeny were monitored to determine the effects of the toxicant on their survival, growth, and reproduction. Average measured exposure concentrations were O (control), 0.027, 0.077, 0.12, 0.31, and 0.72 microgram/liter. Embryos exposed to 0.31 and 0.72 microgram/liter hatched early; all fry exposed to 0.72 microgram/liter died by day 9 of exposure. At 0.31 microgram/liter, fry were initially stunted and some died. Survivors seemed unaffected until maturity, when some females died during spawning; fewer eggs were fertile and survival of exposed progeny decreased. No significant effects were observed th roughout this fish's life cycle at an exposure concentration of 0.12 microgram/liter. Four-week-old juvenile fish accumulated 2,500 times the concentration of endrin in the exposure water; adults, 6,400 times; and their eggs, 5,700 times. The specific application factor (calculated by dividing the limits on the maximum acceptable toxicant concentration, greater than 0.12 and less than 0.31 microgram/liter, by the concentration lethal to 50% of the juvenile fish in 96 hr, 0.34 microgram/liter) ranged from 0.35 to 0.91. To our knowledge this is the first toxicity test carried out through the entire life cycle of an oviporous esturarine fish. Data from this experiment and from experiments with another estuarine fish and four freshwater fish all demonstrate that there is little difference between endrin concentrations that produce acute effects and concentrations that do not affect the fish in chronic exposures lasting four or more weeks.

Age Factors↗