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Biomedical subjects

R L Schalock

Publications and source records attributed to R L Schalock.

5 recordsLinked to original sources
PubMed1979

Long-term effects of propylthiouracil-induced neonatal hypothyroidism.

Hypothyroidism was induced in neonatal Sprague-Dawley rats by adding propylthiouracil to the lactating female's food and water. Behavioral evaluation on a 6-item battery occurred from 70 to 114 days of age. Results indicated long-lasting behavioral changes in the neonatal hypothyroid animals characterized by increased activity and decreased performance on avoidance and escape learning. Serum thyroxine levels were reduced in the hypothyroid animals throughout the 120-day period. Experimental animals also had fewer synaptic contacts in the cerebellar cortex when analyzed at 90 days of age.

Animals↗
PubMed1978

para-Chloro-D, L-phenylalanine induced filicidal behavior in the female rat.

The administration of para-chloro-D, L-phenylalanine (PCPA) produces a high incidence of aggressive (filicidal) behavior in pre-, postpartum, and nulliparious rodents. PCPA inhibits brain tryptophan 5-monooxygenase and can produce a reduction in whole brain serotonin. Apparently PCPA mediates the release of a natural latent aggressive tendency which is potentiated by the interference in, or reduction of, a suppressing system governed by serotonin. Latency of attack, intensity phases, and characteristics of the filicidal behavior were found to vary inversely with brain serotonin content, and be reversed or eliminated by replacement of serotonin i.e., via 5-hydroxytryptophan, serotonin's immediate precursor. Although aggressive tendencies were in evidence prior to filicide, filicide became evident once the apparently minimal whole brain level of serotonin reached ca 0.10 microgram/g. Neither the parturition process nor severe food deprivation are strong causative factors in the precipitation of filicidal behavior. Since not all animals become filicidal, other behavioral and/or biological variables must be involved in the mediation of this aggressive phenomenon.

Aggression↗
PubMed1978

Placement from community-based mental retardation programs: how well do clients do?

Mentally retarded clients (N = 131) placed during a 2-year period from either an independent living or competitive employment training program were evaluated as to placement success. Thirteen percent returned to the training program. Successful independent living placement was related to intelligence and demonstrated skills in symbolic operations, personal maintenance, clothing care and use, socially appropriate behavior, and functional academics. Successful employment was related to sensorimotor, visual-auditory processing, language, and symbolic-operations skills. Major reasons for returning from a job to the competitive employment training program included inappropriate behavior or need for more training; returning from community living placement was related to money management, apartment cleanliness, social behavior, and meal preparation.

Activities of Daily Living↗
PubMed1975

Model phenylketonuria (PKU) in the albino rat: behaviroal, biochemical, and neuroanatomical effects.

Model phenylketonuria was induced in albino rats by injecting (at 1-20 days of age) and feeding (at 21-80 days) L-phenylalanine and D-L-para-chloro-phenylalanine. Behavioral testing on an eight-item battery occurred twice: first, whil the animals were either receiving the excess phenylalanines or not (original); and second, following a 90-day drug-free recovery period (retention). Results indicated drug-dependent deficits in learning and activity on both original and retention tests. Serum phenylalanine, serum tryptophan, and liver phenylalanine hydroxylase activity levels were positively correlated with the behavioral deficit. Clumped dense material in some myelin sheaths and associated degeneration of axons were found in experimental subjects.

Animals↗