Protein metabolism in the developing brain: influence of birth and gestational age.

Incorporation of carbon-14-labeled phenylalanine into brain protein of newborn pigs falls sharply within 24 hours after birth. This decrease is related to the time of birth rather than the gestational age of the piglets, although the latter is also associated with a gradual decrease in brain protein synthesis.

Filicidal behavior: behavioral correlates and role of sensory systems.

The administration of para-chloro-D,L-phenylalanine (PCPA) produces a high incidence of filicidal (pup-killing) behavior in female rodents. The present series of experiments determined the major behavioral, sensory, and temporal correlates of filicidal behavior in nulliparous adult Sprague-Dawley female rats. In Experiment 1, behavioral episodes involving the interaction of test pups and PCPA-induced filicidal females were videotaped, and subsequent analyses of behaviors related to locating, carrying, mauling, attacking, gnawing, and consuming the prey object were performed. Analysis indicated that the primary behavioral correlates in the PCPA animals included location, initiation of the attack (mauling), and killing of the pup (filicide). Only location was observed in control animals. Experiment 2 evaluated the effects of sensory impairments on location, mauling, and filicide. Sensory impairment occurred at 24 days of age for enucleation and 62 days of age for olfactory bulbectomies and/or auditory destruction. Animals were injected either at 110 or 130 days of age with PCPA for three consecutive days and tested for filicide for five additional days. Locating of the test pup was not affected by sensory impairment. Mauling was reduced significantly in the enucleation/auditory destructed animals. Filicide was significantly lower in animals with visual/auditory destruction, and, compared to controls, was reduced in all sensory impaired groups.

Relationship between preexposure to prey and PCPA-induced filicidal activity in Sprague-Dawley rats.

Experiments, involving para-chloro-D,L-phenylalanine-induced pup-killing (filicide), were conducted to determine the effect of preexposure to the goal entity on the initial development and long-term expression of PCPA-induced filicide. Three groups of Sprague-Dawley rats (n = 50) were either preexposed/not preexposed, or preexposed for varying periods (5, 8, or 13 days) prior to receiving PCPA. Two major results were obtained: 1) preexposed animals were less filicidal than those not preexposed; and 2) there was an inverse relationship between the number of preexposures and filicide occurrence. The results are interpreted in reference to a serotonin-depletion habituation hypothesis.

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.

Thin-layer chromatographic separation of dimethylphosphatidates derived from lecithins.

The separation of lecithin derivatives based on their fatty acid substituents has been investigated. Several synthetic and natural lecithins were converted to their corresponding dimethylphosphatidates by hydrolysis with phospholipase D (phosphatidylcholine phospholipase D (phosphatidylcholine phosphatidohydrolase, EC 3.1.4.4) and methylation of the resulting phosphatidic acids with diazomethane. These dimethylphosphatidates were separated into fractions by reversed-phase thin-layer chromatography. Separations were dependent on the total number of methylene groups and double bonds in the two fatty acid chains. Fractionated dimethylphosphatidates were extracted from the plates and fatty acids were determined.

Effects of a forced institutional relocation on the mortality and morbidity of nursing home residents.

Residents of a county nursing home underwent a forced, mass relocation. Gerontologists advised on preparation of staff and residents. No increase in residents' mortality or morbidity was found after the relocation. The highest death rate was in the anticipatory period, the year prior to the move.

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.