Studies on the biochemistry of mitochondria and cell morphology in the neonatal swine hepatocyte

Mitochondrial preparations isolated from neonatal swine hepatocytes show a marked increase in oxidative and concomitant phosphorylative capacity between birth and 2 days postpartum. There are no changes in the coupling parameters (respiratory control ratio and adenosine diphosphate/O ratio) with age. Changes in sedimentation properties in a sucrose gradient suggest qualitative changes in the mitochondria. Some of the lipid measurements (increased phospholipid) might be interpreted as supportive of this suggestion, although most could also be regarded as indicative of quantitative changes (increased number of mitochondria). Electron microscopy of isolated mitochondria and of the hepatocyte demonstrated an increased number of mitochondria but no change in shape, size, or structure as the pig developed. An increase in a number of cytoplasmic components (Golgi apparatus and endoplasmic reticulum) and a decrease in glycogen were also observed. The functional changes in mitochondria seem to occur within a short period of time (6-12 hr postpartum).

Children's identification and reproduction of (w), (r), and (l)

The purpose of this study was to examine preschool children’s identification and reproduction of the speech sounds /w/, /r/, and /l/, and to compare the performance of children and adults in these tasks. The stimuli consisted of three sets of synthetically produced CVC syllables that ranged in equally spaced formant contour changes from “light” to “white” /wait/, “light” to “write,” and “white” to “write.” Subjects were asked to reproduce the word they heard, and to identify it by pressing a button under a picture of the word. Neither children nor adults observed sharp boundaries between the speech sounds in this set. The responses of children were different in the reproduction and identification tasks. More children observed speech sound boundaries in the identification than in the repetition task, and significantly more frequently produced /w/ in response to the stimuli than the other two sounds, but they did not identify /w/ significantly more often. These results were not found with the adult population. We hypothesized that the developmental sequence in the acquisition of the members of this speech sound set is, first, the ability to identify differences between the members of the set and, second, the ability to reproduce the differences.