Taurine in developing rat brain: maternal-fetal transfer of [35 S] taurine and its fate in the neonate

When dealing with the problem of obtaining information concerning consumer preferences for two competing brands of a product, one would like to assume that the consumers sampled can actually distinguish between the two brands. Often this is not the case and we have combined the standard triangle test of sensory perception with a preference test in order to obtain information concerning the consumers' ability to distinguish between the two brands. Assuming an underlying multinomial distribution, the maximum likelihood estimators (MLE) of the conditional probability that a person prefers brand A given that he can discriminate between the two products is then obtained. The estimator obtained is a ratio of linear combinations of observed multinomial proportions. The variability of this estimator is assessed by means of the jackknife statistic, the asymptotic variance of the MLE, and Monte Carlo studies. Application of the results obtained to taste test involving two brands of potato chips is discussed.     

Luteinizing hormone releasing factor in pituitary stalk plasma from long-term ovariectomized rats: effects of steroids

The concentration of LH releasing factor (LH-RF) was measured by radioimmunoassay in blood collected from the cut pituitary stalk of long-term ovariectomized rats anaesthetized with Althesin. Stalk plasma LH-RF concentrations were increased immediately after ovariectomy (carried out at oestrus) and low at 2 and 4 days after operation. The concentrations then began to increase to reach a level at 24-28 days which was significantly higher than the concentrations during the oestrous cycle except for the time of the ovulatory surge at pro-oestrus. This pattern was similar to that of the concentrations of LH in jugular venous plasma taken from the same animals before exposure of the pituitary stalk. Like peripheral plasma LH concentrations, the concentrations of LH-RF in stalk plasma fluctuated and fell significantly and rapidly after the intravenous injection of 1 microgram oestradiol-17 beta. The release of LH-RF in long-term ovariectomized rats, into which had been implanted an oestradiol-containing Silastic capsule, was similar to the diurnal pattern of LH release; the afternoon increase in stalk plasma LH-RF concentration could be blocked by sodium pentobarbitone administered at 13.00 h and augmented by administering this anaesthetic at 13.00 h of the preceding day. The stalk plasma LH-RF concentrations in animals injected with oestradiol benzoate (OB) followed 72 h later with either OB or progesterone were lower than the concentrations in animals injected only with oil. These data show that in the rat (1) ovarian steroids could moderate LH release ('negative feedback') by inhibiting LH-RF release, and that in long-term ovariectomized animals (2) the oestradiol-induced circadian pattern of LH release is due to a circadian pattern of LH-RF release, and (3) the surge of LH produced by administering OB followed by either OB or progesterone is probably due mainly to a massive increase in the responsiveness of the anterior pituitary gland to LH-RF.     

Catalase in salivary gland striated and excretory duct cells. II. phi body: an ellipsoidal peroxisomal organelle with crystalloid axial projections

A new distinctive and unique peroxisomal organelle with a spindle shape has been observed in luminal epithelial cells of striated and excretory ducts of mouse salivary glands. Light microscopic studies indicate it has an ellipsoidal centre from which catalase-positive filamentous or rod-like processes protrude along its major axis; hence, it is called a phi body. A role for this specialized peroxisome in the formation of nearby free filaments and rods is suggested by the frequent observation of segmentation of its axial processes. Complementary ultrastructural studies of osmium-fixed preparations show that the deformation to an oval shape results from the pressure of the extruding crystalloid coincident with the major axis of the ellipsoidal body. The size range and conformation of phi body axial processes are comparable to those of free catalase-positive rods and filaments observed in the same cells. The periodic substructure of the crystalloid in the phi body core is identical with that of nearby cytoplasmic rods. These observations are consistent with the view that the rods and filaments observed free in the cytoplasm are formed by extrusion from the crystalloid core of the phi body. phi Bodies could also be responsible for the Aver rods of leukemic leukocytes.     

A comparative study of speech perception in young severely retarded children and normally developing infants

The discrimination of minimally paired speech sounds by seven retarded children with a mean age of 3 years, 2 months and a mean IQ of 38.4 was compared with the discrimination performance of eight normally developing 7-month-old infants. Children and infants were tested using the Visually Reinforced Infant Speech Discrimination (VRISD) paradigm in which they were taught to respond with a head turn to a change in a repeating background auditory stimulus. Responses were reinforced by activation of an animated toy. All children proved to be conditionable and both groups evidenced discrimination of the speech contrasts tested. The data suggest that the retarded children have moree difficulty processing a contrast cued by rapid spectral changes (often associated with consonant discrimination) than they do a contrast cued by steady-state spectral information (often associated with the perception of slowly articulated vowels). The normally developing infants did not find rapid spectral cues mor difficult than steady-state cues These results parallel those of Tallal (1976) who found that dynamic cues were specifically difficult for dysphasic children (with normal nonverbal intelligence), but not for linguistically-normal elementary school children.