Heterogeneous growth in the Nile tilapia: social stress and carbohydrate metabolism

Increase in heterogeneous growth as a result of grouping in the Nile tilapia, Oreochromis niloticus (L.), is presumed to be partially promoted by the social stress imposed by the dominant fish on the subordinates. Such stress may decrease the energy available for growth. In this study, the effect of social stress on carbohydrate metabolism was studied in adult, growing males. All animals were deprived of food during the experimentation period and pairing was imposed for either 2 or 4 days. Glycemia was measured before and after pairing, and muscle and liver glycogen contents were determined only after pairing. Subordinate fish showed the highest consumption of carbohydrate reserves. This response was caused by the social stress imposed which corroborates the idea that metabolic differences promoted by social stress may be involved in the rouping effect on heterogeneous growth in the Nile tilapia.     

Pancultural explanations for life satisfaction: adding relationship harmony to self-esteem

The first part of the study confirmed an additive effect of the newly proposed construct of relationship harmony to self-esteem in predicting life satisfaction across student samples from the United States and Hong Kong. As predicted from the dynamics of cultural collectivism, the relative importance of relationship harmony to self-esteem was greater in Hong Kong than in the United States. In the second part of the study, the independent and interdependent self-construals (H. R. Markus & S. Kitayama, 1991) and the 5 factors of personality (P. T. Costa & R. R. McCrae, 1992) were advanced to be the culture-general determinants of life satisfaction, acting through the mediating variables of self-esteem and relationship harmony. Both self-construals and the 5 factors of personality were shown to influence life satisfaction through the mediating agency of self-esteem and relationship harmony in equivalent ways across these 2 cultural groups.     

Patch-clamp analysis of the mechanism of PACAP-induced excitation in rat supraoptic neurones

In neurosecretory cells of the supraoptic nucleus (SON) of rats, pituitary adenylate cyclase activating polypeptide (PACAP) causes an increase in [Ca2+]i, and stimulates somatodendritic vasopressin (VP) release. In this report, to elucidate the ionic mechanism of the action of PACAP, membrane potentials and ionic currents were measured from SON neurones in slice preparations or from dissociated SON neurones. In the current clamp mode, PACAP depolarized membrane potentials of both phasic and non-phasic neurones and increased the firing rate. Moreover, simultaneous measurements of membrane potentials and [Ca2+]i revealed that the membrane depolarization correlated well with increases in [Ca2+]i. In the voltage-clamp mode, PACAP induced inward currents at a holding potential of -70 or -80 mV in a dose-dependent manner and the time course of the currents was similar to that of the PACAP-induced membrane depolarization. The averaged reversal potential of the PACAP-induced currents obtained from dissociated SON neurones was -33 mV, which was close to the reversal potential of non-selective cation currents in SON neurones. The currents were rapidly and reversibly inhibited by a cation-channel blocker, gadolinium. Analysis of synaptic inputs into SON neurones in slice preparations revealed that PACAP had little or no effects on the frequency of spontaneous excitatory and inhibitory postsynaptic currents. These results suggest that pituitary adenylate cyclase activating polypeptide (PACAP) activates PACAP receptors in the postsynaptic membrane of the supraoptic nucleus (SON) neurones, and that the activation of PACAP receptors leads to opening of non-selective cation channels, depolarization of the membrane potential, and increase in the firing rate in SON neurones. Such mechanisms may account for the PACAP-induced increase in [Ca2+]i and vasopressin (VP) release observed in SON neurones.     

Transabdominal ultrasound study of stomach and duodenum: standardization and potentialities

The paper presents an original procedure for transabdominal ultrasound examination of the stomach and duodenum, which yields an objective piece of information on the status of all wall layers of the above organs. The procedure is rather easy-to-use, noninvasive, and well tolerable. Its efficiency is confirmed by the date of examination of 46 patients.     

Selective induction of protection against influenza virus infection in mice by a lipid-peptide conjugate delivered in liposomes

We have previously reported (Muller et al. Vaccine 1990, 8, 308) that two cyclic peptide analogues called D loop and K loop, corresponding to residues 139-147 in site A of the haemagglutinin (HA) of influenza A virus (strain X31), were both able to provide protective immunity to infected OF1 mice when administered in the form of peptide-ovalbumin conjugates. The predicted conformation of the D loop is nearly identical to that of the native loop known from the X-ray structure of HA, while the predicted conformation of the K loop differs significantly from the native one. In this study, the two peptides were conjugated to small unilamellar liposomes, thus creating a chemically defined immunogen, and OF1 mice were immunized with these liposomes containing monophosphoryl lipid A as adjuvant. Compared with protein carrier systems, the liposomal preparations are completely synthetic and avoid the use of Freund's adjuvant. By using liposomes associated with the D loop, we were able to achieve 70% protection of the mice against intranasal challenge with the influenza virus while no protection was obtained with the liposome-associated K loop. The difference in effect between the two liposome and ovalbumin carrier systems may result from the induction of different structures in the peptides when coupled to lipid anchors than when coupled to proteins.     

Tin oxide as a transparent electrode material for light-emitting diodes fabricated with poly (p-phenylene vinylene)

We have fabricated light emitting diodes (LED) with poly (p-phenylene vinylene) (PPV) as the emissive layer and tin oxide (TO) as the transparent conducting positive electrode and aluminium as the negative electrode. The fabrication conditions are optimized for visible light emission in these TO/PPV/Al LEDs. The threshold voltage for substantial charge injection for visible light emission in these LEDs lies below 10V. The device fabrication and electrical characterization of TO/PPV/Al LEDs are discussed in this communication.