Showing papers by "University of Naples Federico II published in 1969"
TL;DR: In this paper, the authors proposed a theory of the thinning of a liquid film between two touching bubbles, which predicts the bubble thinning to occur in two stages, i.e., the first stage is an extremely rapid thinning down to a quasi-equilibrium thickness, which is calculated by the equation: the second stage is the further thinning up to the rupture and the time required for the overall coalescence time.
294 citations
TL;DR: It is concluded that, although conformational factors such as electrostatic facilitation and ligand binding influence the reactivity of certain histidyl residues, the major factors in Histidine iodination are the instrinsic properties of the residue.
Abstract: Factors that determine the reactivity toward iodine of the histidyl residues of various proteins are compared. The proteins studied include lysozyme, ribonuclease, insulin, lactic, malic and glutamic dehydrogenases, phosphoglucomutase, thyroglobulin, trypsin, chymotrypsin and β-lactoglobulin. Relatively fewer histidyl residues than tyrosyl residues are iodianated at pH 8.5 both in water and in guanidine. The fraction of iodine present in histidyl residues increases with increasing pH. Diiodohistidine is formed primarily in proteins that do not contain tryptophane.
Thyroglobulin can be iodinated to contain 8% histidine iodine. However, mono- and diiodohistidine formation in equilibrium-labelled thyroids accounts for < 1% of the total iodine.
Histidine iodination requires the dissociable proton of the imidazole ring as shown by lack of iodination of N-methylated model compounds. The assumption that iodination proceeds by an attack on the imidazole anion (rather than via an N-I intermediate) is supported by the finding that the sterically hindered 2-t-butyl imidazole is iodinated.
It is concluded that, although conformational factors such as electrostatic facilitation and ligand binding influence the reactivity of certain histidyl residues, the major factors in histidyl iodination are the instrinsic properties of the residue.
54 citations
TL;DR: No strict correlation was found between the depletion of brain amine stores induced by prenylamine or p‐chlorophenylalanine and adrenocortical activation, even at times in which the peak effect ofbrain amine depletion occurs.
Abstract: 1. The effect of a pharmacologically induced increase or depletion of brain monoamines (5-hydroxytryptamine, noradrenaline, dopamine) was investigated with respect to adrenocortical function.
2. No strict correlation was found between the depletion of brain amine stores induced by prenylamine or p-chlorophenylalanine and adrenocortical activation, even at times in which the peak effect of brain amine depletion occurs.
3. Restraint stress causes a manifest increase in brain 5-hydroxytryptamine while decreasing the cerebral noradrenaline and dopamine content. This stress strongly stimulates corticosterone secretion by the adrenals.
4. A monoamine oxidase inhibitor, nialamide, at a dose which causes an evident increase in brain amine concentrations, does not modify plasma corticosterone. At the same dose it was, furthermore, unable to prevent the adrenocortical stimulation induced by restraint stress.
5. Brain amine content does not seem to play an important part in the control of corticotrophin releasing factor in corticotrophin secretion by the pituitary gland. The relationship between hypothalamic monoamines and other neurohumours is discussed.
37 citations
TL;DR: In this article, a phenomenological analysis of the mechanism of drag reduction is presented for five concentrations of a water-soluble polymer and three tube diameters, and the data are correlated by a single curve relating two dimensionless parameters.
Abstract: Drag reduction data for five concentrations of a water-soluble polymer and three tube diameters are presented. The data are correlated by a single curve relating two dimensionless parameters; these have been obtained from a phenomenological analysis of the mechanism of drag reduction.
36 citations
TL;DR: In this article, a contamination test method is proposed that can be applied to almost any piece of apparatus, such as suspension insulators, bushings, lightning arresters, and station equipment.
Abstract: A contamination test method is proposed that can be applied in any existing laboratory without adding expensive new facilities or equipment. The method can be applied to almost any piece of apparatus, such as suspension insulators, bushings, lightning arresters, and station equipment.
30 citations
TL;DR: The changes in brain 5-HT, dopamine and noradrenaline levels provoked by restraint stress, do not seem to be due to the negative feedback effect of endogenous corticosterone.
27 citations
TL;DR: This study does not seem to show a relationship between the neurosecretory cells and cerebral organs of Coe, and in certain characteristics the neuro secretory system of Cerebratulus may resemble that of the earthworm.
20 citations
TL;DR: Crystals of fragment Fab, which has a molecular weight of 50,000 and contains the combining site of an antibody, may be of particular value because of its large molecular weight.
Abstract: INFORMATION concerning the three-dimensional structure of an antibody and the contours of its combining site can in theory be derived by X-ray crystallography. In view of the large molecular weight of antibody molecules (150,000 or greater), crystals of fragment Fab, which has a molecular weight of 50,000 and contains the combining site of an antibody, may be of particular value.
17 citations
TL;DR: The slowest sedimenting component was obtained by labeling thyroid glands in vivo or in vitro with radioactive L-leucine and D-mannose and has been purified and further characterized and shown to partially associate in vitroWith half molecules of thyroglobulin (12 S subunits) and to react with antibodies against rat thyrogLobulin.
14 citations
TL;DR: During the adreno-cortical activation caused by stress the tryptophan shunt from the serotonin to the kynurenine pathway is almost abolished and probably occurs because during stress there are a greater number of precursors available which may satisfy both the brain and liver metabolic pathways.
13 citations
TL;DR: In this paper, velocity profiles in turbulent pipe flow of drag-reducing liquids have been measured by means of Pitot previously calibrated by towing, and the results are compared with classical Newtonian velocity profiles, and differences are discussed.
TL;DR: In this paper, the Pb-Sn eutectic alloy in the superplastic state yielded velocity fields nearly identical with those obtained using lead, and the authors attributed the small differences observed in the velocity fields to differences in boundary friction.
Abstract: Flow studies in extrusion tests revealed that the Pb-Sn eutectic alloy in the superplastic state yielded velocity fields nearly identical with those obtained using lead. Slight differences observed in the velocity fields were attributed to differences in boundary friction. The test results appear to support the contention that the flow field within a plastically moving metal or alloy essentially is unique for identical boundary conditions. It is suggested that moderate variations in the properties of the material and in the flow condition will contribute only minor changes in the velocity distribution. Uniqueness is supported by the present results but not proved unequivocally.
TL;DR: The chemical nature of neurosecretory material of the brain and lateral nerve cords in the heteronemertean Cerebratulus marginatus has been examined by a variety of histochemical methods and it appears that the secretions of the cell types are characterized by a content of cystine and tryptophan or other 3-indolyl derivatives.
TL;DR: Es wird gezeigt, dass die Freisetzung von ACTH in der durchströmten Katzennebenniere nur bei Anwesenheit von Kalzium erfolgt.
Abstract: Es wird gezeigt, dass die Freisetzung von ACTH in der durchstromten Katzennebenniere nur bei Anwesenheit von Kalzium erfolgt. Strontium, nicht aber Magnesium kann Kalzium freisetzen, wahrend Magnesium (15 mM die Freisetzung von ACTH in Gegenwart von Kalzium hemmt. Ein Vergleich zwischen Brenzkatechinamin und Kortikosteronfreisetzung wird diskutiert.
TL;DR: In Phallusia mamillata and Ascidia malaca the cells containing sulfated acid mucopolysaccharides at the sides of the intestine originate from the A 4.1 blastomeres of stage 8, or, more accurately, from the blastomere A 6.3, of stage 32.
TL;DR: Potentiometric titrations of cations in the presence and in the absence of membranes-H show that cations are bound by the dissociated groups of the membrane and the fall in pH value for bivalent cations is greater than that for monovalent cations.
Abstract: A study was made of H(+), Na(+), K(+), Ca(++), and Mg(++) binding and ion-exchange properties of the plasma-mesosome membrane system isolated from Micrococcus lysodeikticus strain NCTC 2665. Titration curves were obtained on membranes prepared according to the method of M. R. J. Salton and further exposed to pH 4 for 4 hr (membranes-H). The dissociation coefficients and binding capacities were obtained by applying the mass law equation and the plot of G. Schatchard to the data. The membranes-H possess four kinds of dissociable groups with pK 4.96, 4.18, 3.60, and 3.09, respectively, and a total binding capacity of 0.65 meq/g (dry weight). Potentiometric titrations of cations in the presence and in the absence of membranes-H show that cations (Na(+), K(+), Ca(++), and Mg(++)) are bound by the dissociated groups of the membrane. The fall in pH value for bivalent cations is greater than that for monovalent cations. Cations of the same valency produce equal diminutions on pH. Furthermore, ion-exchange tests carried out on membranes saturated with Mg(++) or Na(+) and suspended in a medium containing (45)Ca show that the cations are reversibly bound.
TL;DR: The tests revealed an increase in the number of PAS-positive test cells in oocytes of 60–80 μ and of 90–100 μ during February and April and a parallel increase during these periods of mitotic activity in the cells in question.
Abstract: A morphological and cytochemical study (mucopolysaccharides, proteins and DNA) was made of the test cells of oocytes of Ciona intestinalis collected in February, April, July and September.
TL;DR: In this paper, a deep-red tetramethoxybenzene complex is isolated, which is shown to be a bis(diazonium oxide) structure, and its properties are described.
TL;DR: The hypothesis that increased levels of acid secretion may explain partially the high incidence of duodenal ulcer among subjects possessing one or both the phenotypic traits—blood group O and nonsecretor—is supported.
Abstract: The aim of the present study was to determine whether blood group O and nonsecretor status are associated with gastric hyperacidity. Total output of gastric acid after maximal histamine stimulation was evaluated in 515 patients—220 males and 295 females—aged 20–50 years, with and without a familial history of duodenal ulcer. All of them were free of gastroduodenal disease. HCl output was found to be significantly higher in patients of blood group O than in those of A, B, and AB, irrespective of family history of duodenal ulcer. Furthermore HCl output was significantly higher, when blood group O was concerned, in nonsecretors than in secretors. In groups A, B, and AB there were no differences between secretors and nonsecretors. These results support the hypothesis that increased levels of acid secretion may explain partially the high incidence of duodenal ulcer among subjects possessing one or both the phenotypic traits—blood group O and nonsecretor.
01 Mar 1969
TL;DR: The developmentin vitro of mouse embryos was explanted at the 11th day of gestation and culturedin vitro on the surface of a plasma clot for up to 7 days, except for the absence in culture of blood vessels and therefore also of the glomerular anlage.
Abstract: Metanephros of mouse embryos was explanted at the 11th day of gestation and culturedin vitro on the surface of a plasma clot for up to 7 days. Microscopic sections were cut from cultures fixed every day; the differentiation process was followed and compared with development under normal conditions. The ureter branches out and gives rise by means of dichotomous division to straight canals, lined by a light, columnar epithelium, which correspond to collecting ducts. Around the blind ends of their terminal branches, mesenchyme condenses and forms caps, in which the layer of cells in contact with the ducts acquires a palisade-like appearance. Subsequently, vesicles differentiate from the caps, representing the first rudiment of the nephron. The next stage is the change of the vesicle to an S-shaped tubule, the “lower” end of which becomes crescentic or bowl-shaped and is the first anlage of Bowman's capsule: the “upper” end connects with the collecting duct.
TL;DR: It is concluded that the inhibition or stimulation of the adrenal steroidogenesis does not modify the noradrenaline contents of the cat adrenal medulla and therefore norad Renaline is not merely a precursor for adrenaline.
TL;DR: In this paper, it was shown that the Cohen and Turnbull relationship describes the atmospheric pressure viscosities of many liquids with remarkable accuracy, and that it describes the average free volume per molecule.
Abstract: IN previous articles1,2 we have shown that the equation describes the atmospheric pressure viscosities of many liquids with remarkable accuracy. Equation (1) was obtained from the Cohen and Turnbull relationship between the diffusion coefficient D and “the average free volume per molecule”, Vf, defined by Vf = v−v0, where v is the average volume per molecule in the liquid and v0 the van der Waals volume of the molecule3.