Showing papers by "National University of La Plata published in 1982"
TL;DR: It is reported that peptides derived from the N-terminal non-γ-melanocyte-stimulating hormone (MSH) portion of the precursor of ACTH, proopiocortin, are potent stimulators of adrenal DNA synthesis in vitro and mitosis in vivo and may thus be involved in the physiological control of Adrenal growth.
Abstract: Although it was generally believed that corticotropin (ACTH) maintained both the size of the adrenal gland and its level of steroid production1, there is a growing body of evidence for a specific factor(s) distinct from ACTH which may be responsible for the stimulation of adrenocortical growth and proliferation. While direct neural influences have been proposed to be responsible for the compensatory adrenal growth following unilateral adrenalectomy2, several observations have suggested the involvement of peptides such as angiotensin3 and vasopressin4, which have other hormonal effects, or, for example, fibroblast growth factor5, which has more general mitogenic actions. Moreover ACTH inhibits cell proliferation in vitro6–8, and physiological doses in vivo cannot induce the compensatory growth and hyperplasia seen in the remaining adrenal gland after unilateral adrenalectomy9. These observations coupled with the lack of effect of chronic treatment with an ACTH antiserum on adrenal size10 and the existence of adrenal weight-maintaining activity in the plasma of patients with ACTH-secreting adenomas11, have led to the search for a pituitary factor related to ACTH which is capable of stimulating adrenal growth. We now report that peptides derived from the N-terminal non-γ-melanocyte-stimulating hormone (MSH) portion of the precursor of ACTH, proopiocortin, are potent stimulators of adrenal DNA synthesis in vitro and mitosis in vivo and may thus be involved in the physiological control of adrenal growth.
147 citations
TL;DR: In this article, a model for interpreting recrystallization of ice in frozen beef was established considering that the driving force is the tendency to a decrease in surface energy of the crystalline phase and that rate of movement of the grain boundary is proportional to its curvature.
Abstract: Temperature fluctuations produced during storage and transport of frozen food lead to activation of the recrystallization processes, causing enlargement of the ice crystals and diminishing advantages obtained in quick freezing of products. A model for interpreting recrystallization of ice in frozen beef was established considering that in this phenomenon the driving force is the tendency to a decrease in surface energy of the crystalline phase and that rate of movement of the grain boundary is proportional to its curvature. Meat samples were frozen and submitted to higher storage temperatures. Histological analysis of tissues immediately after freezing and of samples stored at different times made it possible to measure evolution of ice crystal size and obtain kinetic constants for proposed recrystallization model. Mechanisms for interpreting the phenomena were discussed, determining that transition of molecules occurs preferently through the liquid phase.
68 citations
TL;DR: In this paper, the energy difference between the Gamow-Teller and Fermi resonances is given in units of MeV, by E GT − E F =26A − 1 3 −18.5 (N − Z)/A.
61 citations
01 Jan 1982
TL;DR: The references to which the reader is referred for further discussion of the subjects covered in this section are Flory (1953, 1969), Tanford (1967), Billmeyer (1971), Vollmert (1973), Elias (1972), Hoffman et al. (1977), and Cantow (1967) as discussed by the authors.
Abstract: General references to which the reader is referred for further discussion of the subjects covered in this section are Flory (1953, 1969), Tanford (1967), Billmeyer (1971), Vollmert (1973), Elias (1972), Hoffman et al. (1977), and Cantow (1967).
35 citations
TL;DR: In this paper, the i.r. spectra of matrix isolated and vapour phase OVCl 3 were investigated and several vibrational isotopic splittings due to the natural abundance of 35 Cl/37 Cl were observed.
25 citations
TL;DR: In this article, the properties of the monazite compounds LnAsO 4 (Ln ≡ La, Ce, Pr, Nd ) were determined from X-ray powder diagrams.
Abstract: Crystallographic data for the compounds LnAsO 4 ( Ln ≡ La , Ce , Pr , Nd ) which crystallize in the monazite structural type were determined from X-ray powder diagrams. Their vibrational spectra are also reported and discussed in comparison with those of some related compounds.
24 citations
TL;DR: In this paper, the electrosorption and electrooxidation of formic acid were studied on Pt+Rh electrodes of different surface compositions, and the surface characteristics (composition, true area, stability) of the alloy electrodes were estimated in situ from voltammograms recorded in a supporting electrolyte.
21 citations
TL;DR: In this article, the regularization of fermionic functional integrals is investigated with the method of finite-dimensional approximations, and conditions for preserving gauge invariance in these approximation are stated.
Abstract: The regularization of fermionic functional integrals is investigated with the method of finite-dimensional approximations. The conditions for preserving gauge invariance in these approximations are stated. This regularization is applied to describe the divergences of vector and axial-vector currents.
19 citations
TL;DR: Several models that account for deviations from ideality of osmotic flow have been developed as discussed by the authors, which correspond to the boundary layer, cavitation and partial clogging effects with an effectively semi-permeable membrane.
18 citations
TL;DR: In this paper, the retention behavior of olefins in ethylene glycol was studied and the contribution of so-called Kelvin retention to the overall retention process was calculated and its significance for different systems was discussed.
18 citations
TL;DR: Three lipoproteins differing in hydrated densities were isolated by ultracentrifugal procedures from the haemolymph of adult and fasted Triatoma infestans and HDL was the predominant lipoprotein.
Abstract: 1.
1. Three lipoproteins differing in hydrated densities were isolated by ultracentrifugal procedures from the haemolymph of adult and fasted Triatoma infestans.
2.
2. They are the high density lipoprotein HDL (d = 1.115−1.152) and the two very high density lipoproteins VHDL-I (d = 1.190−1.231) and VHDL-II (d = 1.245−1.260). HDL was the predominant lipoprotein.
3.
3. The total lipid content expressed as % of lipoprotein weight in HDL, VHDL-I and VHDL-II was 30.1, 7.8 and 2.9% respectively. Diacylglycerols are the predominant lipids of HDL (38.7%) and VHDL-I (27.0%) but only amount to 6.2% in VHDL-II.
4.
4. Triacylglycerols are minor components (about 6.0%) of all fractions.
5.
5. The phospholipids (phosphatidylethanolamine and phosphatidylcholine), sterols, sterol esters and hydrocarbons were present in all lipoprotein fractions.
6.
6. Phospholipids and hydrocarbons were the most abundant lipids of VHDL-II.
TL;DR: In a principal-monitor-agent model, the principal’s choice of the timing to monitor the agent presents a trade-off so that a signal from an ex ante monitor (supervisor) provides flexibility in contracting and can be used to punish the agent.
Abstract: In a principal-monitor-agent model we show that the principal’s choice of the timing to monitor the agent presents a trade-off. On the one hand, a signal from an ex ante monitor (supervisor) provides flexibility in contracting (since both output and wages can be contracted on this signal). On the other hand, a signal from an ex post monitor (auditor) can be used to punish the agent. Auditing is optimal when (i) strong punishment schemes can be implemented and enforced by courts or (ii) when punishment instruments are not expected to be strong and the monitor’s signal is noisy. Supervising is optimal otherwise.
TL;DR: In this article, the resonance Raman spectrum of the MnO 4 − ion labeled with 18 O and dispersed in a RbBr matrix was measured during a vibrational study of manganates, which allowed the calculation of harmonic wavenumbers and anharmonicity constants for the symmetric stretching mode.
01 Jan 1982
TL;DR: Mean amplitudes of vibration for the XeOF5− anion have been calculated from known Raman data in a wide temperature range as mentioned in this paper, and some comparisons with other ZXY5 species, as well as with related Xenon compounds are made.
Abstract: Mean amplitudes of vibration for the XeOF5− anion have been calculated from knownRaman data in a wide temperature range. The results are briefly discussed and some comparisons with otherZXY5 species, as well as with related xenon compounds are made.
TL;DR: The expression and maintenance of nitrogenase (C(2)H(2)) activity in growing, microaerobic liquid cultures of Rhizobium japonicum 3I1b110 was found to be stringently dependent on the sustained supply of CO(2).
Abstract: The expression and maintenance of nitrogenase (C2H2) activity in growing, microaerobic liquid cultures of Rhizobium japonicum 3I1b110 was found to be stringently dependent on the sustained supply of CO2. This requirement for CO2 appeared to exceed the basal requirement for growth and was not related to effects on pH.
TL;DR: The wide distribution of cross-reaction with the antibody among vertebrates suggests that a sequence of the cryptic region of the corticotropin/lipotropin common precursor may be responsible for a yet undiscovered biological effect.
TL;DR: In this paper, the vibrational behavior of water molecules in hydrated alkaline-earth nitroprussides, M [Fe(CN)5NO] n H2O, which were previously studied in this laboratory, was compared.
01 Jan 1982
TL;DR: In this article, X-ray powder data for oxoapatites of general formula Ca8Ln2(PO4)6O2 withLn=La, Pr-Ho has been obtained.
Abstract: Crystallographic data for the oxoapatites of general formula Ca8Ln2(PO4)6O2 withLn=La, Pr-Ho) have been obtained from X-ray powder data. The vibrational spectra, which are also discussed, allow to make a proposal about the location of the lanthanide cations present in these lattices.
TL;DR: In this article, the motion of an accelerated charge in vacuum is analyzed, via the superposition principle and Fourier analysis, into uniform motion components, which include bradyonic as well as tachyonic contributions.
Abstract: The motion of an accelerated charge in vacuum is analyzed, via the superposition principle and Fourier analysis, into uniform-motion components, which include bradyonic as well as tachyonic contributions. It is shown that the former contribute only to the induction fields whereas the latter are the source of the radiation emitted by the charge, via the Sommerfeld-\ifmmode \check{C}\else \v{C}\fi{}erenkov mechanism. This result calls for a reexamination of some recently formulated theories of superluminal particles.
TL;DR: In this paper, the resonance Raman spectrum of the MnO ion enriched in 18O and dispersed in a RbBr matrix was obtained, and the symmetric stretching fundamental band and its first three overtones were measured for the five possible isotopomers.
Abstract: The resonance Raman spectrum of the MnO ion enriched in 18O and dispersed in a RbBr matrix was obtained. The symmetric stretching fundamental band and its first three overtones were measured for the five possible isotopomers, allowing an estimation of the corresponding harmonic frequencies and anharmonicity constants. An explanation for the observed trend in these constants is proposed.
TL;DR: In this article, the electronic structure of an interstitial hydrogen atom in an octahedral cluster of ferromagnetic nickel in a condensed matter-like boundary potential was analyzed using multiple scattering.
Abstract: We apply the multiple scattering cluster‐in‐condensed‐matter technique to study the electronic structure of an interstitial hydrogen atom in an octahedral cluster of ferromagnetic nickel in a condensed matter‐like boundary potential. From the calculation we obtain the approximate absorption energies, the vibrational frequencies for hydrogen, the effect on the magnetic moment of the cluster, and the change in local paramagnetic susceptibility and hyperfine field at the hydrogen and neighboring nickel sites. The obtained values compare favorably with available experimental data. The bonding between the hydrogen and the nickel is discussed, by comparing the results with those for H2, Ni2, and Ni2H2 molecules.
01 Jan 1982
TL;DR: By computing exactly the Wilson loop expectation value for two-dimensional quantum electrodynamics, it was shown that the non-leading terms depend drastically on the shape of the contour.
Abstract: By computing exactly the Wilson loop expectation value for two-dimensional quantum electrodynamics, we show that the nonleading terms depend drastically on the shape of the contour.
TL;DR: In this article, the resonance Raman spectra of the title compounds of the Tetraphenylarsonium and tetrahenylphosphonium were used to study the vibrational properties of the MnO ion in these lattices.
Abstract: Die Messung von Raman- und Resonanz-Raman-Spektren der Titelverbindungen ermoglichte weitere Einsicht in das schwingungsspektroskopische Verhalten des MnO-Ions in diesen Gittern. Aus den Resonanz-Raman-Messungen konnten weiterhin die Anharmonizitatskonstanten und harmonische Schwingungsfrequenzen fur die totalsymmetrische Valenzschwingung sowie die X13-Anharmonizitatskonstante ermittelt werden. Die Ergebnisse werden kurz besprochen.
Raman and Resonance Raman Spectra of the Permanganates of Tetraphenylarsonium and Tetraphenylphosphonium
The measurement of Raman and resonance Raman spectra of the title compounds allow a wider insight into the vibrational properties of the MnO ion in these lattices. The anharmonicity constants and harmonic vibrational frequencies for the totally symmetric stretching vibration as well as the X13 anharmonicity constant could be determined from the resonance Raman spectra. The results are briefly discussed.
01 Jan 1982
TL;DR: In this article, it was shown that linearity and extended special relativity are incompatible, if superposition principle holds, which leads unambiguously to the unphysical conclusion that an accelerated charged particle does not emit electromagnetic radiation in vacuum.