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21.
Daniele Arobba Andrea Quaglia Paolo Panagia Paolo Minuti Sergio Innocenti Pier Luigi Odda 《Aerobiologia》1988,4(1-2):38-46
Riassunto Sono state rilevate durante un monitoraggio aerobiologico effettuato a Pietra Ligure (Savona) nel corso del 1987 le concentrazioni
polliniche di 50 taxa ed è stata valutata l'influenza relativa dei fattori meteorologici. Le osservazioni palinologiche sono
state rapportate alle concentrazioni sieriche delle IgE specifiche, alla reattività bronchiale specifica ed aspecifica valutate
in 101 pazienti allergici (rinitici ed asmatici), sensibilizzati a Graminaceae ed Urticaceae (Parietaria) al fine di riconoscere
correlazioni tra le caratteristiche aerobiologiche di questi allergeni edi meccanismi patogenetici che sostengono la reattività
bronchiale.
相似文献
22.
Claudio Toniolo Gian Maria Bonora Richard J. Freer Scott P. Kennedy Kirsten L. Pittenger Elmer L. Becker 《Peptides》1988,9(6):1195-1205
The two diastereomeric sulphoxides and the sulphone derived from the formyl-methionyl tripeptide chemoattractant CHO-L-Met-L-Leu-L-Phe-OMe have been synthesized and fully characterized. The diastereomeric sulphoxide tripeptides have been separated at the stage of their N-tert-butyloxycarbonyl synthetic precursors. All of the oxidized sulphur derivatives induce secretion of granule enzymes with ED50s from 1–2×10−9 M with no significant differences in activity among them. They are also active to the same relative extent in inducing chemotaxis. In parallel, a solution conformational analysis has been performed in solvents of widely different polarities and capabilities of H-bond formation using circular dichroism, infrared absorption and 1H nuclear magnetic resonance. No significant propensity for formation of intramolecularly (C=O…H-N) H-bonded folded forms has been detected in any of the four tripeptides. Intermolecular S=O…H-N interactions are postulated to tentatively explain the 1H nuclear magnetic resonance behavior of the Met and, particularly, Leu NH resonances of the two sulphoxide tripeptides in CDCl3 solution. The biological and conformational data agree with the recently proposed model of the chemotactic peptide receptor of rabbit neurotrophils, which involves the extended backbone of the integrity of the Met side-chain sulphide sulphur atom as a corollary point of ligand interaction. 相似文献
23.
Giampaolo Manao Luigia Pazzagli Paolo Cirri Anna Caselli Guido Camici Gianni Cappugi Ahmad Saeed Giampietro Ramponi 《Journal of Protein Chemistry》1992,11(3):333-345
Two lowM
r phosphotyrosine protein phosphatases have been isolated from rat liver. The enzymes were previously known as lowM
r acid phosphatases, but several recent studies have demonstrated that this family of enzymes possesses specific phosphotyrosine protein phosphatase activity. We determined the complete amino acid sequences of the two isoenzymes and named them AcP1 and AcP2. Both consist of 157 amino acid residues, are acetylated at the NH2-terminus, and have His as the COOH-terminus. The molecular weights calculated from the sequences are 18,062 for AcP1 and 17,848 for AcP2. They are homologous except in the 40–73 zone, where about 50% of residues are different. This fact suggests that the two isoenzymes are produced by an alternative splicing mechanism. There is no homology between these two isoenzymes and the receptor-like phosphotyrosine protein phosphatases LAR, CD45, human placenta PTPase 1B, and rat brain PTPase-1. AcP1 and AcP2 are also distinct from rat liver PTPase-1 and PTPase-2, since these last enzymes have higher molecular weights. AcP1 differs from AcP2 with respect to (1) substrate affinity and (2) its sensitivity to activators and inhibitors, thus suggesting a their different physiological function. 相似文献
24.
Enzo Ottaviani Antonella Franchini Paolo Fontanili 《Cellular and molecular neurobiology》1992,12(5):455-462
1. Using an immunocytochemical procedure a wide range of immunoreactive vertebrate bioactive peptides (BAPs) has been found in hemocytes of Viviparus ater: bombesin, calcitonin, CCK-8, CCK-39, GH, glucagon, insulin, oxytocin, neurotensin, secretin, serotonin, somatostatin, substance P, vasopressin, and VIP. 2. No immunostaining was observed for antigastrin and antithyroglobulin antibodies. 3. The presence of BAP-like molecules in hemocytes suggests a correlation between hemocyte and APUD cells and is evidence of a relationship between the neuroendocrine and the immune systems. 相似文献
25.
Alba Vecchini Luciano Binaglia Paolo Di Nardo Marilena Minieri Giuseppe Tallarida 《Molecular and cellular biochemistry》1992,110(1):47-54
The activity of phospholipid base exchange enzymes has been evaluated in cardiac sarcolemmal membranes from Syrian Golden
hamsters and from a hamster strain (UM-X7.1) characterized by a genetic form of hypertrophic cardiomyopathy. No choline base
exchange activity and only a little serine base exchange activity were detected, whereas the ethanolamine base exchange enzyme
was found highly active in membranes from both strains. For this reason, the present study is focussed on the ethanolamine
base exchange enzyme. The apparent Km for ethanolamine of ethanolamine base exchange enzyme from Syrian Golden membranes and
from UM-X7.1 strain membranes are 18 and 32 μM, respectively. The specific activity of the sarcolemmal ethanolamine base exchange
enzyme is lower in the UM-X7.1 strain than in Syrian Golden hamsters. The calcium-dependence of the enzyme appears different
when the membranes from the two strains are compared. Indeed, after removal of the membrane-bound divalent cations, comparable
activities are found in both membrane preparations, whereas, upon addition of Ca2+ to the incubation mixtures, the activity of the enzyme is enhanced in the membranes from Syrian Golden strain more than in
those from UM-X7.1 strain. The cholesterol content of sarcolemmal membranes is higher in the cardiomyopathic strain than in
the Syrian Golden hamsters. A possible relation between changes of the membrane lipid composition and of the ethanolamine
base exchange activity is discussed. 相似文献
26.
Paolo Gaudiano 《Biological cybernetics》1992,67(1):23-34
This article makes use of a push-pull shunting network, which was introduced in the companion article, to model certain properties of X and Y retinal ganglion cells. Input to the push-pull network is preprocessed by a nonlinear mechanism for temporal adaptation, which is ascribed here to photoreceptor dynamics. The complete circuit is used to show that a simple change in receptive field morphology within a single model equation can change the network's response characteristics to closely resemble those of either X or Y cells. Specifically, an increase in width of the receptive field center mechanism is sufficient to account for generation of on-off (Y-like) instead of null (X-like) responses to modulated gratings. In agreement with experimental data, the Y cell on-off response is independent of spatial phase. Also, the model accurately predicts that on-off responses can be observed in X cells for particular stimulus configurations. Taken together, the results show how the retina combines individually inadequate modules to efficiently handle the tasks required for accurate spatial and temporal visual information processing. The model is also able to clarify a number of controversial experimental findings on the nature of spatiotemporal visual processing in the retina. 相似文献
27.
Phenylarsine oxide induces the cyclosporin A-sensitive membrane permeability transition in rat liver mitochondria 总被引:2,自引:0,他引:2
Ewa Lenartowicz Paolo Bernardi Giovanni Felice Azzone 《Journal of bioenergetics and biomembranes》1991,23(4):679-688
This paper reports an investigation on the effects of the hydrophobic, bifunctional SH group reagent phenylarsine oxide (PhAsO) on mitochondrial membrane permeability. We show that PhAsO is a potent inducer of the mitochondrial permeability transition in a process which is sensitive to both the oxygen radical scavanger BHT and to cyclosporin A. The PhAsO-induced permeability transition is stimulated by Ca2+ but takes place also in the presence of EGTA in a process that maintains its sensitivity to BHT and cyclosporin A. Our findings suggest that, at variance from other known inducers of the permeability transition, PhAsO reacts directly with functional SH groups that are inaccessible to hydrophilic reagents in the absence of Ca2+. 相似文献
28.
The rheological properties of aqueous solutions of hydroxyethyl guar gum, a synthetic derivative of guar gum, have been studied under continuous and oscillatory shear flow conditions. Data obtained from both experimental techniques were satisfactorily fitted according to Cross-type models. The effect of polymer concentration, molecular weight and temperature on the rheological behavior of hydroxyethyl guar gum systems have been investigated and discussed in terms of rheological parameters like the zero-shear viscosity η0 and the characteristic times λ and λ′. 相似文献
29.
Jean-Marc Gilli Paolo Mariani Franco Rustichelli Bin Yang Hervé Delacroix 《Molecular Engineering》1992,2(2):177-188
We recently showed that a side-chain industrial co-oligosiloxane presents a quenchable enlarged blue phase behaviour at the cholesteric-isotropic phase transition. In this paper, we present the results of a structural study based on X-ray diffraction, differential scanning calorimetry and optical measurements. In particular, the smectic A organisation is demonstrated in the lower temperature domain, which was hitherto understood as a cholesteric phase. A structural model for this phase is proposed on the basis of the analysis of the anisotropic scattering of stretched fibers. Our results also suggest that the observed glass transition is indeed a rather complex phenomenon, which seems to involve not only the freezing of the main chains, but also smectic correlations at the side-chain level. Moreover, the calorimetric study indicates that, notwithstanding the conservation of the processed film's optical properties, low kinetic reorganisations occur at room temperature. 相似文献
30.
Antonella Angiolillo Fausto Panara Gina Piccinini Gian Luigi Gianfranceschi 《Molecular biology reports》1991,15(1):39-43
A protein kinase, type NII, has been purified from wheat germ chromatin. The enzyme, which uses both ATP and GTP as phosphoryl donors, catalyzes the phosphorylation of casein, phosvitin and E. coli RNA polymerase, but not of histone proteins. Polypeptide bands at 46 kDa, 37 kDa and 25 kDa were estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Autophosphorylation of the 25 kDa subunit was observed following incubation of the purified kinase with (-32P)ATP and (-32P)GTP. 相似文献