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排序方式: 共有3456条查询结果,搜索用时 31 毫秒
31.
Daniela Pinzani Anna Maria Papini Mario Chelli Mauro Ginanneschi Carlo Alberto Maggi Riccardo Patacchini Laura Quartara Gianfranco Rapi 《Letters in Peptide Science》1996,2(5):307-313
Summary The adamantane moiety was introduced in the tachykinin NK2 receptor-selective agonist [-Ala8]-NKA(4–10) (H-Asp-Ser-Phe-Val--Ala-Leu-Met-NH2, MEN 10210) and in different positions of the NK2 receptor antagonist MEN 10376 (H-Asp-Tyr-d-Trp-Val-d-Trp-d-Trp-Lys-NH2) in order to investigate how this substitution affects their biological activity at tachykinin NK1, NK2 and NK3 receptors. 1-Adamantaneacetic acid (1-Ada-CH2COOH) was directly conjugated in the solid phase as the preformed OBt active ester to the N-terminal position of MEN 10210, obtaining MEN 10586 (1-Ada-CH2CO-Asp-Ser-Phe-Val--Ala-Leu-Met-NH2). The Pfp ester of adamantaneacetic acid (1) was prepared and used for the acylation of the N-terminal position of MEN 10376, yielding MEN 10606 (1-Ada-CH2CO-Asp-Tyr-d-Trp-Val-d-Trp-d-Trp-Lys-NH2). Compound 1 was then used to obtain the building block Fmoc-Lys(1-Ada-CH2CO)-OH as a modified amino acid for the synthesis of MEN 10818 [H-Asp-Tyr-d-Trp-Val-d-Trp-d-Trp-Lys(1-Ada-CH2CO)-NH2]. In order to investigate the biological activity of the peptide bearing the adamantane group together with the free N-terminal amino function, we synthesised MEN 10676 [H-Asp(O-2-Ada)-Tyr-d-Trp-Val-d-Trp-d-Trp-Lys-NH2] using Fmoc-Asp(O-2-Ada)-OH, in which 2-adamantanole was the protecting group of the aspartate -COOH moiety during the peptide synthesis and survived the final peptide cleavage and deprotection carried out under controlled conditions. MEN 10586 showed an agonist activity comparable to that of the parent compound MEN 10210 at NK1 and NK2 receptors of guinea pig ileum, rabbit isolated pulmonary artery and hamster isolated trachea preparations, while it showed a 25-fold higher agonist activity at NK3 receptors of rat isolated portal vein. The three modified antagonist analogs displayed similar or reduced affinity at NK1, NK2 and NK3 receptors as compared to MEN 10376. The drop was particularly evident (>2 log units) at the NK2 receptors of the rabbit isolated pulmonay artery. 相似文献
32.
Laura Chiarantini Luigia Rossi Alessandra Fraternale Mauro Magnani 《Molecular and cellular biochemistry》1995,144(1):53-59
Human and murine blood cells treated with ZnCl2 and bis(sulfosuccinimidyl)suberate (BS3) (a cross linking agent) undergo band 3 clustering and binding of hemoglobin to red blood cell membrane proteins. These clusters induce autologous IgG binding and complement fixation, thus favouring the phagocytosis of ZnCl2/BS3 treated cells by macrophages. The extension of red blood cell opsonization can be easily modulated by changing the ZnCl2 concentration in the 0.1–1.0 mM range thus providing an effective way to affect blood cell recognition by macrophages. In fact, murine erythrocytes treated with increasing ZnCl2 concentrations have proportionally reduced survivals when reinjected into the animal. Furthermore, the organ sequestration of ZnCl2/BS3 treated cells strongly resembles the typical distribution of the senescent cells. Since the ZnCl2/BS3 treatment can also be performed on red blood cells loaded with drugs or other substances, this procedure is an effective drug-targeting system to be used for the delivery of molecules to peritoneal, liver and spleen macrophages. 相似文献
33.
S. Aime Mauro Botta S. Geninatti Crich Giovanni B. Giovenzana Roberto Pagliarin Maurizio Piccinini Massimo Sisti Enzo Terreno 《Journal of biological inorganic chemistry》1997,2(4):470-479
A novel heptacoordinating ligand consisting of a thirteen-membered tetraazamacrocycle containing the pyridine ring and bearing
three methylenephosphonate groups (PCTP-[13]) has been synthesized. Its Gd(III) complex displays a remarkably high longitudinal
water proton relaxivity (7.7 mM–1 s–1 at 25 °C, 20 MHz and pH 7.5) which has been accounted for in terms of contributions arising from (1) one water molecule
bound to the metal ion, (2) hydrogen-bonded water molecules in the second coordination sphere, or (3) water molecules diffusing
near the paramagnetic chelate. Variable-temperature 17O-NMR transverse relaxation data indicate that the residence lifetime of the metal-bound water molecule is very short (8.0 ns
at 25 °C) with respect to the Gd(III) complexes currently considered as contrast agents for magnetic resonance imaging. Furthermore,
GdPCTP-[13] interacts with human serum albumin (HSA), likely through electrostatic forces. By comparing water proton relaxivity
data for the GdPCTP-[13]-HSA adduct, measured as a function of temperature and magnetic field strength, with those for the
analogous adduct with GdDOTP (a twelve-membered tetraaza macrocyclic tetramethylenephosphonate complex lacking a metal-bound
water molecule), it has been possible to propose a general picture accounting for the main determinants of the relaxation
enhancement observed when a paramagnetic Gd(III) complex is bound to HSA. Basically, the relaxation enhancement in these systems
arises from (1) water molecules in the hydration shell of the macromolecule and protein exchangeable protons which lie close
to the interaction site of the paramagnetic complex and (2) the metal bound water molecule(s). As far as the latter contribution
is concerned, the interaction with the protein causes an elongation of the residence lifetime of the metal-bound water molecule,
which limits, to some extent, the potential relaxivity enhancement expected upon the binding of the paramagnetic complex to
HSA.
Received: 27 January 1997 / Accepted: 12 May 1997 相似文献
34.
Studies of AIDS vaccination using an ex vivo feline immunodeficiency virus model: protection conferred by a fixed-cell vaccine against cell-free and cell-associated challenge differs in duration and is not easily boosted. 总被引:4,自引:2,他引:2 下载免费PDF全文
D Matteucci M Pistello P Mazzetti S Giannecchini D Del Mauro I Lonetti L Zaccaro C Pollera S Specter M Bendinelli 《Journal of virology》1997,71(11):8368-8376
Cats immunized with cells infected with a primary isolate of feline immunodeficiency virus (FIV) and fixed with paraformaldehyde were challenged with cell-free or cell-associated homologous virus obtained ex vivo. Complete protection was observed in animals challenged with cell-free virus 4 months after completion of vaccination (p.v.) or with cell-associated virus 12 months p.v. In contrast, no protection was observed in cats challenged with cell-free virus 12 or 28 months p.v. or with cell-associated virus 37.5 months p.v. Prior to the 28- and 37.5-month challenges, the animals had received a booster dose of vaccine that had elicited a robust anamnestic immune response. These results show that vaccine-induced protection against ex vivo FIV is achievable but is relatively short-lived and can be difficult to boost. 相似文献
35.
A simple mathematical model of the interaction between intracranial pressure and cerebral hemodynamics 总被引:6,自引:0,他引:6
Ursino, Mauro, and Carlo Alberto Lodi. A simplemathematical model of the interaction between intracranial pressure andcerebral hemodynamics. J. Appl.Physiol. 82(4): 1256-1269, 1997.A simplemathematical model of intracranial pressure (ICP) dynamics oriented toclinical practice is presented. It includes the hemodynamics of thearterial-arteriolar cerebrovascular bed, cerebrospinal fluid (CSF)production and reabsorption processes, the nonlinear pressure-volumerelationship of the craniospinal compartment, and a Starling resistormechanism for the cerebral veins. Moreover, arterioles are controlledby cerebral autoregulation mechanisms, which are simulated by means ofa time constant and a sigmoidal static characteristic. The model isused to simulate interactions between ICP, cerebral blood volume, andautoregulation. Three different related phenomena are analyzed: thegeneration of plateau waves, the effect of acute arterial hypotensionon ICP, and the role of cerebral hemodynamics during pressure-volume index (PVI) tests. Simulation results suggest the following:1) ICP dynamics may become unstablein patients with elevated CSF outflow resistance and decreasedintracranial compliance, provided cerebral autoregulation is efficient.Instability manifests itself with the occurrence of self-sustainedplateau waves. 2) Moderate acutearterial hypotension may have completely different effects on ICP,depending on the value of model parameters. If physiological compensatory mechanisms (CSF circulation and intracranial storage capacity) are efficient, acute hypotension has only negligible effectson ICP and cerebral blood flow (CBF). If these compensatory mechanismsare poor, even modest hypotension may induce a large transient increasein ICP and a significant transient reduction in CBF, with risks ofsecondary brain damage. 3) The ICPresponse to a bolus injection (PVI test) is sharply affected, viacerebral blood volume changes, by cerebral hemodynamics andautoregulation. We suggest that PVI tests may be used to extractinformation not only on intracranial compliance and CSF circulation,but also on the status of mechanisms controlling CBF. 相似文献
36.
Angela S. Barbosa Thaís E. Ferraz-Costa Mauro Semer Bernardo Liberman Carlos A. Moreira-Filho 《Human genetics》1995,95(1):63-66
This paper reports a case of XY gonadal dysgenesis in two sisters. Both patients presented an eunochoid female phenotype with normal external genitalia. At laparotomy, the elder sister was found to have bilateral gonadoblastoma. Cytogenetic studies, which included G and C banding and in situ hybridization, showed that the patients had an apparently normal 46, XY karyotype. PCR analyses revealed absence of the conserved portion (HMG box) of the SRY gene and of the Y chromosome pseudoautosomal boundary region sequence in both patients. The presence of the ZFY sequence was detected by Southern hybridization in the two affected sisters. The patients' father (46, XY, no mosaicism detected in peripheral blood lymphocytes) was positive for SRY and ZFY sequences. The occurrence of gonadoblastoma is discussed in terms of the genetic factors that may lead to tumor development. 相似文献
37.
Marcela F. Lopes Vânia Lúcia C. Merquior JoséMauro Peralta Lúcia M. Teixeira 《FEMS immunology and medical microbiology》1995,12(3-4):205-211
Abstract Exosubstances (cohemolysins) produced by Streptococcus agalactiae (CAMP-factor) and Streptococcus uberis (Uberis-factor) showing hemolytic synergism with β-lysin produced by Staphylococcus aureus were compared. Cohemolytic activity was evaluated in the supernatants of bacterial cultures, before and after ammonium sulfate precipitation. Sheep erythrocytes sensitized with β-lysin were used as substrate. The assays were performed in microtiter plates and results were expressed as cohemolytic units/ml. Maximum cohemolytic activity was detected, respectively, after 8 h and 14 h of growth in Columbia broth in S. uberis and S. agalactiae cultures. Cohemolytic activities of both microorganisms showed similarities when submitted to various physical and chemical treatments. They were significantly decreased by heating at 60°C and 100°C, or in presence of trypsin, and were abolished in the presence of Tween 20. Activities were found to be stable in crude supernatants and concentrated preparations maintained at −20°C for 3 months. Differences were related to levels of activity and kinetics of detection during the growth cycle. The results indicate the proteic nature, at least in part, of the Uberis factor. Analysis by PAGE in the presence or absence of SDS allowed us to correlate Uberis activity with a protein band with apparent molecular mass of 42 kDa, while CAMP activity was associated with a protein band of 27 kDa. 相似文献
38.
Mauro Magnani Vilberto Stocchi Marina Dachà Giorgio Fornaini 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1984,804(2):145-153
The true level of hexokinase in rabbit erythrocytes was determined by three different methods, including the spectrophotometric glucose-6-phosphate dehydrogenase coupled assay and a new radioisotopic assay. The value found at 37°C (pH 7.2) was 10.23±1.90 μmol/h per ml red blood cells, which is lower than previously reported values. More than 40 cellular components of the rabbit erythrocytes were tested for their effects on the enzyme. Their intracellular concentrations were also determined. Several of these compounds were found to be competitive inhibitors of the enzyme with respect to Mg·ATP2?. Furthermore, reduced glutathione at a concentration of 1 mM was able to maintain hexokinase in the reduced state with full catalytic activity. The ability of orthophosphate to remove the inhibition of some phosphorylated compounds was examined under conditions similar to cellular (pH 7.2 and 50 μM of orthophosphate) and found to be of no practical interest. In contrast, the binding of ATP4? and 2,3-diphosphoglycerate to the rabbit hemoglobin significantly modifies their intracellular concentrations and the formation of the respective Mg complexes. The pH-dependence of the reaction velocity and of the kinetic properties of the enzyme in different buffer systems were also considered. This information was computerized, and the rate of glucose phosphorylation in the presence of the mentioned compounds was determined. The value obtained, 1.94±0.02 μmol/h per ml red blood cells, is practically identical to the measured rate of glucose utilization by intact rabbit erythrocytes (1.92±0.3 μmol/h per ml red blood cells). These results provide further evidence for the central role of hexokinase in the regulation of red blood cell glycolysis. 相似文献
39.
Mauro Magnani Vilberto Stocchi Marina Dachà Giorgio Fornaini 《Molecular and cellular biochemistry》1984,61(1):83-92
Summary Rabbit hexokinase (EC 2.7.1.1) has been shown to exist in reticulocytes as two distinct molecular forms, designated hexokinase Ia and Ib, but only one of these was consistently present in mature red cells. In vivo, hexokinase la and Ib show a decay rate of 3 and 8% a day, respectively, while in vitro they show a similar stability.The possibility that the proteolytic activities of the reticulocyte could be responsible for the fast decay of hexokinase was investigated. No differences were found in the decay rates of hexokinase la and Ib during in vitro reticulocyte maturation in presence or absence of proteolytic inhibitors. Contrariwise, many findings indicate the ATP-dependent proteolytic system of the reticulocyte as a possible mechanism. In fact, the decay of hexokinase and the degradation of 3H-globins are both stimulated by ATP and ubiquitin; they show similar kinetic properties and both disappear during reticulocyte maturation.The cellular localization of hexokinase la and Ib was shown to be responsible for the differences found between their decay rates.Abbreviations PMSF
phenylmethylsulfonyl fluoride
- TPCK
1-1-tosylamide-2-phenylethyl-chloromethyl ketone
- TLCK
N -p-tosyl-L-lysine chloromethyl ketone 相似文献
40.