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M Corti

Publications and source records attributed to M Corti.

At least 91 records · Page 5Linked to original sources
PubMed1990

Application of scattering techniques in the domain of amphiphiles.

Light and neutron scattering techniques are discussed in connection with experiments on micellar solutions of gangliosides--amphiphilic molecules of biological origin. Micellar properties, like molecular weight, hydrodynamic radius and shape, are obtained with precise scattering measurements in conditions of negligible intermicellar interactions. It has also been verified that the GM1 ganglioside micelle does not change molecular weight and shape on addition of salt. Scattering techniques are also shown to be useful in studying intermicellar interactions, like the Coulomb repulsion between GM1 micelles, in the regime fo the long-range interactions obtainable at very low ionic strength.

Gangliosides↗
PubMed1990

Aggregation properties of semisynthetic GM1 ganglioside (II3Neu5AcGgOse4Cer) containing an acetyl group as acyl moiety.

The aggregative properties of GM1 ganglioside containing an acetyl group as acyl moiety [GM1(acetyl)] in aqueous solution have been studied by static and dynamic light scattering measurements and surface tension experiments. GM1 (acetyl) spontaneously aggregates as small micelles showing a hydrodynamic radius and molecular weight of 34 A and 102 kDa, respectively, down to a concentration of 2.0 x 10(-5) M.

Acetylation↗
PubMed1990

Aggregation properties of GM3 ganglioside (II3Neu5AcLacCer) in aqueous solutions.

The aggregative properties of highly pure GM3 ganglioside in aqueous solution have been studied by static and dynamic laser light scattering measurements and fluorescence spectroscopy experiments performed by the use of a GM3 derivative containing the pyrene group at the end of the fatty acid moiety. GM3 ganglioside spontaneously aggregates as unilamellar vesicles, down to a concentration of 1.25 x 10(-8) M, showing molecular weight and hydrodynamic radius ranging from 15,000 to 30,000 kDa and from 350 to 470 A, respectively. GM3 vesicles are stable with dilution and can be stored at room temperature for some weeks without appreciable change.

Chemical Phenomena↗
PubMed1990

Evidence for spontaneous segregation phenomena in mixed micelles of gangliosides.

A light scattering study of the effect of mixing in aqueous solution two gangliosides, GM2 and GT1b, having different hydrophilic headgroups and similar lipid moieties is presented. Mixed micelle formation with spatial segregation of one ganglioside with respect to the other was observed. It is also shown that segregation is a spontaneous phenomenon which is explainable only in terms of simple geometrical arguments, that is by the fact that the large headgroup of GT1b provides the lipidic core of the aggregate with a better shielding from water in the highly curved regions than the smaller headgroup of GM2 can do. This finding may be of help in understanding the behaviour of gangliosides in artificial and natural membranes.

Carbohydrate Sequence↗
PubMed1990

Relationship between the regulation of membrane enzyme activities by gangliosides and a possible ganglioside segregation in membrane microdomains.

Laser and neutron scattering experiments showed that in mixed micelles of ganglioside GM2 and GT1b, a membrane mimicking system, the segregation of gangliosides may occur spontaneously. Photolabeling experiments using nitrophenylazide containing ganglioside GM1 proved that gangliosides added to cells in culture enter the cell and bind to its membrane as components of microdomains, which specifically interact with a protein of about 30 kDa. This suggests that ganglioside segregation may be a natural phenomenon. Gangliosides when added to granule cells in culture led to increase in protein phosphorylation, the effect exerted being related to the amount of ganglioside molecules inserted stably into the cell lipid layer and an increase of 0.7% of the cell original ganglioside content promoted an increase of 57% in the incorporation of 32P into cell membrane proteins. From the above results a possible relationship between ganglioside segregation and involvement of ganglioside in enzyme activity control is suggested.

Animals↗
PubMed1990

[Multiple retrofascial abscesses caused by staphylococcal sepsis].

A case of multiple retrofacial abscesses (left psoas and left paraspinal muscles) due to septic embolization probably arising from a staphylococcus aureus infection of a phlebopathic ulcer of the leg is reported. The Authors stress the pathogenetic rarity of the clinical picture, the usefulness of computed tomography for a correct diagnosis and for the follow-up of the treatment's efficacy, the favourable clinical course with medical therapy.

Abscess↗
PubMed1987

[Rabies and activity of the antirabies center in the province of Mantua].

After an examination of the aetiological, anatomopathological and clinical aspects of rabies, the latest epidemiological studies are described with emphasis on the ways the virus enters Italy. Particular emphasis is given to prophylaxis with gamma globulin and vaccines with a review of their preparation and use past and present. Details are also given of the latest vaccine prepared from human diploid embryonic cells (HDCV). The general and specific procedures adopted in the case of injuries by an animal belonging to a species capable of contracting and transmitting the infection are then described. The last part of the paper presents a case series covering 5 years' activity in the Antirabbies Centre in the Province of Mantua (1979-83). It is concluded that in order to prevent the spread of the disease we need veterinary vigilance, the presentation of information about the problem in schools and the mass media and local Antirabbies Centres providing a round the clock service of assistance and information.

Female↗
PubMed1986

Left ventricular dysfunction versus paravalvular leak in patients with mitral disc prostheses.

UNLABELLED: Left ventricular dysfunction and prosthesis malfunction are the main causes of hemodynamic deterioration following prosthetic mitral valve replacement. The aim of this study is to reassess the usefulness of a combined echo-phonocardiographic technique to differentiate these different situations in order to select medical or surgical treatment in patients with a mitral disc prosthesis. Two patient groups were studied. The first group consists of five patients with paravalvular leak (PL), surgically or pathologically verified. Second group: nine patients with left ventricular failure (LVF) and normal functioning prosthesis. The diastolic diameter of the left ventricle (LV) was significantly increased in the LVF group compared with the PL group. A protodiastolic hump was present in four cases of PL. The variability of the interval between A2 and the mitral valve opening (delta A2-MVO) was less than 30 msec in the LVF group and greater than 30 msec in the PL group. The interval between A2 and maximal LV posterior wall (A2-PW) exceeded 60 msec in the PL group and was shorter than 60 msec in the LVF group. IN CONCLUSION: the echo-phonocardiographic technique, especially when by using two newly proposed parameters, seems to be very useful to discriminate between PL and LVF.

Adult↗
PubMed1981

GM1-ganglioside-Triton X-100 mixed micelles: changes of micellar properties studied by laser-light scattering and enzymatic methods.

The micellar properties of mixtures of GM1 ganglioside and the non-ionic amphiphile Triton X-100 in 25 MM Na phosphate-5 mM di Na EDTA buffer (pH = 7.0) were investigated by quasielastic light scattering in a wide range of Triton/GM1 molar ratios and in the temperature range 15-37 degrees C. These measurements: (a) provided evidence for the formation of mixed micelles; (b) allowed the determination of such parameters as the molecular weight and the hydrodynamic radius of the mixed micelles; (c) showed the occurrence of statistical aggregates of micelles with increasing temperature and micelle concentration. Galactose oxidase was chosen for studying the relation between enzyme activity and micellar properties. The action of the enzyme on GM1 was found to be strongly dependent on the micellar structure. In particular: (a) galactose oxidase acted very poorly on homogeneous GM1 micelles, while affecting mixed GM1/Triton X-100 micelles; (b) at fixed GM1 concentration the oxidation rate increased by enhancing Triton X-100 concentration and followed a biphasic kinetics with a break at a certain Triton X-100 concentration; (c) the formation of statistical micelle aggregates was followed by inhibition of the enzyme activity.

Colloids↗
PubMed1980

Laser-light scattering investigation of the micellar properties of gangliosides.

The micellar properties of gangliosides in water solutions were investigated by quasielastic light scattering measurements. GM1 and GD1a gangliosides were isolated from calf brain, purified to more than 99% and dissolved in 0.025 M Tris--HCl buffer (pH 6.8) at 37 degrees C. The average intensity of scattered light and the intensity correlation function were measured by an apparatus including a 5145 A argon laser and a real-time digital correlator. The scattered intensity data allowed the derivation of an upper limit to the critical micelle concentration (c0) and the evaluation of the molecular weight (M) of the micelle. The intensity correlation function gave the diffusion coefficient D, and hence the hydrodynamic radius RH, and also contained information on the polydispersity of the sample. We find co less than 1 x 10(-6) M for both GM1 and GD1a, M = 532000 +/- 50000 and RH = 63.9 +/- 2 A for GM1, and M = 417000 +/- 40000 and RH = 59.5 +/- 2 A for GD1a. The mixture 3:1 of the two gangliosides gave intermediate values for all examined parameters. The presence of cations, within the physiological concentration range, and, in particular of Ca2+, did not influence significantly the values of co and the main features of the micelle.

Animals↗