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Biomedical subjects

M Morini

Publications and source records attributed to M Morini.

At least 19 recordsLinked to original sources
PubMed1997

Modulation of alpha 6/beta 1 integrin expression during differentiation of F9 murine embryonal carcinoma cells to parietal endoderm.

In vitro differentiation of the murine embryonal carcinoma (EC) cell line F9 parallels that of the early blastocyst, where visceral (VE) and parietal endoderm (PE) diverge from a common precursor, the primitive endoderm. This differentiation pathway is induced by retinoic acid (RA) and dibutyryl cyclicAMP (dcAMP) and is accompanied by progressive and dramatic changes in cell morphology and functions. Within 7 days of treatment the cells organize their cytoskeleton and synthesize large amounts of extracellular matrix proteins, becoming fully differentiated migratory cells; all these changes are likely to involve integrins expression and organization. We have investigated the changes in beta 1 integrin expression, its maturation, and organization on the cell surface in association with alpha 6, during the transition from undifferentiated F9 stem cells to migrating PE cells. By Western blotting and immunoprecipitation we showed a gradual decrease in the amount of the beta 1 subunit on the cell surface and a parallel progressive accumulation of immature protein, indicating that the control of beta 1 expression during F9 cells differentiation occurs first at post-translational level and then at the level of transcription. Moreover, the induction of differentiation produces a marked decrease of alpha 6B and its association to a high molecular weight protein, while alpha 6A level increases. By immunofluorescence we found that upon differentiation there is a relocation of the beta 1 and alpha 6B integrin subunits from cell-cell contacts to focal contacts where they colocalize with vinculin. On the contrary alpha 6A, weakly present in F9 stem cells, is present in the focal contacts of PE cells and along the stress fibers. We suggest different roles for the two alpha 6 isoforms.

Animals↗
PubMed1995

A simple method for overcoming some problems when observing thick reflective biological samples with a confocal scanning laser microscope.

A simple device is described, which allows the range of depth of scanning to be reduced when observing thick reflecting biological samples with a confocal scanning laser microscope (CSLM). Thick histological sections of human skin and rat brain stem were mounted between two coverslips ('sandwich' style) and the optical tomography was performed from both sides by turning the 'sandwich' upside-down. The samples were impregnated using standard Golgi-Cox, 'rapid Golgi' or other silver methods. The ability to turn the 'sandwich' upside-down is particularly useful when the reflective structure inspected is deep inside the section, i.e., near the lower surface of the specimen, or when it is opaque to the laser beam or excessively reflective.

Animals↗
PubMed1995

Three-dimensional reconstruction of the Meissner corpuscle of man, after silver impregnation and immunofluorescence with PGP 9.5 antibodies using confocal scanning laser microscopy.

The 3-dimensional organisation of the neural component of the human Meissner corpuscle was studied after silver impregnation and following immunofluorescence for protein gene product 9.5 (PGP 9.5) by confocal scanning laser microscopy. The morphology of the Meissner corpuscle was found to show consistent differences depending on the labelling method used. After silver impregnation by the Winkelmann technique the branches of the afferent nerve fibres of the corpuscle showed both thin regions and varicose elements, the latter probably corresponding to the portions rich in mitochondria observed by transmission electron microscopy. The bulkier elements were never more than 5-6 microns in diameter. After immunolabelling for PGP 9.5 the nerve fibre branches in the corpuscle always presented flattened and discoidal expansions with a diameter of up to 30 microns. On the basis of what is known as to the mechanism of action of silver impregnations it is considered that the black precipitate preferentially labels the parts of neurons that are rich in neurofilaments. In any case the precipitate is deposited throughout the neuronal cytoplasm except in the mitochondria and the nucleus. Accordingly, in the varicosities of the Meissner corpuscles that are rich in mitochondria, there is little space for the formation of the precipitate. The use of antiserum against PGP 9.5, which labels the larger proteinaceous component of the axoplasm, demonstrates the complete architecture of the neural component of the Meissner corpuscle, and visualises the discoidal and flattened expansions which are absent in the impregnated corpuscles. It is concluded that immunostaining provides images of the corpuscles, and of peripheral neural structures that are in general closer to reality.

Antibodies, Monoclonal↗
PubMed1994

Central and peripheral nervous structures as seen at the confocal scanning laser microscope.

Central neurons and peripheral nervous structures, e.g. cutaneous free endings, perifollicular nets, Meissners corpuscles and intramuscular fibres, were studied using various impregnation methods. The confocal scanning laser microscopes (CSLMs) used were equipped with different laser sources, in order to evaluate their limitations and advantages with these techniques and to contribute to a better understanding of the general morphology of the nervous system. When staining with silver sections with clouds of tiny silver granules which are beyond the resolution power of the conventional light microscope but which show a high reflectivity with the CSLM are obtained. Golgi-Cox mercuric impregnation, however, provides specimens which are precipitate-free, thus ensuring the reliability of information obtained. It does, however, have the disadvantage of being applicable only to the central nervous system. In all cases it is an advantage for the instrument to be fitted with different lasers (e.g. Ar and He-Ne), so as to optimize the images of samples impregnated with different methods. Notwithstanding the possibility that artefacts may distort the geometry of the sample and reduce the resolution, the images presented in this paper show that with careful selection of optical sectioning distances, the use of a suitable stack of sections and, if necessary, the aid of false electronic colours and of partial or complete rotation, it is possible to achieve a more precise interpretation of the morphology and organization of complex structures, such as those of the nervous system.

Animals↗
PubMed1993

Effects of low molecular weight heparins on fibrin polymerization and clot sensitivity to t-PA-induced lysis.

We have previously demonstrated that therapeutic concentrations of unfractionated heparin (UFH) impair fibrin polymerization leading to the formation of clots which are more sensitive to lysis induced by tissue plasminogen activator (t-PA). The aim of this study was to compare the effect of UFH with that of three different low molecular weight heparins (LMWHs) on clot sensitivity to t-PA-induced lysis. Labelled fibrin clots, prepared from plasma containing UFH, Fraxiparine, Reviparine, Enoxaparine or saline, were incubated in phosphate buffer containing t-PA (0.1 and 0.5 microgram/ml) and plasminogen (20 micrograms/ml). The extent of clot lysis was quantified by counting the residual radioactivity of the clots and by measuring D-dimer levels released into the medium. Fibrin polymerization and clot structure were evaluated by means of a turbidimetric assay and by electron microscopic scanning. Pre-incubation of plasma with 0.5 or 1.0 U/ml UFH resulted in a marked dose-dependent acceleration of lysis induced by 0.1 or 0.5 microgram/ml t-PA. In contrast, lysis rates induced by 0.5 microgram/ml t-PA were not modified by pre-incubation of plasma with LMWHs. When exposed to 0.1 microgram/ml t-PA clots formed from plasma containing 0.5-2 IU/ml of Fraxiparine, Reviparine and Enoxaparine showed only a minor increase in lysis rates compared to control clots. There was not a clear dose-response curve with LMWHs. Furthermore, lysis rates obtained with UFH-treated clots were always significantly higher than those seen with LMWHs-treated clots.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Coagulation↗
PubMed1992

Fibrin clots obtained from plasma containing heparin show a higher sensitivity to t-PA-induced lysis.

Although heparin is currently used in concomitance with thrombolytic agents to improve their efficacy, its effect on fibrinolysis is controversial. We have evaluated the sensitivity to t-PA-induced lysis of clots prepared from plasma preincubated in vitro with therapeutic concentrations of heparin. The extent of t-PA-induced lysis was significantly increased by preincubation of plasma with 0.5 and 1.0 U/ml heparin. The concentration of t-PA required to give similar lysis rates were reduced by up to five times after adding 1.0 U/ml heparin to plasma prior to clot formation. Heparin added to the t-PA-containing medium after clot formation did not exert any significant effect. The effect of heparin was not mediated by the inhibition of thrombin as preincubation of plasma with hirudin did not modify clot sensitivity to t-PA. We also found that heparin significantly modified fibrin assembly and clot structure as assessed by a turbidimetric assay. Pre-incubation of fibrinogen with heparin caused an increase in the speed of fibrin fibre polymerization and in the turbidity of the final fibrin gel; changes known to be associated with the formation of thicker fibrin fibres. Thus the effect of heparin on clot sensitivity to lysis appears to be due to an increased permeability of these clots to fibrinolytic components. This may contribute to the antithrombotic activity and to the haemorrhagic risk of heparin. These findings could be particularly important for clinical thrombolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug Synergism↗
PubMed1991

Unmyelinated nerve fibers associated with Meissner's corpuscle in the green monkey (Cercopithecus aethiops L.).

The ultrastructure and organization of free nerve fibers occurring in dermal papillae containing Meissner's corpuscles were studied in the fingertips of the Green Monkey (Cercopithecus aethiops L.). The course of the thin unmyelinated fibers leads in the vicinity of Meissner's corpuscles in the connective tissue of its sheaths, between the epidermis and the peripheral fibroblast layer; they never come into contact with the nervous component of the receptor. Consequently, neither a "pericorpuscular reticulum" nor an "apparatus of Timofeew" is formed. The presence of thin axons containing dense-cored vesicles is evident, but they are not autonomous fibers, as indicated by the negative results of the Falck-Hillarp test for catecholamines. The nerve fibers occasionally seem to bear a close resemblance to the "open" and "plain" endings described by other authors in papillae devoid of corpuscles. Despite failure for close mutual contact to be established between the Meissner's corpuscle and the unmyelinated fibers ramifying in the connective tissue surrounding it, the hypothesis that the two may cooperate to form a "multimodal sensory package" is not without interest.

Animals↗
PubMed1991

[Carotid thromboendarterectomy. Comparison of two anesthesiologic techniques].

The authors have examined two homogeneous groups of patients suffering from "carotid stenosis", operated by TEAC with two different techniques of anaesthesia: general and local-regional (block). Neurological and cardiovascular complications have been recorded in pre and post-operative period. The results analysed statistically with the Pearson test, were homogeneous. However the authors, on the basis of their experience, prefer local-regional (block) anaesthesia for good haemodynamic stability and a better neurologic control. Moreover the block anaesthesia was better in patients.

Aged↗
PubMed1990

Circadian rhythmicity in the rat exocrine pancreas: chronomorphological patterns.

Circadian rhythmicity of the structural morphometric model of rat endocrine pancreas has been studied in 24 Wistar female rats, four months old, kept in LD 12:12. The following parameters were evaluated: the volume fractions of nucleus and cytoplasm of exocrine cells, the size distribution and number in unit tissue volume of acinar cell nuclei, the mean nuclear diameter, the shape coefficient of glandular acini (that is the ratio acinar area/perimeter2 which indicates the shifting of structures from circularity). A statistically significant circadian rhythm was demonstrated for the shape coefficient of glandular acini. Results obtained in the present experiment are compared with data recorded in a previous study.

Animals↗
PubMed1989

Effects of chronic and subchronic treatment with antiulcer drugs in repairing rat gastric mucosa experimentally and chronically damaged.

An experimental model concerning the development of chronic gastric mucosa damage in rat is proposed making it possible to evaluate both the preventive and curative properties of a number of antiulcer drugs. Furthermore, the possible modification of the sensitivity to a stimulus regulating gastric functions after a prolonged administration of antiulcer drugs is assessed.

Animals↗
PubMed1987

Gravity-dependent distribution of parietal subpleural interstitial pressure.

Using liquid-filled catheters, we recorded, in 30 anesthetized, spontaneously breathing supine rabbits, the hydraulic pressure from the parietal subpleural interstitial space (Pspl). Through a small exposed area of parietal pleura a plastic catheter (1 mm ED), with a closed and smooth tip and several holes on the last centimeter, was carefully advanced between the muscular layer and the parietal pleura, tangentially to the pleural surface to reach the submesothelial layer. Simultaneous measurements of pleural liquid pressure (Pliq) were obtained from intrapleurally placed cannulas. End-expiratory Pspl decreased (became more negative) with increasing height (LH) according to the following: Pspl (cmH2O) = -1 - 0.4 LH (cm), the corresponding equation for Pliq being Pliq (cmH2O) = -1.5 - 0.7 LH (cm). Thus at end expiration a transpleural hydraulic pressure difference (Pliq-Pspl) developed at any height, increasing from the bottom to the top of the cavity as Pliq - Pspl (cmH2O) = -0.5 - 0.3 LH (cm). The Pliq-Pspl difference increased during inspiration due to the much smaller tidal change in Pspl than in Pliq. By considering the gravity-dependent distribution of the functional hydrostatic pressure in the systemic capillaries of the pleura (Pc) and the Pspl and Pliq values integrated over the respiratory cycle we estimated that on the average, the Pc-Pspl difference is sevenfold larger than the Pspl-Pliq difference.

Animals↗
PubMed1984

Considerations on the dynamics of adipose cells in relation to ponderal variations: morphoquantitative aspects.

The sizes and numbers of subcutaneous adipose-tissue fat cells were determined in obese patients, some of whom had undergone severe weight reduction induced by a jejuno-ileal bypass operation, and others a moderate thinning by a reducing diet, for comparison with those in normals. The size-class distribution of the fat cells suggests a morphoquantitative, dynamic interpretation of the two known forms of obesity, one being of moderate degree and called hypertrophic, the other more severe and called hyperplastic. The hypertrophic obese condition is characterized by a bimodal size-distribution curve of the adipocytes, similar to the curve in normal individuals. In both the normal and the hypertrophic obese, ponderal variations displace this curve forwards or backwards without altering its shape. By contrast, the hyperplastic obese shows a flat size-distribution curve without discernible modes. The smallest size-class of fat cells are the most sensitive to weight-reduction process and hypotrophize so much that they can no longer be recognized as adipocytes in histological sections; thus the size-distribution curve for hyperplastic obese individuals losing weight changes in shape from uniform to bimodal. The relationship which expresses the mean fat cell diameter as a function simultaneously of the initial weight and of ponderal variation was also studied, and tested by multiple regression analysis.

Adipose Tissue↗