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E Becchetti

Publications and source records attributed to E Becchetti.

At least 73 records · Page 4Linked to original sources
PubMed1989

Beta-N-acetyl-D-glucosaminidase activity in embryonic chick skin and lung tissue and cultured fibroblasts.

During development the content of mesenchymal glycosaminoglycans (GAG) undergoes prominent changes, currently considered to act as regulatory signals in the epithelial-mesenchymal interactions. The factors involved in controlling GAG composition are as yet completely unknown. Lysosomal enzymes play a key role in GAG turnover. A possible mechanism for regulating GAG content could therefore be linked to developmental modulation of lysosomal glycosidases activity. We have examined the activity of the beta-N-acetyl-D-glucosaminidase (EC 3.2.1.30; a lysosomal hydrolase cleaving glycosidic linkage of the non-reducing terminal beta-N-acetyl-D-glucosamine residues) in chick embryo skin and lung (rudiments whose GAG composition has previously been studied) at various embryonic stages. Determinations were carried out on whole organs as well as on primary cultures of fibroblasts obtained from the two rudiments. beta-N-acetyl-D-glucosaminidase activity varied greatly during development, and it was significantly different in embryonic skin and lung tissues at various incubation days. In cultured fibroblasts, the enzymatic activity varied at different incubation days correlating with the in vivo data. Developmental changes of beta-N-acetyl-D-glucosaminidase paralleled mesenchymal GAG pattern both in vivo and in vitro. Our results, therefore, support the possibility that lysosomal enzymes could be involved in the regulation of mesenchymal GAG content during development.

Acetylglucosaminidase↗
PubMed1988

Developmental heterogeneity of mesenchymal glycosaminoglycans (GAG) distribution in chick embryo lung anlagen.

The presence and distribution of mesenchymal components in the extracellular matrix during lung development in the chick embryo (from 5 1/2/6 to 18 incubation days) has been examined histochemically. Attention is focused mainly on glycosaminoglycans (GAG). Morphological reconstructions show three main stages: first (5 1/2/6-8 days), formation of 2nd-order branching; second (9-12 days), proliferation of parabronchi and third (from 13th day on), formation of air capillaries. In the first phase, hyaluronic acid (HA) prevails around the mesobronchus, but chondroitin sulfate (CS) dominates the 2nd-order branches. Basement membranes of 2nd-order branches are strongly positive for sulphated GAG. In the second phase, CSA increases in the ground substance of mesenchyme. This increase is irregular, being smaller in older areas (mesobronchus, branches of 2nd order) and larger in the more recent parabronchi, which extend into the lateral and dorsal areas of the rudiment. An increase in both sulfated GAG and glycoprotein (GP) occurs in basement membranes. In the third phase, GAGs are uniformly distributed in the mesenchymal septa and around the interlobular vascular network. This concentration decreases while the GP concentration increases. Basement membranes around every branch of the 1st, 2nd, and 3rd orders possess large quantities of GP. Mesenchymal GAG occurs in every stage of lung development, temporally correlating with the morphogenesis and differentiation of epithelium. Our results provide necessary information, which has not been available so far. Experimental studies specifically designed to clarify the developmental significance of such a heterogeneous distribution may be interpreted in the light of this information.

Animals↗
PubMed1988

Age related and lectin influenced changes of exoglycosidases activity in cultured chick embryonic skin fibroblasts.

beta-N-acetyl-D-glucosaminidase, beta-N-acetyl-galactosaminidase and a beta-D-galactosidase activity was determined in untreated and lectins (ConA, PNA, SBA and WGA) treated chick embryonic skin fibroblasts at two incubation stages. Activity of all three glycosidases increased between 7 and 14 incubation days. ConA and WGA affected the levels of enzymatic activity; while SBA and PNA were uneffective. We discuss these findings in relation to a possible role of glycosidases in controlling mesenchymal GAG turnover.

Acetylglucosaminidase↗
PubMed1985

Avian skin embryonal fibroblasts heterogeneity for lectins surface receptors.

Using several fluorescein-coupled lectins (ConA, WGA and SBA) the distribution of surface ligands in chick embryonic skin fibroblasts was studied at two incubation stages. On the basis of the percentage of lectin marked cells, at least, three fibroblastic populations heterogeneous for surface specific-saccharide binding sites were found. Their relative concentration were changed in the course of incubation, thus indicating developmental changes. We discuss this finding in relation to the regulatory mechanism of the spatial and temporal mesenchymal glycosaminoglycan pattern.

Age Factors↗
PubMed1984

Extracellular glycosaminoglycans (GAG) released by chick embryonic fibroblasts. A possible involvement of surface receptors.

Administration of Concanavalin A (Con A) to cultured skin fibroblasts derived from chick embryos at two developmental stages produce variations in the relative concentration of individual glycosaminoglycan (GAG) secreted by the cells. This effect is different: at 7 days (increase of hyaluronic acid and dermatan sulphate and decrease of chondroitin sulphate) and at 14 days (dermatan sulphate is not detectable). All the cells bind the Con A specifically, but a different pattern of agglutination is present in fibroblasts of the two embryonic ages. Since Con A is well known to bind carbohydrate-containing surface proteins, the result suggests that the release of GAG by chick embryonic fibroblasts can be modulated by cell surface receptors.

Animals↗
PubMed1984

Exogenous glycosaminoglycans (GAG) are able to modulate avian skin differentiation (epithelial keratinization and feather formation).

Several reports have suggested that mesenchymal glycosaminoglycans (GAG) may be involved in the regulatory role of epithelial differentiation. Some researchers have pointed out that exogenous GAG affects extracellular GAG accumulation. We have therefore examined the effect of added GAG on two typical processes of avian skin differentiation: keratinization and feather formation. Glycosaminoglycans, either obtained from fibroblasts cultures (conditioned media) or purified commercially available GAG were administered to 5/6-day chick embryo back skin explants. Control cultures were supported with 199 synthetic medium, chick embryo extract or calf serum. Explants have been examined by histological and histochemical procedures. Skin explants maintained in vitro for 7 days exhibited an epithelial differentiation and a dermal histochemical reactivity which were related to the composition of the culture medium. In conditioned media from dermal fibroblasts, but not from heart or lung fibroblasts, explants always exhibited keratinization. In purified-GAG-containing media, keratinization was observed with condroitinsulphates and not with hyaluronic acid. Keratinization was always related to prevalent accumulation of hyaluronic acid in the underlying mesenchyme whereas feather formation was in relation to deposits of condroitinsulphates in dermis pulp. The above findings demonstrate that exogenous GAG is able to modulate avian skin differentiation and that this regulation is linked to an influence on the mesenchymal GAG pattern.

Animals↗
PubMed1983

[Experimental intrauterine surgery. Morphological study of lung development in the sheep fetus with congenital diaphragmatic hernia].

Experimental comparison of the lungs of 7 sheep foetuses with surgically induced CDH and 7 controls permitted an assessment to be made of the changes that take place in lung growth, generally described as hypoplasia, through a study of their morphology and histology, and the lung: lamb weight ratio. Changes increased in gravity in function of the duration of hernia. They included: reduced alveolar expansion, fewer generations of bronchi and alveoli, and septal thickening. An increase in the smooth muscle component of 5th-6th generation arteries (i.e. resistance) may offer an explanation of the hypertension characteristic of CDH, and the non-reactivity of these vessels in response to vasodilators. It is also suggested that damage to the mesenchyma can be regarded as the sole cause of the changes in lung growth observed in CDH. Early treatment before these changes become irreversible is thus advisable.

Animals↗
PubMed1983

[Analysis, by lectin fluorescence, of the cell surface of embryonal fibroblasts cultivated in vitro].

Cultured fibroblast derived from 7 and 14 days chick embryonic skin were tested with three fluorescent lectins (Con A, WGA and SBA). The result obtained shown that the percentage of cells that bind WGA decrease from 7 to 14 days, supporting the presence of an age-dependent heterogeneity at cell surface level. In both cellular population only the 50% of the cell bind to SBA, suggesting a more subtle heterogeneity into the same population.

Animals↗
PubMed1978

Serum-dependent avian skin differentiation in vitro: time sequence of induced events.

Information concerning the developmental mechanisms involved in skin differentiation have been mainly derived from in vitro experiments. We have previously observed that 6-day chick embryonic thigh skin keratinizes in vitro in chicken serum-containing medium, but does not do so in chick embryo extract-containing medium. This system seems adequate in many respects for investigating the mutual regulative relationship between epithelium and mesenchyme (so called epithelio-mesenchymal interactions). We have therefore attempted better to define the time course of differentiative events and their dependence upon the time of serum administration. Skin explants have been sequentially supplemented with differentiation-stimulating or non-stimulating nutrient, removed at different intervals and examined by histological and histochemical procedures. Different epithelial and mesenchymal behaviour results according to serum supplementation time. Serum administered in the first 48 h of in vitro maintenance is unable to stimulate either the subsequent epidermal keratinization or the correlated changes in dermal histochemical pattern. On the other hand, serum-containing medium induces keratinization and changes in dermal intercellular composition (glycoproteins accumulate to a greater extent than glycosoaminoglycans, as does hyaluronic acid relative to chondroitin sulphuric acids), if added for only the second two days. In the last 48 h, serum may promote epidermal keratinization provided that in vitro incubation has been prolonged. Administration of actinomycin D with serum in the second 48 h prevents epidermal keratinization and modifies dermal histochemical reactivity, but is ineffective if added in the last 48 h. The above findings demonstrate that serum factor(s) stimulating epidermal differentiation act(s) on skin explants in the central incubation period and that correlatively mesenchyme acquires a characteristic histochemical pattern, supporting the possibility that the effect of serum may be mediated by changes in the composition of dermal ground substance.

Animals↗
PubMed1976

Studies on the mechanism of in vitro estradiol-17 beta induced synthesis of phosvitin in chick embryo liver cells.

The effect of estradiol-17-beta treatment on phosvitin synthesis by cultured chick embryo liver cells has been studied. Phosvitin synthesis occurs approximately 15 hr of hormone treatment; the synthesis being blocked by actinomycin D treatment suggests that RNA synthesis is required. The life time of the newly synthesized RNA is at least 24 hr. The significance of these findings with respect to the mechanisms involved in hormone-mediated protein synthesis is discussed.

Animals↗