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Biomedical subjects

A Ruggeri

Publications and source records attributed to A Ruggeri.

At least 91 records · Page 5Linked to original sources
PubMed1989

Ultrastructural changes of collagen and elastin in human gingiva during orthodontic tooth movement.

After 15 days of mesializing or distalizing orthodontic treatment, 10 permanent premolars of young patients were extracted with the interdental gingiva. The connective tissues of the compressed or stretched interdental papillae were compared to that of untreated samples by light and transmission electron microscope. Large collagen fibres bundles represented by fibrils with a banding pattern of 64 nm and a mean diameter of 75 nm were observed in compressed interdental gingiva. Several elastic fibres with a mean diameter of 950 nm were also present. In some central areas of compressed gingiva collagen fibrils longitudinally split into widely spaced microfibrils were often observed in proximity to the elastic fibres. In stretched and untreated interdental papillae the collagen fibrils presented a mean diameter of 66 nm and 57 nm respectively. In both groups, few elastic fibres ranging in diameter 600 nm were seen. The increased size of the gingival collagen fibrils undergoing pressure and tension is indicative of remodelling of the fibrous collagen system. The fair increase in number and size of elastic fibres in compressed gingiva suggests that the elastic fibre system takes over the place whenever a collapse of the collagenous framework occurs.

Child↗
PubMed1988

Effects of pulsed extremely-low-frequency magnetic fields on skin wounds in the rat.

Rats with skin-wounds surgically created on their backs were exposed immediately after surgery and every 12 h thereafter to pulsed, extremely-low-frequency magnetic fields. The shape of the pulse was a positive triangle (50 Hz, 8 mT peak). The rate of healing of skin wounds was evaluated macroscopically and by light and electron microscopy at 6, 12, 21, and 42 days after the operation. A significant increase in the rate of wound contraction was found in rats treated with magnetic fields. Forty-two days after surgery all treated animals show fully closed wounds, while control rats at the same time intervals still lacked a final 6% of the wound surface to be covered. Treated rats showed earlier cellular organization, collagen formation and maturation, and a very early appearance of newly formed vascular network.

Animals↗
PubMed1988

Ultrastructural aspects of freeze-fractured and etched elastin.

The ultrastructural organization of fresh and purified elastin from beef ligamentum nuchae was studied by means of the freeze-etching technique. Both fresh and purified elastin showed a regular three-dimensional network of filaments which seemed to be composed of a sequence of globular subunities. There were also areas, along the regular network, in which ridges of various lengths, packed with perpendicular side filaments, were visible. In replicas of deep-etched and rotary-shadowed specimens, a thicker and more defined three-dimensional network was observable. A great variability in appearance among the globular subunits of the filaments was noticed which was at least partially due to the etching treatment. By means of computerized simulation of replicas of various hypothetically collapsed globular structures, we obtained patterns which were superimposable on those obtained in the replicas of the specimens analyzed. It is thus assumed that each globular subunit of the filament, being subjected to collapsing, has a less dense central core.

Animals↗
PubMed1987

Pharmacokinetics and organ distribution in rats of a low molecular weight heparin.

Fluorescein-labelled low molecular weight heparin (OP/LMWH) pharmacokinetics and organ distribution were studied in the rat after intravenous administration at doses of 3 and 15 mg/kg. The pharmacokinetics of labelled OP/LMWH was dose-dependent like heparin, however, the anticoagulant activity such as anti-Xa was more prolonged. The rapidity of the disappearance of the fluorescence was quicker than the biological activity. The fluorescence was observed mainly in the liver and kidney as a diffuse aspect in the short time and as a globular aspect in the long time, mainly in Disse's space of the liver. These results confirm that the liver is important in the regulation of heparin metabolism and activity.

Animals↗
PubMed1987

Striae albae: a morphological study on the human skin.

Specimens of abdomen skin, comprising alternate areas of striae albae and healthy skin, were removed during surgical lipectomy from multiparous and obese women between the ages of 24 and 53 years. A flattening and thinning of the striae albae surface and the almost complete disappearance of dermal papillae was observed in paraffin and thin sections. The papillary dermis was found to be almost completely replaced by straight bundles of collagen fibres running parallel to the skin surface. Immunofluorescence data revealed in these bundles high positivity for type I collagen. The underlying reticular dermis was also found to contain large densely packed bundles of collagen fibres running parallel to the skin surface. Both papillary and reticular dermis collagen fibres were mainly arranged orthogonally to the main axis of the stria. Furthermore, the density of the collagen fibre bundles and the diameter of the collagen fibrils was found to be greater than that of the clinically healthy skin. A larger number of elastic fibres, which presented an abnormal ultrastructural appearance, were visible in pathological papillary and reticular dermis.

Adolescent↗
PubMed1986

"In vitro" fibril formation of type I collagen from different sources: biochemical and morphological aspects.

Acid soluble type I collagen was prepared from foetal and adult bovine tendon and skin and from adult bovine cornea. The degree of hydroxylysine glycosylation and the hydroxylysine di-to monoglycoside ratio as well as the "in vivo" fibril diameters, were shown to be tissue and age-dependent. Fibrils of type I collagens were reconstituted "in vitro" monitoring at 313 nm. The fibrils obtained were examined by electron microscopy. It was shown that the "in vitro" lateral growth of collagen fibrils leads to the formation of fibrils with maximum diameters which may be correlated to those of the corresponding native fibrils. Moreover it is suggested that one of the factors controlling the lateral growth of collagen may be at the level of hydroxylysine glycosylation.

Animals↗
PubMed1986

Differences in the fibril structure of corneal and tendon collagen. An electron microscopy and X-ray diffraction investigation.

A detailed analysis of the D-period and axial electron density distribution of cornea and tendon collagen was carried out by means of X-ray diffraction and electron microscopy. Ultrastructural observations were made on replicas of freeze fractured and deep-etched specimens. Synchrotron radiation was used to obtain high resolution small angle X-ray diffraction patterns. The data provide evidence that D-period and intraperiod distances in cornea are shorter than in tendon collagen fibrils. The observed different banding observed is interpreted on the basis of the different morphological arrangement of the microfibrils in the two tissues: "helicoidal" in cornea and "straight" in tendon microfibrils.

Animals↗
PubMed1985

Ultrastructural aspects of rat tail tendon sheaths.

An investigation was carried out on the sheaths which envelop rat tail tendons. The samples were processed for observation by light and electron microscopy. In the case of electron microscopy, thin sections of specimens embedded in epoxy resin and replicas of freeze etched samples were used. On the basis of histological and ultrastructural observations, four distinct connective tissue sheaths have been detected. The paratendineum is a thick fibrous sheath that covers externally the four groups of tendons arranged around the vertebrae of the tail; the epitendineum is a distinct fibrous sheath surrounding each tendon group; the peritendineum is composed of concentric cellular laminae enveloping each tendon; lastly, the endotendineum is made up of one cellular lamella which adheres to the fibres of the tendon, projecting trabeculae between the individual tendon fascicles. In the para- and epitendineum, thick bundles of collagen fibrils, running parallel to the fibres of the tendon, were visible. The collagen fibrils had a wide variability of diameters (from 35 to 220 nm) and, when examined in replica, their microfibrillar arrangement appeared to be straight. In the peri- and endotendineum, thin bundles of collagen fibrils were visible between the cellular laminae, parallel to the main axis of the tendon. Among these collagen bundles, elastic fibres and numerous glycoproteins containing microfibril-like filaments were visible. The collagen fibrils were small and of uniform diameter (50 nm) and, when observed on replica, showed a helicoidal microfibrillar arrangement. The cell layers of the peri- and endotendineum were made up of flattened fibroblasts which were connected by specialised junctions and which contained numerous micropinocytotic vesicles. A thin layer of granular electron-dense material, with ultrastructural characteristics similar to those of a basement membrane, was visible on the surface of the most external cellular layer of the peritendineum and on the outer surface of the cellular lamella of the endotendineum. Due to their morphological characteristics it is supposed that the four tendon sheaths are involved in different and special functions. Moreover, collagen Type I and collagen Type III, demonstrated by means of immunofluorescence techniques in previous investigations, show respectively a close similarity in distribution to the thick collagen fibrils, with a straight microfibrillar arrangement, of the two external sheaths, and to the thin collagen fibrils, with a helicoidal microfibrillar arrangement, of the two internal sheaths.

Animals↗