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Biomedical subjects

G Biagini

Publications and source records attributed to G Biagini.

At least 127 records · Page 7Linked to original sources
PubMed1991

Morphological study of the capsular organization around tissue expanders coated with N-carboxybutyl chitosan.

Expanders coated with N-carboxybutyl chitosan were inserted into surgical wounds in the dorsal skin of rabbits and the formation of capsular tissue was studied by scanning electron microscopy and transmission electron microscopy. N-carboxybutyl chitosan, in the course of the capsular organization, favours and potentiates the correct proliferation and organization of the tissue, rather than sustaining reactive processes leading to scar formation. N-carboxybutyl chitosan stimulates physiologically the tissue repair process and favours angiogenesis, whilst depressing fibrogenesis to a certain extent. Applications are envisaged in the treatment of wounds and in plastic surgery.

Animals↗
PubMed1991

A new model of focal brain ischemia based on the intracerebral injection of endothelin-1.

Endothelin-1 and its receptors are widely distributed in the brain of rodents and humans. In view of its potent and long-lasting vasoconstrictor activity, a role of endothelin-1 has been proposed in brain ischemia. In the present paper, the local injection of endothelin-1 was utilized to induce ischemia in rat striatum. An evaluation of the rostrocaudal extension of the lesion is reported. By using intracerebral microdialysis, a marked increase of lactate and dopamine, but not glutamate, was observed in this region upon endothelin-1 administration. Moreover, preliminary data reported show a protective effect of ganglioside treatment on endothelin-1 lesion of rat striatum. The characteristics of the present model of brain ischemia are discussed in comparison with well characterized models, such as the Pulsinelli's four vessel occlusion and the middle cerebral artery occlusion.

Animals↗
PubMed1991

Pain, analgesia, and stress: an integrated view.

The different theories on the neuroanatomical substrate of pain have been revised in the frame of new concepts on the intercellular communication in the central nervous system. In fact, it has recently been proposed that two kinds of electrochemical transmission exist in the brain: the first one, called wiring transmission (WT), uses neuronal chains (neuronal plasma membranes and synaptic contacts), whereas the second one, called volume transmission (VT), uses the extracellular fluid as physical substrate. The old concept of a separate system of afferents and central cells that constitute the pain mechanism is no more longer tenable. To reach a better understanding of the psychophysiological basis of pain, we should consider a view where WT and VT cooperate within neuronal systems functionally affected by the pervading modulatory action of endocrine signals.

Analgesia↗
PubMed1991

Clinical and morphologic response to interdental brushing therapy.

The interdental papilla is the anatomic site most susceptible to periodontal disease. The gingival epithelium plays an important role as a barrier to protect the underlying connective tissue from exogenous noxious agents. A study was undertaken to evaluate the papillary epithelial response to reconstructive stresses conducted by gingival brushing (oral therapy) and scaling and root planing, intended to induce a keratinization associated with reduction or resolution of connective tissue inflammation. Results showed that patients who prolonged the interproximal hygiene practices for more than 30 minutes a day achieved a satisfactory keratinization of the papillary gingival epithelium.

Dental Plaque↗
PubMed1990

Evidence for a role of neosynthetized putrescine in the increase of glial fibrillary acidic protein immunoreactivity induced by a mechanical lesion in the rat brain.

The effect of alpha-difluoromethylornithine (alpha-DFMO), an irreversible inhibitor of ornithine decarboxylase (ODC) the rate limiting enzyme of polyamine biosynthesis, was studied on the astroglial reaction in a model of mechanical brain injury. alpha-DFMO markedly decreased the astroglial activation induced by the microdialysis probe implantation in the striatum of the male rat, as studied by glial fibrillary acidic protein (GFAP) immunocytochemistry. This response was restored by putrescine (20 nmol/ml) administered via the microdialysis probe. These results suggest that the astroglial reaction and the polyamine biosynthesis activation induced by a localized mechanical lesion are causally linked phenomena.

Animals↗
PubMed1990

The capsule surrounding primary liver tumors: wherefrom its prognostic significance?

Primary liver neoplasms in cirrhotic and non-cirrhotic patients were studied by electron microscopy and immunohistochemical methods for extracellular matrix (ECM) antigens. A capsule of variable thickness was present in many expanding hepatocellular carcinomas, while it was absent in those of small size, and either fragmented or absent in the infiltrating ones. In the capsules of early onset, fibronectin was the most frequent stromal glycoprotein. In the completely formed capsular structures, fibronectin, type-V collagen and laminin were the most common macromolecules seen. No differences were evident in the pattern of ECM macromolecules in the capsules surrounding hepatocellular carcinomas compared with those found in benign lesions, such as hepatocellular adenomas or focal nodular hyperplasia. The possibility is discussed that the capsule could be a result of the following sequence: tissue with expansive (not infiltrative) growth-mechanical compression-ischemic necrosis of surrounding tissues-repair process with ECM deposition.

Carcinoma, Hepatocellular↗
PubMed1990

Effects of indole-pyruvic acid on sleep and food intake in the rat.

Indole-pyruvic acid was studied for its short- and long-term effects on electroencephalographic sleep and on food intake in rats implanted with cortical and muscular electrodes. Following a single injection, indole-pyruvic acid (10-50 mg kg-1 i.p.) reduced by 16-23 min (range) the latency of the first slow-wave episode in a dose-related fashion and produced a significant increase in slow-wave sleep time (12-40%) in doses of 10-30 mg kg-1. Rapid eye movement sleep latency and rapid eye movement sleep time were increased (by 23-37 min) and reduced (57-71%) respectively. The effects of indole-pyruvic acid on slow-wave sleep time were still present after 3, 7 and 14 days of chronic administration (10 mg kg-1 day-1), whereas tolerance to the effect of indole-pyruvic acid on rapid eye movement sleep was observed. Daily food consumption was reduced (20-28%) by acute administration of indole-pyruvic acid (15-30 mg kg-1 i.p.), but tolerance developed after 5 days of repeated injections. These findings are in accordance with previous evidence suggesting that indole-pyruvic acid effects may be related to the activation of central serotonin neurons, which are involved in the inhibitory control of sleep and food intake.

Animals↗
PubMed1990

Antimicrobial properties of N-carboxybutyl chitosan.

N-Carboxybutyl chitosan, a modified chitin of crustacean origin, displayed inhibitory, bactericidal, and candidacidal activities when tested against 298 cultures of various pathogens. Examination by electron microscopy showed that microbial cells exposed to N-carboxybutyl chitosan underwent marked morphological alterations. The data are of importance in defining the suitability of N-carboxybutyl chitosan as a wound dressing.

Anti-Bacterial Agents↗
PubMed1990

[In vitro structural aspects of the human trophoblastic cell].

Maternal- fetal exchanges are mainly regulated by trophoblast, which displays an active role during embryo growth. Trophoblast organization into a syncytial layer involves structural and functional steps that may be monitored and better elucidated by "in vitro" studies. In light of this, we have carried out morphological and biochemical analyses in order to evaluate 1) the syncytiotrophoblast formation in culture (48 h, 5-30 days) the Na+/K+ATPase activity and 3) the plasmalemmal microviscosity changes occurring during "in vitro" trophoblast production. Morphological and biochemical modulations have been pointed out.

Cells, Cultured↗
PubMed1990

Effects of chemical pretreatments on dentin bonding.

The aim of this study was to evaluate several chemical pretreatments on the shear bond strength of three dentin bonding agents (DBAs) and to try to correlate dentin morphology with bond strength using scanning electron microscopy (SEM). The DBAs tested were: Gluma Primer in association with Scotchbond DC, Scotchbond DC alone and Clearfil New Bond. Bond strengths of Scotchbond DC and Clearfil New Bond were not significantly modified or reduced by acidic dentin pretreatments. Gluma/Scotchbond adhesion was increased by several treatments but only maleic acid treatment produced shear bond strengths significantly higher than EDTA treatment. SEM evaluation of dentin treatments revealed a wide variety of morphological changes in the dentin surface with partial and complete removal of smear layer by acidic solutions, and only minor modification by amino acid solutions. Only maleic acid was capable of the complete removal of the smear layer and smear plugs coupled with extensive exposure of dentin collagen fibrils.

Acid Etching, Dental↗
PubMed1990

Shear bond strength and SEM evaluation of dentinal bonding systems.

Shear bond strength of seven dentin bonding systems (DBS) was evaluated. After shear bond testing, the specimens were analyzed under scanning electron microscope (SEM). Buccal dentin just below the dentin-enamel junction of erupted third molars of young subjects were used. A statistical difference was observed among the material bond values. SEM examination of both sides of the sheared bonds frequently showed an adhesive failure between dentin and bonding agents in the specimens where resin penetrated into the opened dentinal tubules. A complex cohesive fracture of both resin and dentin was observed for bonding agents that required the treatment of the smear layer, while a cohesive fracture in the smear layer thickness was noted when dentin was not altered by primer solutions. The study demonstrated that the DBS that require the removal of the smear layer showed a significantly higher shear bond strength and that the bond value reflects the mode of material fracture and the presence of smear layer.

Composite Resins↗
PubMed1989

Reconstruction of parodontal tissue with chitosan.

Chitosan ascorbate, obtained by mixing chitosan with ascorbic acid and sodium ascorbate, was produced in a gel form suitable for the treatment of periodontitis according to current dental surgery. While chitosan ascorbate underwent degradation in vitro, especially in the presence of atmospheric oxygen and at pH 6.0, the protection from oxygen offered by the surgical cements and the physiological pH value permitted chitosan ascorbate to play an important biological role in vivo, where it kept a honeycomb structure, as indicated by SEM on biopsies taken on 10 patients. The proliferation and organization of the cells were thus favoured with a subsequent enhanced capability of reconstructing a histoarchitectural tissue. Chitosan was progressively reabsorbed by the host, with very satisfactory clinical recoveries of the 52 defects treated, for which tooth mobility and pocket depths were significantly reduced.

Adult↗
PubMed1989

Liver fibrosis and extracellular matrix.

Liver fibrosis and extracellular matrix play a central role in liver function impairment. Little information is available on the dynamic aspects and the natural history of fibroplasia, even if there is growing evidence that extracellular matrix accumulation (collagen I, III, IV, fibronectin, laminin, proteoglycans, etc.) is not to be considered only a passive structural support for damaged hepatic tissue, but may actively modulate liver cell behaviour. Clinicians need to date liver fibrosis and to monitor connective tissue synthesis and degradation, but attempts to develop reliable serological markers for collagen metabolism are hampered by the absence of a well defined golden standard to validate them. Nevertheless, serum type III aminoterminal procollagen peptide, at the moment, seems to be the most acceptable parameter of fibrogenesis. The data concerning the mechanisms of collagen production-degradation are becoming so precise and numerous that even if they have not, to date, led to 'routine' advantages for patients, they will end up becoming important tools in the clinical practice and management of liver fibrosis.

Absorption↗
PubMed1989

Morphological development of the human placenta in normal and complicated gestation: a quantitative and ultrastructural study.

In order to evaluate the structural potentialities of the placenta, we analyzed placentas in the following conditions: normal full term gestation, hypertensive status, twin pregnancy and abortion at 8-12 weeks of gestation, comparing cell structures, surface organization and tissue reaction. We quantitatively evaluated (1) the arborization of the placental villous tree, and (2) the microvillous density per unit of surface area, paralleling these data with ultrastructural and immunohistochemical features. In early gestation (8-12 weeks of pregnancy) the limited degree of branching of placental villi parallels a reduced number of clefts per unit of surface area (0.7/1,000 microns2), if compared with controls (2.7/1,000 microns2). In the full term twin placenta, the number of furrows is 2.26/1,000 microns2: this value reflects a low arborization potentiality, testifying to a low placental maturity. On the contrary, a high branching of the placental villous tree is present at term in hypertension. In this gestational condition, the number of sulci of 3.1/1,000 microns2 reveals a compensatory attitude of the placenta, aiming to sustain the impaired fetal-maternal metabolic interchange. In all these cases, syncytiotrophoblastic microvilli are reduced in number in comparison with the normal placenta, and this is likely to be an expression of a low trophoblastic maturation degree. The placenta is a barrier with a highly specialized function that conditions fetal outgrowth, and microenvironmental modifications are promptly faced by this structure through morphofunctional modulations.

Female↗
PubMed1989

[Staphylococcus haemolyticus. Bacterial resistance to teicoplanin and associated morpho-structural aspects].

To improve our understanding of the bases of teicoplanin resistance we studied a "one-step" mutant of S. haemolyticus from a morphological point of view. The results show that the organization of peptidoglycan is altered in the resistant S. haemolyticus strain. It is suggested that the alterations, including the spongier cell wall structure, may prevent the teicoplanin from reaching its target.

Anti-Bacterial Agents↗
PubMed1989

[Hypertension and syncytiotrophoblast: morpho-structural aspects].

Hypertension is a pathological condition that involves maternal fetal relationship. In hypertension placenta displays a syncytiotrophoblast plasmalemma with aspects of anomalous behaviour concerning Intramembranous Particles (IMP) and actin content of microvilli cytoskeleton. Decrease of syncytiotrophoblast microvilli IMP and microvilli actin further sustain the tendency of hypertensive placenta to show some features of immaturity that might deeply influence fetal-maternal exchanges during pregnancy associated with pathological status.

Calcium↗