Biomedical subjects

S Guizzardi

Publications and source records attributed to S Guizzardi.

At least 19 recordsLinked to original sources

PubMed2006

Analysis of living cells grown on different titanium surfaces by time-lapse confocal microscopy.

In this study we have combined fluorescence- and reflection-confocal laser scanning microscopy for the simultaneous visualization of living cells and surface topography beneath them. To this purpose we have designed a specific flow chamber and we have tested it with osteoblasts grown on an opaque, thick support, made of smooth or sandblasted titanium. Cells were loaded with Calcein-AM or tetramethylrhodamine methyl ester (TMRM), two probes employed as indicators of cell viability/morphology and mitochondrial membrane potential, respectively. Besides the acquisition of stacks of confocal sections, the system allowed also vertical views and faithful three-dimensional reconstruction of the samples. Confocal microscope implemented with our flow chamber proved to be a promising tool for time-lapse investigation of cell-biomaterial interactions.

Biocompatible Materials↗

PubMed2006

Non-apoptotic programmed cell death induced by a copper(II) complex in human fibrosarcoma cells.

A0, a Cu(II) thioxotriazole complex, produces severe cytotoxic effects on HT1080 human fibrosarcoma cells with a potency comparable to that exhibited by cisplatin. A0 induced a characteristic series of changes, hallmarked by the formation of eosin- and Sudan Black-B-negative vacuoles. No evidence of nuclear fragmentation or caspase-3 activation was detected in cells treated with A0 which, rather, inhibited cisplatin-stimulated caspase-3 activity. Membrane functional integrity, assessed with calcein and propidium iodide, was spared until the late stages of the death process induced by the copper complex. Vacuoles were negative to the autophagy marker monodansylcadaverine and their formation was not blocked by 3-methyladenine, an inhibitor of autophagic processes. Negativity to the extracellular marker pyranine excluded vacuole derivation from the extracellular fluid. Ultrastructural analysis indicated that A0 caused the appearance of many electronlight cytoplasmic vesicles, possibly related to the endoplasmic reticulum, which progressively enlarge and coalesce to form large vacuolar structures that eventually fill the cytoplasm. It is concluded that A0 triggers a non-apoptotic, type 3B programmed cell death (Clarke in Anat Embryol (Berl) 181:195-213, 1990), characterized by an extensive cytoplasmic vacuolization. This peculiar cytotoxicity pattern may render the employment of A0 to be of particular interest in apoptosis-resistant cell models.

Antineoplastic Agents↗

PubMed2004

Ethanol increases the paracellular permeability of monolayers of CAPAN-1 pancreatic duct cells.

When grown on permeable supports, pancreatic duct adenocarcinoma CAPAN-1 cells establish very high values of transepithelial resistance (TER). The addition of ethanol produced a dose-related, reversible drop in the TER of these cells, ranging from 15% (with 1% ethanol) to 65% (with 10% ethanol). The ethanol effect was rapid and reversible. The resistance decrease was associated with an increase in monolayer permeability to mannitol. No significant decrease in cell ATP was detected for ethanol concentrations lower than 7%. Confocal vertical sections of calcein-loaded monolayers of CAPAN-1 cells, grown on plasticware, showed a progressive deflation of domes detectable after 5 min of treatment with 2% ethanol. Incubation in an ethanol-free medium caused a progressive dome restoration. Immunocytochemical analysis of ethanol-treated cells indicated that ZO-1 and occludin exhibited clear cut distribution changes while the perijunctional actin pattern was slightly modified. Electron microscopy showed that a discrete intercellular space was detectable between adjacent ethanol-treated cells but not between control cells. These data indicate that ethanol is a tight junction barrier opener in pancreatic duct cells.

Actins↗

PubMed2003

Detachment of titanium and fluorohydroxyapatite particles in unloaded endosseous implants.

The shape, surface composition and morphology of orthopaedic and endosseous dental titanium implants are key factors to achieve post-surgical and long-term mechanical stability and enhance implant osteointegration. In this study a comparison was made between 12 titanium screws, plasma-spray-coated with titanium powders (TPS), and 12 screws with an additional coating of fluorohydroxyapatite (FHA-Ti). Screws were implanted in the femoral and tibial diaphyses of two mongrel sheep and removed with peri-implant tissues 12 weeks after surgery. The vibrational spectroscopic, ultrastructural and morphological analyses showed good osteointegration for both types of implants in host cortical bone. The portion of the FHA-Ti implants in contact with the medullary canal showed a wider area of newly formed peri-implant bone than that of the TPS implants. Morphological and EDAX analyses demonstrated the presence of small titanium debris in the bone medullary spaces near the TPS surface, presumably due to the friction between the host bone and the implant during insertion. Few traces of titanium were detected around FHA-Ti implants, even if smaller FHA debris were present. The present findings suggest that the FHA coating may act as a barrier against the detachment of titanium debris stored in the medullary spaces near the implant surface.

Animals↗

PubMed2003

Osteoblast growth and function in porous poly epsilon -caprolactone matrices for bone repair: a preliminary study.

Current methods for the replacement of skeletal tissue involve the use of autografts, allografts and, recently, synthetic substitutes, which provide a proper amount of material to repair large bone defects. Engineered bone seems a promising approach, but a number of variables have to be set prior to any clinical application. In this study, four different poly caprolactone-based polymers (PCL) were prepared and tested in vitro using osteoblast-like Saos-2 cells. Differences among three-dimensional polymers include porosity, addition of hydroxyapatite (HA) particles, and treatment with simulated body fluid. Biochemical parameters to assess cell/material interactions include viability, growth, alkaline phosphatase release, and mineralization of osteoblastic cells seeded onto three-dimensional samples, while their morphology was observed using light microscopy and SEM. Preliminary results show that the polymers, though degrading in the medium, have a positive interaction with cells, as they support cell growth and functions. In the short-term culture (3-7 days) of Saos-2 on polymers, little differences were found among PCL samples, with the presence of HA moderately improving the number of cells onto the surfaces. In the long term (3-4 weeks), it was found that the HA-added polymers obtained the best colonization by cells, and more mineral formation was observed after coating with SBF. It can be concluded that PCL is a promising material for three-dimensional scaffold for bone formation, and the presence of bone-like components improves osteoblast activity.

Biocompatible Materials↗

PubMed2003

Efficacy of different Cynara scolymus preparations on liver complaints.

Cynara scolymus leaves extracts have long been used in folk medicine for their choleretic and hepatoprotective activities, that are often related to the cynarin content. These therapeutic properties are also attributed to mono- and di-caffeoylquinic acids and since commercial C. scolymus preparations can differ for their activities, we studied four extracts to evaluate, if present, a relationship between the hepatobiliary properties of the different preparations and their content in phenolics. The antioxidant activity of the commercial preparations examined was also considered in an in vitro system. The results showed that the extract with the highest content in phenolic derivatives (GAE) exerted the major effect on bile flow and liver protection. Also the results of the antioxidant capacity (BR) of the different preparations are in good agreement with the results obtained in vivo. On the contrary, administering rats with doses of chlorogenic acid, equivalent to those present in this extract, we did not observe any choleretic or protective action. An histopathological analysis of liver sections confirmed the biochemical results. Perhaps caffeoyl derivatives have a role in the therapeutic properties of C. scolymus extracts, as reported in literature for "in vitro" studies, but when administered alone, they are not so effective in exerting this action.

Alanine Transaminase↗

PubMed2002

Anti-inflammatory and cicatrizing activity of Echinacea pallida Nutt. root extract.

Among the different species belonging to the Echinacea family, largely used in traditional medicine, Echinacea pallida, Echinacea purpurea and Echinacea angustifolia were investigated. These different species, due to their difficult identification, were commonly confused in the past and probably used indifferently for the same therapeutic purposes. In fact, the three species have in common, some pharmacological activities, based on the presence of active compounds that act additively and synergistically. Nevertheless, the composition of each species has slight variation in the amount of each active component. In particular, echinacoside, a caffeoyl derivative, is present in E. pallida and only in traces in E. angustifolia. It seems to have protective effects on skin connective tissue and to enhance wound healing. The anti-inflammatory and wound healing activities of echinacoside, compared with the ones of the total root extract of E. pallida and E. angustifolia, were examined in rats, after topical application. The tissues of the treated animals were evaluated after 24, 48 and 72 h treatment and excised for histological observation at the end of the experiment. Results confirm the good anti-inflammatory and wound healing properties of E. pallida and of its constituent echinacoside, with respect to E. purpurea and control. This activity probably resides in the antihyaluronidase activity of echinacoside.

Animals↗

PubMed2002

Ultrastructural basis for the efficiency of an ileal orthotopic neobladder 27 years after surgery.

The morphological and functional basis of the excellent clinical outcome of ileal orthotopic neobladders are largely unknown. Only long-term follow-up studies will provide an adequate answer to this unsettled question. We have studied a patient who underwent this type of surgery over 27 years ago. Besides an important secretive adaptation we have found, at the ultrastructural level, that the monolayered epithelium does not show signs of true metaplasia and that changes had occurred in the intercellular junctions, namely that desmosomes are significantly increased. Although limited to a single case, these features, if confirmed by further observations, suggest a working hypothesis for the understanding of the definitive phenotypic adaptation of the ileal epithelium to the new aggressive environment.

Aged↗

PubMed2001

Tapping-mode atomic force microscopy in fluid of hydrated extracellular matrix.

Fragments of native, hydrated rat tail tendon were imaged by tapping-mode atomic force microscopy while immersed in fluid. The specimens were soft and sensitive to the operating parameters, and with minimal imaging pressure the collagen fibrils appeared covered by irregular blobs or by filamentous material. A slight increase in pressure caused the underlying fibril surface to appear, with an evident D-period, gap- and overlap-zones and three intraperiod ridges. Fibrils often ran parallel and in phase, implying some coupling mechanism. Longitudinal subfibrils, 8-9 nm thick, occasionally appeared. The simultaneous acquisition of the "tapping amplitude" along with the usual "height" channel clearly confirmed the presence of longitudinal subfibrils, indicative of the inner architecture of the fibril.

Animals↗

PubMed2000

Qualitative assessment of natural apatite in vitro and in vivo.

Among the natural and synthetic materials investigated as bone graft substitutes, much interest has been focused on natural apatite obtained from low temperature heat-deproteinated compact bone. Previous research demonstrates that, when treated at a temperature below 500 degrees C, this material maintains its characteristic ultrastructural features, with a high surface/volume ratio, while as an implant material, it offers the host tissue a large surface of interaction. In vitro and in vivo tests showed that natural apatite is well tolerated and is a good osteoconducing material. The present in vivo study in rabbits was carried out to first investigate the behavior and capacity of natural apatite implants to stimulate bone ingrowth, and then to analyze the cells located at the bone/material interface. Synthetic hydroxyapatite was used as a control material. In a parallel in vitro study, we investigated the activity of differentiated osteoblasts and periosteal cells obtained from rats and new-born rabbits, incubated with natural apatite and synthetic hydroxyapatite. The in vivo study showed that natural apatite allows osteoblasts to form new bone tissue, adhering to the implant with ingrowth into the implant structure. In the presence of synthetic hydroxyapatite, a less pronounced osteoblastic activity was observed. In agreement with these observations, the in vitro study showed that natural apatite is more effective in attracting cells, favoring their proliferation and stimulating alkaline phosphatase activity. These findings suggest that natural apatite is more suitable for bone filling or bone regeneration than synthetic hydroxyapatite.

Animals↗

PubMed1996

The opioid peptide DAMME modulates histamine's content in gastric mucosa of the rat.

The effects of a synthetic Met-enkephalin analogue D-Ala2, MePhe4Met(O)5-ol]enkephalin (DAMME) (1 mg/kg. IP) on gastric damage produced by necrotizing agents (0.6 N HCl, ethanol 1 ml/rat, PO) were evaluated, and the correlation between histamine and opioids in stomach was investigated, Rats pretreated with DAMME bad significantly less severe lesions and lower histamine content in gastric tissue. The histamine level, expressed in mg/g of gastric tissue, changed from 0.41 +/- 0.10 of control animals to 1.33 +/- 0.12 for HCl and 1.51 +/- 0.20 for ethanol treatment, whereas in animals pretreated with DAMME the values were significantly reduced to 0.55 +/- 0.13 and 0.65 +/- 0.15. These results confirm a link between the gastroprotection produced by opioids and the modulation of histaminergic activity in the rat stomach.

Animals↗

PubMed1996

Collagen fibril patterns in compact bone: preliminary ultrastructural observations.

A comparative study of the Haversian architecture was carried out on compact bone derived from the anterior and posterior edges of the diaphysis of horse radius, regions which have different mechanical requirements in vivo. Samples were heat-deproteinated prior to SEM analysis, a treatment which effectively removes cells and vascular structures as well as exposing large areas of the mineralization front along the walls of the haversian canals. Bone subject to tensile stress revealed a prevalent alignment of its collagen fibrils in the stress direction, and the vast majority of its osteons were composed of fibrils running almost parallel and crossing at very acute angles. Bone subject to compressive forces showed either an orthogonal alternation of collagen lamellae or a multidirectional arrangement corresponding to the twisted plywood pattern described by other authors. Our observations substantiate both the classical model of the osteon and the twisted plywood concept, and suggest that osteon ultrastructure is modulated according to biomechanical requirements.

Animals↗

PubMed1995

Low-temperature heat-deproteinated compact bone to heal large bone defects.

The potential of low-temperature (400 degrees C), heat-treated bone matrix in osteorepair has been evaluated in vivo by implantation into defects artificially created in rodent tibia. Histological and ultrastructural analysis of the bone--implant interface has been carried out on samples obtained at 1 to 6 weeks from operation. The obtained data showed that calcined bone is well tolerated and does not cause acute or chronic inflammatory reactions. Osteoid tissue, tightly adhered to the implant, appears within 2 weeks of the operation, while after 6 weeks newly formed bone surrounds and infiltrates the implant. Of greater note, the detection of good adhesion between bone and implant ultrastructurally is demonstrated by the absence of fibrillar connective tissue at the interface. For these reasons, our preliminary observations suggest that low-temperature calcined bone (biological apatite or heat-deproteinated bone) may have a rightful place among the osteointegrators.

Animals↗

PubMed1995

Different fibrillar architectures coexisting in Haversian bone.

Samples of compact bone were deproteinated by heat treatment and analysed by SEM. This technique removes very effectively cells and vascular structures and brings into full view the mineralization front along the wall of the Havers canal. The present study was confined to samples of equine bone that are known to be subjected to different functional requirements. Bone subjected to high tensile stress exhibited collagen fibrils substantially aligned with the stress direction, and the vast majority of its osteons appeared made of almost parallel fibrils crossing at very narrow angles. On the contrary, bone subjected to prevalent compressive forces showed either an orthogonal alternation of collagen lamellae, or a multidirectional arrangement corresponding to the twisted plywood described by other authors. Our observations substantiate the classical concept of the osteon structure as well as the twisted plywood; they indicate that several osteon architectures coexist in the same specimen, and that the different structures have a different preferential distribution in different parts of the same bone; and suggest that the relative distribution of the osteon ultrastructure across the bone matrix is modulated by mechanical factors.

Animals↗

PubMed1994

Ultrastructure of heat-deproteinated compact bone.

Heat-deproteinated bone (calcined bone) is a natural candidate for an osteoreproductive biomaterial. Ultrastructural investigation has pointed out an important aspect of the preparation technique. Treatment of bone at temperatures exceeding 500 degrees C causes complete disruption of the tissue architecture and the reorganization of the mineral phase into tightly packed, dense crystals. At 500 degrees C or less the structure and distribution of the mineral phase remain unaffected, so that cross-banded 'shadows' of collagen fibrils are still readily observable, although collagen is no longer present in the samples. By its excellent structural preservation and natural porosity, low-temperature calcined bone seems to be a promising alternative for osteoreproduction.

Animals↗

PubMed1994

Pulsed electromagnetic field stimulation on posterior spinal fusions: a histological study in rats.

This study reports the histological data relative to the effect of pulsed electromagnetic fields (PEMFs) on the evolution of posterior arthrodesis induced in the lumbar vertebrae of 12 adult male Sprague-Dawley rats. After the operation, one group of six rats was stimulated with PEMFs for 18 h per day, by means of a pair of coils fixed to the outside of the cage. A control group of six rats was given no stimulation after surgery. In the groups stimulated with PEMFs an acceleration of the process of bone callus organization was already observed after 4 weeks, and even more so after 8: An early replacement was in fact observed of the newly formed cartilage tissue with primary bone (at 4 weeks) and subsequently with secondary bone (after 8 weeks).

Animals↗

PubMed1994

[The development of the vertebral articulations in the fetal period].

In this paper the thoracic tract of fetal rachis aging between 9 and 19 weeks has been investigated. The study has been carried out with histological and radiological techniques. The histological examination of these samples reveals that the articular processes are completely formed at week 12, in this period it is also evident a primitive joints between the articular processes. Nevertheless the joint is completely formed only at week 19, when the fibrous capsula and the synovial cavity are well formed. These data are confirmed by the sectional radiography.

Arthrography↗

PubMed1992

Antithrombotic and thrombolytic activity of sulodexide in rats.

We evaluated the ability of sulodexide, an extracted glycosaminoglycan, to prevent thrombus formation and to reduce a stabilized thrombus in a rat venous thrombosis model (vena cava ligature). Injection of sulodexide 10 min before induction of venous stasis, prevented thrombus formation in a dose-dependent manner (median effective dose 0.55 mg/kg). When given to rats with 6-h-old thrombi, sulodexide caused a marked reduction in thrombus size which reached 70% after 2 h with the highest dose tested (2 mg/kg). The effect of sulodexide on established thrombi appears to be due, at least in part, to a fibrinolysis-mediated mechanism, since it was significantly inhibited by epsilon-aminocaproic acid, a well-known antifibrinolytic drug. Treatment with sulodexide did not noticeably affect plasma levels of plasminogen activator and its specific inhibitor. We also showed that fluorescein-labelled sulodexide, when given to animals with 6-h-old thrombi, was present within the thrombi harvested 2 h later, but was then absent from blood. The fluorescence was mainly located in areas filled with amorphous material, that was identified as fibrin by staining with phosphotungstic acid-hematoxylin. No fluorescein-labelled material could be detected in rats treated with fluorescein alone. These findings indicate that, besides preventing venous thrombus formation, sulodexide is able to promote thrombus dissolution by a mechanism that is partly related to local fibrinolysis stimulation.

Animals↗