Biomedical subjects

C Cassinelli

Publications and source records attributed to C Cassinelli.

16 recordsLinked to original sources

PubMed2000

Force measurements on cell repellant and cell adhesive alginic acid coated surfaces.

The atomic force microscope (AFM) was used to acquire force versus distance curves between the cantilever tip and samples bearing a surface overlayer of covalently linked alginic acid. The alginic acid coating resists cell-adhesion in in vitro experiments involving a normal and a tumor cell line. However, the surface becomes cell adhesive when alginic acid coated samples are subjected to glow discharge treatment. Force curves show in both cases the typical features resulting from the interaction between the cantilever tip and a hydrophilic, compressible polymer overlayer, suggesting that in both cases a diffuse interface with water exists. Following some recent findings on oligoethyleneglycol-terminated self-assembled-monolayers, it is suggested that conformational and molecular aspects of hydrophilic surface layers, rather than steric repulsion effects, could play a significant role in the mechanism that controls resistance to bio-adhesion.

Journal Article↗

PubMed1999

Biological monitoring of occupational exposure to cyclohexane by urinary 1,2- and 1,4-cyclohexanediol determination.

OBJECTIVES: This article reports the results obtained with the biological and environmental monitoring of occupational exposure to cyclohexane using 1,2-cyclohexanediol (1,2-DIOL) and 1,4-DIOL in urine. The kinetic profile of 1,2-DIOL in urine suggested by a physiologically based pharmacokinetic (PBPK) model was compared with the results obtained in workers. METHODS: Individual exposure to cyclohexane was measured in 156 workers employed in shoe and leather factories. The biological monitoring of cyclohexane exposure was done by measurement of 1,2-DIOL and 1,4-DIOL in urine collected on different days of the working week. In all, 29 workers provided urine samples on Monday (before and after the work shift) and 47 workers provided biological samples on Thursday at the end of the shift and on Friday morning. Another 86 workers provided biological samples at the end of the work shift only on Monday or Thursday. RESULTS: Individual exposure to cyclohexane ranged from 7 to 617 mg/ m3 (geometric mean value 60 mg/m3). Urinary concentrations of 1,2-DIOL (geometric mean) were 3.1, 7.6, 13.2, and 6.3 mg/g creatinine on Monday (pre- and postshift), Thursday (postshift) and Friday (pre-shift), respectively. The corresponding values recorded for 1,4-DIOL were 2.8, 5.1, 7.8, and 3.7 mg/g creatinine. A fairly close, statistically significant correlation was found between environmental exposure to cyclohexane and postshift urinary 1,2-DIOL and 1,4-DIOL on Monday. Data collected on Thursday and Friday showed only a poor correlation to exposure with a wide scatter. Both metabolites have a urinary half-life of close to 18 h and accumulate during the working week. CONCLUSIONS: Comparison between data obtained from a PBPK model and those found in workers suggests that 1,2-DIOL and 1,4-DIOL are urinary metabolites suitable for the biological monitoring of industrial exposure to cyclohexane.

Cyclohexanes↗

PubMed1997

Reduced plaque accumulation on hydrocarbon thin film deposited on restorative acrylic polymers.

The deposition of a thin polymeric film from ethylene plasma was used to modify the surface properties of acrylic teeth, commonly used in the dental practice for crown and bridge restorations. The effects of the surface modification process on the surface composition, morphology, and energetics were evaluated by electron spectroscopy for chemical analysis, atomic force microscopy, and contact angle measurement respectively. Plaque accumulation on the plasma-coated and untreated material was evaluated in in vivo experiments, in which the same patient received conventional and plasma-coated restorations. The hydrocarbon-like surface of the plasma-coated restoration remained remarkably free from plaque, even in the absence of brushing. On the other hand, plaque accumulation was observed on the unmodified restoration. Results are discussed according to recent theories on bioadhesive phenomena.

Acrylates↗

PubMed1997

Organic surface chemistry on titanium surfaces via thin film deposition.

In order to develop a synthetic strategy for the fine tuning of the interfacial properties of titanium-based implants and implant parts, a thin polymeric film was deposited from ethylene plasma on the surfaces of Ti foils. The intended aim was to further modify the adherent, delamination-resistant organic coating using the techniques of surface modification of polymers to direct interfacial interactions at the metal foil-biological phase interface. In particular, air-plasma treatment and Ce(IV)-induced hydroxyethylmethacrylate grafting, two typical reactions of biomedical polymers surface chemistry, were used to improve cell adhesion or to impart cell resistance to the plasma-coated Ti. Results indicate that a plasma-deposited thin polymeric film effectively can act as a viable substrate for further surface chemical modifications and allow the application of a huge background of surface-modification polymers to metallic devices.

Animals↗

PubMed1997

Bacterial adhesion to polymer surfaces: a critical review of surface thermodynamic approaches.

This paper presents a review of the theories based on wetting measurements/interfacial thermodynamics most frequently used to explain bacterial adhesion to solid surfaces. The physical meaning of data stemming from the application of the different theories is discussed and compared with current knowledge on interactions between components of matter. It is underlined that existing theories are either in disagreement with accepted knowledge on interfacial interactions or yield conflicting results from a quantitative point of view. It is concluded that, according to the present state of the art, no completely satisfactory theory exists, and that theoretical and experimental difficulties still hinder the understanding of the relationship between surface/interface free energy and bacterial adhesion to solid substrates. The recognition of existing shortcomings should be the first step towards a more satisfactory state of the art.

Bacterial Adhesion↗

PubMed1997

Surface-modified polyester fabrics.

The plasma treatment of poly(ethylene terephthalate) fabric offers new opportunities for product designers. The technique enhances surface properties while maintaining the beneficial physical characteristics of the bulk material. This article compares the surface properties of treated and untreated materials and looks at the specific application of treated fabric in the rapidly growing field of tissue engineering.

Cells, Cultured↗

PubMed1997

Anti-adhesive surfaces through hyaluronan coatings.

The ability to resist adhesion of proteins, bacteria, cells and tissue is an important requirement for the surfaces of medical devices. This article describes a surface-modification process that imparts anti-adhesive properties to the surfaces of biomedical materials through the covalent binding of hyaluronan. It can be applied to a wide range of materials to yield anti-adhesive surfaces on plastics, metals and ceramics.

Bacterial Adhesion↗

PubMed1996

Staphylococcus epidermidis adhesion to films deposited from hydroxyethylmethacrylate plasma.

The adhesion of S. epidermidis ATCC 35984 strain on polystyrene (PS) disks coated by films deposited from hydroxyethylmethacrylate (HEMA) plasma was evaluated and compared to adhesion on untreated PS and oxygen-plasma-treated PS. Films were deposited keeping constant the monomer flow rate while the discharge power ranged from 40-100 W in order to obtain coating with different surface properties. Surface chemistry, energetics, and morphology were evaluated by Electron Spectroscopy for Chemical Analysis (ESCA), contact angle measurement, and Atomic Force Microscopy (AFM), respectively. Bacteria adhered more to the plasma-deposited or plasma-treated surfaces than to untreated PS, but no significant difference was recorded among the samples obtained using different deposition conditions. According to the surface energetic analysis, plasma-deposited and plasma-treated surfaces bear a strong Lewis-base character, so it is possible to hypothesize a marked contribution of electron donor-electron acceptor interactions to the mechanism(s) controlling adhesion between synthetic and bacterial surfaces.

Bacterial Adhesion↗

PubMed1996

Evaluation of slipperiness of catheter surfaces.

A test method is described that allows the characterization of the subjective feeling of lubricity of catheter surfaces in a quantitative way. The test consists in pulling out, by a weight, a catheter tubing from a test tube filled with agar. Results show that the surface of a polyurethane catheter tubing coated with the hydrophilic poly (hydroxyethylmethacrylate) is readily hydrated by the water contained in the agar. The hydrogel coated tubing slides very quickly, due to the lubricating surface layer of water. The untreated polyurethane tubing and the same tubing after plasma treatment were definitely less slippery than the poly (hydroxyethylmethacrylate) coated ones. Atomic force microscopy was used to evaluate the contribution of the surface morphology of the samples to the obtained results.

Catheterization↗

PubMed1995

Surface field of forces and protein adsorption behavior of poly(hydroxyethylmethacrylate) films deposited from plasma.

Polymeric films were deposited from hydroxyethylmethacrylate (HEMA) plasma on non-woven poly(butyleneterephtalate) (PBT) filter materials. To test the effect of deposition conditions on surface properties, film were deposited using a constant monomer flow rate and a discharge power ranging from 40-100 W. Surface composition and surface energetics were evaluated by Electron Spectroscopy for Chemical Analysis (ESCA) and contact angle measurement, respectively. Albumin (Alb) and fibrinogen (Fg) adsorption from single protein solutions to the plasma-coated filters was measured. Results illustrate the marked effects of the deposition condition on the surface composition, the surface field of forces, and the protein adsorption behavior. The latter is modeled by the application of the Good-van Oss-Chaudhury theory of Lewis acid-base contribution to interfacial energetics. Materials endowed with widely different properties are obtained from the same monomer and different deposition conditions, a result that must be taken into account both in the production step, to assure constant quality, and in the development of specifically tailored materials.

Adsorption↗

PubMed1994

Skin contamination and low airborne nickel exposure of electroplaters.

The present study was performed to evaluate the role of hand and facial contamination in the absorption of soluble nickel compounds in 41 male subjects employed in electroplating operations in 25 small factories in the province of Florence (Italy). Personal exposure to airborne nickel ranged from 0.10 to 42 micrograms/m3; the median (range) urine, hands and face nickel levels were 4.2 (0.7-50) micrograms/l, 39 (1.9-547) micrograms, 9.0 (1.0-86) micrograms, respectively. Face nickel values explained the bulk of the variance in urine nickel levels (42%). In stepwise multiple regression analysis all other variables were not significant. The log-linear model can be expressed as: log (urine-Ni) = 0.295 + 0.593 log (face-Ni). Our results suggest that skin contamination, especially facial skin, plays an important role in nickel absorption in exposed workers.

Absorption↗

PubMed1994

Atomic force microscopy studies of the interaction of a dentin adhesive with tooth hard tissue.

The usefulness of atomic force microscopy (AFM) in the study of dental biomaterials was investigated. Two basic points were addressed: the first is the use of an atomic force microscope for the imaging of tooth hard tissue; the second is a study by AFM of the interaction of a liquid adhesive (Gluma) with dentin. Results show that dental tissues are readily imaged by AFM and that high-resolution images of the dentin ultrastructure can be obtained. As to the dentin adhesive, it was possible to elucidate the mechanism of action of Gluma. In particular, polymerization of the hydroxyethylmethacrylate present in the Gluma mixture was observed to occur in < 30 seconds.

Dentin↗

PubMed1993

A preliminary survey of cycloheximide-resistant airborne fungi in Turin, Italy.

Numbers and type of the cycloheximide-resistant part of the aerially transmitted mycoflora of Turin were studied. Samples from three areas characterized by differing human usage were taken in the first week of March. During each sampling, 12 m3 of air were aspirated, using an one-stage volumetric sieve sampler. Fifty-two mesophilic species and eight thermotolerant were isolated. Propagule load varied from 2.92 to 120.31 cfu m-3. The following species appear not to have been reported previously from air samples: Ascotricha bosei, Blastobotrys navarrensis, Cryptendoxyla hypophloia, Chrysosporium an. gymnoascus demonbreunii, Ophiostoma piceae, Penicillium vulpinum, Phialophora mustea, Rhinocladiella pedrosoi, Scopulariopsis croci, S. komngii and Sesquiallium candelabrum. A significant number of potential opportunistic pathogens was isolated.

Air Microbiology↗

PubMed1991

Keratinolytic and keratinophilic fungi in the soils of Papua New Guinea.

A study was made of soil samples collected during an expedition to the Highlands of Papua New Guinea. Fungi were isolated from the samples by the method of hair baiting (To-Ka-Va). Of the 33 species isolated, about half showed keratinolytic activity. Such activity is previously unreported for Mucor hiemalis f. hiemalis, Myrothecium roridum, Paecilomyces carneus, P. marquandii, Penicillium brevicompactum, Rhinocladiella mansonii and Verticillium lecanii. The species most active keratinolytically were Chrysosporium an. Arthroderma cuniculi, C. an. A. curreyi, C. indicum, Myceliophthora vellerea and Trichophyton ajelloi. The spectrum of fungi with keratinolytic activity isolated from the different sites differed considerably according to the frequency of use by man, heaviest use being correlated with greatest activity. The pH of the soil (varying from 5.8-7.5) had little influence on the type of such fungi isolated.

Fungi↗

PubMedDate not supplied

Outdoor airborne dermatophytes and related fungi: a survey in Turin (Italy).

Aerial dispersal of propagules, an important mechanism of fungal spread, has not been sufficiently studied for skin-infecting fungi. Over a period of one year, we have monitored the distribution of dermatophytes in the air of Turin. We have also examined the related aleurioconidic and arthroconidic fungi, which share physiological and morphological characters with dermatophytes and are sometimes considered to cause similar infections. A viable volumetric collector was used. Samples were taken each month; each sample collected 9.6 m3 of air. The medium was Dermasel agar supplemented with cycloheximide and chloramphenicol. Thirty-two species were isolated, within the genera Aphanoascus, Arthrographis, Chrysosporium, Geomyces, Gymnoascus, Malbranchea, Myceliophthora, Myxotrichum, Ovadendron, Trichophyton. The total mycoflora load obtained was rather low throughout the year and particularly in the hottest months. Apart from T. rubrum and T. mentagrophytes, which are dermatophytes very frequently encountered in Turin, many of the species detected have known pathogenic potential and/or keratinolytic activity.

Air Microbiology↗

PubMedDate not supplied

Dermatophytes from cases of skin disease in cats and dogs in Turin, Italy.

In urban environments, pet animals such as dogs and cats may be largely responsible for the progressive increase of zoophilic over anthropophilic dermatophytes in the aetiology of human dermatophytoses. Mapping, in each city, of the natural foci of zoophilic dermatophytes may thus be important for understanding the epidemiology of human dermatophytoses, and for planning preventive measures. We have surveyed dogs and cats suspected of carrying dermatophytic lesions in the Turin area. Hairs, skin scrapings and the contents of pustules or vesicles were inoculated on Dermasel agar supplemented with choramphenicol and cycloheximide. The mating type of the isolates was checked, testing their compatibility with the two mating types of Arthroderma simii Stockdale, Mackenzie and Austwick. We isolated dermatophytes from about 40% of the cases examined. Microsporum canis Bodin was the only dermatophyte found in the lesions. In the cats the lesions were more frequent, in the dogs more severe. Animals less than a year old and male dogs were most often affected. Some cases of transmission of the infection between animals and from animals to man are described. All the isolates of M. canis, tested for mating behaviour, were non-reactive.

Age Factors↗