Cytotoxicity in vitro analysis of ceramic materials for ''metal free'' prosthetic substructures.

AIM: The aim of this study was to investigate the in vitro cytotoxicity of 5 ceramic materials for metal-free fixed prosthodontics: In-Ceram, Cergo, IPS Empress II, Cercon ZrO2, Finesse All Ceram compared each other and to commercially pure Titanium (CpTi). METHODS: The materials, prepared directly from manufacturers as 10 mm diameter and 3 mm thickness disks, have been tested following the ISO 10993-l guidelines, performing the in vitro cytotoxicity test with the use of mouse's cells, fibroblasts L-929, isolated by muscular tissue and cultured in an appropriate medium. The MTT test has been used to evaluate the cell viability through the succinate dehydrogenase enzyme activity. The originality of this investigation is that all the materials examined have been tested under the same conditions: the cytotoxicity test has been performed on these materials at the same time, in the same period, under the same conditions of temperature and humidity and by the same operator. RESULTS: Not all tested materials were free from cytotoxicity. Cercon, within the limits of this in vitro study, showed the lower cytotoxicity. CONCLUSIONS: This in vitro study suggested that ceramic materials for metal free prosthetic substructures are in competition with the CpTi which is very used in implant prosthodontics.

Settlement of the alien mollusc Brachidontes pharaonis in a Mediterranean industrial plant: bioassays for antifouling treatment optimization and management.

In this work, we investigated the efficacy of three new biocides (77351, 73532, 73503--NALCO®) as specific antifouling products against adult organisms of the bivalve Brachidontes pharaonis (Fischer P., 1870), a Lessepsian species introduced in the Mediterranean Sea by sea transport (ballast water), and which has recently shown invasive behaviour in an industrial plant in Southern Italy (Sicily). These biocides were tested to verify their efficacy, as well as their environmental compatibility at discharge point, using the crustacean belonging to the genus Artemia (Leach, 1819) as model organism, according to Government Decree (D. Lgs) No. 152/06. Biocides were also tested using alternative crustaceans, Amphibalanus amphitrite (Darwin, 1854), and Tigriopus fulvus (Fischer, 1860), in order to check whether their introduction as model species in the national regulation could affect discharge limit concentrations (DLC) due to their different sensitivity, with likely economic and technical repercussions in the industrial water treatment sector.

Adhesion of bacteria and diatoms to the exoskeleton of the harpacticoid copepod Tigriopus fulvus in culture: electron and epifluorescent microscope study.

In the marine environment associations between picoplankton and copepods are very important not only for the lifestyle of these animals, but also for marine ecosystems and human health. In the present study we investigated the biofouling of Tigriopus fulvus in culture and possible effects of this colonization by means of scanning electron microscopy and epifluorescence microscopy. These investigations show that T. fulvus is heavily and not uniformly colonized by bacteria and algae.

Cultures and thermal analysis of the marine microalga Tetraselmis suecica Kylin (Butch).

In this paper, the growth of the marine microalga Tetraselmis suecica was investigated using thermogravimetry (TG) and differential thermal analysis (DTA) to determine suitable diets for larval and juvenile development in aquaculture systems. Microalgae were maintained in synthetic sea water (19@1000 salinity, 18 degrees C constant temperature) and the algal growth was evaluated by cell abundance. Exponential, stationary and senescence cells were analyzed by TG and DTA. The results of thermal analysis pointed out marked differences between exponential, stationary and senescence phases and showed that exponentially growing microalgae could represent a suitable food in aquaculture systems.

[Plankton from the Riva Trigoso Bay(Ligurian Sea): presence of various trace elements]. / Il plancton della Baia di Riva Trigoso (Mar Ligure): presenza di alcuni elementi in traccia.

Between March and June 1989 zooplankton and sea-water samples were taken in three different areas of Riva Trigoso Bay (eastern Ligurian Sea) every two weeks. The analysis of eight trace elements (Cd, Co, Cr, Cu, Fe, Ni, V, Zn) was conducted by means of a graphite furnace atomic absorption spectrophotometer (GFAAS). Biological material values resulted to be limited and quite homogeneous in all metal species thus with no apparent influence from sampling area or time. Observed concentrations (ng/g dry weight) ranged between 12 and 45 for Cd, 52 and 117 for Co, 30 and 71 for Cr, 428 and 1063 for Cu, 730 and 1440 for Fe, 265 and 512 for Ni, 361 and 510 for V, and 1403 and 2499 for Zn. Sea-water values confirmed the results of biological material thus testifying a particularly interesting environmental condition due to low contamination level detected in this part of the coast.

Inorganic mercury in the rock pool environment (Ligurian Sea).

In the present study the mercury concentration has been investigated in three components of a rock pool environment of Genoa Nervi (Ligurian Sea): water, particulate matter and Tigriopus fulvus (Harpacticoid copepod). The influence of some parameters (pH, temperature, salinity, rainfall) on mercury concentration has been evaluated. These data show that the mercury concentration is greater in Tigriopus males than in females and that the concentration also depends on temperature variations.

[Percent composition of fatty acids in Tigriopus fulvus from rocky pools on the Ligurian coast (Copepoda harpacticoida)]. / Rapporto di composizione percentuale degli acidi grassi nel Tigriopus fulvus delle pozze di scogliera della costa Ligure (Copepoda harpacticoida).

The study concerns the Tigriopus fulvus specimens fatty acid composition, sampled in Ligurian coast rockpools from September 1980 to June 1981. By the study of frequency distribution it was observed that the fatty acid found in greater quantity was the palmitic one, followed by the palmitoleic, the oleic and stearic acids. Short and long chain fatty acids are less frequent. Investigation about each fatty acid concentration shows that the seasonal trends between males and females are different and the trend of some fatty acids (e.g. linolenic and stearic acid) is characteristic.

The carotenoid pigments of a marine Bacillus firmus strain.

As carotenoids have important biological functions, it is important to discover new natural sources of these pigments. The bacterial strains isolated from a sea water rock pool were cultivated on marine agar containing yeast extract and identified by conventional methods. The bacterial pigments were extracted with methanol and analyzed by reversed-phase HPLC with diode array detection. The major pigment of a Bacillus firmus strain was identified as astaxanthin; the results obtained suggest potential use of this bacterium in aquaculture and in pharmaceutical field.

Occurrence of Vibrio alginolyticus in Ligurian Coast Rock Pools (Tyrrhenian Sea, Italy) and Its Association with the Copepod Tigriopus fulvus (Fisher 1860).

A study of heterotrophic bacteria and vibrios adhering to the copepod Tigriopus fulvus, which lives in Ligurian coast rock pools (Tyrrhenian Sea), was carried out from November 1990 to October 1991. Heterotrophic bacteria, which were always found both free in the water and bound to the T. fulvus organisms, showed a correlation with water temperature and salinity. Vibrio alginolyticus was found free in the water and bound to T. fulvus surfaces during the warmest months. Temperature is the main factor influencing the presence of V. alginolyticus in the rock pool. Attachment of this microorganism to the copepod provides a mechanism for its extended geographic distribution.

Attachment of Vibrio alginolyticus to chitin mediated by chitin-binding proteins.

Vibrio alginolyticus is the only culturable vibrio associated with the chitinaceous carapace of the copepod Tigriopus fulvus (Fisher 1860) living in Ligurian coastal rock pools (Tyrrhenian Sea). The characteristics of the interaction between chitin particles and V. alginolyticus were studied by analysing strains isolated both from the copepod surface and from rock-pool water. The highest degree of attachment to chitin was observed at 20 degrees C, in the presence of 3% NaCl. Bacterial treatment with N-acetylglucosamine and pronase E caused a reduction in attachment of 52-62% and 77-94%, respectively. Chitin pretreatment with either wheat germ agglutinin or membrane proteins (MPs) from V. alginolyticus caused a reduction in attachment, of 50-57% and 53-70%, respectively. No inhibition was observed when bacteria were pretreated with D-glucose, D-fucose or D-fructose, or when chitin was pretreated with concanavalin A and Escherichia coli DH5 alpha MPs. V. alginolyticus MPs able to bind chitin were isolated and analysed by SDS-PAGE. Four chitin-binding proteins were visualized in all tested strains (53, 35, 20 and 14 kDa); in vivo these peptides may efficiently mediate V. alginolyticus attachment to chitin-containing substrates.