Biomedical subjects

S O Rogero

Publications and source records attributed to S O Rogero.

7 recordsLinked to original sources

PubMed2006

Cytotoxicity study of plasma-sprayed hydroxyapatite coating on high nitrogen austenitic stainless steels.

Stainless steel has been frequently used for temporary implants but its use as permanent implants is restricted due to its low pitting corrosion resistance. Nitrogen additions to these steels improve both mechanical properties and corrosion resistance, particularly the pitting and crevice corrosion resistance. Many reports concerning allergic reactions caused by nickel led to the development of nickel free stainless steel; it has excellent mechanical properties and very high corrosion resistance. On the other hand, stainless steels are biologically tolerated and no chemical bonds are formed between the steel and the bone tissue. Hydroxyapatite coatings deposited on stainless steels improve osseointegration, due their capacity to form chemical bonds (bioactive fixation) with the bone tissue. In this work hydroxyapatite coatings were plasma-sprayed on three austenitic stainless steels: ASTM-F138, ASTM-F1586 and the nickel-free Böhler-P558. The coatings were analyzed by SEM and XDR. The cytotoxicity of the coatings/steels was studied using the neutral red uptake method by quantitative evaluation of cell viability. The three uncoated stainless steels and the hydroxyapatite coated Böhler-P558 did not have any toxic effect on the cell culture. The hydroxyapatite coated ASTM-F138 and ASTM-F1586 stainless steels presented cytotoxicity indexes (IC50%) lower than 50% and high nickel contents in the extracts.

Animals↗

PubMed2005

A comparative study of the in vitro corrosion behavior and cytotoxicity of a superferritic stainless steel, a Ti-13Nb-13Zr alloy, and an austenitic stainless steel in Hank's solution.

In this study, the in vitro corrosion resistance of a superferritic stainless steel in naturally aerated Hank's solution at 37 degrees C has been determined to evaluate the steel for use as a biomaterial. The potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS) were used to determine the corrosion resistance. The polarization results showed very low current densities at the corrosion potential and electrochemical behavior typical of passive metals. At potentials above 0.75 V (SCE), and up to that of the oxygen evolution reaction, the superferritic steel exhibited transpassive behavior followed by secondary passivation. The superferritic stainless steel exhibited high pitting resistance in Hank's solution. This steel did not reveal pits even after polarization to 3000 mV (SCE). The EIS results indicated high impedance values at low frequencies, supporting the results obtained from the polarization measurements. The results obtained for the superferritic steel have been compared with those of the Ti-13Nb-13Zr alloy and an austenitic stainless steel, as Ti alloys are well known for their high corrosion resistance and biocompatibility, and the austenitic stainless steel is widely used as an implant material. The cytotoxicity tests indicated that the superferritic steel, the austenitic steel, and the Ti-13Nb-13Zr alloy were not toxic. Based on corrosion resistance and cytotoxicity results, the superferritic stainless steel can be considered as a potential biomaterial.

Alloys↗

PubMed2002

Alpha-tricalcium phosphate cement: "in vitro" cytotoxicity.

Calcium phosphate-based bioceramics have revolutionized orthopedic and dental repair of damaged parts of the bone system. Among these materials, calcium phosphate-based cements, with hydraulic setting, stand out due to their biocompatibility and in situ hardening, which allow easy manipulation and adaptation to the shape and dimensions of bone defects. An investigation was made of the in vitro cytotoxic effect of calcium phosphate cement based on alpha-tricalcium phosphate, immersed for different lengths of time in simulated body fluid (SBF), based on the ISO-10993 "Biological Evaluation of Medical Devices" standard. The culture medium was Chinese hamster ovary (CHO) cells in contact with diluted cement extracts. The results revealed that the calcium phosphate cement used was cytotoxic and that the material's cytotoxicity decreased the longer the cement was immersed in SBF.

Animals↗

PubMed2000

Production of porous hydroxyapatite by the gel-casting of foams and cytotoxic evaluation.

This study presents the manufacture of highly porous hydroxyapatite by a novel technique that employs the foaming of suspensions prior to the in situ polymerization of organic monomers contained in the compositions. This method produces strong gelled bodies with up to 90% porosity that can withstand machining in the green state. Complex-shaped components can be obtained if the process comprises casting in one of the processing steps. The organic additives are eliminated at temperatures above 300 degrees C, and sintering is carried out for consolidation of the ceramic matrix. Spherical interconnected cells with sizes ranging from 20 to 1000 micrometer characterize the porous structure, depending on the specimen density. Cytotoxicity tests were conducted on extracts from sintered HA foams based on a quantitative method of cell colony formation and the determination of cell death after indirect contact of the porous material with mammalian cells. This in vitro test of biological evaluation revealed that the original purity of the biomedical-grade hydroxyapatite powder was affected neither through processing nor by the employed reagents.

Animals↗

PubMed2000

Cytotoxicity due to corrosion of ear piercing studs.

It is well known that allergic and/or inflammatory reactions can be elicited from the use of gold-coated studs, particularly the type used for piercing ears, since they are left in contact with body fluids until the puncture heals. Inasmuch as gold is known as a non-toxic element, other elements of the substrate material may be responsible for some allergies. Therefore, characteristics of the coating, such as defects that expose the substrate to the human skin or body fluids, play an important role in the development of skin sensitization. In this study, the cytotoxicity of commercial studs used for ear piercing and laboratory-made studs was determined in a culture of mammalian cells. The corrosion performance of the studs was investigated by means of weight loss measurements and electrochemical impedance spectroscopy. The elements that leached out into the medium were also analysed by instrumental neutron activation analysis. Further, the surfaces of the studs were examined by scanning electron microscopy and analysed by energy dispersive spectroscopy to identify defects and reaction products on the surface, both before and after their exposure to the culture medium. The stud which showed lower corrosion performance resulted in higher cytotoxicity. Ti showed no cytotoxicity and high corrosion resistance, proving to be a potential material for the manufacture of ear piercing studs.

Alloys↗

PubMed1994

Determination of trace elements in human lung samples.

Lung samples from smokers, nonsmokers, and one stillborn were analyzed by an instrumental neutron activation analysis (INAA) method. Pulmonary tissue and hilum lymph node samples were obtained separately from autopsies, and then submitted to cryogenic homogenization, lyophilization, and sterilization. Short and long irradiations were performed in an IEA-R1 nuclear reactor, and gamma-ray activities were measured using a Ge(Li) or hyperpure Ge detector. Precision of results was evaluated by analyzing one lung tissue in replicates and their accuracy by analyzing reference materials. Comparisons were carried out between results obtained in pulmonary tissues and lymph nodes, as well as those obtained in samples from different groups of individuals.

Adult↗

PubMed1994

Neutron activation analysis of biological samples at the radiochemistry division of IPEN-CNEN/SP.

Neutron activation analysis is a very useful method for determination of a great number of elements in biological samples. At the Radiochemistry Division of the IPEN-CNEN/SP, this method is being extensively applied to study several materials, such as extracts from medicinal plants, human hair, snake venoms, human lungs, food-stuffs, and corn samples. Both instrumental neutron activation analysis (INAA) and radiochemical neutron activation analysis (RNAA) are used to analyze real samples, as well as biological standard reference materials to evaluate the accuracy and precision of the results.

Brazil↗