Biocompatibility and Toxicity of Poly(vinyl alcohol)/N,O-Carboxymethyl Chitosan Scaffold

The in vivo biocompatibility and toxicity of PVA/NOCC scaffold were tested by comparing them with those of a biocompatible inert material HAM in a rat model. On Day 5, changes in the blood parameters of the PVA/NOCC-implanted rats were significantly higher than those of the control. The levels of potassium, creatinine, total protein, A/G, hemoglobulin, erythrocytes, WBC, and platelets were not significantly altered in the HAM-implanted rats, when compared with those in the control. On Day 10, an increase in potassium, urea, and GGT levels and a decrease in ALP, platelet, and eosinophil levels were noted in the PVA/NOCC-implanted rats, when compared with control. These changes were almost similar to those noted in the HAM-implanted rats, except for the unaltered potassium and increased neutrophil levels. On Day 15, the total protein, A/G, lymphocyte, monocyte, and eosinophil levels remained unaltered in the PVA/NOCC-implanted rats, whereas urea, A/G, WBC, lymphocyte, and monocyte levels remained unchanged in the HAM-implanted rats. Histology and immunohistochemistry analyses revealed inflammatory infiltration in the PVA/NOCC-implanted rats, but not in the HAM-implanted rats. Although a low toxic tissue response was observed in the PVA/NOCC-implanted rats, further studies are necessary to justify the use of this material in tissue engineering applications.

Development of Ceramic Dental Crowns and Bridges Using Electrophoretic Deposition

In the dental branch much effort is undertaken for production of metal-free ceramic restoration. Because of esthetical aspects and their biocompatibility ceramics are the material of choice. Allergic reactions or toxic tissue damages can be prevented largely by application of ceramic dental products. Zirconia in its tetragonal yttria stabilized polycrystal form (TZP) and alumina toughened zirconia (ATZ) offer highest strength combined with highest toughness. Unfortunately this favourable, outstanding combination of mechanical properties leads to difficulties in conventional hard machining in the sintered state, which is too time- and costconsuming. For this reason, electrophoretic deposition of alumina toughened zirconia powder and TZP powder was used for preparation of metal-free dental crowns and bridges. The electrophoretic deposition process was carried out directly onto the plaster moulds for single crowns, three-unit and four-unit bridges. The electrophoretic deposition process was investigated concerning the deposition rate and the output of dental crowns per volume of ethanolic ceramic suspension. Furthermore, the influence of the amount of dispersing agent on the rheological properties of the ceramic suspensions was investigated.

Monitoring of Adverse Drug Reactions by means of Autopsy Tissue Examination

Morphologic examination of autopsy tissue specimens was undertaken to establish the incidence of adverse drug reactions in a population of hospitalised patients. By removal of subjective bias recording of adverse reactions, the incidence of toxic tissue manifestations was 33%. In those reactions classified as definitely linked to a specific causative agent males between the ages of 41 and 60 displayed the highest frequency of adverse effects. In the probable and possible categories the incidence of toxic manifestations was equal amongst both sexes and highest in patients over 40 y. Regardless of the type of adverse reaction the most common causative agent identified was alcohol and hepatic tissue was primarily altered morphologically. Unlike the conventional mechanism used to monitor adverse drug reactions, autopsy tissue examination provides a system of measurement of toxic manifestations to both prescription as well as non-prescription compounds.