Direct determination of monolinuron, linuron and chlorbromuron residues in potato samples by gas chromatography with nitrogen-phosphorus detection.

A gas chromatography with nitrogen-phosphorus detection direct method for methoxyurea herbicide determination in powdered potato and fresh potato samples has been developed. A previous study of the thermal stability of the phenylurea herbicides seems to confirm that the ones containing the methoxy radical, i.e. monolinuron, linuron and chlorbromuron, were stable. The herbicides were extracted from the sample through liquid-liquid extraction with dichloromethane-light petroleum (1:1), followed by solid-phase extraction in a C8 cartridge. The recoveries were in the range 84-95% for powdered potato and 86-101% for fresh potato. The RSD values were less than 10%, at 0.1 microg g(-1) concentration level (n = 4) for both types of samples. Detection limits of the method were 7.0-30 ng g(-1) for powdered potato and 6.0-50 ng g(-1) for fresh potato.

[Composite materials, carbon fiber-resin: a solution to the problem of aging of denture bases of removable prostheses]. / Les materiaux composites, fibre de carbone-resine: une solution au probleme du vieillissement des bases de prothese adjointe.

The growing age of resin prosthesis is a worry for dentists, and chiefly for patients. Their reinforcement with carbon fiber appears to be a solution that frankly improves their life expectancy.

[Toward a more resistant resin, more economical and better suited to conditions in developing countries]. / Pour une resine plus resistante, plus economique et adaptee aux contextes des pays du sud.

The breakage of prosthesis constructed in polymethacrylate resin is a reality in daily practice. Several solutions have been proposed to overcome this problem. Thus, the reinforcement of resin with carbon fibre improved greatly the mechanical properties, notably the fatigue strength. The technique of elaboration of such prosthesis proposed in this study has little impact on aesthetic as well as on the final cost. This proposition could be a relevant solution for third world countries opposite to economical and technological problems generated by cast metallic framework.

Development of a synthetic bolus using silicone elastomer for the study of masticatory efficiency.

STATEMENT OF PROBLEM: Masticatory efficiency has been proposed as an outcome measure for prosthetic rehabilitation. However, no standardized method is available for this type of assessment. PURPOSE: This study developed a normalized synthetic test food with reproducible physical and rheologic properties. MATERIAL AND METHODS: Two silicone putties of different hardness were studied. The texture of each putty varied by the addition of silicone oil. Rheologic characteristics of 7 samples were compared with the same properties of 5 natural food substances. RESULTS: Seven varieties of synthetic bolus were produced, each of which were of a different hardness, modulus of elasticity, and tensile strength. The natural food substances demonstrated great rheologic variability. The synthetic bolus samples exhibited a texture profile approaching that of natural foods. The principal difference between the 2 groups tested was that of the homogeneity of the silicone samples. CONCLUSION: None of the samples reproduced all the rheologic properties of the natural food substances; however, the results showed that their characteristics were sufficiently similar for the silicone samples to be suggested as a reproducible alternative for the testing of masticatory efficiency.

[Removable prosthesis: masticatory efficiency]. / Prothese adjointe: efficacite masticatoire.

The late consultation in odontology often leads to tooth extraction. This negligence, in a long term, will cause complete toothlessness. This state of invalidity will be compensated by prosthesis. The removable prosthesis is often indicated because of the cost price. It is the result of a successful therapeutics, only if it fits aesthetically and functionally, within a chewing efficiency. In a first part, we will define masticatory efficiency, as different from masticatory capacity and capability. Then, in a second part, through some experimentation, we will show how fundamental research can guide the practitioner in his prosthetics choices and assessments.

[Implant-supported complete denture]. / Prothese totale supra-implantaire.

Total toothlessness too lately or wrongfully compensated remain at the origin of prosthetic problems often difficult to solve through conventional prosthesis. We shall explain the importance of implantology in this type of medication. After presenting the different solutions brought by the importance in the rehabilitation of toothless maxilla we shall describe the process of making a supra-implanted lower maxilla prosthesis. Applications and non-applications will be directed; then the different elements and stages of the making of this type of this mucous-membrane-held prosthesis will be described. The retention is assured by two hooks tightly clasped onto a crossbar supported by the implants.

Influence of nitrovasodilators on bovine pulmonary histamine release.

The organic nitrates and related nitrovasodilators are relaxants of vascular and airway smooth muscle. Very little information is currently available regarding the influence of nitrates and related nitrovasodilators on pulmonary autacoid release. This study examined the influence of glyceryl trinitrate, isosorbide dinitrate and sodium nitroprusside on histamine release from bovine lung mince. Spontaneous histamine release from bovine lung mince was not altered by 0.1 nM to 1 microM glyceryl trinitrate, isosorbide dinitrate or sodium nitroprusside. Glyceryl trinitrate, isosorbide dinitrate and sodium nitroprusside produced a concentration-dependent decrease in A23187 (10 microM) stimulated histamine release. Glyceryl trinitrate also inhibited histamine liberation following the addition of compound 48/80. Further studies indicated that the inhibitory action of glyceryl trinitrate was reversed by coincubation with the guanylate cyclase inhibitor, methylene blue (10 microM). These findings indicate that glyceryl trinitrate, sodium nitroprusside and isosorbide dinitrate inhibit non-immunologically stimulated pulmonary histamine release and suggest that alterations in guanylate cyclase activity may influence pulmonary histamine release.

Comparative studies of in vitro renal cephaloridine toxicity between normoglycemic and diabetic rats.

This study investigated if the attenuation in cephaloridine toxicity associated with streptozotocin (STZ)-induced diabetes can be attributed to a direct cellular effect. Comparative studies examined the direct toxicity of cephaloridine 14 days after (35 mg kg-1, i.p.) STZ or vehicle injection of male Fischer 344 (F344) rats. In vitro cephaloridine toxicity was assessed by measuring lipid peroxidation, renal gluconeogenesis and organic ion accumulation in renal cortical slices. The in vitro toxicity of cephaloridine was reduced in the diabetic group since lipid peroxidation was not increased following a 120-min exposure to cephaloridine. This was in contrast to a concentration- and time-dependent increase in lipid peroxidation in renal tissue derived from normoglycemic animals pre-incubated with 0-5 mM cephaloridine. Renal gluconeogenesis was inhibited in a concentration-dependent manner in the normoglycemic group following a 15-90-min exposure to 0-5 mM cephaloridine. Pyruvate-stimulated gluconeogenesis was diminished in the diabetic group only after a 90-min preincubation. Renal cortical slice accumulation of p-aminohippurate (PAH) and tetraethylammonium (TEA) was decreased in the normoglycemic group. Accumulation of TEA, but not PAH, was decreased (P less than 0.05) in the diabetic group. These results indicate that in vitro cephaloridine toxicity was attenuated by STZ-induced diabetes.