Microleakage and Shear Bond Strength of Composite Restorations Under Cycling Conditions.

OBJECTIVES: The aim of this study was to evaluate microleakage and shear bond strength of composite restorations under different cycling conditions. METHODS AND MATERIALS: Class V cavities were prepared in the buccal and lingual surfaces of 30 human molars (n=60). A further 60 molars were used to prepare flat enamel and dentin specimens (n=60 each). Cavities and specimens were divided into six groups and pretreated with an adhesive (self-etch/Clearfil SE Bond or etch-and-rinse/Optibond FL). Composite was inserted in the cavities or adhered to the specimens' surfaces, respectively, and submitted to cycling (control: no cycling; thermal cycling: 10,000 cycles, 5°C to 55°C; thermal/erosive cycling: thermal cycling plus storage in hydrochloric acid pH 2.1, 5 minutes, 6×/day, 8 days). Microleakage was quantified by stereomicroscopy in enamel and dentin margins after immersion in silver nitrate. Specimens were submitted to shear bond strength testing. Statistical analysis was done by two-way analysis of variance and Kruskal-Wallis tests (p<0.05). RESULTS: Microleakage in enamel margins was significantly lower in the control group compared with thermal cycling or thermal/erosive cycling. Erosive conditions increased microleakage compared with thermal cycling (significant only for Clearfil SE Bond). No significant differences were observed in dentin margins. Bond strength of enamel specimens was reduced by thermal cycling and thermal/erosive cycling when Clearfil SE Bond was used and only by thermal/erosive cycling when Optibond FL was used. No differences were observed among dentin specimens. CONCLUSIONS: Thermal/erosive cycling can adversely affect microleakage and shear bond strength of composite resin bonded to enamel.

[The influence of macrophages on the leukemogenic activity of Rauscher murine leukemia virus]. / Untersuchungen über den Einfluss der Makrophagen auf die leukämogene Wirkung des Virus der murinen Rauscher-Leukämie (RLV).

A single application of trypan blue 3 to 24 hours before or simultaneous with inoculation of the Rauscher leukemia virus (RLV) resulted in enhancement of leukemogenesis with an especially high viremia. Repeated administration of trypan blue after RLV infection resulted in reduced spleen weight. Viremia, however, was also increased compared with controls (no application of trypan blue), but in a lower rate than in mice treated with the virus plus trypan blue. Since trypan blue is known as an inhibitor of the functions of macrophages the results point at an important role of this cell type in preventing infection with this oncogenic retrovirus. In this regard there are differences in the role of macrophages in human immunodeficiency virus (HIV) infections.

Factors affecting serum sialic acid levels.

Inoculation of certain immunostimulators (BCG, Freund's adjuvant) as well as several antigens or Silasorb resulted in a 2- to 3-fold increase of the serum sialic acid level in mice. In contrast, treatments causing immunosuppression, like gamma-radiation and application of cyclophosphamide, did not influence the serum sialic acid level. Furthermore, immunosuppression did not prevent the increase caused by immunostimulators. The results suggest that macrophages may be involved in regulating the serum sialic acid levels after immunostimulation.

Differences in phosphorylation of isolated phospholamban in dependence on the preparation procedure.

Phospholamban was purified by two different preparation protocols. The products of both preparations are immunochemical similar. They differ, however, with regard to their phosphorylation by the catalytic subunit of cAMP-dependent protein kinase. It is suggested that the lipid environment plays a crucial role in the exposition of the phosphorylation sites of phospholamban.

Reconstitution of phospholamban--an approach to its function.

Isolated cardiac Ca,Mg-dependent ATPase of the sarcoplasmic reticulum and purified phospholamban, a proteolipid involved in the regulation of the calcium transport systems of the heart muscle, were reconstituted into soybean lecithin liposomes. Whereas the enzymatic activity of the CaATPase in the obtained liposomes was unaffected as well as by unphosphorylated and cAMP-dependent phosphorylated phospholamban, the capacity of oxalate-supported calcium uptake was lowered in the presence of phospholamban. The proteolipid is discussed not as a regulatory protein of the enzyme but as a mediator of the calcium storage in the lumen of the liposomes or sarcoplasmic reticulum network.

The putative role of phospholamban in the regulation of the heart muscle.

We describe the 50fold purification of phospholamban, the production of antibodies against it and preliminary experiments of reconstitution of purified phospholamban into vesicles of skeletal sarcoplasmic reticulum (SR). Purified phospholamban migrates in a modified Laemmli SDS polyacrylamide gel electrophoresis (PAGE) system with a relative molecular mass (Mr) of 22 kD and 6 kD. The higher Mr form is detectable by immunoreaction on Western blots only in heart SR preparations, whereas the low Mr form is also present in sarcolemmal preparations. No immunoreactivity was found in SR of skeletal muscle. Reconstituted skeletal SR vesicles were not influenced by phospholamban in respect to their Ca++-ATPase activity and calcium accumulation rate, but the obtained data suggest that phospholamban alters the calcium storage capacity of SR.

Purification of phospholamban and characterization of its antibodies.

Phospholamban was extracted from pig heart microsomal membranes with a methanol-chloroform (2:1) mixture. The proteolipid was further purified to electrophoretic homogeneity by chromatography in organic solvents and in SDS-containing medium. Purification was about 50-fold with respect to specific 32P-phospholamban radioactivity. Antisera were produced in rabbits against phospholamban. Electroblot analysis demonstrates specific binding of the antisera to purified phospholamban and to phospholamban in preparations of cardiac sarcoplasmic reticulum and sarcolemma.

Characterization of endogenous phosphorylation in isolated cardiac sarcolemma.

The cardiac sarcolemma contains kinases which catalyze the incorporation of 32P-phosphate into acid stable and acid precipitable membrane components of low molecular weight. The phosphorylation is not influenced by cyclic AMP or calmodulin. Analysis of phosphorylation products using proteolytic digestion, organic solvent extraction, thin layer chromatography and gel filtration reveals both polypeptides and lipids as kinase substrates. Polypeptides are phosphorylated at their serine and threonine residues, while lipid phosphorylation gives rise to 32P-labelled phosphatidylinositol phosphates and some nonidentified compounds. Phosphorylated polypeptides and phosphorylated lipids do not separate in SDS polyacrylamide gel electrophoresis. On the basis of the fast time course of 32P-phosphate incorporation, it may be supposed that endogenous phosphorylation may play a role in the short term regulation of the cardiac sarcolemmal function.

[Activities of several enzymes of glycolysis and of the glucose shunt in the Albert hepatoma of mouse (author's transl)]. / Die Aktivität einiger Enzyme der Glykolyse und des Glukose-shunt in Albert-Hepatom der Maus.

The activities of key enzymes of glycolysis and of the glucose shunt as well as the capacity of lactic acid formation were determined in the high-speed tissue supernatant of the transplantable Albert hepatoma of mouse [originally produced by oral application of chrysoidin (2,4-diaminoazobenzene) on C57 Black mice]. Furthermore, the particle-bound hexokinase activity was determined. The following results were obtained: In the hepatoma the activities of aldolase, pyruvate kinase and lactic dehydrogenase are hardly altered compared with normal liver. The activities of hexokinase and phosphofructokinase are increased 2,5-fold, those of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase 2-fold. The capacity for lactic acid formation from glucose is 7 times as high in the hepatoma supernatant. Strong differences emerge from the liver-to-hepatoma relationship in terms of intracellular distribution of the hexokinase (total homogenate 1 : 5, supernatant 1 : 2,5 and particle-bound hexokinase activity 1 : 18). A summarizing consideration of all the results obtained so far for the Albert hepatoma shows that this malignoma departss in several biochemical parameters from the "Molecular Correlation Concept" maintained by Weber, providing more evidence for the individuality of tumors.

[Pharmacocinetic behaviour of alpha-L-arabinofuranosidase in therapeutical application to toxify transport forms of cancerostatic substances (author's transl)]. / Uber das pharmakokinetische Verhalten der alpha-L-Arabinofuranosidase bei der therapeutischen Anwendung zur Giftung von Transportformen Kanzerostatischer Stoffe

The present studies were carried out to obtain pharmacokinetic data about the elemination of intravenously administered alpha-Larabinofuranosidase from the blood stream and about the distribution and retention of the enzyme in different organs and in a transplantable sarcoma of mouse. The results were used for the planning of therapeutical experiments, in which detoxified transport forms of cancerostatic agents were to be toxified by exogenous enzymes specifically in the tumour tissue. The alpha-Larabinofuranosidase is eliminated from the blood circulation quite rapidly (half-life about 20 min); a large portion is apparently excreted through the kidneys. The distribution in the organs, as compared with the tumour tissue, is very favourable for the planned therapeutical experiments in relation to other enzymes: The enzyme is scarcely accumulated in the RES-containing organs. In the tumour tissue, the enzymatic activity declines linerly with time of the experiment, while elimination of the enzyme from the kidney and muscle follows rather an exponential function. The optimal time interval between the enzyme and substate injections was determined to be 6 hrs.

Evidence for cyclic AMP-dependent protein kinase activity in isolated guinea pig and rat liver mitochondria.

Purified preparations of guinea pig and rat liver mitochondria contain considerable latent cAMP-dependent protein kinase activity that is revealed by treatment with 1% Triton X-100. The solubilized kinase was partly purified by DEAE-cellulose chromatography. It accepts protein in the washed Triton-extracted mitochondria as substrate.