Focal nodular hyperplasia of the liver: a rational approach to treatment

Focal nodular hyperplasia of the liver in a 3 year old child has been successfully treated by ligation of the hepatic artery branches supplying the lesion. The prominence of the abnormal vasculature in the lesion and its possible aetiological involvement is stressed. Because of the risks of partial hepatectomy, hepatic artery ligation is suggested as the treatment of choice for focal nodular hyperplasia.     

Temperature-sensitive mutant of Schizosaccharomyces pombe exhibiting enhanced radiation sensitivity

A conditional lethal and radiation-sensitive mutant of Schizosaccharomyces pombe is described in which both characteristics result from a single gene mutation. Confirmation of the pleiotropic nature of this mutant was obtained by tetrad analysis and by testing the radiation sensitivity of a large number of revertants that grew normally at the restrictive temperature. The colony-forming ability of the mutant after ultraviolet radiation, gamma radiation, and ethyl methane sulfonate treatment is considerably altered by the post-treatment incubation temperature, showing higher survival at 25 than at 30degreesC. The radiosensitivity of the mutant is also influenced by the stage of growth. The difference in radiation sensitivity between the wild type and mutant is greater when log-phase cultures are compared. The characteristics of this mutant suggest that it is defective in a step common to both deoxyribonucleic acid replication and repair.     

Water sorption and water-induced molecular mobility in dental composite resins

Water sorption in two resin composites, Kulzer's Solitaire (S) and SDI's Wave (W), and in a polyacid-modified composite resin, 3M's F2000 (compomer F), was investigated by means of equilibrium sorption isotherms (ESI) and of dynamic sorption (DS) measurements. Molecular mobility in these materials was studied by means of dielectric relaxation spectroscopy (DRS) and of thermally stimulated depolarization currents (TSDC) measurements. The results of ESI measurements show that at equilibrium, water is molecularly distributed in the materials and the effects of hydrophilic sites and clustering are negligible. Hysteresis effects in sorption–desorption cycles are larger in the resin composites than in the compomer. Equilibrium water uptakes in both ESI and DS conditions are rather low, in the range 1–2%. Diffusion coefficients of water are about 1×10^–8 cm²/s in the resin composites and by a factor of about 2 smaller in the compomer. Molecular mobility increases with hydration, as suggested by preliminary DRS and TSDC measurements. Detailed dielectric measurements may give important information for understanding, at the molecular level, water-induced degradation in dental materials.