Engineering of functional supramacromolecular complexes of proteins (enzymes) using reversed micelles as matrix microreactors

The size of the inner water cavity of reversed micelles formedin a triple system ‘water-surfactant-organic solvent’can be widely varied by changing the degree of surfactant hydration.This gives grounds to use reversed micelles as matrix microreactorsfor the design of supramolecular complexes of proteins. Usingultracentrifugation analysis, it has been demonstrated thatthe oligomeric composition of various enzymes (ketoglutaratedehydrogenase, alkaline phosphatase, lactic dehydrogenase, glyceraldehyde-3-phosphatedehydrogenase) solubilized in reversed micelles of Aerosol OT[sodium bis(2-ethylehexyl)sulfosuccinate] in octane changesupon variation of the degree of hydration. An oligomeric complexforms under conditions when the radius of the micelle innercavity is big enough to incorporate this complex as a whole.At lower degrees of hydration the micelles ‘uncouple’such complexes to their components. The catalytic propertiesof various oligomeric complexes have been studied. Possibilitiesof using reversed micelles for the separation of subunits ofoligomeric enzymes under non-denaturating conditions have beendemonstrated. In particular, the isolated subunits of alkalinephosphatase, lactic dehydrogenase and glyceralde-hyde-3-phosphatedehydrogenase have been found to be active in Aerosol OT reversedmicelles. The dependences of the catalytic activity of oligomericenzymes represent saw-like curves. The maxima of the catalyticactivity observed at these curves relate to the functioningof various oligomeric forms of an enzyme. The radii of the micelleinner cavity under conditions when these maxima are observedcorrelate with the linear dimensions of the enzyme oligomericforms. Correlation of the position of a maximum with the shapeof an oligomeric complex is discussed.     

Ganciclovir induces reproductive hazards in male rats after short-term exposure

1. The effect of short-term treatment of ganciclovir on male reproduction in adult rats was studied. The animals were treated subcutaneously with either a single dose of 60 mg/kg daily for 5 days (Gan5day) or with 100 mg/kg administered three times at 4 h-intervals (Gan1day). The effects were investigated every 2 weeks up to 8 weeks, followed by investigations 16 and 24 weeks after treatment to detect the potential of recovery. 2. Time to mating was significantly increased in Gan1day group. The pregnancy index and outcome were only decreased 8 weeks (Gan5day and Gan1day) or 16 weeks (Gan1day) after treatment. 3. The lowest values of sperm variables studied were registered 8 weeks after treatment: The number of spermatid was reduced up to 4% (Gan5day) or 2% (Gan1day) of control; the sperm number was 5% and 8% of control in Gan5day and Gan1day, respectively. Over 80% of sperm were abnormal in Gan5day group, and only few normal sperm was detected in Gan1day group. 4. Morphological investigation of testes revealed a clearcut time-dependency effect. Four weeks after treatment distinct alterations were located exclusively in the peripheral part of the tubuli which included fat inclusions, cell and pyknotic nuclear debris and swellings of Sertoli cells. The effect was reversible 24 weeks after treatment. 5. Ganciclovir induces testicular damage and affects sperm variables after short-term exposure. The intensity and degree of the hazards varied in between the time of investigation after treatment.     

Comparative evaluation of ultrastructural changes in articular cartilage of ofloxacin-treated and magnesium-deficient immature rats

Ultrastructural changes in immature articular cartilage were studied after treatment of 5-wk-old rats with ofloxacin-a fluoroquinolone-and in magnesium deficiency. Magnesium deficiency was induced by feeding a magnesium-deficient diet for 9 days; the condition was confirmed by measuring the concentrations of the mineral in plasma, bone, and cartilage samples of the animals by atomic absorption spectrophotometry. Oral administration of single doses of 600 or 1,200 mg ofloxacin/kg body weight and magnesium deficiency were sufficient to induce gross structural cartilage defects. Alterations observed on the ultrastructural level showed striking similarities in magnesium-deficient rats and in rats treated with single doses of 600 mg ofloxacin/kg body weight. Typical observations were (a) bundle-shaped, electron-dense aggregates on the surface and in the cytoplasm of chondrocytes, (b) detachment of the cell membrane from the matrix and necrotic chondrocytes, (c) reduction of the extracellular matrix, and (d) swelling of cell organelles such as mitochondria. These findings further substantiate the histological finding that quinolone treatment and a dietarily induced magnesium-deficiency induce indistinguishable pathological conditions in immature joint cartilage, and they suggest that quinolone-induced arthropathy is probably caused by a reduction of functionally available magnesium (ionized Mg2+) in cartilage (42). Furthermore, they provide a basis for aimed studies with human cartilage samples from quinolone-treated patients that might be available postmortally or after hip replacement surgery.     

Increase in the efficiency of electric melting of pellets in an arc furnace with allowance for the energy effect of afterburning of carbon oxide in slag using fuel–oxygen burners

The problems of increasing the efficiency of electric steelmaking using fuel–oxygen burners to supply oxygen for the afterburning of effluent gases in an arc furnace are considered. The application of a new energy-saving regime based on a proposed technology of electric melting is shown to intensify the processes of slag formation, heating, and metal decarburization.     

Two new heuristic algorithms for the maximal planar layout problem

The adjacency problem is an important subproblem in facility layout planning. It is known to be NP-complete, so heuristics are required to solve large problem instances. In this paper two new heuristics for the adjacency problem are introduced which belong to a special class of constructive methods called Triangulation Expansion Heuristics. Extensive numerical experiments have been carried out in order to evaluate the proposed methods in terms of computing times and solution quality. It has been found that at least one method is clearly superior to the best methods proposed in the literature so far (Eades et al. 1982, Leung 1992).