Effects of subsite alterations on substrate-binding mode in the active site of hen egg-white lysozyme

The primary sequence of the low-molecular-mass cadmium-binding protein metalloprotein II of Nereis diversicolor (Hediste diversicolor, recent denomination) has been determined. This protein is composed of 119 amino acids and has 80.8% identity with the N. diversicolor myohemerythrin [Takagi, T. & Cox, J. A. (1991) FEBS Lett. 285, 25-27]. The fact that iron, which normally binds to myohemerythrin, is not found to be associated with the cadmium-binding protein metalloprotein II in cadmium-exposed animals could be the result of the complete abolition of the iron-binding capacity of the protein due to the binding of cadmium.     

An experimental 220-MHz 1-Gb DRAM with a distributed-column-controlarchitecture

A distributed-column-control architecture is proposed to reduce the burst-mode cycle time of large-capacity DRAMs. It features independent operation of the I/O block and subarrays, eliminating the wiring delay in the internal buses from the longest pipeline stage. The timing difference between the I/O block and the subarrays is compensated for by event-driven circuits. This architecture also eliminates the timing margin between the activation of column selection lines, reducing the cycle time by 25%. To evaluate this architecture, an experimental synchronously operating 1-Gb DRAM was designed and fabricated using a 0.16-μm CMOS process. It operates with a 22O-MHz clock and a 1.5-V power supply     

Primary biliary cirrhosis complicated by severe hypoxemia

The case reported here is of a 61-year-old woman diagnosed with hepatopulmonary syndrome. She had had severe hypoxemia for 5 years. In room air, her arterial oxygen tension was low, and although we anticipated that treatment with oxygen would increase it, the treatment failed to do so. Pulmonary perfusion imaging with Tc-99m-labelled macroaggregated albumin showed an arterio-venous shunt in the lungs. Blood tests and liver scanning with Tc-99m-labelled galactosyl human serum albumin showed abnormalities of liver function, and per-rectal portal scintigraphy with Tc-99m pertechnetate showed severe portal hypertension. Inspection of a biopsy specimen taken under ultrasonographic guidance showed primary biliary cirrhosis of Scheuer stage I. The causes of hepatopulmonary syndrome are unknown, but seem to include a decrease in hepatic functional reserve, portal hypertension, or other factors. The development of hepatopulmonary syndrome due to portal hypertension in this patient is of interest.     

Charge disproportionation in CaFeO3 studied with the Mössbauer effect

The Mössbauer effect spectrum of stoichiometric CaFeO₃ at 4 K consisting of two magnetic hyperfine patterns with nearly the same intensities is explained assuming a charge disproportionation 2Fe⁴⁺→Fe³⁺ + Fe⁵⁺. The disproportionation is supposed to set in at or in the vicinity of the Nèel temperature. The single magnetic hyperfine pattern for SrFeO₃ at 4 K, on the other hand, indicates a rapid electron exchange between Fe³⁺ and Fe⁵⁺ ions, for the center shift and the hyperfine field coincide approximately with the average values of the corresponding parameters for CaFeO₃.     

Stimulation of cyclic adenosine monophosphate formation by the novel vasorelaxant peptide adrenomedullin in cultured rat mesangial cells

This study was conducted to compare the tensile bond strength at the two interfaces of the "sandwich technique". 48 hours after the specimens were tested, using Hounsfield tensometer. Load was gradually applied on to the specimen till the bond at the interface failed. The load at which the bond failed was recorded and analysed for statistical significance. From the present study it can be concluded that the bond between glass ionomer and dentine is better than the bond between glass ionomer and composite resin.     

Diffraction efficiency of a grating coupler for an array illuminator

The diffraction efficiency of a grating coupler having a surface-relief grating is calculated by the use of coupled-wave theory. The grating couplers are fabricated to examine the validity of the calculated result. The dependence of the measured diffraction efficiency on the groove depth of the grating coupler agrees well with the calculated results. The array illuminator, which emits 10 and 20 beams with equal intensity, is designed and fabricated through the use of these numerical results. The uniformity error of the output beam caused by the error of the diffraction efficiency is also discussed.     

Kinetics of association processes of d-fructose dehydrogenase onto liposome surfaces

Summary Association processes of D-fructose dehydrogenase (FDH) onto surfaces of liposomes which were composed of N-(5-dimethylamino-1-naphthalenesulfonyl)-L--dimyristoylphosphatidylethanolamide and L--dimyristoylphosphatidylcholine or L--dimyristoylphosphatidylglycerol (1:9) were investigated by the fluorescence stopped-flow technique. The association processes were divided into two relaxation processes: the faster process whose apparent rate constant monotonously increased with the concentration of FDH, and the slower process whose rate constant showed a saturation behavior. Taking the number of binding sites on the liposome surface into consideration, the corrected association rate constant of the faster process was 4.4% of the theoretical value for a binary collision, probably due to a disadvantageous surface-searching and dehydration processes on the liposome and protein surfaces. The Arrhenius plots of the rate constants both for the faster and slower steps showed a discontinuous change around the gel to liquid-crystal phase transition temperature of the liposomes. Strong influences of deformability of liposomes, and state of hydrating water molecules around polar heads, on the rate of association processes were suggested.     

Circular multilayer zone plate for high-energy x-ray nano-imaging

A circular multilayer zone plate (MZP) was fabricated and its focusing performance was evaluated using 20-keV x-rays. MoSi(2) and Si layers were alternately deposited by DC magnetron sputtering on a wire core; all the interfaces satisfied the Fresnel zone condition. The measured line spread function was converted to a point spread function by tomographic reconstruction. The results suggest that the MZP has the potential to realize the diffraction-limited resolving power, which is calculated to be 35 nm using the diffraction integral. Furthermore, scanning transmission microscopy using the MZP could resolve a 50-nm line-and-space pattern.