Bacillus subtilis Ffh, a homologue of mammalian SRP54, can intrinsically bind to the precursors of secretory proteins

We analyzed the binding activity of B. subtilis Ffh to the precursors of secretory proteins by purifying mature and precursor proteins of beta-lactamase derived from pUC18 and its derivatives, of which the signal peptide region was replaced with that of E. coli OmpA, B. subtilis AprE, PBP5* or an alkalophilic Bacillus sp. #1011 CGTase. Each of them was mixed with purified B. subtilis Ffh in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC). The tested precursor proteins, including those of E. coli, of which the signal sequences differ from those of B. subtilis in the number of charged amino acids and hydrophobicity, cross-linked with Ffh, whereas mature proteins did not. The addition of scRNA, the B. subtilis counterpart of mammalian SRP 7S RNA, into the mixture did not affect the complex formation. These findings suggest that B. subtilis Ffh intrinsically binds to several precursor proteins.     

A geometric approach to multivariable control system design of a distillation column

A multivariable control problem of a distillation column is considered, where the object is to maintain two output variables, the compositions of the distillate and the bottom product at some desired values by manipulating the reflux flow rate and the boil-up rate.Based on a linearized model, a geometric approach is applied to the design problem of disturbance rejection control. In other words, a feedback control strategy is desired which enables the complete rejection of the effect of disturbances on both output variables.In obtaining the feedback control, the problem of how many and what state variables are to be measured and fed back has been made clear. In this control strategy, only five state variables are fed back. Thus, only five columns of the feedback gain matrix have non-zero values. Furthermore, two out of these five columns are uniquely determined, and the other three columns can be assigned arbitrary values and used for pole assignment of the controlled system.For the disturbances in composition and flow rate of the feed stream, Δx_F and ΔL_F, the effect of the disturbance Δx_F is completely rejected by the feedback controller, but the effect of the disturbance ΔL_F can only be eliminated from the output Δx_D.A digital simulation of a distillation column composed of nine plates, a condenser and a reboiler was carried out to confirm these results and to show that the linearized model used in this paper is valid for fairly large step changes.     

Mission Reliability for a 1-Unit System with Allowed Down-Time

This paper considers a 1-unit system; the unit is repaired upon failure. The failure and repair rates need not be constant. The system fails if the unit is not repaired within a fixed time, or if the number of failures during the mission exceeds a fixed number. As a special case, that number is allowed to be ``infinite.' The Laplace transforms of the reliability and mean time to system failure are derived; they are not easily solved. The special case of constant failure and repair rates is treated. The results are compared with those of Calabro.     

Condensation heat transfer of binary refrigerant mixtures of R22 and R114 inside a horizontal tube with internal spiral grooves

An experimental study of the condensation of pure and mixed refrigerants of R22 and R114 inside a spirally grooved horizontal copper tube has been carried out. A double-tube counterflow condenser in the pressure range 3–21 bar and at a mass flow-rate 26–70 kg h⁻¹ was used. The axial distributions of refrigerant, tube wall and cooling water temperatures, wall heat flux density and vapour quality are shown graphically. The variation of tube wall temperature around the circumference of the tube is also shown. The local Nusselt number depends on the molar fraction, whereas the average Nusselt number can be correlated by an equation which is modified from a previously established equation for pure refrigerants inside a horizontal smooth tube. The frictional pressure drop evaluated is correlated well by the Lockhart-Martinelli parameters and is independent of the concentration of the mixture.     

Midkine as a novel target gene for the Wilms' tumor suppressor gene (WT1)

Midkine (MK) is a heparin-binding growth factor which is strongly expressed during the midgestation period of mouse embryogenesis. Wilms' tumor is an embryonal kidney malignancy in infants, and WT1 has been identified as its tumor suppressor gene. The high expression level of MK in all Wilms' tumor specimens so far examined and the presence of two WT1 elements (5'-GCGGGGGCG-3') in the human MK promoter region led us to examine the possible role of the WT1 gene product in the regulation of MK gene expression. A gel shift assay verified the complex formation between the WT1 gene product and WT1 consensus sequence of MK gene. DNase1 footprint analysis also demonstrated that the downstream WT1 element was protected from DNase1 cleavage by the addition of the WT1 protein. The human MK promoter fused with the chloramphenicol acetyltransferase gene (phMK2.3kCAT) was co-transfected with an effector plasmid containing the WT1 gene into several cell lines. Transient transfection assays showed suppression of the MK promoter by WT1 co-transfection in recipient cells; deletion of the WT1 binding site abolished the suppression. The evidence reported in this study indicates that MK gene is a newly identified WT1 target gene.     

Sequential changes of tau-site-specific phosphorylation during development of paired helical filaments

It has been reported that many tau sites in neurofibrillary tangles (NFT) are abnormally phosphorylated. We investigated the phosphorylation of tau in the hippocampus of nondemented patients and Alzheimer's disease patients by immunostaining with five site-specific antibodies against phosphorylated tau. In the pretangle stage, tau in neuropil threads was phosphorylated at serines 199, 202 and 409, numbered according to the longest human tau isoform, whereas tau in some neuronal soma was phosphorylated at serines 199, 202, 409 and 422. Tau at the stage of NFT was phosphorylated at serine 396 and threonine 231 in addition to serines 199, 202, 409 and 422. In the advanced stage, tau in ghost tangles was phosphorylated mainly at serine 396. These results suggest that the phosphorylation of each site in tau differs among the maturing stages of neurofibrillary change and that abnormal phosphorylation of tau in the neuronal soma occurs at 199, 202, 409 and 422 earlier than at threonine 231 and serine 396.     

Development of the evaluation method for crack propagation due to thermal striping

The evaluation code “THERST” was developed to estimate the fatigue crack propagation behavior under thermal stresses due to high-frequency temperature fluctuations, called “thermal striping”. This paper presents fundamental formulations of the evaluation method and verifications of the evaluation method by FEM analyses. Experimental data were obtained in high cycle thermal fatigue tests and the effect of a multiple crack which is characteristic for a crack under thermal stress is discussed in addition to the results of the FEM analyses. A modification of the evaluation method was performed to take multiple crack effects into account.     

Xanthogranulomatous pyelonephritis

A 76-year-old woman presented with spiking fever and right back pain. Ultrasonography (US) revealed that her right kidney was enlarged. Computed tomography (CT) showed the parenchyma was replaced by non-enhancing masses but the overall kidney shape was maintained. These findings were compatible with those of xanthogranulomatous pyelonephritis (XP). The nonenhancing masses on CT coincided with the multiple butter yellow nodules of the resected kidney and microscopically these lesions were proved to be abscesses with xanthoma cells. In this case, the US and CT findings reflected the pathological feature of XP and thus these techniques are thought to be useful for the diagnosis of XP.