Cloning and disruption of the gene encoding an extracellular metalloprotease of Aspergillus fumigatus

Aspergillus fumigatus secretes a serine alkaline protease (ALP) and a metalloprotease (MEP) when the fungus is cultivated in the presence of collagen as sole nitrogen and carbon source. The gene encoding ALP was isolated and characterized previously. We report here the cloning and the sequencing of the gene encoding MEP. Genomic and cDNA clones were isolated from A. fumigatus libraries using synthetic oligonucleotides as probes. Stretches of the deduced amino acid sequence were found to be in agreement with the N-terminal amino acid sequence of MEP and with internal peptide sequences. The amino acid sequence of the enzyme contains a putative active-site sequence HEYTH homologous to the active site of other bacterial and eukaryotic zinc metalloproteases. Sequence analysis reveals that MEP has a pre-proregion consisting of 245 amino acid residues preceding the 388 amino acid residues of the mature region (molecular mass of 42 kDa). An alp mep mutant, deficient in proteolytic activity at neutral pH in vitro, was constructed and tested for pathogenicity in a murine model. No difference in pathogenicity was observed between the wild-type strain and the alp mep double mutant, suggesting that ALP and MEP are not essential for the invasion of the lung tissues by A. fumigatus.     

Object and texture classification using higher order statistics

The problem of the detection and classification of deterministic objects and random textures in a noisy scene is discussed. An energy detector is developed in the cumulant domain by exploiting the noise insensitivity of higher order statistics. An efficient implementation of this detector is described, using matched filtering. Its performance is analyzed using asymptotic distributions in a binary hypothesis-testing framework. The object and texture discriminant functions are minimum distance classifiers in the cumulant domain and can be efficiently implemented using a bank of matched filters. They are immune to additive Gaussian noise and insensitive to object shifts. Important extensions, which can handle object rotation and scaling, are also discussed. An alternative texture classifier is derived from a ML viewpoint and is statistically efficient at the expense of complexity. The application of these algorithms to the texture-modeling problem is indicated, and consistent parameter estimates are obtained     

Effect of the method of activation on properties of zeolite-containing hydrotreatment catalysts

Translated from Khimiya i Tekhonologiy Topliv i Masel, No. 3, pp. 33–34, March, 1992.     

Identification and characterization of the murine homologue of CD22, a B lymphocyte-restricted adhesion molecule

The human B lymphocyte-specific Ag, CD22, is a cell adhesion molecule expressed on the surface during a narrow window of B cell development, coincident with surface IgD. A ligand for CD22 has recently been identified on human T cells as the low molecular mass isoform of the leukocyte common Ag, CD45RO. CD22 has been reported to function in the regulation of both T and B cell activation in vitro. In this study, we report the isolation and expression of a molecular cDNA clone encoding the murine homologue of CD22, mCD22. Within their predicted protein sequences, murine and human sequences overall have 62% identity, which includes 18 of 20 extracellular cysteines and six of six cytoplasmic tyrosines. BHK cells transfected with mCD22 cDNA specifically adhere to resting and activated T lymphocytes and in addition bound activated, but not resting, B cells. Five Th clones were analyzed for their ability to adhere to mCD22; two Th0 clones and one Th1 clone bound CD22+ BHK transfectants, but not all T cell clones bound CD22+ cells: another Th1 clone and a Th2 clone did not. mCD22+ BHK transfectants were also specifically bound by the B cell-specific mAb, NIM-R6, demonstrating that this mAb is specific for murine CD22. Human cell lines expressing the counter-receptors for human CD22 were also examined for adhesion to the murine CD22 homologue; the epitope responsible for B cell adhesion to CD22 is conserved, whereas the T cell epitope binding to CD22 is not. The cDNA and mAb to murine CD22 will be useful for defining the in vivo function of CD22.     

Determination of indicatrices of surface brightness of materials and coatings from measurements on their spherical specimens

The main principles of a measurement procedure are given and its implementation with the aid of an IR-imager AGA-780 is shown.State Institute of Applied Optics, Kazan. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 1, pp. 109–113. July, 1992.     

On the Theory of Electrical Phenomena in Combustion of Heterogeneous Systems with Condensed Products

The effect of the electromotive force arising in combustion of heterogeneous systems with condensed products is explained. A convective mechanism of arising regions with different charge densities due to charge transfer by the gas filtered in the pores is formulated on the basis of the developed physical concepts, estimates, and analysis of experimental data. Key words: combustion, electron emission, filtration, electromotive force.     

Substrate-connected high voltage pumping circuits for low supplyvoltages

Novel high voltage pumping circuits for low supply voltages are proposed. Utilising a small pumping circuit and the new substrate-connected techniques can enhance charge transfer efficiency and eliminate the body effect at low supply voltages. Furthermore, a diode-connected transistor technique can improve the reverse charge sharing phenomenon when the output has a load current. With this technique high boosted voltages can be obtained at low supply voltages     

Optical dot gain on newsprint determined with the Lund nuclear microprobe

A technique for measuring optical dot gain, i.e. the relative difference between the actual screen dot and the optically perceived one, is presented. By combining measurements from the non-optical nuclear microprobe with data from image analyzing technique the optical dot gain can be determined. The procedure to reach pixel by pixel correlation on a micrometer scale is discussed. In the newsprint sample studied in this investigation a typical optical dot gain between 15 and 20% was deduced. The variation in the optical dot gain was correlated with other characteristic parameters of the print and newsprint and especially a positive correlation to the mass density of the newsprint was observed.