Genetic engineering employing MPB70 and its promoter enables efficient secretion and expression of foreign antigen in bacillus Calmette Guérin (BCG) Tokyo

Vaccination is an important factor in public health. The recombinant bacillus Calmette Guérin (rBCG) vaccine, which expresses foreign antigens, is expected to be a superior vaccine against infectious diseases. Here, we report a new recombination platform in which the BCG Tokyo strain is transformed with nucleotide sequences encoding foreign protein fused with the MPB70 immunogenic protein precursor. By RNA-sequencing, mpb70 was found to be the most transcribed among all known genes of BCG Tokyo. Small oligopeptide, namely, polyhistidine tag, was able to be expressed in and secreted from rBCG through a process in which polyhistidine tag fused with intact MPB70 were transcribed by an mpb70 promoter. This methodology was applied to develop an rBCG expressing the receptor binding domain (RBD) of severe acute respiratory syndrome coronavirus 2. Immunoblotting images and mass spectrometry data showed that RBD was also secreted from rBCG. Sera from mice vaccinated with the rBCG showed a tendency of weak neutralizing capacity. The secretion was retained even after a freeze-drying process. The freeze-dried rBCG was administered to and recovered from mice. Recovered rBCG kept secreting RBD. Collectively, our recombination platform offers stable secretion of foreign antigens and can be applied to the development of practical rBCGs.

Unidirectional phase-Doppler method for particle-size measurements

We propose what we believe to be a novel unidirectional phase-Doppler method for sizing moving spherical particles on the basis of the phase difference of two polarized Doppler beat signals in a single scattering direction. Light scattered by a moving particle is divided into two rays, which are detected with different polarization angles to transmit dominantly reflected or refracted rays. The phase difference between two signals is linearly proportional to the particle diameter with a given particle refractive index and geometrical parameters of the optical system. To explore the optimum polarization condition, we numerically investigated the phase-diameter properties in relation to polarization angles by using the geometrical optics approximation and generalized Lorenz-Mie theory. We also performed experiments with polystyrene and glass particles to verify the usefulness of the proposed method.

Angiotensin-converting enzyme genotype is associated with Alzheimer disease in the Japanese population

We compared the distribution of an insertion (I)/deletion (D) polymorphism of the gene coding for the angiotensin-converting enzyme (ACE) in 133 Japanese sporadic Alzheimer disease (AD) patients with 257 controls. The association between AD and ACE genotypes or alleles was found to be significant. The frequency of II genotypes was 1.4 times higher in AD than controls, while that of DD genotypes was only 0.4 times as high. The altered distribution of ACE alleles in patients with AD appeared to be independent of apolipoprotein E.

Coherent optical techniques for diagnostics of retinal blood flow

Up to now, a variety of coherent optical techniques have been proposed and extensively studied for diagnostics of the retinal blood flow. These techniques are mainly based on dynamic laser light-scattering phenomena such as the laser Doppler effect and the laser speckle fluctuation. This paper reviews, first, spectral reflectance properties of the ocular fundus tissue layers and, then, principles of the techniques with the comparison of the Doppler and the speckle methods. Some physical phenomena are also discussed in the origin of the techniques such as heterodyne and homodyne beatings, and time-varying speckles. Developing processes of each technique are briefly outlined. Peculiarities of blood flow measurements at the retina are finally examined from the methodological point of view. © 1999 Society of Photo-Optical Instrumentation Engineers.

Compensation of eye movements in retinal speckle flowmetry using flexible correlation analysis based on the specific variance

Bio-speckle flowmetry using the photon correlation technique is useful for measuring the retinal blood flow velocity. In practical situations, however, it often suffers from eye-movement artifacts and other external moving factors. To solve this problem, we studied in this paper a flexible correlation analysis, by which the blood flow information can be effectively extracted from erroneous data influenced by displacement of the measuring point. The signal-analyzing system including the photon correlator directly stores the sequential counts of photoelectron pulses into a memory. After measurements, the stored data are read out and used to calculate the first-order statistics of time-integrated bio-speckles and the autocorrelation function with an arbitrary delay-time unit for an arbitrary period. These results are used to specify and to eliminate the erroneous parts of data due to the displacement of the measuring point. The usefulness of this technique was verified for a glass capillary model and human retinal vessels. © 1998 Society of Photo-Optical Instrumentation Engineers.

Evaluation of blood flow at ocular fundus by using laser speckle

We report a method for noninvasively evaluating blood flow at the ocular fundus by using laser speckle phenomena. The intensity fluctuation of speckles scattered from a 1-mm-diameter illuminated area at the fundus is detected and analyzed by the photon-correlation technique, which gives us the relative degree of total blood flows within the probe area. The method is used to evaluate blood flows at the ocular fundus of a rabbit and normal human volunteers. The experimental results show that the present laser speckle method is useful for the relative evaluation of blood flows in the ocular fundus tissue.

The influence of sulfate content and molecular weight of a fucan sulfate from the brown seaweed Ecklonia kurome on its antithrombin activity

The antithrombin effects of the sub-fractionated fucans with different molecular weights and sulfate contents, which were prepared from a fucan sulfate isolated from the brown seaweed Ecklonia kurome, were examined for their abilities to inhibit thrombin-fibrinogen reaction and amidolytic activity of thrombin, and to bind to fibrinogen. The inhibitory effects of the fucans on both fibrinogen clotting by thrombin and amidolysis of the protein in the presence of heparin cofactor II were improved with increase in their molecular weights and reduced with decrease in their sulfate contents. The binding abilities of the fucans with almost the same sulfate content to fibrinogen were unchanged independently of their molecular weights, although the ability diminished with decrease in the sulphate content. These results suggest that heparin cofactor II-mediated antithrombin activity of the fucan sulfate is dependent on both its sulfate content and molecular weight, and also that the inhibitory effect of the polysaccharide on fibrinogen clotting by thrombin may be attributable to the steric hindrance by its binding to fibrinogen.

Antithrombin activity of a fucan sulfate from the brown seaweed Ecklonia kurome

The mechanism of antithrombin action of a fucan sulfate (C-II), which was isolated from the brown seaweed Ecklonia kurome, was examined by clotting method using a thrombin-fibrinogen system and by amidolytic method using a chromogenic substrate in the presence and the absence of antithrombin III (AT III) or heparin cofactor II (HC II). C-II significantly inhibited the clotting of fibrinogen by thrombin even in the absence of the protease inhibitors, and the amidolytic activity of the protein only in the presence of HC II. C-II was not adsorbed on an AT III-agarose column and its anticoagulant activity in AT III-depleted plasma was the same as that in normal one. Examination of interaction of C-II with fibrinogen by gel filtration chromatography demonstrated that C-II bound to the protein. These results indicated that the antithrombin activity of C-II was mediated by HC II and not by AT III, and that the polysaccharide bound to fibrinogen, thereby blocking thrombin action, and also that its direct thrombin inhibition was very weak.