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Biomedical subjects

Jun Arai

Publications and source records attributed to Jun Arai.

16 recordsLinked to original sources

Microlens arrays for integral imaging system.

When designing a system capable of capturing and displaying 3D moving images in real time by the integral imaging (II) method, one challenge is to eliminate pseudoscopic images. To overcome this problem, we propose a simple system with an array of three convex lenses. First, the lateral magnification of the elemental optics and the expansion of an elemental image is described by geometrical optics, confirming that the elemental optics satisfies the conditions under which pseudoscopic images can be avoided. In using the II method, adjacent elemental images must not overlap, a condition also satisfied by the proposed optical system. Next, an experiment carried out to acquire and display 3D images is described. The real-time system we have constructed comprises an elemental optics array with 54 H x 59 V elements, a CCD camera to capture a group of elemental images created by the lens array, and a liquid crystal panel to display these images. The results of the experiment confirm that the system produces orthoscopic images in real time, and thus is effective for real-time application of the II method.

Journal Article↗

Optical screen for direct projection of integral imaging.

We describe a way to display three-dimensional images by integral imaging using an ordinary projector. We first explain a method that uses a large-aperture converging lens, then we explain the proposed method that uses two sets of lens array. Based on the principle of this new approach, front projection as well as rear projection is possible. Only a proper viewing area can be formed on the optical screen by this method, which improves the brightness of images on the screen. The projector itself does not need an additional optical system. We report on the results of an experiment carried out to confirm the validity of the proposed method.

Data Display↗

Amplified optical window for three-dimensional images.

A proposed amplified optical window can form an observable three-dimensional image of an object in darkness. The window comprises two gradient-index (GRIN) lens arrays with an image intensifier between them. The length of the individual GRIN lenses that constitute the arrays is three fourths of the cycle of the meandering optical path on the input side and one fourth of the cycle on the output side. A primitive experimental result proved that the method produces three-dimensional images to be observed. This device would be used as a viewer for observing three-dimensional objects in a dark space without a camera and display equipment.

Journal Article↗

Integral three-dimensional television using a 2000-scanning-line video system.

We have developed an integral three-dimensional (3-D) television that uses a 2000-scanning-line video system that can shoot and display 3-D color moving images in real time. We had previously developed an integral 3-D television that used a high-definition television system. The new system uses -6 times as many elemental images [160 (horizontal) x 118 (vertical) elemental images] arranged at -1.5 times the density to improve further the picture quality of the reconstructed image. Through comparison an image near the lens array can be reconstructed at -1.9 times the spatial frequency, and the viewing angle is -1.5 times as wide.

Journal Article↗

The properties of carbachol-induced beta oscillation in rat hippocampal slices.

The rhythmical and pharmacological properties of carbachol-induced beta oscillation were studied using rat hippocampal slices. With the application of 30 microM carbachol, beta-range oscillations with frequencies of 13-20 Hz were recorded from the CA3 region. An AMPA receptor antagonist, CNQX, diminished the oscillations. An NMDA receptor antagonist, APV, significantly suppressed the pre-established beta oscillations. The pre-application of APV blocked the start of the carbachol-induced beta oscillations. When bicuculline (BIC), a GABAA receptor antagonist, was applied to the pre-established beta oscillations, the frequency decreased to the theta-range. When 5 microM BIC was applied with 30 microM carbachol, the beta oscillations did not start; instead, theta-like activities were induced. It has been reported that carbachol in hippocampal slices can induce theta-like activities, which are not modulated by BIC, while BIC's facilitating the start of the activities. The results of the present study suggest that the GABAA receptor-mediated inhibitory transmission modulates the beta oscillation and that the transmission is needed for the start process of the oscillations. Therefore, the start and generation mechanisms of carbachol-induced beta oscillation will be different from those of carbachol-induced theta-like activities.

Animals↗

Moire fringe reduction by optical filters in integral three-dimensional imaging on a color flat-panel display.

We propose a method to reduce the color moire fringes that are attributable to the structure of a color flat-panel display in integral three-dimensional imaging. The method uses two types of optical low-pass filter, diffuser and defocus. The effectiveness of the method was confirmed in an experiment. We describe a way to design these filters with moire's residual energy and video signal energy as indices and demonstrate the validity of the model, which combines two filters to reduce moire fringes.

Journal Article↗

Apolipoprotein E polymorphisms in Japanese patients with polypoidal choroidal vasculopathy and exudative age-related macular degeneration.

PURPOSE: To study the genotypes, allelic frequencies, and polymorphisms of apolipoprotein E (Apo E) in unrelated Japanese patients with polypoidal choroidal vasculopathy (PCV) or exudative age-related macular degeneration (AMD) and control subjects without macular degeneration. DESIGN: Cross-sectional study. METHODS: Blood samples from 225 subjects older than 50 years were used. The 225 subjects included 58 patients with PCV, 85 with AMD, and 82 without macular degeneration. Coding exons of the Apo E gene were amplified by polymerase chain reaction, and the DNA sequences were determined by direct sequencing with an automated sequencer. RESULTS: Apo E epsilon3/epsilon3 was the most frequent genotype with a prevalence of 79.3% in PCV patients, 76.5% in AMD patients, and 67.1% in the control subjects. However, the differences in the percentages were not statistically significant among the three groups. The most frequently found allele in the three groups was epsilon3. Patients with PCV and AMD were less likely to have epsilon2 and epsilon4 than the control subjects, but the differences were not statistically significant. Five minor Apo E single nucleotide polymorphisms, including epsilon5 and epsilon7, were found. CONCLUSION: Japanese patients with PCV and AMD were less likely to have epsilon2 and epsilon4 polymorphisms, but the differences from the normals were not statistically significant for the Apo E genotypes and allelic frequencies.

Aged↗

Geometrical effects of positional errors in integral photography.

The effects of misarrangement of elements (elemental lenses and elemental images) that construct three-dimensional (3-D) images in integral photography are presented. If the lens arrays of the capturing system and the display system are not aligned accurately, positional errors of elements may occur, causing the 3-D image to be reconstructed in an incorrect position. The relation between positional errors of elements and the reconstructed image is derived. As a result, it is shown that a 3-D image is separated by local positional errors and blurred by global positional errors. In both local and global positional errors, 3-D images reconstructed far from the lens array are greatly affected.

Equipment Failure Analysis↗

Effects of focusing on the resolution characteristics of integral photography.

The effects of focusing on the resolution characteristics of integral photography (IP) are analyzed. First, there is an attempt to obtain the resolution characteristics of capture and display systems as the product of their modulation transfer functions (MTFs). Next, the relationship between this overall MTF and focusing during the capture is studied. The results show that, with focusing set at infinity, IP can provide three-dimensional images without remarkable resolution degradation over a wide range of depth.

Journal Article↗

Intranasal immunization with recombinant outer membrane protein P6 induces specific immune responses against nontypeable Haemophilus influenzae.

OBJECTIVE: Nontypeable Haemophilus influenzae (NTHi) is one of the leading causative pathogens for otitis media. The outer membrane protein P6 of NTHi is highly conserved among the strains and is an attractive candidate for a preventive vaccine. However, for the production of a relatively small amount P6 containing lipopolysaccharides, the development of a recombinant version of this protein is required. This study was designed to investigate the specific mucosal immunity induced by intranasal immunization of recombinant P6 (rP6) with cholera toxin (CT). METHODS: BALB/c mice were immunized with of rP6 (30 microg) and CT (2 microg) intranasally every 2 days for 2 weeks. Anti-rP6 specific IgG, IgA and IgM antibodies and the subclass of anti-rP6 specific IgG antibody were determined by enzyme linked immunosorbent assay (ELISA). Anti-rP6 specific IgA in nasopharyngeal washings were also determined by ELISA. Nasopharyngeal clearance of inoculated NTHi after the intranasal immunization were assessed. All statistical differences between the two groups were assessed by ANOVA parametric test. RESULTS: Intranasal immunization with rP6 and CT evoked rP6-specific mucosal IgA immune response as well as the systemic IgG immune response against rP6 and enhanced nasopharyngeal clearance of inoculated live NTHi. CONCLUSION: These results indicate the good immunogenicities of rP6 to induce specific immune responses against NTHi. Intranasal immunization with rP6 will be an effective approach to protect infections of NTHi.

Analysis of Variance↗

Optical shifter for a three-dimensional image by use of a gradient-index lens array.

We propose a new function of the two-dimensional lens array that is composed of many gradient-index lenses. The array forms three-dimensional (3D) images. The characteristics of the 3D images depend on the length of the gradient-index lens. Especially, if the length of the lens is an odd-integer multiple of the half period of the optical path, 3D images are pseudoscopic with a reversed depth. The two lens arrays are positioned at a suitable distance, so that orthoscopic 3D images with the correct depth are formed in front of the lens array.

Journal Article↗

Polypoidal choroidal vasculopathy with large vascular network.

PURPOSE: To report characteristics of polypoidal choroidal vasculopathy (PCV) of large vascular networks that expand across the retinal vascular arcade. METHODS: Among 60 consecutive eyes diagnosed as having PCV by fluorescein and indocyanine green (ICG) angiography, 12 eyes (9 patients) showed large lesions. The clinical and angiographic features of these 12 eyes were studied retrospectively. RESULTS: Cases of large PCV typically showed dilated network vessels, which spread radially, and multiple polypoidal dilations at the end of the network vessels. Most of the polypoidal dilations formed clusters resembling bunches of grapes and caused large serous and/or hemorrhagic pigment epithelial detachments (PEDs). Among the 12 eyes, 5 showed rapid expansion of the lesions and became large PCVs within 3-24 months. In these eyes, ICG angiography revealed mesh-like choroidal vessels beneath the retinal pigment epithelium. CONCLUSION: PCV with a large vascular network that expands across the vascular arcade is not uncommon. Some of these cases seems to have characteristics of choroidal neovascularization rather than choroidal vasculopathy. It is not easy to distinguish such cases from exudative age-related macular degeneration even though they showed typical findings of PCV on ICG angiography.

Aged↗

Role of PTB-like protein, a neuronal RNA-binding protein, during the differentiation of PC12 cells.

PTB-like protein (PTBLP) is a new homologue of pyrimidine tract binding protein (PTB), and has been cloned as a possible autoantigen in cancer-associated retinopathy. PTBLP has two functional domains, the nuclear localization signal and the RNA recognition motifs (RRMs). Full-length PTBLP (PTBLP-L) has four RRMs, and its alternative splicing product (PTBLP-S) lacks the third and fourth RRMs. Although PTBLPs are expressed in neuronal tissues, the function of PTBLPs has not been determined. We have studed whether PTBLP plays a role in neuronal differentiation using PC12 cells. During the process of nerve growth factor-induced neuronal differentiation of PC12 cells, PTBLP-L was down-regulated whereas PTBLP-S was up-regulated. Transfection of PTBLP-L into PC12 cells led to the suppression of neuronal differentiation. In PTBLP-S transfected cells, however, this suppression was not evident. When both PTBLP-L and PTBLP-S were co-transfected, the suppressive effect of PTBLP-L decreased. In differentiated cells, PTBLP-S localized in the nucleus and PTBLP-L was found dispersed throughout the cytoplasm and neuronal growth cone. These findings suggest that PTBLP-L acts as a negative regulator of neuronal differentiation and PTBLP-S acts as a competitor of PTBLP-L.

Animals↗

Expression and neuroprotective effect of hepatocyte growth factor in retinal ischemia-reperfusion injury.

PURPOSE: To investigate the expression and possible neuroprotective effects of hepatocyte growth factor (HGF) in a rat model of retinal ischemia-reperfusion injury. METHODS: Retinal ischemia was induced in adult male Sprague-Dawley rats by raising the intraocular pressure to 110 mm Hg for 45 minutes. To study expression of HGF and its receptor c-Met, reverse transcription-polymerase chain reaction (RT-PCR), Western blot analysis, and immunohistochemical staining were performed on eyes enucleated at 6, 12, 24, 48, and 96 hours after reperfusion. To examine the neuroprotective effects of HGF, recombinant human (rh)HGF (1, 6, and 12 microg in 2 microL PBS) or vehicle was administered intravitreally 1 minute after reperfusion, and the eyes were enucleated at 6, 12, 24, 48, and 96 hours and 28 days after reperfusion. The retinal damage was assessed by electroretinogram (ERG) recordings, by measuring the inner retinal thickness, and by counting the number of TUNEL-positive cells in each retinal layer. RESULTS: RT-PCR and Western blot analyses showed upregulation of HGF and c-Met-HGF receptor mRNA at 6, 12, 24, and 48 hours after reperfusion, compared with the normal rat retina. Immunohistochemically, expression of HGF was found in the retinal pigment epithelial cells at 6 hours after reperfusion and in some cells in the ganglion cell layer and inner nuclear layer at 24 hours after reperfusion. The amplitudes of the ERG b-wave and oscillatory potentials were significantly larger in the eyes treated with 6 and 12 microg rhHGF than in those of vehicle-treated control rats (P < 0.01). On day 28, the thicknesses of the inner retina of vehicle-treated rats and that of 6-microg rhHGF-treated rats were 54.4 +/- 6.12 (mean +/- SD, n = 9) and 71.5 +/- 9.81 microm (n = 8), respectively (P < 0.01). The number of TUNEL-positive cells at 6, 12, 24, and 48 hours after reperfusion was decreased significantly by treatment with 6 microg rhHGF, compared with those in the control rats (P < 0.01). CONCLUSIONS: Upregulation of HGF in the retina may play a role in retinal ischemia-reperfusion injury. Intravitreal injection of rhHGF is neuroprotective against the injury.

Animals↗

Decreased retinal neuronal cell death in caspase-1 knockout mice.

PURPOSE: To determine whether apoptosis of retinal neurons induced by excessive light exposure and ischemia-reperfusion injury is altered in caspase-1 knockout mice. METHODS: Eight- to 10-week-old caspase-1 knockout mice (Casp1-/-) and wild-type (WT) mice (C57BL/6) were exposed to diffuse, cool, white fluorescent light of 25,000 lux for 2 h. Other mice were subjected to retinal ischemia by increasing the intraocular pressure to 110 mmHg for 45 min. Electroretinograms (ERGs) were recorded before and after the light exposure. TdT-dUTP terminal nick-end labeling (TUNEL) was performed to identify the apoptotic cells after the insults. The inner retinal thickness was measured to evaluate the retinal injury after the ischemia-reperfusion. Expression of caspase-1 protein was studied by immunohistochemical analysis and Western blotting. Caspase-1-like protease activity was determined by a colorimetric tetrapeptide substrate. RESULTS: The morphology of the retina and the amplitudes of the a and b waves of the ERGs of Casp1-/- mice did not differ from those of WT mice. After the light exposure, TUNEL-positive cells were observed in the outer nuclear layer of the WT mice retina. The number of TUNEL-positive photoreceptor nuclei after the light exposure, and the number of nuclei in the inner nuclear layer after the ischemia-reperfusion injury, were significantly less in Casp1-/- mice than in WT mice. There were more caspase-1-positive photoreceptor cells in WT mice after the light injury. The inner retinal layer of Casp1-/- mice was significantly thicker in Casp1-/- mice than in WT mice 2 weeks after the ischemic insult. CONCLUSIONS: Retinal neuronal apoptosis was less prominent in Casp1-/- mice after excessive light exposure and ischemia-reperfusion injury. These data indicate that caspase-1 plays a role in retinal neuronal apoptosis.

Animals↗