Search

Noise suppression in an avalanche multiplication photodiode (APD) occurs during its operation in a charge accumulation mode. Increasing avalanche gain suppresses the noise arising due to avalanche multiplication. Feedback effect of the inherent quenching on the charges, successively accumulated within the charge storage period, may cause the noise suppression. A description of the photoelectric conversion characteristics of an APD is given.

This paper describes a diagonal autostereoscopic three-dimensionel (3-D) television system with a liquid-crystal video projector, the picture of which could be observed without the need to use special glasses. As the representation method of 3-D images of this system, the pixels from four television cameras are composed electronically to make stripe images which are projected onto the rear surface of a lenticular screen by a high-quality HDTV liquid-crystal video projector. In this way, clear full-color diagonal stereoscopic 50-inch television pictures could be displayed. Besides the lack of obligation to use special glass- a, the advantages of this system are: the observation range is broadened, compared to the previous stereoscopic 3D television; and the pictures are more natural and easier to observe. The newly realized diagonal autostereoscopic 3-D television system, the lenticular screen, the diagonal autostereoscopic 3-D cameras, the recording equipment of 3-D pictures, etc., are discussed in this paper. [ABSTRACT FROM AUTHOR]

A newly developed liquid crystal display generated (LCD-generated) parallax harrier method for an autos stereoscopic three-dimensional (ID) display is described. This system consists of two LCD panels constituting a 3- D display and a slit barrier. Compared to a conventional parallax barrier method, the slit bather is not fixed but variable electrically. Therefore, the method can be flexible for any desired multiviewpoint 3-D image display system. The compatibility with the usual 2-D image display is fully ensured. Also, both 2-D and 3-D images can simultaneously be displayed. A prototype 3-D image display apparatus suitable for a personal computer has been demonstrated to indicate a strong feasibility for a new 3-D image display application. [ABSTRACT FROM AUTHOR]

Focuses on at study which look at the pathological features of Alzheimer's disease. Identification of the ...4 allele of apoliproprotein E (APOE); Aims of the study; Design of the study; Discussion and conclusion of the study.

It has been reported that there is no stereoscopic depth perception under isoluminant color random-dot stereograms (RDS), and that color information does not contribute to human depth perception. this paper describes the results of experiments on stereoscopic depth perception of isoluminant color RDS, obtained by using the prototype flickerless field-sequential stereoscopic television system developed by the present authors. The results of the experiments show that stereoscopic depth perception clearly does exist even in isoluminant color RDS. It was also found that the binocular fusion area an color RDS is about two-thirds that on black/white stimuli, and that the temporal-frequency limits of binocular disparity for the isoluminant color RDS is about 3 Hz, while that for black/white stimuli are 4 to 5 Hz. These results suggest that not only does the luminance channel contribute to human depth perception, but also the chromatic channels. [ABSTRACT FROM AUTHOR]

To confirm a synergistic effect between the polymorphic K variant of the butyrylcholinesterase (BChE-K) gene and the epsilon4 allele of the apolipoprotein E (APOE) gene in Alzheimer's disease, the frequency of the BChE-K allele was re-examined in a large series of Japanese patients with Alzheimer's disease and controls. Two hundred and three patients with Alzheimer's disease and 288 age and sex matched controls were genotyped by polymerase chain reaction and restriction fragment length polymorphism for BChE-K and APOE. No changes were found in the frequency of BChE-K, either in the Alzheimer's disease group as a whole (0.17 v 0.14; p=0.36) or in early (0.16 v 0.16; p=0.98) or late (0.17 v 0.13; p=0.24) onset patients compared with age matched controls. The study failed to confirm the findings of a previous study which found a significantly higher incidence of BChE-K in patients with Alzheimer's disease with APOE epsilon4 allele than in controls. In the Japanese population studied here, there was no association between BChE-K and Alzheimer's disease, nor an interaction between BChE-K and APOE epsilon4 allele. [ABSTRACT FROM AUTHOR]

Mutations in the gene encoding the microtubule-associated protein tau (MAPT) cause frontotemporal dementia and parkinsonism linked to chromosome 17. Clinical variability is seen not only among families with different mutations, but also among family members with the same mutation. We investigated a newly identified familial frontotemporal dementia and parkinsonism family. The disease was of early onset and was inherited as an autosomal dominant trait. Clinically, parkinsonism was the prominent and often early feature, and it preceded dementia. Three autopsied cases shared involvement predominantly in the frontal and temporal lobes and also in the subcortical nuclei, including substantia nigra, globus pallidus, and subthalamic nucleus, that microscopically consisted of neuronal loss, microvacuolation, and astrocytic fibrosis. Immunohistochemistry demonstrated neuropil threads, ballooned cells, and glial fibrillary tangles. Sequencing analysis of the MAPT gene showed an alteration in one allele, resulting in a P301S substitution. These findings suggest that the MAPT P301S mutation can cause pathologically subcortical-predominant, neuropil thread-rich, tau-containing lesions, which could result in consistent parkinsonism. Our study confirms the notion that the phenotype observed in affected individuals from P301S MAPT mutation families is heterogeneous and is broader than the phenotypes seen to date in affected family members carrying other MAPT mutations.

To investigate a possible effect of the apolipoprotein (APOE) epsilon4 allele on memory decline in Alzheimer's disease (AD), we examined 64 AD patients with the APOE epsilon3/3, epsilon3/4, or epsilon4/4 allele using the Alzheimer Disease Assessment Scale-Cognitive subscale (ADAS-Cog) and its subtests at the initial examination and at the 1-year follow-up visit. One-year changes in the scores of the Word Recall subtest, Word Recognition subtest, and total ADAS-Cog were significantly correlated with the number of APOE epsilon4 alleles after controlling for the effects of age, sex, education, test interval, and baseline scores. Findings revealed that APOE epsilon4 allele is related to an accelerated memory decline in AD.

Since the original description of frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) during the Consensus Conference held in Ann Arbor, Michigan in 1996, it has become apparent that this syndrome has worldwide distribution. More than 70 families have been described in North America, Europe, Australia and Asia. The molecular genetic studies have identified 29 mutations outside and on exon 10 of tau gene. Here, we report the progress in clinical, genetic and pathological studies of FTDP-17 in Japan. There have been 15-separetely ascertained families described in Japan. These kindreds harbor following tau mutations: exon 10, exonic mutations, N 279 K, N 296 H, P 301 L and P 301 S; exon 10 5' splice-site mutations, S 305 N (-2), +11, and +12; exon 1, R 5 H mutation; exon 9, L 266 V mutation; and exon 13, R 406 W mutation. The phenotype of FTDP-17 kindreds varies significantly between families with different mutations and among the families carrying the same mutation. This variability is also seen in Japanese kindreds. Exon 10, P 301 L, +16 and N 279 K mutations are the most common but only P 301 L and N 279 K mutations have been described so far in Japan. On the other hand, R 5 H, N 296 H, +11, and +12 mutations have not been identified outside of Japan. Comparison of phenotypes of Japanese and non-Japanese families with P 301 S, P 301 L and R 406 W mutations uncovers significant differences in clinical presentations. It is difficult to compare pathology of Japanese and non-Japanese families on the basis of available medical literature but no apparent differences can be seen. Autopsies demonstrate the presence of neuronal and glial tau inclusions and ballooned neurons, frequently in the distribution seen in other sporadic tauopathies. A search for the common founder in Japanese families may be successfully performed. FTDP-17 families have been identified with increasing frequency in Japan. The discovery of tau mutations and the fact that they are responsible for the disease processes in the brain lead to the major advancement of our understanding of neurodegeneration. It is hoped that future studies of these families will also lead to finding the curative treatments for the tauopathies.

Early onset familial Alzheimer disease (FAD) has been associated with mutations in three genes, of which presenilin 1 (PSEN1) mutations are the most frequent. We reported previously a variant form of FAD, due to deletion of exon 9 of PSEN1, with spastic paralysis and rigidity. We describe a novel PSEN1 mutation in a family of Japanese origin with six affected individuals of both genders in two generations. The disease is characterized by presenile dementia, which is preceded by spastic paraparesis and apraxia. This mutation, which is predicted to cause a missense substitution of serine for glycine, occurred at codon 266 in exon 8 of PSEN1. The mutation was not found in 200 controls and 200 sporadic AD patients. On this basis alone, it seems this mutation is pathogenic. Our findings provide a new clue to the etiology of the familial early onset dementia., (Copyright 2002 Wiley-Liss, Inc.)

Myristoylated alanine-rich C kinase substrate (MARCKS), a protein associated with cell growth, neurosecretion and macrophage activation, is activated by protein kinase C (PKC) phosphorylation. We reported that amyloid beta protein (Abeta) activated MARCKS through a tyrosine kinase and PKC-delta in rat cultured microglia. Here we report that Abeta signaling pathway through a specific PKC isoform is involved in the phosphorylation of MARCKS in Neuro2A cells. Selective PKC inhibitors but not tyrosine kinase inhibitors significantly inhibited the phosphorylation of MARCKS induced by Abeta. Abeta selectively activated PKC-alpha among the four PKC isoforms localized in Neuro2A cells. PKC-alpha activated by Abeta directly phosphorylated a recombinant MARCKS in vitro, Translocation of PKC-alpha from the cytoplasm to the membrane and accumulation of phospho-MARCKS in the cytoplasm were induced by Abeta. These results suggest involvement of a phosphoinositide signaling system through PKC-alpha in the phosphorylation of MARCKS in neurons, an event which may be associated with mechanisms underlying neurotrophic and neurotoxic effects of Abeta.