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631.
Ryoji Suzuki Sachiko Saino-Saito Hiroyuki Sakagami Kiyotaka Toshimori Hiroshi Abe Hisatake Kondo 《Journal of molecular histology》2009,40(1):77-80
ADP ribosylation factors (ARFs) of small GTPase are molecular switches regulating various membrane dynamics. Among them, ARF6
has recently been highlighted because of its function to facilitate the interaction between the cytoskeleton and the plasma
membrane. Each ARFs has its preferable or even specific guanine nucleotide exchange factors (GEFs) as its activators. According
to our previous RT-PCR analysis, EFA6A, a guanine nucleotide exchange factor for ARF6, was restrictedly expressed in the brain,
retina and testis. Different from previous studies on neurons, EFA6A, a guanine nucleotide exchange factor for ARF6, was first
shown to be localized intensely in nuclei of spermatocytes of adult mouse testes in the present immunohistochemical study.
This suggests a possible involvement of EFA6A-ARF6 signaling in the karyokinesis and cytokinesis. 相似文献
632.
Shinichi Nakamura Naomi Tanabe Kiyotaka Yamakawa Shoki Nishida 《Microbiology and immunology》1983,27(6):495-502
A total of 55 strains of Clostridium sordellii, 21 lethal toxin-positive and 34 lethal toxin-negative, were tested for cytotoxin production in brain heart infusion medium supplemented with 0.2% Na2HPO4 (m-BHI) and cooked-meat-glucose (CMG) medium using baby hamster kidney (BHK-21/WI-2) cells as indicator cells. The m-BHI medium was preferred to CMG medium and 24 hr of incubation was sufficient for cytotoxin production. Nineteen of the 21 toxigenic strains were also cytotoxigenic, and the strength of the cytotoxigenicity was approximately parallel with that of the lethal toxigenicity. Clostridium difficile antitoxin neutralized C. sordellii cytotoxin and also C. sordellii antitoxin neutralized C. difficile cytotoxin. 相似文献
633.
Takayuki Nagao Kimiaki Saito Emiko Hirayama Kumi Uchikoshi Kiyotaka Koyama Shinsaku Natori Naoko Morisaki Shigeo Iwasaki Tijiro Matsushima 《Mutation research》1989,215(2)
Ptaquiloside, a potent carcinogen of an illudane-type sesquiterpene glycoside isolated from Pteridium aquilium, and its related compounds, hypolosides having the same nucleus isolated from the Pteridaceae, exhited marked mutagenicity in the modified Ames test with Salmonella typhimurian TA98 and A100 using a preincubation at pH 8.5 Illudins M and S, sesquiterpenes of the same illudane type from basidiomycetes, also exhibited mutagenicity. The structural requirements for mutagenicity are discussed. 相似文献
634.
635.
Shinichi Nakamura Masato Mikawa Satoshi Nakashio Manabu Takabatake Imiko Okado Kiyotaka Yamakawa Toshihiko Serikawa Seiichi Okumura Shoki Nishida 《Microbiology and immunology》1981,25(4):345-351
Attempts were made to isolate Clostridium difficile from a total of 431 fecal specimens from 149 young and 213 elderly healthy adults, and 69 elderly adults with cerebrovascular disease but no gastrointestinal disease. C. difficile was isolated from 49 specimens, and the frequency of isolation was 15.4% in healthy young adults, 7.0% in healthy elderly adults, and 15.9% in elderly adults with cerebrovascular disease. Thirty-four (about 70%) of the 49 C. difficile strains isolated produced cytotoxin which was neutralized by Clostridium sordellii antitoxin in vitro; in both young and elderly adults approximately 30% of the C. difficile isolates were nontoxigenic. The mean concentration of C. difficile in feces was 104.1/g in young adults and 104.6/g in elderly adults, with a range of 102.0 to 106.9/g. Antibody against C. difficile toxin was found in most of the sera obtained from young adults carrying toxigenic C. difficile, but not in sera of elderly adults, no matter how abundant was toxigenic C. difficile in the feces. 相似文献
636.
Yushiro Take Yusaku Chikai Keiya Shimamori Masahiro Kuragano Hiroki Kurita Kiyotaka Tokuraku 《Biochemistry and Biophysics Reports》2022
Cerebral amyloid angiopathy (CAA) is a disease in which amyloid β (Aβ) is deposited on the walls of blood vessels in the brain, making those walls brittle and causing cerebral hemorrhage. However, the mechanism underlying its onset is not well understood. The aggregation and accumulation of Aβ cause the occlusion and fragility of blood vessels due to endothelial cell damage, breakdown of the blood-brain barrier, and replacement with elements constituting the blood vessel wall. In this study, we observed the effect of Aβ on human primary brain microvascular endothelial cells (hBMECs) in real-time using quantum dot nanoprobes to elucidate the mechanism of vascular weakening by Aβ. It was observed that Aβ began to aggregate around hBMECs after the start of incubation and that the cells were covered with aggregates. Aβ aggregates firmly anchored the cells on the plate surface, and eventually suppressed cell motility and caused cell death. Furthermore, Aβ aggregation induced the organization of abnormal actin, resulting in a significant increase in intracellular actin dots over 10 μm2. These results suggest that the mechanism by which Aβ forms a fragile vessel wall is as follows: Aβ aggregation around vascular endothelial cells anchors them to the substrate, induces abnormal actin organization, and leads to cell death. 相似文献
637.
Hideomi Asanuma Kei Numazaki Nobuo Nagata Tomoyuki Hotsubo Kiyotaka Horino Shunzo Chiba 《Microbiology and immunology》1996,40(3):201-204
Breast-fed infants are susceptible to human cytomegalovirus (HCMV) infection via breast milk. In our previous study, HCMV was isolated more frequently from breast milk at later than one month after delivery than from colostrum or early breast milk. To clarify the role of milk cells and whey in vertical infection by breast feeding, we separated breast milk into milk cells and whey and examined each fraction for the presence of HCMV. We collected breast milk from mothers who breast-fed their infants (aged from 3 days to 2 months). The breast milk was centrifuged and separated into the middle layer (layer of milk whey) and the pellet (containing milk cells). We attempted to isolate HCMV from whey and to detect HCMV immediate early (IE) DNA in both milk whey and cells. HCMV was isolated from 7 out of 35 (20.0%) whey samples and HCMV IE DNA was detected from 15 out of 35 (42.9%) whey and/or milk cells. Detection rates of HCMV IE DNA in the whey layer and milk cells were 39.1% (25 out of 64) and 17.2% (11 out of 64), respectively. HCMV IE DNA was not detected in colostrum, but was detected in breast milk samples one month after delivery. Therefore, cell-free HCMV shed into milk whey may have a more important role in vertical infection by breast milk than cell-associated HCMV in the milk. 相似文献
638.
Inhibition of second meiotic division and a switching over to flagellar formation in secondary spermatocytes of newt by cycloheximide 总被引:2,自引:0,他引:2
10.0 micro M cycloheximide (CH) was found to completely inhibit the second meiotic division of newt spermatocytes. Under continuous incubation with CH from the beginning of interphase II, secondary spermatocytes fail to initiate chromosomal condensation and thus remain in interphase II. After 12-15 h of incubation, a single motile flagellum, about 5 micrometers in length, was observed on each of the secondary spermatocytes. These flagella grew to a length of 60-80 micrometers, but thereafter ceased to grow, whereas ordinarily spermatids grew flagella up to 500 micrometers in length in the absence of CH [1]. When CH was applied within 2 h following telophase I, the percentage of meiosis II inhibition was almost 100% and when applied even later, it became less, which showed that the early half period during interphase II was sensitive to CH. Regardless of the length of incubation time with CH, flagella were found to grow within a period of 12-15 h following telophase I. Upon removal of CH, even after 60 h of incubation, the flagella of the secondary spermatocytes shortened and disappeared completely. These spermatocytes underwent the second meiotic divisions. Also, flagella grew on the resulting spermatids. The possibility that a particular centriole which participated in the first meiotic division changes into a basal body for flagellar formation under the influence of CH and vice versa upon removal of it, is discussed in the following. 相似文献