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Hiroki Saito

Publications and source records attributed to Hiroki Saito.

13 recordsLinked to original sources
PubMed2026

Fusarium oxysporum f. sp. crypti, a novel forma specialis causing Fusarium wilt of mitsuba, Cryptotaenia japonica.

Fusarium oxysporum isolates causing Fusarium wilt in mitsuba (Cryptotaenia japonica Hassk.; also referred to as Japanese honeywort, Japanese honewort, or Japanese parsley) have traditionally been classified as f. sp. apii. However, some reports have indicated that the host-pathogenic F. oxysporum isolates derived from mitsuba are nonpathogenic to celery, the principal host of f. sp. apii. In this study, we aimed to elucidate the differences among isolates from mitsuba, coriander, and celery in terms of host range, phylogenetic relationships, genomic synteny, and effector profiles. Inoculation assays revealed a clear distinction in host range between the mitsuba, coriander, and celery isolates. Phylogenetic analyses based on the rDNA intergenic spacer and translation elongation factor sequences indicated a distant relationship between mitsuba isolates and those from coriander and celery. Whole-genome analysis based on high-quality de novo-assembled genomes, including telomere-to-telomere-level assemblies of isolates from mitsuba, coriander, and celery, showed that the mitsuba isolates possess conserved accessory chromosomal regions absent in celery and coriander isolates. Moreover, effector profiling identified a specific pattern of effector repertoires shared by the mitsuba isolates. These findings suggest that the host-pathogenic F. oxysporum isolates derived from mitsuba represent a forma specialis distinct from f. sp. apii. Thus, we propose designating the F. oxysporum isolates from mitsuba that cause Fusarium wilt as Fusarium oxysporum f. sp. crypti forma specialis nova.

Cryptotaenia japonica↗
PubMed2006

Spontaneous circulation in ground-state spinor dipolar Bose-Einstein condensates.

We report on a study of the spin-1 ferromagnetic Bose-Einstein condensate with magnetic dipole-dipole interactions. By solving the nonlocal Gross-Pitaevskii equations for this system, we find three ground-state phases. Moreover, we show that a substantial orbital angular momentum accompanied by chiral symmetry breaking emerges spontaneously in a certain parameter regime. We predict that all these phases can be observed in the spin-1 87Rb condensate by changing the number of atoms or the trap frequency.

Journal Article↗
PubMed2006

Primary signet-ring cell carcinoma of the colon at early stage: a case report and a review of the literature.

A 67-year-old man, who had undergone surgery to resect multiple gastric cancers 4 years ago, visited our hospital for surveillance colonoscopy. Colonoscopy revealed a discolored, 7-mm in diameter, flat-elevated lesion with central depression in the transverse colon near the splenic flexure. Although the findings of endoscopy and barium enema were suggestive of submucosal invasion, the patient chose to undergo endoscopic mucosal resection. Pathological examination of the resected specimen revealed signet-ring cell carcinoma and a positive surgical margin. A second operation was performed, and no residual tumor or metastasis to lymph nodes was found in the resected specimens. Primary colorectal cancers composed of signet-ring cell carcinoma detected and treated at an early stage are extremely rare. We present a case and review the literature.

Aged↗
PubMed2006

Einstein-de Haas effect in dipolar Bose-Einstein condensates.

The general properties of the order parameter for a dipolar spinor Bose-Einstein condensate are discussed based on symmetries of interactions. An initially spin-polarized dipolar condensate is shown to dynamically generate a nonsingular vortex via spin-orbit interactions--a phenomenon reminiscent of the Einstein-de Haas effect in ferromagnets.

Journal Article↗
PubMed2005

Symmetry breaking and enhanced condensate fraction in a matter-wave bright soliton.

An exact diagonalization study reveals that a matter-wave bright soliton and the Goldstone mode are simultaneously created in a quasi-one-dimensional attractive Bose-Einstein condensate by superpositions of quasidegenerate low-lying many-body states. Upon formation of the soliton the maximum eigenvalue of the single-particle density matrix increases dramatically, indicating that a fragmented condensate converts into a single condensate as a consequence of the breaking of translation symmetry.

Journal Article↗
PubMed2004

Long-term culture of hepatic progenitors derived from mouse Dlk+ hepatoblasts.

We previously demonstrated that hepatoblasts can be isolated from mouse fetal liver based on the expression of delta-like [corrected] (Dlk), also known as Pref-1. Each Dlk+ hepatoblast forms a colony containing both albumin+ hepatocytes and cytokeratin 19+ (CK19) cholangiocytic cells on either type IV collagen or laminin. Here we show that extracellular matrices (ECMs) significantly affect the growth of Dlk+ cells. Dlk+ cells vigorously proliferated on type IV collagen-coated dishes in the presence of EGF and HGF during the first 5 days, but their proliferative capability declined thereafter. Dlk+ cells also proliferated on laminin-coated plates and some colonies continued to expand even beyond one month after plating. These hepatic progenitor cells proliferating on laminin (HPPL) efficiently proliferated even after replating. Moreover, they were induced to differentiate into hepatocytes and cholangiocytes by overlaying Engelbreth-Holm-Swarm sarcoma (EHS) gel and by embedding in type I collagen gel, respectively. HPPL acquired the metabolic functions of accumulating polysaccharides and detoxifying ammonium ions after hepatic differentiation. Surprisingly, HPPL expressed pancreatic genes such as Pdx1 when dexamethasone was depleted from the culture medium. Therefore, the long-term culture of hepatoblasts on laminin produces multi-potential hepatic progenitors, which possess a strong proliferative capability, differentiate into both hepatocytes and cholangiocytes, and potentially give rise to pancreatic cells.

Albumins↗
PubMed2004

Emergence of BLOCH bands in a rotating Bose-Einstein condensate.

A rotating Bose-Einstein condensate is shown to exhibit a Bloch band structure even in the absence of a periodic potential. Vortices enter the condensate via Bragg reflection if the frequency of a rotating drive is adiabatically increased or decreased, or if the interaction is adiabatically changed at a constant rotating drive. A localized state analogous to a gap soliton in a periodic system is predicted to occur near the edge of the Brillouin zone.

Journal Article↗
PubMed2004

Hepatocyte proliferation and tissue remodeling is impaired after liver injury in oncostatin M receptor knockout mice.

Oncostatin M (OSM) is a member of the IL-6 family of cytokines. Mice deficient in the OSM receptor (OSMR(-/-)) showed impaired liver regeneration with persistent parenchymal necrosis after carbon tetrachloride (CCl(4)) exposure. The recovery of liver mass from partial hepatectomy was also significantly delayed in OSMR(-/-) mice. In contrast to wildtype mice, CCl(4) administration only marginally induced expression of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 genes in OSMR(-/-) mice, correlating with the increased gelatinase activity of matrix metalloproteinase (MMP)-9 and matrix degradation in injured livers. The activation of STAT3 and expression of immediate early genes and cyclins were decreased in OSMR(-/-) liver, indicating that OSM signaling is required for hepatocyte proliferation and tissue remodeling during liver regeneration. We also found that CCl(4) administration in IL-6(-/-) mice failed to induce OSM expression and that OSM administration in IL-6(-/-) mice after CCl(4) injection induced the expression of cyclin D1 and proliferating cell nuclear antigen, suggesting that OSM is a key mediator of IL-6 in liver regeneration. Consistent with these results, administration of OSM ameliorated liver injury in wildtype mice by preventing hepatocyte apoptosis as well as tissue destruction. In conclusion, OSM and its signaling pathway may provide a useful therapeutic target for liver regeneration.

Animals↗
PubMed2003

Nonrandomized comparison between definitive chemoradiotherapy and radical surgery in patients with T(2-3)N(any) M(0) squamous cell carcinoma of the esophagus.

PURPOSE: To compare the treatment results between radical surgery and definitive chemoradiotherapy for resectable squamous cell carcinoma of the esophagus and to identify useful clinicopathologic and biologic markers to select better treatment. METHODS AND MATERIALS: Between August 1992 and April 1999, 98 consecutive patients were selected for this study; 53 were treated with chemoradiotherapy and 45 with surgery. The patients in the chemoradiotherapy group received 5-fluorouracil combined with cisplatin plus 60 Gy of radiation, and those in the surgery group received an esophagectomy with radical node dissection. Biologic markers were investigated immunohistochemically using pretreatment biopsy specimens. RESULTS: The baseline clinical TNM stage was more advanced in the chemoradiotherapy group than in the surgery group. With a median follow-up period of 43 months, the 5-year survival rate was 46% in the chemoradiotherapy and 51% in the surgery group, without statistical significance (p = 0.47, log-rank test). Cox regression analysis for prognosis revealed that epidermal growth factor receptor positivity, high microvessel density, and cyclin D1 positivity yielded a low value for relative risk (0.66, 0.54, and 0.62, respectively), which favored chemoradiotherapy over surgery, without statistical significance. CONCLUSION: This nonrandomized study showed a trend for the chemoradiotherapy in the treatment of esophageal carcinoma, but the results need to be confirmed by additional study.

Adult↗
PubMed2003

Isolation of hepatoblasts based on the expression of Dlk/Pref-1.

Hepatoblasts are common progenitors for hepatocytes and biliary epithelial cells, although their nature remains largely unknown. In order to isolate and to characterize hepatoblasts, we searched for cell surface antigens expressed in mouse fetal hepatic cells by the signal sequence trap method and found that Dlk, also known as Pref-1, was strongly expressed in fetal liver. Immunohistochemical as well as northern analysis indicated that Dlk was highly expressed in the E10.5 liver bud. The strong expression continued until the E16.5 stage and was significantly downregulated thereafter. Using a monoclonal antibody against Dlk, we isolated Dlk+ cells either by a fluorescence-activated cell sorter or by an automatic magnetic cell sorter. Dlk+ cells isolated from fetal livers expressed albumin and formed colonies when cultured at low density with HGF and EGF for 5 days. Over 60% of colonies derived from E14.5 Dlk+ cells contained both albumin+ and cytokeratin 19+ cells, indicating that a majority of colony-forming Dlk+ cells are able to differentiate into both hepatocyte and biliary epithelial cell lineages. In addition, numerous microvilli were observed by electronmicroscopic analysis in most of those cultured cells, also indicating differentiation of Dlk+ cells under this condition. Furthermore, 7% of the colony-forming Dlk+ cells were not only bipotential but also highly proliferative, forming a large colony containing more than 100 cells during 5 days of culture. By transplantation of Dlk+ cells into the spleen, donor-derived hepatocytes were found in the recipient liver, indicating that Dlk+ cells differentiated into hepatocytes in vivo. These results indicate that Dlk+ cells are hepatoblasts and that Dlk is a useful marker to enrich highly proliferative hepatoblasts from fetal liver.

Animals↗
PubMed2002

Split instability of a vortex in an attractive Bose-Einstein condensate.

An attractive Bose-Einstein condensate with a vortex splits into two pieces via the quadrupole dynamical instability, which arises at a weaker strength of interaction than the monopole and the dipole instabilities. The split pieces subsequently unite to restore the original vortex or collapse.

Journal Article↗