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Biomedical subjects

T Azuma

Publications and source records attributed to T Azuma.

At least 73 records · Page 4Linked to original sources
PubMed1998

Systematic laparoscopic left lateral segmentectomy of the liver for hepatocellular carcinoma.

A systematic technique for the resection of hepatocellular carcinoma (HCC) prevents the dissemination of cancer cells through the portal vein of the remnant liver. We successfully performed a systematic laparoscopic left lateral segmentectomy in a 62-year-old man with HCC. The tumor was located in the left lateral segment of the liver, and measured approximately 4 cm in diameter. Since no other tumors were detected in the liver or in any distant organs, the patient was considered to be a candidate for surgery. A laparoscopic hepatic resection was selected as the procedure of choice. Prior to dissection of the liver parenchyma, the arteries and branches of the portal vein feeding the left lateral segment were divided and dissected, together with the branches of the biliary tree in the umbilical portion of the left pedicle of Glisson's capsule. The liver parenchyma was then dissected and the left hepatic vein divided and dissected, and transection of the left lateral segment was completed. The patient's postoperative course was uneventful and he was discharged on postoperative days 14. No evidence of recurrence has been noted in the 22 months after surgery (the time of this report). This less invasive surgery, taking into consideration the pathogenesis of HCC, may be a useful new approach in selected patients with this tumor.

Carcinoma, Hepatocellular↗
PubMed1998

Caspase-3-induced gelsolin fragmentation contributes to actin cytoskeletal collapse, nucleolysis, and apoptosis of vascular smooth muscle cells exposed to proinflammatory cytokines.

Gelsolin, an 80 kDa actin-severing protein, has been recently identified as a substrate for the cell death-promoting cysteinyl protease caspase-3 (CPP32/apopain/YAMA). We investigated the role of gelsolin and its cleavage product in apoptosis of vascular smooth muscle cells (SMC) induced by the proinflammatory cytokines interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha). Treatment with a combination of IFN-gamma and TNF-alpha reduced viability of SMC in a time- and concentration-dependent manner. Immunoblotting revealed that SMC treated with the cytokines generated a 41 kDa gelsolin fragment. The gelsolin fragmentation required activation of caspase-3, as the caspase-3 inhibitor diminished cytokine-induced cell death as well as the fragmentation. Gelsolin cleavage was accompanied by a reduction in F-actin content and by a marked disruption of cell structure. Adenovirus-mediated transfection of this N-terminal gelsolin fragment into SMC altered cell morphology, reduced cell viability, increased the number of TUNEL-positive cells, and promoted internucleosomal DNA fragmentation. Compared to wild-type cells, gelsolin-deficient SMC showed resistance to apoptosis induced by the inflammatory cytokines. These results suggest a mechanistic role for gelsolin cleavage during SMC apoptosis, a process implicated in vessel development as well as stability of atherosclerotic plaque.

Actins↗
PubMed1998

Graft rejection and recovery of host-derived hematopoiesis after allogeneic bone marrow transplantation: relation to conditioning with high dose etoposide and total body irradiation.

Engraftment failure following allogeneic bone marrow transplantation (BMT) is rare in patients with acute leukemia, after frequent conditioning with marrow-lethal chemoradiotherapy. We evaluated the efficacy of a preparatory regimen consisting of fractionated total body irradiation (TBI) (12 Gy in six fractions) and high dose etoposide (60 mg/kg) administered as an 8-h infusion for allogeneic BMT in 16 consecutive patients with acute leukemia. Although 14 patients showed complete and sustained engraftment, the remaining two patients rejected bone marrow grafts from HLA-identical sibling donors and showed subsequent recovery of host-derived hematopoiesis. Despite the limited number of patients, this observation suggests that the immunosuppressive potential of etoposide may be inferior to that of cyclophosphamide (CY) and that etoposide as an alternative to CY as an antileukemic and immunosuppressive agent in allogeneic BMT may increase the risk of graft rejection.

Acute Disease↗
PubMed1998

Deleted HTLV provirus in peripheral blood cells of a patient with T-cell prolymphocytic leukaemia.

We describe the first case of T-cell prolymphocytic leukaemia (T-PLL) in which the peripheral blood cells contained a human T-lymphotropic virus (HTLV) related tax sequence. Serum screening tests for anti-HTLV-I/II antibodies were negative. Polymerase chain reaction disclosed the presence of an HTLV-I tax sequence in the peripheral blood. Other sets of oligonucleotide primers for HTLV-I gag, pol, env and the long terminal repeat regions and for the HTLV-II pol region were negative in the DNA of the cells. Although patients with T-PLL have been reported to be seronegative for HTLV-I, our findings point to the possibility that HTLV-I infection might be involved in the aetiology of at least some cases of T-PLL and that there may be alternative mechanisms involved in HTLV-associated leukaemogenesis.

Base Sequence↗
PubMed1998

Full-length sequence analysis of the vacA gene from cytotoxic and noncytotoxic Helicobacter pylori.

Some clinical isolates of Helicobacter pylori fail to express vacuolating cytotoxin, despite possessing a copy of the vacA gene on the chromosome. To gain insight into the differences between vacA from cytotoxic and noncytotoxic strains, the vacA open-reading frames from 16 cytotoxic and 22 noncytotoxic strains were sequenced. Mutations that cause truncation of VacA in 11 of 22 noncytotoxic strains were identified, including internal duplication, large deletion, 1-bp insertion, and non-sense mutations. In contrast, none of the 16 cytotoxic strains had any truncation of VacA. Four cytotoxic strains had inserted sequences downstream of vacA. Three were mini-IS605, and the other was a putative rfaJ gene that encodes lipopolysaccharide glucosyltransferase. The rfaJ gene identified in this study had a poly(C) tract, resulting in premature termination of the gene product. The phylogenetic tree based on the vacA open-reading frame indicated that two different H. pylori lineages are circulating in Japan and the West.

Bacterial Proteins↗
PubMed1998

Regulation of promoter and intron enhancer activity in immunoglobulin heavy-chain genes during B-cell differentiation.

Chloramphenicol acetyltransferase (CAT) transgenic mice, in which the transgene is regulated by the VH promoter and heavy-chain intron enhancer (E mu), were examined to investigate the variation of activity of these cis-acting elements during the late stage of B-cell development. CAT enzyme activity decreased when resting B cells were stimulated through B-cell receptors (BCR) with goat anti-mouse IgM antibodies in vitro. On the other hand, when these B cells were stimulated by lipopolysaccharide (LPS) in vitro, they showed enhanced CAT activity, accompanied by an increase in the number of CD43+ B220+ cells (pro-plasma and plasma cells). In addition, the CAT activities in CD43+ B220+ and PNAhi B220+ cells from immunized mice were higher than those in CD43- B220+ and PNAlo B220+ cells, respectively. These results suggest that the activity of E mu in the context of VH promoter was transiently down-regulated by stimulation through the BCR but enhanced at the pro-plasma and plasma stages.

Animals↗
PubMed1998

Somatic hypermutation in mouse lambda chains.

The frequency and distribution of somatic hypermutation in immunoglobulin genes and the effect of amino acid substitution on the structure/function of antibodies were studied using hybridomas that secrete anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) monoclonal antibodies bearing lambda 1 chains. A high frequency of mutation was observed in V-J exons and J-C introns of rearranged and active lambda 1 chains but not in the 5'-non-coding regions of these chains. Since a similar distribution was observed in inactive lambda 2 chain genes, 5'-non-coding regions containing a promoter were considered to be protected from mutation in view of their apparent importance. Using transgenic mice carrying chloramphenicol acetyl transferase transgenes driven by the VH promoter and heavy-chain intron enhancer, it was also revealed that these cis-acting elements are important in the induction of somatic hypermutation and are capable of inducing mutation even in non-immunoglobulin genes. Affinity of anti-NP Abs to NP increased with time after immunization to approximately 8,000-fold (affinity maturation); however, fine specificity, such as heteroclicity, remained unchanged. Memory B cells, which are responsible for affinity maturation, were analyzed in terms of the mutation from Trp to Leu at position 33, a change known to raise affinity about 10-fold and considered to be a memory B-cell marker. These cells were found predominantly in the early stage (2-3-week) hybridomas but rarely in late stage (> 12-week) ones, suggesting that a dynamic change in the memory B-cell population occurs during the immunization process.

Animals↗
PubMed1998

Gelsolin, a protein that caps the barbed ends and severs actin filaments, enhances the actin-based motility of Listeria monocytogenes in host cells.

The actin-based motility of Listeria monocytogenes requires the addition of actin monomers to the barbed or plus ends of actin filaments. Immunofluorescence micrographs have demonstrated that gelsolin, a protein that both caps barbed ends and severs actin filaments, is concentrated directly behind motile bacteria at the junction between the actin filament rocket tail and the bacterium. In contrast, CapG, a protein that strictly caps actin filaments, fails to localize near intracellular Listeria. To explore the effect of increasing concentrations of gelsolin on bacterial motility, NIH 3T3 fibroblasts stably transfected with gelsolin cDNA were infected with Listeria. The C5 cell line containing 2.25 times control levels of gelsolin supported significantly higher velocities of bacterial movement than did control fibroblasts (mean +/- standard error of the mean, 0.09 +/- 0.003 micro(m)/s [n = 176] versus 0.05 +/- 0.003 micro(m)/s [n = 65]). The rate of disassembly of the Listeria-induced actin filament rocket tail was found to be independent of gelsolin content. Therefore, if increases in gelsolin content result in increases in Listeria-induced rocket tail assembly rates, a positive correlation between gelsolin content and tail length would be expected. BODIPY-phalloidin staining of four different stably transfected NIH 3T3 fibroblast cell lines confirmed this expectation (r = 0.92). Rocket tails were significantly longer in cells with a high gelsolin content. Microinjection of gelsolin 1/2 (consisting of the amino-terminal half of native gelsolin) also increased bacterial velocity by more than 2.2 times. Microinjection of CapG had no effect on bacterial movement. Cultured skin fibroblasts derived from gelsolin-null mice were capable of supporting intracellular Listeria motility at velocities comparable to those supported by wild-type skin fibroblasts. These experiments demonstrated that the surface of Listeria contains a polymerization zone that can block the barbed-end-capping activity of both gelsolin and CapG. The ability of Listeria to uncap actin filaments combined with the severing activity of gelsolin can accelerate actin-based motility. However, gelsolin is not absolutely required for the actin-based intracellular movement of Listeria because its function can be replaced by other actin regulatory proteins in gelsolin-null cells, demonstrating the functional redundancy of the actin system.

3T3 Cells↗
PubMed1998

Decreased expression of the interleukin 2 receptor on CD8 recipient lymphocytes in intestinal grafts rendered tolerant by liver transplantation in rats.

BACKGROUND: In a previous study, it was shown that a spontaneously tolerated DA (RT1a) liver allograft in a PVG (RT1c) recipient was able to induce tolerance of a DA small bowel graft performed 17 days later in spite of infiltration of the intestinal grafts by mononuclear cells. AIMS: To compare the phenotype of graft infiltrating cells in rejecting and tolerated small bowel grafts in order to elucidate the mechanism(s) which block the graft infiltrating cells from mediating rejection. METHODS: Multiparameter immunofluorescence was used to compare the phenotype and state of activation of donor and recipient cells isolated from intestinal grafts rejected or tolerated after liver transplantation. RESULTS: Three differences were found. Firstly, there was a more rapid replacement of lamina propria (LP) cells by recipient lymphocytes in tolerated than in rejected grafts. Secondly, the proportion of LP recipient CD8alphabeta+ lymphocytes bearing the high affinity receptor for interleukin 2 was significantly less in tolerated grafts (1.1%, range 0-2%) than in rejected grafts (21.3%, range 9-26%). Finally, tolerated grafts contained significantly less NK lymphocytes (NKR-P1+) and macrophages than rejected intestinal allografts. CONCLUSIONS: These observations make it possible to delineate clear cut differences in the phenotype of cells infiltrating rejecting versus tolerated grafts. Furthermore, the data suggest that liver transplantation induces tolerance of intestinal grafts by hampering the activation of recipient TcRalphabeta+ CD8alphabeta+ T cells and subsequently the recruitment of non-specific effector cells.

Animals↗
PubMed1998

Determination of insulin content in pancreatic beta cell line MIN6 cells by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

The insulin content in mouse insulinoma MIN6 cells was determined using matrix-assisted laser desorption ionization (MALDI) time-of-flight mass spectrometry (TOF/MS). A mass spectrum of cellular insulin was obtained with a cell burst of MIN6 by hypotonic water. Signal intensities of intracellular insulin were proportional to the number of MIN6 cells. The present method was applied to the determination of intracellular insulin content of MIN6 before and after glucose stimulation.

Animals↗
PubMed1998

Immunocytochemical localization of chromogranin A and secretogranin II in female rat gonadotropes.

Ultrastructures of pituitary gonadotropes are known to show a prominent sex-related difference: typical male rat gonadotropes contain both large- and small-sized granules, whereas typical female rat gonadotropes appear to exhibit uniformly small-sized granules. Our preceding studies have demonstrated that two representative granins, chromogranin A (CgA) and secretogranin II (SgII), are separately localized to each type of granule in male rat gonadotropes. To clarify whether or not there is a certain relationship between granin proteins and characteristic features of secretory granules in female rat gonadotropes, we examined the expression levels and immunocytochemical localizations of CgA and SgII in the cells. Northern blot and immunoblot analyses demonstrated that both CgA and SgII were synthesized and stored in the female pituitary, although the amount of CgA was much lower in the female than that in the male pituitary. Immunocytochemical observations clarified that gonadotropes in the female pituitary possessed intermediate secretory granules containing both CgA and SgII, in addition to solely CgA-positive and SgII-positive ones. However, secretory granules containing CgA in the female gonadotropes were much smaller in size and appeared less frequently than those in the male cells, whereas no sexual difference was discerned in SgII-positive granules. Moreover, the size and appearance of CgA-positive secretory granules varied depending on stages of the estrous cycle. These findings suggest that the size and appearance of secretory granules containing CgA are closely associated with the expression and storage levels of CgA in the pituitary.

Animals↗
PubMed1998

[A combination chemotherapy with cytarabine ocfosfate, low dose etoposide, and G-CSF for the treatment of high risk MDS (RAEB, RAEBt)--a pilot study].

We evaluated a combination chemotherapy with cytarabine ocfosfate (SPAC), low dose etoposide and G-CSF for the treatment of high-risk MDS (RAEB, RAEBt). Seven patients with high-risk MDS were treated with a daily combination, 200 mg/day SPAC p.o., 50 mg/day etoposide p.o. and 75 micrograms/day G-CSF s.c. One patient achieved complete response, 2 achieved good response and one patient minor response. Although all of the patients developed severe marrow hypoplasia after chemotherapy, the nonhematologic adverse effects were mild enough to be tolerated. This combination chemotherapy should be useful in the clinical management of patients with high-risk MDS.

Aged↗
PubMed1998

[Indications for and operative outcome of hepato-pancreatoduodenectomy in the treatment of carcinoma of the gallbladder].

The indications for hepatopancreatoduodenectomy (HPD) are still controversial. Opinion is divided especially concerning the need to perform pancreatoduodenectomy (PD) for lymph node dissection, with some investigators claiming that the peripancreatic lymph nodes can be dissected adequately without PD. Detailed studies of resected specimens in our department have shown that preservation of the head of the pancreas carries an increased risk of leaving behind cancer cells in small lymph nodes and ducts remaining in the peripancreatic region. We therefore perform HPD in all patients at increased risk for metastasis to peripancreatic lymph nodes, as indicated by subserosal invasion with distinct evidence of lymph node involvement, tumor location at the neck or both fundus and body of the gallbladder, and serosa exposure to tumor irrespective of tumor location and lymph node involvement. When the outcome was compared between HPD and hepatic resection plus dissection of peripancreatic lymph nodes (HR), we found that the operative results of HPD were poor with extended lobectomy plus PD because of high rates of postoperative complications and operative mortality. However, the results have gradually improved with the introduction of percutaneous transehepatic portal embolization and advances in perioperative care. Although overall there is no difference between HPD and HR in long-term outcome, the outcome with HPD is significantly better in node-positive patients and patients without hepatoduodenal ligament involvement, there by demonstrating the value of performing peripancreatic lymph node dissection by PD. However, there is no difference between HPD and HR in patients with hepatoduodenal ligament involvement, and attempts to develop other new and effective means of treatment should continue.

Gallbladder Neoplasms↗
PubMed1997

Caspase-3-generated fragment of gelsolin: effector of morphological change in apoptosis.

The caspase-3 (CPP32, apopain, YAMA) family of cysteinyl proteases has been implicated as key mediators of apoptosis in mammalian cells. Gelsolin was identified as a substrate for caspase-3 by screening the translation products of small complementary DNA pools for sensitivity to cleavage by caspase-3. Gelsolin was cleaved in vivo in a caspase-dependent manner in cells stimulated by Fas. Caspase-cleaved gelsolin severed actin filaments in vitro in a Ca2+-independent manner. Expression of the gelsolin cleavage product in multiple cell types caused the cells to round up, detach from the plate, and undergo nuclear fragmentation. Neutrophils isolated from mice lacking gelsolin had delayed onset of both blebbing and DNA fragmentation, following apoptosis induction, compared with wild-type neutrophils. Thus, cleaved gelsolin may be one physiological effector of morphologic change during apoptosis.

Actins↗