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Biomedical subjects

T Kojima

Publications and source records attributed to T Kojima.

At least 307 records · Page 17Linked to original sources
PubMed1997

Alteration of the kinetics of type I procollagen synthesis in human osteosarcoma cells by 1,25-dihydroxyvitamin D3.

The kinetics of type I procollagen synthesis in a human osteosarcoma cell line, MG 63, were investigated after treatment with 1,25-dihydroxyvitamin D3 (1,25-(OH)2 D3), a hormonal inducer of phenotypic differentiation. Pulse label and chase experiments demonstrated greatly enhanced production and more rapid reduction of intracellular procollagen molecules in the 1,25-(OH)2 D3-treated cells as compared to the nontreated case. After a chase for 1 h, labeled procollagen was reduced by nine-tenths in 1,25-(OH)2 D3-treated cells, while half of the radioactivity still remained in nontreated cells. The expression rate of type I collagen, which was examined by pulse label experiment, was elevated in association with an increase in the mRNA coding for the type I collagen alpha 1 chain by 1,25-(OH)2 D3 treatment. However, the amount of intracellular procollagen present after 4 h continuous labeling was almost the same, independent of the 1,25-(OH)2 D3 treatment. Thus, we conclude that strage of the molecule was not affected. The results therefore suggest an increase in both the synthesis and secretion of type I collagen. The 1,25-(OH)2 D3 treatment was also found to induce the alpha subunit of prolyl 4-hydroxylase and to be associated with an elevated level of hydroxyproline in the procollagen. Moreover, gelatinase B-resistant procollagen molecules, indicative of intracellular procollagen molecules in the stable triple helical form, were detected only in the 1,25-(OH)2 D3-treated cells. These data suggest more efficient proline hydroxylation is involved in rapid secretion of procollagen after hormone administration. The present evidence points to posttranslational control of procollagen synthesis.

Animals↗
PubMed1997

Macrophage activation and migration in interface tissue around loosening total hip arthroplasty components.

The bone-cement interface tissue of failed total hip arthroplasty (THA) has inflammatory characteristics, such as the presence of prostaglandin E2 and interleukin 1 (IL-1). We considered that the bone-cement interface tissue could be the site of granulomatous inflammation caused by a foreign-body reaction. It has been demonstrated that inflammatory cytokines and chemokines have an important role in granulomatous inflammation. Bone-cement interface tissue was obtained at revision from nine patients with failed cemented THA, and the role of macrophages was assessed by immunohistochemistry, electron microscopy, and molecular biological techniques. We used the reverse-transcriptional polymerase chain reaction to examine the expression of mRNA for IL-1 alpha, IL-1 beta, tumor necrosis factor alpha (TNF alpha), macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, IL-8, and monocyte chemoattractant protein. Polyethylene debris surrounded by macrophages and phagocytosis of debris by macrophages was frequently observed in the interface tissue. Macrophage activation and the production of inflammatory cytokines such as IL-1 and TNF alpha might induce the development of interface tissue. Expression of chemokine mRNAs was also commonly seen, suggesting that this led to recruitment of macrophages into the bone-cement interface tissue. Debris released from implants appears to cause activation of macrophages and the production of inflammatory cytokines and chemokines that induce cellular recruitment into interface tissue. This mechanism might form a vicious cycle that aggravates THA loosening.

Aged↗
PubMed1997

Regulation by bivalent cations of phospholipid binding to the C2A domain of synaptotagmin III.

Synaptotagmins are Ca2+-and phospholipid-binding proteins of synaptic vesicles that might function as Ca2+ receptors for neurotransmitter release via their first C2 (C2A) domain. Here we describe the effect of Mg2+ on phospholipid binding to the C2A domains of multiple synaptotagmins (II-VI), and demonstrate that only synaptotagmin III can bind negatively charged phospholipids [phosphatidylserine (PS) and phosphatidylinositol] in a Mg2+-dependent manner. The Mg2+-dependent interaction with PS was found to have an EC50 of approx. 30 microM Mg2+, which is comparable to that of Sr2+ and Ba2+ (EC50 values of approx. 10 microM). This binding property of the C2A domain is specific to synaptotagmin III, because none of the C2A domains of other proteins, such as rabphilin 3A, Doc2alpha, Doc2beta or Gap1(m), showed phospholipid binding activity in the presence of 1 mM Mg2+. Our results suggest that synaptotagmin III is involved in presynaptic functions different from those of synaptotagmins I and II.

Amino Acid Sequence↗
PubMed1997

Measurement of portal venous flow velocity with an implantable miniature Doppler probe in pig liver transplantation.

Portal venous flow (PVF) was serially monitored after pig liver transplantation (LTX) with the use of an implantable, miniature Doppler probe developed in our laboratory. Throughout the study period, the mean PVF in pigs that underwent LTX was significantly greater than that in pigs that were sham operated. For three animals with early graft failure secondary to primary nonfunction and for six that survived longer than 7 days, the mean PVF on postoperative day (POD) 1 was 18.7 +/- 3.8 cm/s and 41.7 +/- 11.2 cm/s, respectively (P < 0.05). For animals with acute cellular rejection (ACR), the mean PVF was 61.3 +/- 9.9 cm/s on POD 7 and 54.3 +/- 6.38 cm/s on POD 14. These values were significantly higher than those for animals without ACR (P < 0.05). Moreover, the increase in PVF correlated well with the degree of ACR. The actual PVF volume was measured by ex vivo perfusion, which showed a clear correlation with the PVF velocity obtained with the implanted, miniature Doppler probe. We feel that the liver graft requires increased PVF volume after transplantation to facilitate functional recovery from damage to hepatocytes due to preservation-reperfusion injury, and that ACR is also associated with an increased PVF. We conclude that monitoring the PVF in the early postoperative period after LTX is useful in the evaluation of graft function, particularly for predicting primary nonfunction and severity of ACR.

Animals↗
PubMed1997

Competitive PCR quantification of pro- and anti-inflammatory cytokine mRNA in the central nervous system during autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the central nervous system that can be induced by immunization with myelin basic protein (MBP)/complete Freund's adjuvant and serves as a model for multiple sclerosis. Recent studies have suggested that cytokines play a crucial role in the clinical course of EAE. To clarify the roles of cytokines in EAE, we examined levels of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta1 (TGF-beta1) and interleukin-10 (IL-10) mRNA in isolates from infiltrating inflammatory cells in EAE lesions induced in Lewis rats. The non-radioactive and sensitive competitive PCR method was employed to quantify the relative amounts of cytokine mRNA. Levels of both IFN-gamma and TNF-alpha mRNA were increased at the early stage of EAE and rapidly decreased at the peak stage. On the other hand, TGF-beta1 mRNA was demonstrated throughout the course of EAE as well as under normal conditions and its amount paralleled the severity of EAE. IL-10 mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR) under normal conditions, but was below the level of detection of competitive PCR. IL-10 mRNA expression peaked at the early stage of EAE and declined gradually thereafter. Taken together, these results suggest that IFN-gamma and TNF-alpha might play a crucial role in the development of EAE. Furthermore, it appears that the peak expression of IL-10 mRNA at the early stage and the following marked TGF-beta1 expression at the peak stage might represent an important endogenous mechanism to limit the extent of inflammation and to prevent relapse in the course of acute monophasic EAE.

Animals↗
PubMed1997

Different changes in expression and function of connexin 26 and connexin 32 during DNA synthesis and redifferentiation in primary rat hepatocytes using a DMSO culture system.

In the present study, we determined in detail the changes of liver gap junctions, connexin 26 (Cx26), and connexin 32 (Cx32), during DNA synthesis and redifferentiation of hepatocytes in vitro. We used primary rat hepatocytes that expressed the liver gap junction proteins, which were cultured in the medium containing epidermal growth factor (EGF) with 2% dimethylsulfoxide (DMSO) and 10(-7) mol/L glucagon (a DMSO culture system), as we previously reported. In the present cultures, almost confluent hepatocytes cultured in the medium containing EGF with 2% DMSO and 10(-7) mol/L glucagon, underwent a nearly synchronous wave of DNA synthesis induced by the removal of 2% DMSO and 10(-7) mol/L glucagon, and the addition of 10 mmol/L nicotinamide, after which the DNA synthesis was completely re-inhibited by the re-addition of 2% DMSO and 10(-7) mol/L glucagon. During stimulation of DNA synthesis, both Cx26 and Cx32 messenger RNA (mRNAs) in hepatocytes transiently increased in the G1 phase and then markedly decreased before the onset of the S phase, while only Cx26 messenger RNA (mRNA) increased slightly in the S/M phase. Furthermore, before the onset of the S phase, a disappearance of both Cx26 and Cx32 immunoreactivities and gap junction plaques were observed. Gap junctional intercellular communication (GJIC), as measured by lucifer yellow, which indicated the function of Cx32, decreased markedly from before the onset of the S phase. GJIC measured by propidium iodide, which indicated the function of Cx26, decreased from before the onset of the S phase and then increased slightly in the S/M phase. During the re-inhibition after the stimulation of DNA synthesis, Cx32 mRNA, but not Cx26 mRNA, rapidly returned to the pretreatment control level. Cx32 immunoreactivity and gap junction plaques also recovered. However, the recovery of GJIC measured by lucifer yellow was later than that of Cx32 expression. These results indicated the different changes of expression and function of Cx26 and Cx32 in the hepatocytes during stimulation and re-inhibition of DNA synthesis. This culture system should be useful as a model in which to study liver gap junctions during hepatocyte growth and differentiation in vitro.

Actins↗
PubMed1997

Endoscopic management of Dieulafoy lesions of the stomach: a case study of 26 patients.

BACKGROUND AND STUDY AIMS: We studied the clinical features and therapeutic outcome in patients with a diagnosis of Dieulafoy lesion. PATIENTS AND METHODS: Twenty-six patients who had upper gastrointestinal bleeding from Dieulafoy lesions received endoscopic therapy. The clinical and endoscopic features, and the outcome of therapy, were analysed retrospectively. RESULTS: Hemostasis was attempted by hemoclipping in 18 patients, heater probe in six patients and ethanol injection in two patients. The initial therapy was successful in 22 (84.6%) cases. Hemostasis was achieved with additional endoscopic therapy in three cases (11,5%). Surgical treatment was needed only in one case, owing to uncontrolled bleeding. One patient died during the hospital stay from a cause unrelated to the Dieulafoy lesion. There were no side effects related to endoscopic therapy. None of these patients presented with rebleeding from Dieulafoy lesions over a mean long-term follow-up of 36 months. CONCLUSIONS: Bleeding from Dieulafoy lesions can be managed successfully by endoscopic methods, and these should be regarded as the first choice in their management. We emphasize the role of hemoclipping, a mechanical method, for the endoscopic treatment of these lesions.

Arteriovenous Malformations↗
PubMed1997

Influence of flavonoids on cell cycle phase as analyzed by flow-cytometry.

Flavonoids were previously reported to have cytostatic activity in vitro and in vivo. In the present study each phase of the cell cycle was observed by flow-cytometry after HCT-15 cells had been cultured with flavonoids for 2 days. In the control group, two peaks were observed on the histogram, the first peak representing double strands of DNA, and the second, tetra strands. Chalcone, which is known to be a precursor of all flavonoids, seemed to block the passage from S to G2 and M phase. Flavonone, which is freely transformed into chalcone in vivo, showed a similar histogram as chalcone. Among the anthocyanins most effective in suppressing the tumor cell growth, cyanin and pelargonidin made a mild rise between the 1st and 2nd peak suggesting block between G1 and S phase. Delphinidin gave a high percent of cells in G1 phase, suggesting prolongation of G1 phase. When quercetin or kaempherol, both of which are flavonols were added to the culture, the second peak rose significantly, indicating a block between G2 and M phases. Thus, the site of these cytostatic agents seems to differ depending on the kind of flavonoid.

Cell Cycle↗
PubMed1997

Effect of allomelanin on tumor growth suppression in vivo and on the cell cycle phase.

Allomelanins are nitrogen-free macromolecular polymers of simple phenols produced by higher plants and fungi. In an earlier work we found that allomelanins were effective in suppressing the growth of cultured tumor cells. In the present study we examined the effect of these polymers on the survival curve of Balb/C mice inoculated i.p. with Meth/A cells (3 x 10(4) cells/mouse), which originated from a malignant lymphoma. Allomelanins were extracted from black sesame seeds and black soybeans, and given p.o. via the drinking water. The dose of allomelanins was approximately 3 mg/mouse/day. The percent of survivals was significantly higher in the experimental groups than in the control. Also, when HCT-15 cells were cultured for 2 days in medium containing 400 micrograms/ml of protein-free allomelanins, histograms obtained from flow-cytometry data showed a significant increase in the fraction between the diploid and tetraploid peaks, indicating blockage of the S phase of the cell cycle. These results suggest that allomelanins suppressed the tumor cell growth in vitro and in vivo, and that the effect was cytostatic, mostly by blockage of the S phase.

Animals↗
PubMed1997

Antitumor effect of anthocyanin fractions extracted from red soybeans and red beans in vitro and in vivo.

Many bioflavonoids extracted from petals of higher plants and from fruit rinds, as well as purified flavonoids, have been reported to have antitumor effects in vitro and in vivo. Bioflavonoids extracted from red soybeans are mostly cyanin conjugated with glucose and rhamnose, whereas bioflavonoids of red beans are cyanin conjugated with rhamnose as revealed by thin-layer chromatogram. Flavonoids extracted from red soybeans were effective in inhibiting the growth of HCT-15 cells in vitro. On the other hand, flavonoids from red beans were not effective, although their hydrolyzed sugar-free forms were growth inhibitory. Sugar-bonded bioflavonoids extracted from both red soybeans and red beans were effective in prolonging the survival of Balb/C mice bearing syngeneic tumor-Meth/A cells, when they were dissolved in drinking water and given at a dose of approximately 500 micrograms/mouse/day.

Animals↗
PubMed1997

Direct tumor growth suppressive effect of melanoidin extracted from immunomodulator-PSK.

Melanoidin, which belongs to the melanin group of molecules, was extracted from the polysaccharide biological response modifier PSK. Melanoidin was cultured together with HCT-15 cells derived from human colon cancer and with AGS cells derived from human gastric carcinoma. After four days of culture, cell count was compared with that of the control cells. Significant suppression was observed, that is, 50% suppression was shown at concentrations of melanoidin between 200 and 100 micrograms/ml. A histogram generated by flow cytometry showed elevation of the tetraploid peak and of that between diploid and tetraploid peaks, suggesting blockage of S phase and G2 to M phase of the cell cycle. Thus, melanoidins contained in the immunomodulator PSK revealed to have a direct tumor cell growth inhibitory effect.

Adjuvants, Immunologic↗
PubMed1997

Tumor cell growth-inhibiting effect of melanoidins extracted from miso and soy sauce

Melanoidins, a group of plant-produced melanins, were extracted from miso and shoyu (soy sauce), which are products of soybeans and widely consumed as food in oriental countries. The molecular weight of these melanoidins was approximately 5600 as revealed by Sepharose CL-4B column chromatography. The melanoidins were cultured together with HCT-15 cells derived from human colon carcinoma and AGS cells derived from human gastric carcinoma. Significant cell growth suppression was observed by incubating the cells with these melanoidins. The 50% growth suppression dose ranged between 100 micrograms/ml and 25 micrograms/ml, that is, between 2 x 10(-5) mM/ml and 0.5 x 10(-5) mM/ml. Flow cytometric analysis suggested that these melanoidins blocked the S phase and G2 to M phase of the cell cycle.

Journal Article↗
PubMed1997

Suppression of growth of cultured malignant cells by allomelanins, plant-produced melanins.

Allomelanins, which belong to the melanins produced by higher plants and fungi, were studied with respect to their growth suppressive effects on cultured HCT-15 cells derived from human intestinal carcinoma and Meth/A cells derived from a Balb/C mouse lymphoma. Allomelanins were extracted from black soy beans and black sesame seeds with 0.2% NaOH in water. Proteins bonded to the allomelanins were removed by boiling the extracts for 20 hours in 30% NaOH. Although native allomelanins conjugated with protein did not suppress the growth of the cells, protein-free allomelanins did suppress it. That is, 50% suppression of HCT- 15 cell growth was found at a concentration between 100 and 200 micrograms/ml of the melanin prepared from the black soy beans, and between 25 and 100 micrograms/ml of that from the sesame seeds. For Meth/A cells, 50% suppression by allomelanin from the black beans was approximately 100 micrograms/ml; and that by the allomelanin preparation from sesame seeds, between 25 and 100 micrograms/ml. Thus, protein-free allomelanins seemingly suppress cultured mammalian and animal tumor cells.

Animals↗
PubMed1997

Tumor cell growth suppression by chalcone (1,3-diphenyl-2-propen-1-one).

Chalcone or 1,3-diphenyl-2-propen-1-one which is widely distributed in higher plants and is considered to be a precursor of all flavonoids, was studies in terms of its anti-tumor growth activity in vitro and in vivo. Mice given the chalcone, which was suspended in the drinking water, showed a statistically significant rise in percent survival: 66% at the 35th day for the chalcone-treated animals vs. 30% for the control ones. The chalcone also gave significant suppression of growth of HCT-15 and Meth/A cells in vitro. The dose of 50% reduction in growth was between 2.5 micrograms/ml and 0.6 microgram/ml for the HCT-15 cells and less than 10 micrograms/ml for the Meth/A cells. Histograms obtained by flow cytometric examination showed an elevated region between the diploid and the tetra-ploid nucleoidal peaks. A third peak heavier than the tetra-ploid peak was also observed, which peak was not observed in the control. The percentage of cells in the S phase was significantly raised. Microscopically, large nucleated cells were observed following addition of the chalcone. These results suggest that the chalcone induced abnormal DNA synthesis and mitosis in the cultured cells.

Animals↗
PubMed1997

Molecular cloning, genomic organization, promoter activity, and tissue-specific expression of the mouse ryudocan gene.

Ryudocan, a ubiquitous heparan sulfate proteoglycan, is a member of the syndecan family of cell surface proteoglycans. The full-length cDNA encoding the murine ryudocan core protein has now been cloned and sequenced. The deduced primary structure of mouse ryudocan, including the three glycosaminoglycan attachment sites in the extracellular domain as well as the transmembrane and cytoplasmic regions, is highly similar to those of the rat, human, and chicken proteins. Northern analysis detected a 2.7-kb transcript in all mouse tissues examined, with the highest concentrations apparent in liver, kidney, and lung. The mouse ryudocan gene was shown to span approximately 19.7 kb of genomic DNA and to contain five exons, with an intron-exon organization identical to that of the human gene. The promoter region of the mouse gene contains various cis-acting elements, including a TATA-like box and a GC box as well as potential binding sites for the transcription factors NF-IL6, MyoD, GATA, C/EBP, AP-2, NF-kappaB, AP-1, and Sp1. Transient transfection experiments with a construct containing the 690 bp upstream of the transcription start site fused to a luciferase reporter gene showed functional promoter activity. Deletion analysis suggested that the proximal promoter region including the TATA-like box, the GC box, and other Sp1 binding sites was required for full transcriptional activity. These findings will be useful for the study of ryudocan gene regulation and the generation of mice with targeted disruption of the gene.

Amino Acid Sequence↗
PubMed1997

Aesthetic fingertip reconstruction with a free vascularized nail graft: a review of 60 flaps involving partial toe transfers.

Microsurgical toe transfer is an established procedure for functional reconstruction of fingers. However, even if the functional loss is minimal, the fingertip defect is often a large problem for patients for not only functional reasons but also aesthetic reasons. In these patients, although the normal appearance of the fingertip is very important, total toe transfer is not acceptable because of resection of an entire toe. With this background, partial toe transfer techniques have greatly progressed. On the other hand, various types of innervated finger flaps also have been developed in hand surgery. Based on this progress, we developed the combined technique of innervated finger flaps in the hand and osteo-onychocutaneous flaps from the toe. This technique provides better aesthetic results in fingertip reconstruction, thus broadening the indications for vascularized nail grafts. We have now experienced 60 flaps in partial toe transfer. In this report, a review of 60 consecutive flaps is presented, and the indications, technique, and postoperative treatment are discussed.

Adult↗
PubMed1997

The value of LYM-1 cells for examining vacuole formation and loss of cell viability induced by culture supernates of Helicobacter pylori.

Some strains of Helicobacter pylori are known to produce an extracellular cytotoxin that causes vacuolation in cultured mammalian cells. Screening for such strains makes use of HeLa cells which may not be sensitive enough to detect minimal changes. The aim of this study was to develop a more sensitive cell line. Vacuole formation was examined in HeLa cells, as well as four other cell lines established in this laboratory by ammonium chloride induction. Among five cell lines tested, LYM-1 cells were most sensitive for the detection of intracellular vacuolation with this agent. Loss of cell viability of LYM-1 and HeLa cells induced by H. pylori culture supernates was also examined: LYM-1 were more sensitive than HeLa cells. Cell death was not always accompanied by vacuole formation. This suggests that the mechanism whereby cell death occurs must be different from that for vacuole formation. LYM-1 cells may be useful when measuring vacuole formation and cell death of the cultured cells induced by culture supernates of clinical isolates of H. pylori.

Ammonium Chloride↗