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Biomedical subjects

J Hamada

Publications and source records attributed to J Hamada.

At least 19 recordsLinked to original sources
PubMed1999

Selective transendothelial migration of hematopoietic progenitor cells: a role in homing of progenitor cells.

To elucidate the mechanisms by which hematopoietic progenitor cells transmigrate via the bone marrow (BM) endothelial cells, we first established endothelial cell lines from BM and lung, and BM fibroblast cell lines; then we established an in vitro model of transendothelial migration of hematopoietic progenitor cells in the presence of chemoattractants secreted by BM fibroblast cells. The BM endothelial cells expressed vascular cell adhesion molecule-1 (VCAM-1), but the lung endothelial cells did not. The BM fibroblast cells secreted chemoattractants including stroma cell-derived factor (SDF)-1, which could attract hematopoietic progenitor cells to BM and activate the adhesion molecules expressed on hematopoietic progenitor cells after rolling along the endothelial cells. Anti-SDF-1 antibody inhibited the transendothelial migration of a hematopoietic progenitor cell line, FDCP-2. FDCP-2 that expressed very late activation antigen-4 (VLA-4) and normal progenitor cells transmigrated through BM endothelial cells but not lung endothelial cells, even if in the presence of chemoattractants produced by BM fibroblasts. Both anti-VLA-4 and anti-VCAM-1 antibodies inhibited the transendothelial migration of FDCP-2 cells and normal hematopoietic progenitor cells. These findings suggest that the transendothelial migration of hematopoietic progenitor cells is characteristic of BM endothelial cells, and that VLA-4/VCAM-1 and SDF-1 play important roles in the transendothelial migration and, consequently, homing of hematopoietic progenitor cells to BM.

Animals↗
PubMed1998

Serine/threonine phosphatase activity of calcineurin is inhibited by sodium orthovanadate and dithiothreitol reverses the inhibitory effect.

Orthovanadate is known to be an inhibitor of protein tyrosine phosphatases. However, we found that it inhibited calcineurin which has the activity of a serine/threonine protein phosphatase, using casein phosphorylated by cyclic AMP-dependent protein kinase as a substrate. Orthovanadate inhibits the Mn2+-activated activity of purified calcineurin to 20%; this is not the case without Mn2+. Furthermore, 10 mM dithiothreitol (DTT) reversed the inhibitory effects of orthovanadate. Orthovanadate showed the same inhibitory effect for calcineurin activity in homogenates as for the purified enzyme; the inhibitory effect was reversed by DTT. These results indicate that orthovanadate inhibits not only protein tyrosine phosphatases as reported, but also serine/threonine phosphatase activity of calcineurin.

Animals↗
PubMed1998

CD44 expression and growth factors.

Soluble factors such as growth factors and cytokines present in the tumor microenvironment regulate a variety of genes associated with malignant properties of tumor cells such as growth, migration, invasion, and metastatic capacities. CD44 is a multi-functional adhesion molecule involved in cell to cell and cell to extracellular matrix interaction, the trapping of growth factors and cytokines, and the regulation of cell traffic. Growth factors and cytokines modify the expression, selective isoform splicing and functions of CD44, resulting in changes in the biological properties of the cells. These include adhesion of circulating tumor cells to endothelium and body cavities, and survival in response to growth factors presented by the CD44 molecule. The modification of CD44 on both tumor and host cells by growth factors may play an important role in tumor progression.

Animals↗
PubMed1998

Polysaccharide K induces Mn superoxide dismutase (Mn-SOD) in tumor tissues and inhibits malignant progression of QR-32 tumor cells: possible roles of interferon alpha, tumor necrosis factor alpha and transforming growth factor beta in Mn-SOD induction by polysaccharide K.

Previously we reported the malignant progression of QR-32, a regressor-type tumor clone, following co-implantation with foreign bodies (gelatin sponge or plastic plate) in normal syngeneic C57BL/6 mice. We also reported that the progression of QR-32 cells by a gelatin sponge was significantly inhibited in the mice administered polysaccharide K (PSK) and that PSK induced an increase of radical scavengers, especially manganese superoxide dismutase (Mn-SOD), locally at the site of tumor tissues. In this study, to reveal the possible mechanism by which PSK induced Mn-SOD in the tumor tissues, we examined the mRNA expression and protein levels of inflammatory cytokines in the tissues. We found that mRNAs of tumor necrosis factor alpha (TNFalpha) and interleukin-1alpha (IL-1alpha) were considerably expressed in both PSK-treated and phosphate-buffered-saline-treated tumors, and that the mRNA expression and protein level of interferon gamma (IFNgamma) increased in the tumor tissues treated with PSK. In vitro treatment of QR-32 cells with IFNgamma did not significantly increase the production of Mn-SOD; however, the combination of IFNgamma with TNFalpha increased the Mn-SOD production more effectively than did any of the cytokines used singly. Furthermore, we observed the down-regulation of the mRNA expression and protein level of transforming growth factor beta (TGFbeta) in the tumor tissues treated with PSK, and that in vitro treatment of QR-32 cells with TGFbeta decreased the production of Mn-SOD. These results suggest that PSK suppresses the progression of QR-32 cells by increasing Mn-SOD via the modulation of inflammatory cytokines; that is, by decreasing TGF-beta and increasing IFN-gamma.

Adjuvants, Immunologic↗
PubMed1998

Cadherin-8 protein expression in gray matter structures and nerve fibers of the neonatal and adult mouse brain.

The topological distribution of mouse cadherin-8 protein in the neonatal and adult mouse brain was studied immunohistochemically using a rabbit antiserum. Cadherin-8 expression was restricted to several areas in neonatal brains constituting particular neural circuits, i.e. the limbic system, the basal ganglia-thalamocortical circuit, and the cerebellum and related nuclei. In addition, the nerve fibers linking some of the cadherin-8-positive areas, i.e. the habenulo-interpeduncular tract, decussation of the dorsal tegmentum, the medial longitudinal fasciculus, transverse pontine fibers, the brachium conjunctivum and the inferior cerebellar peduncle were cadherin-8 positive, as were the spinal tract of the trigeminal nerve, oculomotor nerve, facial nerve and trigeminal nerve. Cadherin-8 expression also showed a patch-like distribution in the intermediate gray layer of the superior colliculus, resembling acetylcholinesterase-rich patches in allocation. Segmentally organized cadherin-8-positive areas were found in the neonatal cerebellar Purkinje cell layer. Some nuclei and fibers in the brainstem and cerebellum, expressing cadherin-8 at neonatal stages, were also stained in the adult mouse brain. These findings suggest that cadherin-8 is involved in the formation of particular neural circuits by connecting areas expressing this molecule with positive nerve fibers, and indicate its possible implication in subdivisional organization in the superior colliculus and cerebellum.

Animals↗
PubMed1998

Characterization of the progressive sublines derived from a weakly malignant cloned cell line, ER-1, co-inoculated subcutaneously with a foreign body.

We previously established an experimental model of tumor progression using a weakly malignant rat mammary carcinoma cell line, ER-1. Using this model, we demonstrated that ER-1 cells converted into highly tumorigenic and metastatic cells, ERpP, by s.c. co-inoculation with plastic plates. We here compared in vitro biological properties associated with malignancy of ER-1 cells with those of ERpP cells which were highly malignant when inoculated into syngeneic rats. In vitro growth rate of ERpP cells was higher than that of ER-1 cells under a low nutrient condition. Invasion capacity of ERpP cells to rat lung endothelial cell monolayer or reconstituted basement membrane, Matrigel, was higher than that of ER-1 cells. Migration of ERpP cells toward fibronectin or laminin was also significantly higher than that of ER-1 cells. There was no difference in gelatinolytic or plasminogen activator activity detected in conditioned media between ER-1 and ERpP cells. Furthermore, we found that ER-1 cells communicated better among themselves and with normal fibroblasts through gap junctions compared to ERpP cells. These results suggest that growth advantage in a poor nutrient condition, enhancement of cell motility, and loss or decrease of junctional communication may be associated with tumor progression of ER-1 cells.

Animals↗
PubMed1998

Inhibitory effects of malotilate on invasion and metastasis of rat mammary carcinoma cells by modifying the functions of vascular endothelial cells.

Malotilate (diisopropyl,1,3-dithiol-2-ylidenemalonate, MT) is clinically used as a hepatoprotective agent. Because we noticed that MT induced the differentiation of cultured vascular endothelial cells, we have examined its effects on lung metastasis of the highly metastatic rat mammary carcinoma c-SST-2. MT was orally administered to syngeneic SHR rats from 7 days before or after s.c. inoculation of c-SST-2 cells to the end of the experiments. In the MT-treated rats, pulmonary metastasis was markedly suppressed compared with the non-treated rats. In the rats treated with MT for 19 days after i.v. inoculation of c-SST-2 cells, lung metastasis was also significantly suppressed. An in vitro invasion assay using a rat lung endothelial (RLE) cell monolayer revealed that pretreatment of the RLE cells with MT, but not c-SST-2 cells, significantly reduced the invasion of the RLE monolayer by c-SST-2 cells. An in vitro vascular permeability assay demonstrated that MT prevented the increase in permeability of the RLE monolayer by serum starvation. On the other hand, in vivo and in vitro growth, gelatinase production and adhesion to the RLE cell monolayer of c-SST-2 cells were not affected by MT treatment. These findings suggest that MT suppressed tumour metastasis by intensifying the cell-to-cell contact of endothelial cells, thus preventing tumour cells from invading vascular endothelium.

Animals↗
PubMed1998

Distribution of fallover in the carboxylase reaction and fallover-inducible sites among ribulose 1,5-bisphosphate carboxylase/oxygenases of photosynthetic organisms.

The biphasic reaction course, fallover, of carboxylation catalysed by ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) has been known as a characteristic of the enzyme from higher land plants. Fallover consists of hysteresis in the reaction seen during the initial several minutes and a very slow suicide inhibition by inhibitors formed from the substrate ribulose-1,5-bisphosphate (RuBP). This study examined the relationship between occurrence of fallover and non-catalytic RuBP-binding sites, and the putative hysteresis-inducible sites (Lys-21 and Lys-305 of the large subunit in spinach RuBisCO) amongst RuBisCOs of a wide variety of photosynthetic organisms. Fallover could be detected by following the course of the carboxylase reaction at 1 mM RuBP and the non-catalytic binding sites by alleviation of fallover at 5 mM RuBP. RuBisCO from Euglena gracilis showed the same linear reaction course at both RuBP concentrations, indicating an association between an absence of fallover and an absence of the non-catalytic binding sites. This was supported by the results of an equilibrium binding assay for this enzyme with a transition state analogue. Green macroalgae and non-green algae contained the plant-type, fallover enzyme. RuBisCOs from Conjugatae, Closterium ehrenbergii, Gonatozygon monotaenium and Netrium digitus, showed a much smaller decrease in activity at 1 mM RuBP than the spinach enzyme and the reaction courses of these enzymes at 5 mM RuBP were almost linear. RuBisCO of a primitive type Conjugatae, Mesotaenium caldariorum, showed the same linear course at both RuBP concentrations. Sequencing of rbcL of these organisms indicated that Lys-305 was changed into arginine with Lys-21 conserved.

Amino Acid Sequence↗
PubMed1998

A new anti-metastatic drug, ND-2001, inhibits lung metastases in rat hepatoma cells by suppressing haptotaxis of tumor cells toward laminin.

We examined the effects of ex vivo treatment of tumor cells with sodium D-glucaro-delta-lactam (sodium 5-amino-5-deoxy-D-glucosaccharic acid-delta-lactam; ND-2001). The ex vivo treatment of rat hepatoma cKDH-8/11 cells with this new synthetic product of the antibiotic nojirimycin, ND-2001 (50 microg/ml), inhibited the experimentally induced lung metastases of the tumor cells significantly at an inhibition rate of 69.2% (one of 10 animals remained metastasis free). Also, it was elucidated in in vitro tumor cell invasion assays that ND-2001 (50 microg/ml) suppressed the invasion activities of cKDH-8/11 cells to Matrigel Matrix at an inhibition rate of 69.3%. However, phagokinetic track assays revealed that ND-2001 did not suppress the random motility of cKDH-8/11 cells. However, ND-2001 (50 microg/ml) suppressed the haptotaxis, another important role in tumor invasion, of cKDH-8/11 cells toward laminin (inhibition rate of 77.0%). These results suggest that ND-2001 suppressed the haptotaxis of tumor cells toward laminin directly at the step of invading the basement membrane and brought about the inhibition of lung metastases.

Animals↗
PubMed1998

ND-2001 suppresses lung metastasis of human renal cancer cells in athymic mice.

Explants of highly metastatic human renal cell carcinoma SN12Cpm6 cells in athymic mice were treated with sodium D-glucaro-delta-lactam (sodium 5-amino-5-deoxy-D-glucosaccharic acid-delta-lactam; ND-2001). ND-2001 (50 micrograms/ml) caused 78% inhibition of lung metastasis of SN12Cpm6 cells (two of five animals remaining metastasis free). The in vitro tumor cell invasion assay showed that ND-2001 (100 micrograms/ml) suppressed the invasive activity of SN12Cpm6 cells to Matrigel matrix at an inhibition rate of 72%. These results suggest that ND-2001 may be a new anti-metastatic drug against human cancer cells.

Animals↗
PubMed1998

An antivirally active sulfated polysaccharide from Sargassum horneri (TURNER) C. AGARDH.

A sulfated polysaccharide was isolated from the hot water extract of a brown alga, Sargassum horneri (TURNER) C. AGARDH. Fucose was detected as the main component sugar of this polysaccharide. This compound showed potent antiviral activity against herpes simplex virus type 1, human cytomegalovirus and human immunodeficiency virus type 1. Time-of-addition experiments suggested that it inhibited not only the initial stages of viral infection, such as attachment to and penetration into host cells, but also later replication stages after virus penetration.

Animals↗
PubMed1998

Reversible and irreversible tumor progression of a weakly malignant rat mammary carcinoma cell line by in vitro exposure to epidermal growth factor.

We examined the effects of epidermal growth factor (EGF) on tumor progression of a weakly malignant rat mammary carcinoma cell line, ER-1. In vitro treatment with EGF enhanced tumorigenicity, metastatic capacity and in vitro invasive capacity of ER-1 cells. The increased malignancy of ER-1 cells was reversible, when the cells were pretreated with EGF for 24 h, whereas it was irreversible when pretreated with EGF for 1 month. EGF treatment elevated the intracellular peroxide level in ER-1 cells. When ER-1 cells were treated with EGF in the presence of N-acetylcysteine, a chemical antioxidant, the reversible or irreversible EGF-induced progression was inhibited. These results suggest that the reversible or irreversible tumor progression in ER-1 cells occur in accordance with the duration of exposure to EGF, and that reactive oxygen species may be involved in the progression.

Acetylcysteine↗
PubMed1998

Hepatocyte growth factor enhances the invasion activity of human hepatocellular carcinoma cell lines.

We investigated whether hepatocyte growth factor (HGF) enhances the invasion activity of three human HCC cell lines, HLF, HLE, and HC-4, in vitro. The analysis of the invasiveness consisted of the production of u-PA and the chemotaxis for fibronectin. Invasion activity of all cell lines was enhanced by the addition of recombinant human hepatocyte growth factor (rhHGF) to the medium. HGF stimulated the production of u-PA in HLF cells. HGF accelerated the chemotaxis of HC-4 and HLE. These data suggest that HGF increase the invasion activity of human HCC cell lines by affecting the production of u-PA or the chemotaxis for fibronectin.

Carcinoma, Hepatocellular↗
PubMed1997

Distribution of N(omega)-nitro-L-arginine following topical and intracerebroventricular administration in the rat.

The distribution of the nitric oxide synthase inhibitor, N(omega)-nitro-L-arginine (L-NA), in the rat brain following either topical or intracerebroventricular application was examined using 14C-labeled L-NA. Two hours after topical application, the concentration of L-NA 1 mm below the surface was approximately 20% of the concentration at the surface, and less than 3% at 2 mm below the cortical surface. L-NA infused into the lateral cerebral ventricle distributes only in regions in close proximity to the ventricle even 8 h after administration. Consequently, intracerebroventricular administration of nitric oxide synthase inhibitors may not be useful if global inhibition of nitric oxide synthase is desired.

Administration, Topical↗
PubMed1997

Follow-up evaluation of dissecting aneurysms of the vertebrobasilar circulation by using gadolinium-enhanced magnetic resonance imaging.

The authors assessed the reliability of magnetic resonance (MR) imaging contrast enhancement for the detection and follow-up evaluation of dissecting aneurysms of the vertebrobasilar circulation. Twenty consecutively admitted patients who underwent both gadolinium-enhanced MR imaging and conventional angiography were reviewed. Enhancement of the dissecting aneurysm was seen in all but one of the 20 patients, including 10 (71%) of 14 patients examined in the chronic phases, when the T1-hyperintensity signal that corresponded to the intramural hematoma was unrecognizable. The enhanced area corresponded to the "pearl sign" or aneurysm dilation noted on the comparable angiogram. On follow-up MR studies enhancement had spontaneously disappeared in four patients at a time when comparable vertebral angiograms revealed disappearance of the aneurysm dilation. The enhancement persisted in five of nine patients examined more than 24 weeks after symptom onset; in all five patients the aneurysm dilation remained on comparable angiograms. Dynamic MR studies showed rapid and remarkable enhancements with their peaks during the immediate dynamic phase after injection of the contrast material. The authors conclude that gadolinium-enhanced MR imaging is useful for the detection and follow-up evaluation of dissecting aneurysms of the vertebrobasilar circulation.

Adult↗
PubMed1997

Nucleotide pyrophosphohydrolase in human synovial fluid.

OBJECTIVE: To identify the molecular forms of ectonucleotide pyrophosphohydrolase (NTPPHase) in human synovial fluid (SF). METHODS: We examined synovial fluids from 32 patients with various joint diseases [10 calcium pyrophosphate dihydrate (CPPD) deposition disease; 7 osteoarthritis (OA); 6 rheumatoid arthritis (RA); 3 after total knee arthroplasty (TKA); 6 olecranon bursa] and 3 normal joint fluids. Joint fluids were analyzed after sequential centrifugation for NTPPHase activity and by Western blot using polyclonal antibodies against 127 kDa porcine articular cartilage vesicle-associated NTPPHase and against PC-1 and 58 kDa, 2 other ecto-NTPPHases. Lysate from human synoviocytes, porcine chondrocytes, and their conditioned media were examined using antibodies to these ecto-NTPPHases. Radiographs of joints from which fluid was obtained were graded for degenerative changes 0-4 using a standard method. RESULTS: NTPPHase activity was found in all pathological and normal SF tested and correlated with the degree of radiographic degeneration (r = 0.55, p < 0.05). NTPPHase specific activity in ultracentrifugation pellets was highest in CPPD deposition disease fluids (p < 0.05). 127 kDa enzyme was found in both sedimentable and soluble fractions from CPPD, OA, TKA, and normal fluids, and was extensively degraded in all inflammatory fluids. Intact 115 kDa PC-1 was found only in the 2 CPPD fluids with the highest NTPPHase activity. 58 kDa enzyme was found in most fluids, predominantly in the soluble fraction. 127 kDa protein was identified in human synoviocyte conditioned media but not in cell lysate, while PC-1 and 58 kDa proteins were found in the cell lysate but not in the conditioned media. CONCLUSION: There was no disease specific association with any one ecto-NTPPHase. Total enzyme activity correlated with the degree of degenerative change. The specific activity of pelletable 127 kDa enzyme was higher in fluids containing CPPD crystals. All 3 ecto-NTPPHases or their presumed degradation products were detectable in some pathologic and normal fluids. A 200 kDa reactive band often accompanied reactivity to the 127 kDa enzyme. PC-1 and 127 kDa proteins were extensively degraded in inflammatory SF, while 58 kDa protein was not. The relative contribution of each of these enzymes to inorganic pyrophosphate production by human joint tissues remains unclear.

Animals↗
PubMed1997

[Calcification of cervical ligamentum flavum--analysis of calcium compounds and histopathological findings].

We operated 3 patients with cervical myelopathy due to calcification of ligamentum flavum (CLF). Specimens collected surgically were subjected to X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy (Raman) analysis and also histopathological examination. The calcium compounds deposited were calcium pyrophosphate dihydrate (CPPD) in Case 1, apatite in Case 2, and a double-layer structure with an outer CPPD layer and an inner carbonate apatite layer in Case 3. Histopathologically, CPPD deposition in Case 1 could be distinguished from apatite deposition in Case 2 and 3 by hematoxylin-eosin stain. Chondrocytes were observed in all 3 cases, suggesting the chondrocytes may have played a role in calcification in these three cases. To date, 62 cases of CLF (including the present cases) have been reported, and analysis of calcium compound has been performed for 29 of them. Of these 29, 15 were analyzed as calcium phosphate compounds, 9 as CPPD and 4 cases as mixed crystals like Case 3. However the analysis method and result about CPPD are no problem, the analysis result of calcium phosphate compounds depends on the using methods. Calcium phosphate or undetectable compounds was identified by XRD as hydroxyapatite (HAp), and by FTIR as calcium phosphate or undetectable compound. Analysis of calcium phosphate compounds should be condacted and identified by XRD, FTIR, and Raman. We propose two possible mechanisms for the formation of the double-layer structure in Case 3: one is formation of apatite first followed by deposition of CPPD outside, and the other is formation of CPPD first followed by conversion of CPPD in the central region to apatite. What the process of formation of the double-layer was in this cases remains unclear.

Aged↗