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Biomedical subjects

K Imada

Publications and source records attributed to K Imada.

At least 55 records · Page 3Linked to original sources
PubMed1996

The human OX40/gp34 system directly mediates adhesion of activated T cells to vascular endothelial cells.

Fresh leukemic cells from patients with adult T cell leukemia (ATL) and some ATL-derived T cell lines show adhesion to human umbilical vein endothelial cells (HUVECs) mainly through E-selectin, but a proportion of this binding remains unaffected by the addition of combinations of antibodies against known adhesion molecules. By immunizing mice with one of such cell lines, we established monoclonal antibodies (mAbs), termed 131 and 315, that recognize a single cell surface antigen (Ag) and inhibit the remaining pathway of the adhesion. These mAbs did not react with normal resting peripheral blood mononuclear cells (PBMC) or most of the cell lines tested except for two other human T cell leukemia virus type I (HTLV-I)-infected T cell lines. After stimulation with phytohemagglutinin (PHA), PBMC expressed Ag 131/315 transiently, indicating that these mAbs define a T cell activation Ag. Western blotting and immunoprecipitation revealed that Ag 131/315 has an apparent molecular mass of 50 kD. Expression cloning was done by transient expression in COS-7 cells and immunological selection to isolate a cDNA clone encoding Ag 131/315. Sequence analysis of the cDNA indicated that it is identical to human OX40, a member of the tumor necrosis factor/nerve growth factor receptor family. We then found that gp34, the ligand of OX40, was expressed on HUVECs and other types of vascular endothelial cells. Furthermore, it was shown that the adhesion of CD4+ cells of PHA-stimulated PBMC to unstimulated HUVECs was considerably inhibited by either 131 or 315. Finally, OX40 transfectants of Kit 225, a human interleukin 2-dependent T cell line, were bound specifically to gp34 transfectants of MMCE, a mouse epithelial cell line, and this binding was blocked by either 315 or 5A8, an anti-gp34 mAb. These results indicate that the OX40/gp34 system directly mediates adhesion of activated T cells or OX40+-transformed T cells to vascular endothelial cells.

Animals↗
PubMed1996

Serial transplantation of adult T cell leukemia cells into severe combined immunodeficient mice.

The precise mechanism of the neoplastic cell growth of adult T cell leukemia (ATL) still remains unclear. In the present study, we have succeeded in serial transplantation of ATL cells from a patient into severe combined immunodeficient (SCID) mice. In this model, we found that only a leukemic cell clone from an ATL patient could be successively transplanted into SCID mice, although it was difficult to maintain leukemic cell clones in vitro, suggesting that the microenvironment provided by SCID mice is suitable for leukemic cell growth. We could not detect human T cell leukemia virus type I (HTLV-I) mRNA or interleukin 2 (IL-2) mRNA in either the tumor cells growing in mice or the original leukemic cells. Thus, it appears that neither HTLV-I viral expression nor the IL-2 autocrine mechanism is directly involved in the neoplastic cell growth of fresh ATL cells as well as HTLV-I-infected cell lines, at least in SCID mice. In addition, we could passage frozen cells and obtain a large number of expanded leukemic cells in this model. Such a serial transplantation model, which can avoid the changes in the nature of leukemic cells that are frequently observed in in vitro culture, and which can propagate leukemic cell clones, would be very suitable not only to study the mechanism of neoplastic cell growth, but also to test potential therapeutic agents for ATL.

Aged↗
PubMed1996

Idiopathic adulthood ductopenia.

In 1981, a 26 year old man occasionally demonstrated elevated serum transaminase concentrations. He had no history of medication, or a personal or family history of jaundice, except for prolonged physiological jaundice as a neonate. Serum hepatitis B surface antigen, hepatitis C virus antibody and anti-mitochondrial antibody were absent. A wedge biopsy specimen revealed ductular proliferation, mild inflammation of the portal area and disappearance of bile ducts from 80% of the portal tracts. Serial sections demonstrated a vanishing bile duct. Endoscopic retrograde choledochopancreatography, portography and arteriography demonstrated no abnormalities. In 1994, the patient died of hepatic failure following a 12 year observation period. He was subsequently diagnosed with idiopathic adulthood ductopenia on the basis of the criteria proposed by Ludwig.

Adult↗
PubMed1995

Tumorigenicity of human T-cell leukemia virus type I-infected cell lines in severe combined immunodeficient mice and characterization of the cells proliferating in vivo.

The mechanism involved in leukemogenesis and neoplastic cell growth of adult T-cell leukemia (ATL) still remains unclear. We examined the tumorigenicity of human T-cell leukemia virus type I (HTLV-I)-infected cell lines in an in vivo cell proliferation model using severe combined immunodeficient (SCID) mice. Eleven HTLV-I-infected cell lines were injected into SCID mice and we found that 4 of them were capable of proliferating in SCID mice. Three of four transplantable cell lines are derived from the leukemic cell clone and 6 of 6 HTLV-I-infected cell lines of nonleukemic cell origin could not engraft in SCID mice. Interestingly, it was shown that some HTLV-I-infected and interleukin-2 (IL-2)-dependent cell lines could successfully engraft in SCID mice. The expression of IL-2 mRNA was not detected in these cell lines growing either in vivo or in vitro. HTLV-I viral products were not detected in 3 of 4 transplantable cell lines proliferating in vivo. Peripheral blood T cells immortalized by introduction of tax gene of HTLV-I were found to have no tumorigenic potential in SCID mice. These data suggest that (1) HTLV-I-infected cell lines of nonleukemic cell origin do not have enough leukemogenic changes to acquire the tumorigenic potential in SCID mice; (2) the IL-2 autocrine mechanism is not directly involved in the tumor cell growth; (3) viral gene expression is not needed for the maintenance of neoplastic cell growth; and (4) the expression of tax gene is not sufficient for the neoplastic cell growth in vivo.

Animals↗
PubMed1995

Radioimmunodetection of human leukemia with anti-interleukin-2 receptor antibody in severe combined immunodeficiency mice.

Anti-Tac monoclonal antibody recognizes human interleukin-2 receptor, which is overexpressed in leukemic cells of most adult T-cell leukemia (ATL) patients. To examine the potency of anti-Tac for targeting of ATL, biodistributions of intravenously administered 125I- and 111In-labeled anti-Tac were examined in severe combined immunodeficiency (SCID) mice inoculated with ATL cells. Significant amounts of radiolabeled anti-Tac were found in the spleen and thymus. The trafficking of ATL cells in SCID mice was detected using 111In-oxine-labeled ATL cells. These results were coincident with the histologically confirmed infiltration of ATL cells. The radiolabeled anti-Tac seemed potent for targeting of ATL.

Adult↗
PubMed1995

Detection of homing, proliferation, and infiltration sites of adult T cell leukemia cells in severe combined immunodeficiency mice using radiometric techniques.

To clarify the mechanism of in vivo proliferation of adult T cell leukemia (ATL) cells, we examined the organ distribution of ATL-43T cell line cells derived from original leukemic cells in severe combined immunodeficiency (SCID) mice using radiometric techniques. First, we injected 111In-oxine-labeled ATL-43T cells into SCID and CB17 mice. On day 6, significant accumulation of radioactivity was found in the spleen and thymus of SCID mice (33.3 +/- 9.4 and 10.0 +/- 3.6% injected dose/g of tissue [%ID/g], respectively) in comparison with that in CB17 mice (19.1 +/- 2.5 and 3.7 +/- 0.9%ID/g, respectively). Next, we injected radiolabeled anti-Tac monoclonal antibody (MoAb) recognizing human interleukin-2 receptor (IL-2R) alpha chain or isotype-matched control MoAb RPC5 in SCID mice bearing ATL-43T cells 4 weeks after cell inoculation. The amounts of radioactivity found in the spleen and thymus of SCID mice injected with 125I-labeled anti-Tac MoAb (22.5 +/- 6.9 and 22.8 +/- 9.6 %ID/g, respectively) were significantly higher than those in the corresponding organs of SCID mice injected with 125I-labeled RPC5 MoAb (12.0 +/- 5.1 and 7.5 +/- 4.6 %ID/g, respectively). Similar results were obtained with 111In-labeled anti-Tac MoAb. These results were consistent with the histological findings of SCID mice bearing ATL-43T cells, indicating that ATL-43T cells infiltrated preferentially into the lymphoid organs, such as the spleen and thymus, and proliferated there. Thus, the radiometric techniques employed in this study were very useful to evaluate the proliferation sites of ATL-43T cells in SCID mice. Furthermore, this murine model could give us an opportunity to test the feasibility of therapeutic application of radiolabeled anti-Tac MoAb.

Animals↗
PubMed1995

[Legionella pneumophila serogroup 3 isolated from a patient of pneumonia developed after drowning in bathtub of a hot spring spa].

A 71-year-old Japanese female, was found unconscious by drawing, in a hot spring spa, at around noon of 20 October 1994. She recovered by emergency cardiopulmonary resuscitation, and admitted to the Takinomiya General Hospital, with adult respiratory distress syndrome (ARDS). Although she recovered from ARDS within 4 days after her admission, she developed severe pneumonia accompanied with the second attack of ARDS. Ordinary bacteriological culture of her respiratory specimens failed to yield any significant pathogen for her pneumonia, and neither cefazolin nor imipenem/cilastatin was effective. Thus minocyclin was given on the 7th hospital-day and this was effective for blood gas and C-reactive protein (CRP) levels. Intratracheal exsudate inoculated on BCYE alpha agar plate yielded grayish white colonies. Cells of the colonies were clearly agglutinated by anti-Legionella pneumophila serogroup (SG) 3 serum. Antibody titers of patient's paired sera against the strain L. pneumophila SG3 Bloomington-2 and the patient's strain (Y-1) were determined by microplate agglutination test, and a significant rise from 1:20 to 1:320 was demonstrated. Patient recovered by erythromycin treatment and was discharged on the 59th hospital day. L. pneumophila SG3 organisms were again isolated from the spa water where the patient drawn. From these findings described above, we diagnosed the patient as pneumonia due to L. pneumophila SG3, and the spa water was the most probable source of infection.

Aged↗
PubMed1995

Tyrosine kinase may participate in Ca2+ entry for endothelial nitric oxide production.

We have suggested that cyclopiazonic acid (CPA), a Ca(2+)-ATPase inhibitor, produces nitric oxide (NO) by triggering a Ca(2+)-influx resulting from Ca(2+)-depletion in the endoplasmic reticulum of endothelial cells. The tyrosine kinase inhibitor methyl 2,5-dihydroxycinnamate, while having no effect on relaxations induced by A23187 or Na nitroprusside, did inhibit the CPA-induced relaxation and cyclic GMP formation in rat aorta. Tyrosine kinase may participate in endothelial NO synthesis through activation of a Ca2+ entry mechanism.

Animals↗
PubMed1995

Conformation of an arabinoxylan isolated from the rice endosperm cell wall by X-ray diffraction and a conformational analysis.

The chain conformation of an arabinoxylan isolated from the rice endosperm cell wall, which was composed of the linear backbone of a 1,4-linked beta-xylose residue highly substituted at the C3 position with alpha-L-arabinofuranose, was studied by X-ray fiber diffraction and a conformational analysis. From the X-ray results the polysaccharide was suggested to take an extended left-handed, three-fold helical structure which is not a desirable conformation to make a complex firmly associated with cellulose or xyloglucan that was elucidated to be present in the cell wall. A conformational analysis, using the PFOS force field for the O-alpha-L-arabinofuranose-(1-->3)-beta-D-xylose residue and O-alpha-L-arabinofuranose-(1-->3)-[(1-->4)-beta-D-xylose residue]3, in which the arabinose residue was linked to the C3 position of the middle residue of the xylotriose residue, and using the PS79 computer program for the arabinoxylan indicated that the backbone xylan chain could not take a two-fold helix similar to that of cellulose because of significant steric interaction between the arabinose side chain and the backbone. Thus, the left-handed, three-fold helix was found to be reasonable.

Carbohydrate Conformation↗
PubMed1995

[Analysis of in vivo cell proliferation of ATL using SCID mice].

We made a model of in vivo cell proliferation of leukemic cells from adult T cell leukemia (ATL) patients using severe combined immunodeficient (SCID) mice. SCID mice injected with ATL cells from 6 of 8 ATL patients were found to have the tumor. DNA analysis revealed that the clone of the cells proliferating in mice was the same as that of the original leukemic cells. Histologic examination showed that the pattern of the infiltration of ATL cells in mice was similar to that of an ATL patient. Next, we examined the tumorigenicity of HTLV-I infected cell lines using SCID mice. Seven HTLV-I infected cell lines were injected into SCID mice and it was found that 4 of them were capable of proliferating in SCID mice. HTLV-I infected cell lines of non-leukemic cell origin could not engraft in SCID mice, indicating that these cells seemed not to have the enough genetic changes to acquire the tumorigenic potential. Analysis of gene expression suggested that neither IL-2 nor HTLV-I viral product was directly involved in the neoplastic cell growth of ATL. Furthermore, T cells immortalized by introduction of Tax could not engraft in SCID mice, indicating that the expression of tax gene seemed not to be sufficient for the neoplastic cell growth in vivo.

Animals↗
PubMed1995

Oophorectomy predisposes to degenerative spondylolisthesis.

We performed a case-control study on the influence of oophorectomy on the development of degenerative spondylolisthesis, including a clinical review and determination of serum oestradiol levels. We also compared the radiological appearance of the lumbar spine at L4/5 in patients with and without spondylolisthesis and with and without oophorectomy. Oophorectomy was a risk factor for degenerative spondylolisthesis with an odds ratio of 7.5 (95% confidence interval, 1.6 to 46). The incidence of degenerative spondylolisthesis in 69 oophorectomised patients was about three times higher than in 69 non-oophorectomised matched control subjects. There was also a difference in spinal variation between oophorectomised and non-oophorectomised patients with spondylolisthesis. A high incidence of sagittal-plane orientation of the L4/5 facet and an increase in pedicle-facet angle were seen in both groups and are typical radiological features of this disease. An increase in lumbosacral angle and in disc-space narrowing was seen only in the non-oophorectomised patients with this condition. Our results suggest that the abrupt decrease in oestradiol level caused by oophorectomy may be a predisposing factor in degenerative spondylolisthesis at L4/5.

Adult↗
PubMed1994

Suppression of interleukin 8 production by progesterone in rabbit uterine cervix.

Uterine cervical fibroblasts prepared from rabbits at 23 days of gestation were found to produce spontaneously the neutrophil chemotactic factor/interleukin 8 (IL-8). When the cells were treated with recombinant human interleukin 1 alpha and 1 beta (rhIL-1 alpha and -1 beta), both cytokines similarly enhanced the production of IL-8 in a dose-dependent manner. Recombinant tumour necrosis factor alpha also enhanced its production to a lesser extent, but interleukin 6 failed to modulate the production. Physiological concentrations of progesterone suppressed both the spontaneous and IL-1-mediated production of IL-8 in parallel with the decrease in the steady-state levels of its mRNA. These suppressive actions of progesterone were offset by co-treatment of cells with a progesterone antagonist, mifepristone (RU486). In conclusion, basal and IL-1-induced IL-8 production in rabbit uterine cervical fibroblasts is down-regulated by progesterone at the transcriptional level. These results obtained in vitro and our previous observations indicating that progesterone modulates the extra-cellular matrix breakdown via the suppression of production of matrix metalloproteinases and the augmentation of production matrix metalloproteinases and the augmentation of production of their specific inhibitors (TIMP-1) [Sato, Ito, Mori, Yamashita, Hayakawa and Nagase (1991) Biochem. J. 275, 645-650] may explain the mechanisms of the maintenance of pregnancy until parturition and the acceleration of uterine cervical ripening and dilatation at term.

Animals↗
PubMed1994

Progesterone increases the production of tissue inhibitor of metalloproteinases-2 in rabbit uterine cervical fibroblasts.

Rabbit uterine cervical fibroblasts in culture produces tissue inhibitor of metalloproteinases (TIMP)-1 and TIMP-2. When cells were treated with physiological concentrations of progesterone, the production of two TIMPs increased, and essentially all TIMP-2 was found to be complexed with promatrix metalloproteinase 2 (proMMP-2)/progelatinase A. Progesterone did not modulate the production of proMMP-2 and resulted in the increased total amount of proMMP-2-TIMP-2 complex. These observations provide the first evidence that progesterone participates in maintaining the homeostasis of connective tissue matrix in uterine cervix by augmenting both TIMP-1 and TIMP-2 production along with the known suppressive effects on the proMMP-1 and proMMP-3 production.

Animals↗
PubMed1994

Purification and properties of glucosyltransferase from Aureobasidium.

Purification and properties of glucosyltransferase, which produces panose (Glc alpha 1-->6Glc alpha 1-->4Glc) and isomaltose (Glc alpha 1-->6Glc) from maltose (Glc alpha 1-->4Glc), are reported. The enzyme, from Aureobasidium, was purified to homogeneity by fractionations involving ammonium sulfate and DEAE-Cellulofine, S-Sepharose Fast Flow and Sephadex G-200 chromatography. Molecular mass of the enzyme was estimated to be 395 kDa by gel filtration. The enzyme was identified as a glycoprotein which contains 32% (w/w) carbohydrate. The optimum pH for the enzymatic reaction was 4.5-5.5 and the enzyme was stable over a pH range of 4-6. The optimum reaction temperature for the enzyme was 65 degrees C and the enzyme retained more than 96% activity at 60 degrees C after 15 min. The enzyme produced panose from maltose by means of a high efficiency (45.5%) glucosyl-transfer reaction. The enzyme was inhibited by metal ions, such as those of mercury, silver and aluminum, and also by organic inhibitors, especially nitrilotriacetic acid.

Biotechnology↗
PubMed1994

[Early detection of primary liver cancer--diagnosis of small liver cancer by needle aspiration biopsy].

Small liver cancer is defined as a solitary hepatocellular carcinoma (HCC) with a diameter less than 2cm. To detect liver cancer as early as possible, patients with liver cirrhosis are screened by ultrasound scanning. Pathological diagnosis in needle aspiration biopsy materials is needed because of low positivity of imaging other than ultrasound scanning. Pathological features are different from those of classical hepatocellular carcinoma. Most of the small HCCs are characterized by the following features: (1) increased cellularity, (2) increased nucleus/cytoplasm ratio, (3) irregular thin trabecular pattern, (4) pseudoglandular or acinar structures, (5) increased staining affinity (eosinophilic/basophilic), (6) frequent fatty change, and (7) residue of the portal tract. Capsules of HCCs, 1-1.5 cm in diameter, are formed. Before the formation of capsules, cancerous cells show a replacing growth pattern. Two cases of small HCC are presented, and these characteristic features are explained.

Biopsy, Needle↗
PubMed1993

A model of in vivo cell proliferation of adult T-cell leukemia.

We have made a model of in vivo cell proliferation of leukemic cells from adult T-cell leukemia (ATL) patients using severe combined immunodeficiency (SCID) mice. Peripheral blood mononuclear cells (PBMC) or lymph node cells (LNC) depleted of B cells and monocytes were intraperitoneally injected into SCID mice treated with antimurine interleukin-2 receptor (IL-2+) beta chain monoclonal antibody (MoAb)(TM-beta 1), followed by daily injection of human recombinant IL-2 until 60 days after cell injection. SCID mice injected with ATL cells from 6 of 8 ATL patients were found to have the tumor or leukemia 5 to 7 weeks after the inoculation of cells. Serum levels of soluble form of human IL-2R alpha chain (Tac) were markedly elevated in such mice. The cells recovered from the mice injected with leukemic cells from four different ATL patients had the same cell surface phenotype as that of original leukemic cells which were CD4+Tac+. Furthermore, we detected the same integration site of human T-cell leukemia virus type I (HTLV-I) provirus and the same rearrangement pattern of human T-cell receptor (TCR) beta chain gene as those of ATL cells by Southern blot hybridization, indicating that the cells proliferating in SCID mice were derived from the original ATL cell clone. Histologic examination showed that the pattern of the infiltration of ATL cells into various organs in SCID mice was similar to that of an ATL patient. Such a model of in vivo cell proliferation of ATL cells will be useful for the study of the mechanism of neoplastic cell proliferation and for the development of a new and effective treatment of ATL.

Aged↗
PubMed1993

[General pharmacological studies on human natural tumor necrosis factor (MHR-24)].

The general pharmacological properties of MHR-24 were studied in various experimental animals. Intravenously (i.v.)-administered MHR-24 at 8.6 x 10(2) JRU/kg or more produced fever in rabbits. MHR-24 at 3 x 10(4) JRU/kg or more caused tachycardia; and at 1 x 10(5) JRU/kg or more, it lowered arterial blood pressure in anesthetized monkeys. In rats, MHR-24 at 2.9 x 10(4) JRU/kg or more showed a diuretic action and inhibitory effects on gastric juice secretion and carrageenin-induced paw edema. Furthermore, MHR-24 at a large dose (8.6 x 10(4) or 2.9 x 10(5) JRU/kg, i.v.) decreased spontaneous locomotor activity, had an inhibitory effect on acetic acid-induced writhing and potentiated intestinal propulsion in mice; and it caused the appearance of rest wave on acute spontaneous electroencephalograms in rabbits. Pretreatment of the animals with the cyclooxygenase inhibitor indomethacin abolished the fever and potentiation of intestinal propulsion caused by MHR-24. Therefore, these data seem to indicate that some of the effects of MHR-24 are mediated via cyclooxygenase pathways. The results suggested that, except for the above results, MHR-24 has no noticeable effects on the central nervous, autonomic nervous, respiratory and cardiovascular systems and others in general pharmacological studies.

Animals↗