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Biomedical subjects

K Tsukamoto

Publications and source records attributed to K Tsukamoto.

At least 163 records · Page 9Linked to original sources
PubMed1995

Administration of monoclonal antibodies against vascular cell adhesion molecule-1/very late antigen-4 abrogates predisposing autoimmune diabetes in NOD mice.

The interaction of vascular cell adhesion molecule-1 and very late antigen-4 (alpha 4 beta 1-integrin) has been recently known to be profoundly involved in the trafficking of lymphocytes from the circulation into the inflammatory tissues. To elucidate the role of these molecules in the development of autoimmune diabetes, the expression of these adhesion molecules on inflamed islets and the effects of administration of monoclonal antibodies to these molecules on insulitis and overt diabetes were evaluated in nonobese diabetic (NOD) mice. Immunohistochemical study revealed the overexpression of vascular cell adhesion molecule-1 on vascular endothelium near or within inflamed islets and alpha 4-integrin on islet-infiltrating mononuclear cells. Either anti-vascular cell adhesion molecule-1 or anti-alpha 4-integrin monoclonal antibody prevented the transfer of diabetes in irradiated NOD mice which received spleen cells from acutely diabetic NOD mice. When both monoclonal antibodies were administrated to NOD mice during 2-30 weeks of age, neither lymphocytic infiltration to islets nor overt diabetes was observed. Furthermore, administration of these antibodies even from 10 weeks of age could inhibit the development of insulitis and diabetes, whereas administration during 2-5 weeks of age could not. Splenocytes obtained from these treated mice showed no significant change of cytokine production and preserved the ability to transfer diabetes into NOD scid/scid mice. This suggests that treatment with antibodies against these adhesion molecules can inhibit insulitis and diabetes without affecting the Th1/Th2 balance or effector T cells. The blockade of vascular cell adhesion molecule-1/very late antigen-4 interaction would be suitable for therapeutical treatment of the predisposing and latent type I (insulin-dependent) diabetic subjects.

Animals↗
PubMed1995

Concordant factors of depression rating scales and dimensionality of depression.

A redundancy analysis was carried out between a doctor rating scale (D-RS) and a patient self-rating scale (P-SRS) to determine relating dimensions. The first and second major redundancy variates obtained from the P-SRS and the D-RS were rotated to obtain biorthogonality and interpretability. The obtained two concordant dimensions between the P-SRS and the D-RS were interpreted as depression and vegetative factors. Any redundancy factors before the rotations, however, did not reveal a general factor pattern. These results suggest that the two-dimensional structure is more appropriate for understanding the depression symptomatology rather than the unidimensional structure of a general or endogenous factor pattern. We also discussed how dimensional differences caused a low concordance in severity or total scores.

Analysis of Variance↗
PubMed1995

Spectroscopic and kinetic studies on reaction of cytochrome P450nor with nitric oxide. Implication for its nitric oxide reduction mechanism.

Cytochrome P450 purified from Fusarium oxysporum (P450nor) is a unique heme enzyme that catalyzes the reduction of nitric oxide to nitrous oxide with electrons directly transferred from NADH (2NO + NADH + H+--> N2O + H2O + NAD+). We studied the reaction of P450nor with NO and NADH using stopped-flow rapid scan and low temperature spectroscopic methods. The NO ligand can bind to the ferric enzyme to form the stable NO bound complex, P450nor(Fe3+NO). Reduction of P450nor(Fe3+NO) with NADH yielded an intermediate, which transiently formed (tau = approximately 100 ms) and spontaneously decomposed to the Fe3+ state. The optical absorption spectrum of the intermediate was different from that of P450nor(Fe2+NO), which was formed by either a one-electron reduction of P450nor(Fe3+NO) with Na2S2O4 or NO binding to P450nor(Fe2+). On the basis of these observations, we suggested that the intermediate is presumably a two-electron reduced product of P450nor(Fe3+NO) by NADH, formally the (Fe3+NO)2-complex. We determined the rate constants of these reactions at 10 degrees C for the NO binding to P450nor(Fe3+) (2.6 x 10(7) M-1 s-1), the NADH reduction of P450nor(Fe3+NO) (0.9 x 10(6) M-1 s-1), and the spontaneous decomposition of the intermediate (0.027 s-1). In these kinetic measurements, it was found that the former two processes are fast enough, while the latter is extremely slow, compared with the fast turnover of the catalytic reaction (1200 s-1 at 10 degrees C), which we measured by monitoring the NADH consumption. Therefore, we suggested that in the catalytic cycle, decomposition of the intermediate is fairly accelerated by free NO, resulting in such a fast turnover. On the basis of several lines of the spectroscopic and the kinetic evidence, we proposed a possible mechanism of the NO reduction by P450nor.

Cytochrome P-450 Enzyme System↗
PubMed1995

Defect in assembly process of very-low-density lipoprotein in suncus liver: an animal model of fatty liver.

We previously showed that fatty liver was easily induced in suncus by starvation and that the plasma level of apolipoprotein B (apo B) was very low. There are three possible explanations for the low level of apo B in the animals: low synthetic rate, low secretion rate, and rapid catabolism in the circulation of apo B. We measured post-heparin lipolytic activity (lipoprotein lipase activity), which plays a key role in the catabolism of apo B-containing lipoprotein, VLDL, and found no difference between rats and suncus. We also investigated the hepatic synthetic rate of apo B by liver perfusion studies. Newly synthesized apo B in the suncus liver was detected by immunoprecipitation and found to amount to 12.5% of that in rats. The secretion rate of VLDL in suncus, which was estimated by intravenous injection of Triton WR1339, was 13.8% of that in rats. These two results suggest that there is no major defect in the secretory process. We separated Golgi apparatus from rat and suncus livers, and found much fewer lipoprotein particles in suncus than in rat Golgi apparatus. This evidence suggests that there is no defect in the lipolytic process or hepatic secretory process of apo B-containing lipoprotein, VLDL, but there may be a defect in the assembly process of VLDL and/or in the synthetic process of apo B in suncus. Such a defect may be one of the reasons for starvation-induced fatty liver in suncus.

Animals↗
PubMed1995

Notched T wave as evidence of autonomic nervous lability in Duchenne progressive muscular dystrophy.

We investigated the significance of notched T waves on the ECG in 30 patients with Duchenne progressive muscular dystrophy (DMD) and 50 age-matched controls using noninvasive cardiovascular examinations and measurement of urinary catecholamines. Notched T waves were more frequently observed in patients with DMD than in control subjects (46.7% vs. 20.0%, p < 0.05). Moreover, their frequency was age-independent in DMD, whereas they decreased with age in controls. Patients with notched T waves showed significantly increased heart rate, prolonged QTc and augmented excretion of urinary adrenaline compared with patients without them. There were no significant differences in casual BP or incidences of characteristic UCG abnormalities, such as mitral valve prolapse, and ECG abnormalities, such as tall R waves in the right precordial leads, between DMD patients with and without notched T waves. These findings suggest that notched T waves are associated with accelerated sympathetic nervous activity rather than progressive cardiac involvement in DMD.

Adolescent↗
PubMed1995

[The relationship between work factors and psychiatric symptoms--a comparison between anxiety and depression].

The depression scale (Zung Self-rating Depression Scale) and the anxiety scale (State-Trait Anxiety Inventory) have often been used to study the mental health of workers. We carried out a comparative study to determine which these two scales more clearly reflects the work stress. We used two methodologically different materials: a questionnaire survey and mental health consultation records. The questionnaire was sent to 885 male workers in a large industrial company and its related companies, and the consultation cases were 84 male workers coming from the area where the questionnaire survey was conducted. The work problem questionnaire was factored and the four work factors that were obtained were used in the succeeding analyses. The results of the questionnaire survey showed that depression had a higher multiple correlation with the four work factors than did the state anxiety. Similarly, the consultation cases, in which the main symptom was depression, accounted for a little more than 40% of all cases, but the anxiety cases accounted for only 10%-20%. Both studies indicated that depression is a more important manifestation of work stress than anxiety. The questionnaire survey also showed that the "quality-of-work" factor and the "work-quantity/environment" factor had relatively high standardized partial regression coefficients, when depression was predicted by the four work factors. In the case of the consultation cases, more than 50% of the depressive cases were caused by overload. Since the "work-quantity/environment" factor was considered to be closely related to overload, the salient relation between depression and overload agrees with the results of the consultation research.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Expression of intercellular adhesion molecule 1 on pancreatic beta-cells accelerates beta-cell destruction by cytotoxic T-cells in murine autoimmune diabetes.

Intercellular adhesion molecule 1 (ICAM-1) plays an important role in the pathogenesis of insulin-dependent diabetes mellitus (IDDM) by being involved in the extravasation of lymphocytes from the circulation into the inflamed pancreas. However, the mechanism of beta-cell destruction by which expression of ICAM-1 on beta-cells may facilitate adhesion of effector cells still remains to be elucidated. Several lines of evidence suggest that this adhesion molecule is involved in the destruction of pancreatic beta-cells by killer lymphocytes in the NOD mouse, which shows an autoimmune diabetic syndrome similar to that of human IDDM. Immunohistochemical study under light microscopy demonstrated that all of the mononuclear cells infiltrating the islets strongly expressed ICAM-1 and leukocyte function-associated antigen 1 (LFA-1), a counterreceptor of ICAM-1, whereas ICAM-1 expression on islet cells was not apparent. However, immunohistochemical staining under electron microscopy revealed that islet beta-cells adjacent to infiltrating lymphocytes were clearly stained by an anti-ICAM-1 monoclonal antibody (mAb). Flow cytometric analysis showed that the ICAM-1 expression on NOD islet cells and NOD-derived insulinoma cells (MIN6N8a) was inducible by interferon (IFN)-gamma or tumor necrosis factor-alpha. These cytokines had an additive effect on the ICAM-1 induction. Susceptibility of MIN6N8a cells to lysis by a NOD islet-derived CD8+ cytotoxic T-cell clone was greatly enhanced by IFN-gamma pretreatment, and this enhancement was abolished by anti-ICAM-1 and anti-LFA-1 mAbs. When both mAbs were administered into NOD mice with spontaneous or adoptively transferred diabetes, the development of diabetes was significantly prevented.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[A case of necrotizing sarcoid granulomatosis].

A 60-year-old woman was admitted to our hospital because of progressive cough and chest pain for 2 months. She also complained of exertional dyspnea. Bilateral diffuse infiltlative shadows were found on the chest roentogenogram. Ground-glass opacity in the middle lobe and lingula, and subpleural patchy consolidation were seen on the computed tomogram of the chest. Arterial oxygenation and diffusing capacity were low. The level of angiotensin-converting enzyme in serum was normal, but that of lysozyme was high. In the BAL (broncho-alveolar lavage) fluid, total cell count and the number of lymphocytes were high, and the CD 4/8 ratio of the lymphocytes was high. Open lung biopsy revealed numerous confluent sarcoid granulomas with necrosis, which strongly correlated with severe vasculitis. After necrotizing sarcoid granulomatosis was diagnosed, prednisolone was administered, which resulted in improvement of symptoms and disappearance of chest-radiograph shadows. Necrotizing sarcoid granulomatosis may be seen as a variant type of sarcoidosis. However, clinical findings including the chest-radiograph shadows and clinical course of this case differ from those of ordinary sarcoidosis. These clinical findings can be attributed to severe vasculitis, as revealed by histological examination.

Female↗
PubMed1995

The validity of intraoperative frozen section diagnosis based on video-microscopy (telepathology).

The validity of intraoperative frozen section diagnosis (IFSD) via telepathology between Hokkaido University School of Medicine (HUSM) and a remote hospital was evaluated. Video-microscopic images of hematoxylin-eosin (HE)-stained frozen sections were transmitted by a cytoscreener via the Pathtran 1,000 system and a telephone line to a color monitor at HUSM (120 km from the submitting hospital) with a resolution of 512 x 480 pixel matrix. The pathologists at HUSM made diagnoses on the received images. Of the 59 cases, there was diagnostic concordance between telepathology and permanent paraffin sections in 19 malignant, 36 benign, and one borderline case. The latter was a case of atypical ductal hyperplasia of the breast. The telepathology diagnostic modality was inconclusive in three cases, two of which were benign and one malignant by paraffin section examination. These results provide evidence for the diagnostic adequacy of video-microscopic images, the interpretation of which compared favorably with that of conventional frozen sections. Although the need for IFSD is increasing, the proportion of hospital pathologists accepting this modality is not. For the appropriate use of telepathology, it is necessary that more pertinent personnel, especially cytoscreeners and pathologists receive a thorough training and become familiar with the system. Telepathology offers pathologists a diagnostic modality that responds to the needs of physicians and serves to enhance the pathologist's position in health care services.

Adult↗
PubMed1994

[High-resolution MR imaging of the mediastinum and hilus of the lung using surface-coils].

High-resolution MR imaging using surface-coils (Helmholtz-coil) was performed on patients with hilar lung cancer and healthy volunteers. We evaluated the clinical usefulness of this technique compared with MR imaging performed with a conventional body-coil. Although the signal-to-noise ratio was slightly decreased, normal anatomic structures, hilar masses, and enlarged lymph nodes were distinctly visualized in comparison with those on MR images obtained with a body-coil. High-resolution MR imaging with the Helmholtz-coil seemed to be useful for the evaluation of mediastinal and hilar disease, and may able to supplant MR imaging with a conventional body-coil in routine examinations.

Humans↗
PubMed1994

Roles of myosin light-chain kinase in platelet shape change and aggregation.

We examined the roles of myosin light-chain kinase in platelet responses to ADP using wortmannin, which almost completely inhibited myosin light-chain kinase at 3-6 microM. This concentration of wortmannin did not affect ADP-induced changes in the shape of the platelets, but it markedly inhibited aggregation in platelet-rich plasma and washed platelets. ML-9, another inhibitor of myosin light chain kinase, elicited similar effects on the platelet responses to wortmannin. Electron microscopic studies showed that there was no wortmannin effect on the ADP-induced spheration of discoid platelets, pseudopod formation, or granule centralization. Wortmannin at concentrations which prevented myosin light-chain kinase also inhibited platelet aggregation induced by ADP in the presence of U46619, an analogue of thromboxane A2, which is a prerequisite for ADP-induced irreversible aggregation. Although wortmannin partially inhibited protein kinase C, the protein kinase C inhibitor Ro-31-7549 (5 microM) prevented neither ADP- or ADP/U46619-induced changes in the shape of the platelets nor aggregation. These results suggest that myosin light-chain kinase activation is a prerequisite for ADP-induced platelet aggregation, but not for changes in their shape.

Adenosine Diphosphate↗
PubMed1994

Prostaglandin F2 alpha enhances tyrosine phosphorylation and DNA synthesis through phospholipase C-coupled receptor via Ca(2+)-dependent intracellular pathway in NIH-3T3 cells.

Previously, we characterized the prostaglandin (PG) F2 alpha receptor linked to phospholipase C activation and DNA synthesis in NIH-3T3 cells (Nakao, A., Watanabe, T., Taniguchi, S., Nakamura, M., Honda, Z-I., Shimizu, T., and Kurokawa, K. (1993) J. Cell. Physiol. 155, 257-264). To elucidate intracellular events evoked via this receptor, we examined changes caused by PGF2 alpha stimulation in the phosphotyrosine composition of cellular proteins. The addition of PGF2 alpha to cells in quiescent culture rapidly increased the levels of phosphotyrosine in cellular proteins with Mr values of 70,000 (pp70), 85,000 (pp85), 92,000 (pp92), 100,000 (pp100), and 125,000 (pp125); the latter was immunologically identified as p125 focal adhesion kinase. The PGF2 alpha-induced changes in the level of intracellular Ca2+ ([Ca2+]i) elevation, formation of inositol phosphates, and [3H]thymidine incorporation followed a similar dose dependence as PGF2 alpha-induced tyrosine phosphorylation. This tyrosine phosphorylation was independent of extracellular Ca2+, while a [Ca2+]i chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (50 microM), completely inhibited the PGF2 alpha-induced elevation of [Ca2+]i, tyrosine phosphorylation, and [3H]thymidine incorporation. Ionomycin (0.1 microM), which induced [Ca2+]i elevation without formation of inositol phosphates, mimicked the PGF2 alpha-induced tyrosine phosphorylation. 12-O-Tetradecanoylphorbol-13-acetate (TPA) also induced [3H]thymidine incorporation in a dose-dependent manner but had no significant effect on tyrosine phosphorylation. The PGF2 alpha-induced tyrosine phosphorylation could be observed even in the cells pretreated with TPA (5 microM, 24 h). PGF2 alpha exhibited an additive effect on TPA-induced [3H]thymidine incorporation but had no effect on the 32P-phosphorylation of a known 80-kDa protein kinase (PK) C substrate. Both staurosporine and H-7 inhibited the PGF2 alpha-induced increase in [3H]thymidine incorporation and tyrosine phosphorylation in a similar dose-dependent manner whether or not cells were pretreated with TPA (5 microM, 24 h). However, W-7 and KN-62 had no effect on these cellular responses even at the concentration for the almost complete inhibition of Ca2+/calmodulin-dependent PKs (20 microM). These results, taken together, indicate that PGF2 alpha receptor-mediated tyrosine phosphorylation is evoked by a [Ca2+]i-dependent mechanism that is sensitive to staurosporine and H-7 but which is independent of PKC or Ca2+/calmodulin PKs. Finally, the data suggest that this PGF2 alpha-induced signaling pathway is linked to the proliferation of cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Effect of atropine injected into the nucleus tractus solitarius on the regulation of blood pressure.

Previous experiments have demonstrated that stimulation of muscarinic cholinergic receptors in the nucleus tractus solitarius (NTS) of the rat decreases arterial blood pressure and heart rate. The present studies were designed to examine the role of cholinergic mechanisms in the NTS in the tonic regulation of arterial pressure and the baroreceptor reflex. Atropine injected into the NTS of chloralose-anesthetized rats produced a dose-dependent inhibition of cardiovascular responses elicited by injection of acetylcholine into the same site; 240 pmol atropine eliminated acetylcholine-evoked responses. Atropine also increased arterial blood pressure but only at higher doses. Even larger doses of atropine were required to alter cardiovascular responses elicited by electrical stimulation of the aortic depressor nerve. Methylatropine injected into the NTS also blocked acetylcholine-evoked responses but, in contrast to the actions of atropine, did not increase arterial pressure in the dose range required to block acetylcholine-evoked responses. Furthermore, a dose of methylatropine (1 nmol) capable of blocking acetylcholine-evoked cardiovascular responses did not alter aortic depressor nerve-evoked cardiovascular responses. This lack of an effect of methylatropine on arterial pressure and aortic depressor nerve-evoked responses was not due to limited diffusion of the drug within the NTS since 1 nmol methylatropine completely blocked acetylcholine-evoked responses even when injected 0.5 mm distant from the site of acetylcholine injection. These results suggest that cholinergic mechanisms in the NTS are not involved in the tonic regulation of cardiovascular function or the baroreceptor reflex. Furthermore, these results highlight the importance of characterizing doses of drugs used in microinjection studies.

Animals↗
PubMed1994

Protein kinase C-dependent and -independent mechanisms of dense granule exocytosis by human platelets.

We examined the mechanisms of ATP release by human platelets using Ro-31-7549, a specific inhibitor of protein kinase C. Ro-31-7549 almost completely inhibited TPA-induced platelet aggregation and ATP release at 5-10 microM in washed platelets and in platelet-rich plasma. However, it suppressed thrombin- and U46619-induced ATP release by only 48% and 21%, respectively, and had little effect on aggregation in washed platelet suspensions containing serum or in platelet-rich plasma. The addition of GRGDS to prevent aggregation inhibited this residual thrombin-induced release by 53% and the residual U46619 release by 100% in the presence of Ro-31-7549. In washed platelet suspensions free of serum or plasma, Ro-31-7549 almost completely inhibited the ATP release and partially suppressed the aggregation induced by these agonists. These results suggested that there are protein kinase C-dependent and -independent mechanisms for ATP release by human platelets and that activation of the latter mechanism may depend on aggregation and plasma factors.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1994

The inherent cytotoxicity of melanin precursors: a revision.

The potential cytotoxicity of the melanogenic intermediates DOPA, (L-3,4-dihydroxyphenylalanine) and DHI (5,6-dihydroxyindole) has long been recognized and exploited as a targeting concept in experimental melanoma therapy. In recent years, however, a novel branchpoint in the melanin biosynthetic pathway has been shown to divert the metabolism of DOPAchrome to a carboxylated derivative termed DHICA (DHI-2-carboxylic acid) rather than to DHI. In order to evaluate the biological implications of this regulatory control, we have reexamined the inherent cytotoxicity of DHICA versus DHI on different cell lines. We found that under the usual conditions of the biological assay, the apparent cytotoxicity of the two indoles reflect their instability in the culture medium, the less stable DHI being generally more toxic than DHICA to melanoma cells and nonmelanocytic cells. Moreover, the observed cytotoxic effects increased with the time of incubation and were markedly reduced by the addition of catalase to the medium, suggesting that they were probably due to the generation of reactive oxygen species (particularly H2O2) during the autoxidation of the melanin precursors outside the cells. To circumvent this problem, we then tested the diacetylated derivatives of DHI and DHICA (DAI and DAICA) which are sufficiently stable until taken up into the cells whereupon they may be converted by endogenous esterases back to the parent indoles. Although DAI proved to be cytotoxic for nonmelanocytic cells, it had no detectable activity on melanoma cells, whereas DAICA showed no effect on any of the cells examined. These results, when combined with other studies, point to a reconsideration of the inherent cytotoxicity of the 5,6-dihydroxyindoles, as well as DOPA, to melanin producing cells.

3T3 Cells↗
PubMed1994

Cloning and sequencing of an Na+/H+ antiporter gene from the marine bacterium Vibrio alginolyticus.

A gene has been cloned from a DNA library from the marine bacterium Vibrio alginolyticus that functionally complements a mutant strain of Escherichia coli, NM81, defective in an Na+/H+ antiporter (NhaA). The cloned Vibrio gene restored NM81 to grow in a medium containing 0.5 M NaCl at pH 7.5 and concomitantly led to an increase in Na+/H+ antiport activity. The nucleotide sequence of the cloned fragment revealed an open reading frame, which encodes a protein with a predicted 383 amino acid sequence and molecular mass of 40,400 Da. The hydropathy profile is characteristic of a membrane protein with 11 membrane spanning regions. The deduced amino acid sequence is 58% identical with E. coli NhaA.

Amino Acid Sequence↗