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Biomedical subjects

M Sakaguchi

Publications and source records attributed to M Sakaguchi.

At least 199 records · Page 11Linked to original sources
PubMed1998

Anti-glomerular basement membrane nephritis after extracorporeal shock wave lithotripsy.

Rapidly progressive glomerulonephritis was observed in a 37-year-old woman following the administration of extracorporeal shock wave lithotripsy (ESWL) for a single stone in her right kidney. The renal biopsy specimen showed diffuse cellular crescents in all glomeruli, with linear deposits of immunoglobulin G and complement component C3 along the glomerular basement membrane (GBM). Circulating anti-GBM antibodies were detected by enzyme-linked immunosorbent assay. Thus, the patient was diagnosed with anti-GBM nephritis. It is suggested that ESWL produced an alteration in the GBM leading to the production of anti-GBM antibodies.

Adult↗
PubMed1998

Differential localization of two types of transferrin: produced by human fibroblasts or incorporated from culture medium.

In a previous paper, we demonstrated that cultured human fibroblasts synthesize transferrin (Tf). Two types of Tf are present; one is produced by the cells and the other is internalized from the culture medium. To study the metabolism of intracellular Tf, we investigated the subcellular localization of the two types of Tf in human fibroblasts by immunocytochemical and fluorescence-labeling techniques. The internalized Tf was found to be localized in the perinuclear area, and the synthesized Tf was associated with microtubules, forming a fibrous structure in the cytoplasm. When the cells were treated with colchicine which depolymerizes microtubules irreversibly, the synthesized Tf lost its fibrous structure and spread out in cytoplasm, but the internalized Tf remained around the nucleus. These results suggest that the two types of Tf are regulated differently in the cells.

Cell Nucleus↗
PubMed1998

[Role of superoxide generation and degradation system of mast cells in allergic inflammation].

Rat peritoneal mast cells are stimulated to generate superoxide anion (O2) by the addition of compound 48/80 and A23187. Recently, we demonstrated by immunohistochemical and Western blot analysis that the mast cells contained the p47phox protein, which was one of cytosolic component of the NADPH oxidase system. In the present study, it was demonstrated that the mast cells contained the p47phox mRNA, much similar to that of mouse leukocyte. The permeabilized mast cells were stimulated to generate O2- by the addition of Ca2+, phospholipase A2 (PLA2) and arachidonic acid. Our data suggest the following:(1) cytosolic PLA2 may be activated by the elevation of [Ca2+]i; (2) the conjugation of membrane component with cytosolic component may be stimulated by the released arachidonic acid. The mast cell granules contained superoxide dismutase (SOD)-like enzyme, which degradated O2-, generated in xanthine-xanthinoxidase system. SOD-like enzyme was released from the granules by the treatment with Ca2+ and trapped by the treatment with heparin. In conclusion, our studies suggest that the disorder of the degradation system of O2- may contribute to the development of allergic inflammation.

Animals↗
PubMed1998

Antioxidative activity of carp blood plasma on lipid peroxidation.

Antioxidative activity of carp blood plasma was estimated by measuring hydroperoxides formed by liposome peroxidation during the exposure of liposomes to AAPH. Ascorbic acid of high concentration, uric acid of low content, and tocopherol formed special protective system against lipid poroxidation in fish plasma. The decrease of uric acid, ascorbic acid, and tocopherol showed synergism of ascorbic acid and tocopherol, uric acid, and tocopherol. Carp blood plasma with a low concentration of protein (about 2%) and SH groups (88 microM) had a great effect on the antioxidative activity, as the effects of ascorbic acid, uric acid, and tocopherol were dramatically extended. Dialysed carp protein also displayed a very strong antioxidative activity on lipid peroxidation of a multilayer liposome system.

Adult↗
PubMed1998

ATP inhibition of proliferation of immortalized human fibroblasts is greater than that of normal human diploid fibroblasts.

It is known that cancers develop by a multi-step process. Normal cells are first immortalized, and then transformed into tumorigenic cells. Normal human cells are very rarely immortalized, but once they are, they are relatively easily transformed into tumorigenic cells. This indicates that the immortalization step plays a critical part in the development of human cancers. Thus, elucidation of the mechanisms of this step would shed light on the process of carcinogenesis in human cells. To understand the causes of immortalization, it is important to determine the differences in cellular phenotype between immortalized and normal human cells. In this study, we found that immortalized human fibroblasts were more sensitive to the growth inhibitory effects of ATP than normal human fibroblasts. ADP was as effective as ATP, but AMP, adenosine, and phosphoric acid were not. These results indicate that a high-energy bound of ATP and ADP may contribute to the growth inhibition of the cells. When the immortalized cells were pulse-labeled with [32P]-ATP, 30-, 31-, 33- and 40-kDa membrane fraction proteins were more prominently labeled in the immortalized cells than in the normal cells. At present, the characteristics of these proteins are being investigated.

Adenosine↗
PubMed1998

Thiol compounds rescue growth inhibition by retinoic acid on HTLV-I (+) T lymphocytes; possible mechanism of retinoic-acid-induced growth inhibition of adult T-cell leukemia cells.

We demonstrated significant growth inhibition by retinoic acid (RA) of HTLV-I (+) T-cell lines (ATL-2 and HUT102), but not HTLV-I (-) T-cell lines (MOLT-4 and Jurkat). We hypothesized that the mechanism of growth inhibition by RA depends on an imbalance in redox potential. To examine the effect of exogenous thiol compounds for the growth of HTLV-I (+) T-cell lines by RA, HTLV-I (+) T-cell lines were cultured with several thiol compounds (thioredoxin, L-cystine, and GSH), following addition of 13-cis RA or ATRA, respectively, in cultured with thiol free medium. Unexpectedly, thiol compounds alone did not restore growth inhibition of HTLV-I (+) T-cell lines. However, when those cells were preincubated with thiol compounds for 24 hours, no growth inhibition by 13-cis RA or ATRA was observed. These results suggest that thiol compounds are associated strongly with sensitivity to RA of HTLV-I (+) T cells, but not of HTLV-I (-) T cells and that thiol compounds serve an important role on HTLV-I (+) T cells.

Cell Division↗
PubMed1998

[An experience of treatment of double positive myeloperoxidase-antineutrophil cytoplasmic antibodies (MPO-ANCA) and anti-glomerular basement membrane antibodies in Goodpasture's syndrome onset of crescentic glomerulonephritis].

A 68-year-old woman was admitted to Kinki University Hospital because of progressive renal failure. She had been well until two months before admission. Laboratory data were as follows: serum creatinine 4.1 mg/dl, BUN 69 mg/dl, MPO-ANCA 33 EU, anti-glomerular basement membrane antibodies (AGBMA) 118 U. Histological findings showed cellular and fibrocellular crescents in many glomeruli. Therefore, we diagnosed rapidly progressive glomerulonephritis (RPGN) due to MPO-ANCA and anti-GBM associated renal disease. The patient was started on prednisolone and double filtration plasmapheresis (DFPP) therapy. Subsequently, the values of MPO-ANCA and AGBMA decreased. However, the patient's condition suddenly worsened and she died of interstitial pneumonia. Autopsy examination revealed crescentic glomerulonephritis and alveolar hemorrhage with linear deposition of IgG along the glomerular and alveolar capillary walls by immunofluorescence studies. We considered this to be a rare case of Goodpasture's syndrome associated with not only anti-GBM antibodies, but also MPO-ANCA.

Aged↗
PubMed1997

p16INK4, pRB, p53 and cyclin D1 expression and hypermethylation of CDKN2 gene in thymoma and thymic carcinoma.

There have been few reports on genetic alterations in thymomas. To investigate the expression of p16INK4A, RB, p53 and cyclin D1 in thymomas, we first examined 36 thymomas (non-invasive type, 16 cases; invasive type, 20 cases) and 3 thymic carcinomas, using immunohistochemistry. Abnormal expression of p16INK4A, RB, p53 and cyclin D1 was observed in 18, 8, 10 and 7 cases, respectively. Only a subgroup of invasive thymomas and thymic carcinomas showed an inverse correlation between p16INK4A and RB expression. Subsequently, we examined the 36 thymomas and 4 thymic carcinomas for mutations in p53 and CDKN2 genes, using PCR-SSCP and direct-sequencing analyses. No mutation of these genes was detected in the thymomas and thymic carcinomas examined. A polymorphism in the 3' untranslated region of exon 3 of CDKN2 was detected in 5 cases of thymoma. We searched for hypermethylation in the promoter region of CDKN2, observing it in 4 thymomas and 1 thymic carcinoma. Our data suggest that, unlike other more common cancers, alteration of the p53 gene may not play a significant role in the tumorigenesis of thymoma. However, inactivation of p16INK4A and RB may play a role in the progression of thymoma and thymic carcinoma.

Blotting, Southern↗
PubMed1997

Swelling-induced Cl- current in guinea-pig atrial myocytes: inhibition by glibenclamide.

1. Whole-cell currents were recorded from guinea-pig atrial myocytes using the patch-clamp technique under conditions designed to block K+ channels, Ca2+ channels and electrogenic transporters. 2. Exposure of atrial myocytes to the hyposmotic external solution (Na+ reduction to about 70% of control) resulted in hyposmotic cell swelling which was associated with activation of an outwardly rectifying Cl- current (ICl,swell). 3. Whereas the activation of ICl,swell was not significantly affected by replacement of ATP in the pipette solution with the non-hydrolysable ATP analogue 5'-adenylyl-imidodiphosphate (AMP-PNP), its activation was greatly reduced in cells dialysed with an ATP-free pipette solution, thus indicating that the activation process of ICl,swell requires the presence of intracellular ATP, but not its hydrolysis. 4. Bath application of glibenclamide produced a concentration-dependent block of ICl,swell with a half-maximal inhibitory concentration (IC50) of 60.0 microM and a Hill coefficient of 2.1. The maximal effect (100% inhibition) was obtained with 500 microM glibenclamide. The steady-state inhibition showed little voltage dependence, while glibenclamide at concentrations of more than 100 microM inhibited the outward ICl,swell more rapidly than the inward ICl,swell. The glibenclamide inhibition was fully reversible after removal of the drug, even when a maximal effect (full inhibition) was achieved at a high drug concentration (500 microM). 5. These results show that (i) glibenclamide is one of the most potent inhibitors of guinea-pig atrial ICl,swell, and (ii) atrial ICl,swell and the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- currents are almost equally sensitive to inhibition by glibenclamide.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1997

Characterization of chymase from human vascular tissues.

A chymostatin-sensitive angiotensin II-generating enzyme was found in human gastroepiploic arteries. The enzyme was purified using heparin affinity and gel filtration columns. The molecular mass of the purified enzyme was 30 kDa, and the optimum pH was between 7.5 and 9.0. Enzyme activity was inhibited by soybean trypsin inhibitor, phenylmethylsulfonyl fluoride and chymostatin, but not by ethylenediaminetetraacetic acid, pepstatin and aprotinin. The enzyme rapidly converted angiotensin I to angiotensin II (K(m), 67 mumol/l; Vmax, 43 pmol/s, kcat, 65/s), but did not hydrolyse angiotensin II, substance P, bradykinin, vasoactive intestinal peptide, luteinizing hormone-releasing hormone, somatostatin and alpha-melanocyte-stimulating hormone. The N-terminal sequence was identical to the sequence for human skin/heart chymase. Thus, the chymostatin-sensitive angiotensin II-generating enzyme in human vascular tissues is identified as chymase.

Adult↗
PubMed1997

Topological rules for membrane protein assembly in eukaryotic cells.

Insertion into the endoplasmic reticulum membrane of model proteins with one, two, and four transmembrane segments and different distributions of positively charged residues in the N-terminal tail and the polar loops has been studied both in vitro and in vivo. Membrane insertion of these same constructs has previously been analyzed in Escherichia coli, thus making possible a detailed comparison between the topological rules for membrane protein assembly in prokaryotic and eukaryotic cells. In general, we find that positively charged residues have similar effects on the membrane topology in both systems when they are placed in the N-terminal tail but that the effects of charged residues in internal loops clearly differ. Our results rule out a sequential start-stop transfer model where successive hydrophobic segments insert with alternating orientations starting from the most N-terminal one as the only mechanism for membrane protein insertion in eukaryotic cells.

Amino Acid Sequence↗
PubMed1997

The mechanisms of compound 48/80-induced superoxide generation mediated by A-kinase in rat peritoneal mast cells.

This investigation was undertaken to clarify the mechanisms of superoxide anion (O2-) generation in rat peritoneal mast cells. Compound 48/80, a typical histamine liberator mediated by calcium influx, elicited O2- generation from the mast cells in a dose-dependent fashion. It was demonstrated by immunohistochemical study and Western blot analysis that the mast cells contained the 47-kDa phagocyte oxidase (p47phox) protein, which was one cytosolic component of the NADPH oxidase system. Arachidonic acid stimulated O2- generation in the mast cells, but other unsaturated fatty acids had no effect. On the other hand, 48/80-induced O2- generation was inhibited by phospholipase A2 inhibitors, such as arachidonyl trifluoromethyl ketone and manoalide. Forskolin, isoprenaline, and dibutyryl cyclic AMP inhibited the O2- generation, and KT-5720, a cyclic AMP-dependent protein kinase (A-kinase) inhibitor, markedly enhanced the O2- generation. These findings suggest that O2- is generated by a NADPH oxidase-like enzyme system in mast cells and that this enzyme system is activated by arachidonic acid released by cytosolic phospholipase A2. Thus, it is regulated by the cyclic AMP-A kinase system.

Animals↗
PubMed1997

Gelatin-specific humoral and cellular immune responses in children with immediate- and nonimmediate-type reactions to live measles, mumps, rubella, and varicella vaccines.

BACKGROUND: This study was designed to investigate the development of both cellular and humoral immune responses to gelatin in patients with vaccine-related immediate and nonimmediate reactions. Our purpose was to define the nature of the responses in the different clinical states. METHODS: Six patients with immediate reactions and 21 patients with nonimmediate reactions after inoculation of various live vaccines were studied. Measurement of gelatin-specific IgE was performed in all subjects. Gelatin-specific T-cell responses detected by an in vitro lymphocyte proliferation assay and by an assay for IL-2 responsiveness were investigated to compare the immune response in patients with the two types of reaction. RESULTS: All six patients with immediate reactions had IgE responses to gelatin, whereas none of the 21 patients with nonimmediate reactions had any anti-gelatin IgE. All of the six patients with immediate reactions and 17 of the 21 patients with nonimmediate reactions exhibited positive T-lymphocyte responses specific to gelatin. CONCLUSIONS: Immediate and nonimmediate reactions are caused by different types of allergy to gelatin, and cell-mediated immunity to gelatin may play an important role in the pathogenesis of nonimmediate reactions.

Antibodies, Viral↗
PubMed1997

Systemic immediate-type reactions to gelatin included in Japanese encephalitis vaccines.

Three children had systemic immediate-type reactions to Japanese encephalitis (JE) vaccine which contains gelatin as a stabilizer. We found that all the children had anti-gelatin IgE in their sera. Further, two of the three also had experienced systemic allergic reactions to gelatin-containing foods before the vaccination. We assume that the systemic allergic reactions to JE vaccines might be caused by gelatin in the JE vaccine.

Anaphylaxis↗
PubMed1997

Characterization and management of deep neck infections.

A retrospective review was conducted of 91 patients with deep neck infections to determine the pattern of clinical disease and formulate a management plan. The spaces involved, as determined by clinical, radiologic, and operative findings, were the peritonsillar space (72 patients), parapharyngeal space (eight patients) submandibular space (seven patients), retropharyngeal space (one patient) superficial space (one patient), anterior visceral space (one patient), and visceral vascular space (one patient). Of the 19 patients who did not have a peritonsillar space infection the origin of the infection was found in eight; four of these were odontogenic. Thirty-eight patients required surgical drainage of the abscess. Five patients underwent tracheotomy due to increasing dyspnea. One patient with diabetes mellitus and a past history of myocardial infarction died of unknown cause. All other patients had an uneventful recovery without major complications. The combination of early radiologic diagnosis, effective antimicrobial therapy, and intensive surgical management contributed to the good prognosis.

Abscess↗