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Biomedical subjects

Y Hirata

Publications and source records attributed to Y Hirata.

At least 127 records · Page 7Linked to original sources
PubMed2000

[Study of matrix metalloproteinase-2 and -9 in thyroid papillary cancer].

Metastasis of cancer starts with the penetration of cancer cells through the membrane surrounding the cancer focus into the stroma (extracellular matrix). The focal membrane consists of mainly type-IV collagen. An immunochemical study of 28 patients with benign thyroid nodular diseases and 27 patients with papillary carcinoma revealed the fragmentation of type-IV collagen in 4 patients with papillary carcinoma. Matrix metalloprotease (MMP)-2 and MMP-9 are the major enzymes which decompose type-IV collagen, and they have been suggested to be related to cancer metastasis. Therefore, we conducted biochemical and immunohistochemical studies to determine the relationship between these MMPs and the degree of malignancy in thyroid diseases. The concentration of MMP-2 in the serum of patients with papillary carcinoma and patients with benign nodules was 526.0 +/- 96.6 and 522.7 +/- 114.6 ng/ml, respectively, and that of MMP-9 was 53.8 +/- 40.3 and 39.9 +/- 36.0 respectively. There was no significant difference between the two groups in the concentration of either enzyme. The concentration of TIMP-2 in the serum was below the detectable level. On the other hand, the concentration of MMP-2 in the tissue of papillary carcinoma, benign nodules and normal tissue was 12.1 +/- 8.1, 5.7 +/- 4.3, and 0.6 +/- 0.5 ng/mg tissue protein, respectively, and that of MMP-9 was 4.2 +/- 4.1, 2.1 +/- 1.7, and 0.4 +/- 0.3 ng/mg tissue protein, respectively. Concentrations of both enzymes were significantly higher in the papillary carcinoma tissue. Immunohistochemical studies revealed a diffuse granular distribution of MMP-2 in the cytoplasm of the tumor cells. These findings imply that MMP-2 and MMP-9 are related to the degree of malignancy of cancer, especially metastasis.

Biomarkers, Tumor↗
PubMed2000

[Toxicosis of high-dose methotrexate (HD-MTX) for osteosarcoma, cured with treatment by leucovorin (LV) rescue and hemoperfusion--a case report].

A 17-year-old boy suffered from osteosarcoma in his left distal femur. He was treated with 4 courses of HD-MTX preoperatively, then a wide resection and replacement with endprosthesis was performed. After surgery, 4 more courses of HD-MTX were administered. In the last course of HD-MTX, the serum level of MTX had not decreased to a safe level after 48 hours following MTX administration. Liver and renal dysfunction then occurred, so massive leucovorin rescue and hemoperfusion were done. Fortunately, all complications disappeared. The patient is alive and well, and has been disease free for six years since surgery.

Adolescent↗
PubMed2000

Identification of a 97-kDa mastoparan-binding protein involving in Ca(2+) release from skeletal muscle sarcoplasmic reticulum.

Mastoparan (MP) and radiolabeled [Tyr(3)]MP caused a transient Ca(2+) release from the heavy fraction of sarcoplasmic reticulum, which was inhibited by ryanodine. MP enhanced [(3)H]ryanodine binding in a concentration-dependent manner with an EC(50) value of approximately 0.3 microM. The (45)Ca(2+) release was accelerated by MP, [Tyr(3)]MP, or caffeine in a concentration-dependent manner. The EC(50) values for MP, [Tyr(3)]MP, and caffeine were approximately 2. 0 microM, 7.7 microM, and 1.8 mM, respectively. MP, like caffeine, shifted the stimulatory limb of a bell-shaped curve of Ca(2+) dependence to the left. (45)Ca(2+) release induced by caffeine was completely inhibited by typical blockers of Ca(2+)-induced Ca(2+) release, such as Mg(2+), ruthenium red, or procaine. However, (45)Ca(2+) release induced by MP was completely inhibited by Mg(2+), but it was only partially inhibited by ruthenium red or procaine. The rate of (45)Ca(2+) release induced by MP was further increased in the presence of caffeine, showing that the MP binding site is different from that of caffeine on Ca(2+) release channels. We succeeded in the synthesis of (125)I-[Tyr(3)]MP with a high specific activity. (125)I-[Tyr(3)]MP bound specifically to heavy fraction of sarcoplasmic reticulum with a K(d) value of 4.0 microM and a B(max) value of 3.0 nmol/mg. Furthermore, (125)I-[Tyr(3)]MP specifically cross-linked to the 97-kDa protein without direct binding to ryanodine receptor. The protein was not triadin or Ca(2+)-pump, because antitriadin antibody and anti-Ca(2+)-pump antibody did not immunoprecipitate the protein. These results suggest that the 97-kDa MP-binding protein may have an important role in the excitation-contraction coupling of skeletal muscle.

Animals↗
PubMed2000

[Changes in the antibacterial activity of chemotherapeutic agents (especially carbapenems) for 10 species of clinical isolates between 1994 and 1996. Surveillance group of the sensitivities of clinical isolates to antibacterial agents].

During October and December of each year of from 1994 to 1996, 3,849 strains of 10 species of bacteria were isolated from clinical materials in 21 institutions nationwide. The minimum inhibitory concentrations (MICs) for these bacteria of four carbapenems (imipenem [IPM], panipenem [PAPM], meropenem [MEPM], and biapenem [BIPM]) and other representative antibacterial agents were measured to investigate annual changes in antibacterial activity. Carbapenems showed potent activity against methicillin-sensitive S. aureus (MSSA), S. pneumoniae, E. faecalis, H. influenzae, E. coli, K. pneumoniae, E. cloacae, S. marcescens, and the B. fragilis group, with the activity being stable. However, these drugs showed weak activity against methicillin-resistant S. aureus (MRSA) and P. aeruginosa. The antibacterial activity (MIC90) against the tested organisms generally remained stable. Particularly, there was annual improvement of the MIC90 values of IPM and BIPM for S. pneumoniae, as well as the values of IPM and PAPM for H. influenzae, and those of IPM, PAPM, and BIPM for S. marcescens. On the other hand, the activity of carbapenems (including IPM) against MRSA was not necessarily strong, but there was annual improvement of MIC90 values.

Bacteria↗
PubMed2000

[Endothelin].

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Endothelins↗
PubMed2000

[Nitric oxide].

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Humans↗
PubMed2000

[Vascular and metabolic reserve in a case of hypoplasia of bilateral internal carotid arteries].

We report a 64-year-old right-handed man who presented with a hypoplasia of bilateral internal carotid arteries (ICAs). The patient complained of a vertigo and was diagnosed as having a benign paroxysmal positional vertigo. Upon neurological examination, he was completely free from neurological deficits. MR angiogram revealed an occlusion of both ICAs. On conventional angiogram, the right ICA was occluded about 3 cm distal from its origin, and the left ICA was occluded at the precavernous portion. There was an abundant collateral blood flow to the frontal, temporal and parietal lobes through the posterior communicating arteries. Both carotid canals were hypoplastic on 3D-CT. The patient was then diagnosed as having a hypoplasia of both ICAs. Using a positron emission tomography (PET), cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO2), oxygen extraction fraction (OEF), and vascular transit time (VTT) were measured during resting state, and the vascular reactivities to carbon dioxide inhalation (VRCO2), and to the intravenous administration of Acetazolamide (VRACZ) were also evaluated. There was no global or focal reduction in CBF and VTT was within normal limit, whereas a global reduction of CMRO2 caused mild decrease in OEF. Moreover, VRACZ was significantly decreased and an intracerebral steal phenomenon was observed in the parietal cortical areas, whereas VRCO2 was preserved. The discrepancy between VRACZ and VRCO2 observed could be related to the differences in the mechanisms underlying the vasodilating effects of carbon dioxide and ACZ.

Arterial Occlusive Diseases↗
PubMed1999

Intracellular signaling of angiotensin II-induced p70 S6 kinase phosphorylation at Ser(411) in vascular smooth muscle cells. Possible requirement of epidermal growth factor receptor, Ras, extracellular signal-regulated kinase, and Akt.

Activation of p70 S6 kinase (p70(S6K)) by growth factors requires multiple signal inputs involving phosphoinositide 3-kinase (PI3K), its effector Akt, and an unidentified kinase that phosphorylates Ser/Thr residues (Ser(411), Ser(418), Ser(424), and Thr(421)) clustered at its autoinhibitory domain. However, the mechanism by which G protein-coupled receptors activate p70(S6K) remains largely uncertain. By using vascular smooth muscle cells in which we have demonstrated Ras/extracellular signal-regulated kinase (ERK) activation through Ca(2+)-dependent, epidermal growth factor (EGF) receptor transactivation by G(q)-coupled angiotensin II (Ang II) receptor, we present a unique cross-talk required for Ser(411) phosphorylation of p70(S6K) by Ang II. Both p70(S6K) Ser(411) and Akt Ser(473) phosphorylation by Ang II appear to involve EGF receptor transactivation and were inhibited by dominant-negative Ras, whereas the phosphorylation of p70(S6K) and ERK but not Akt was sensitive to the MEK inhibitor. By contrast, the phosphorylation of p70(S6K) and Akt but not ERK was sensitive to PI3K inhibitors. Similar inhibitory pattern on these phosphorylation sites by EGF but not insulin was observed. Taken together with the inhibition of Ang II-induced p70(S6K) activation by dominant-negative Ras and the MEK inhibitor, we conclude that Ang II-initiated activation of p70(S6K) requires both ERK cascade and PI3K/Akt cascade that bifurcate at the point of EGF receptor-dependent Ras activation.

Angiotensin II↗
PubMed1999

Fluorescent Indicators for Imaging Nitric Oxide Production.

The membrane-permeating indicator DAF-FM DA is transformed by intracellular esterases into the highly water-soluble dye DAF-FM, which traps NO produced by NO synthase (NOS) to yield a highly fluorescent triazole compound in cells (see schematic diagram). Monitoring with a fluorescence microscope should allow direct identification of intracellular production and location of NO.

Journal Article↗
PubMed1999

Identification of 30 kDa protein for Ca(2+) releasing action of myotoxin a with a mechanism common to DIDS in skeletal muscle sarcoplasmic reticulum.

The molecular mechanism of Ca(2+) release by myotoxin a (MTYX), a polypeptide toxin isolated from the venom of prairie rattlesnakes (Crotalus viridis viridis), was investigated in the heavy fraction of sarcoplasmic reticulum (HSR) of rabbit skeletal muscles. [(125)I]MYTX bound to four HSR proteins (106, 74, 53 and 30 kDa) on polyvinylidene difluoride (PVDF) membrane. DIDS, 4, 4'-diisothiocyanatostilbene-2,2'-disulfonic acid, bound predominantly to 30 kDa protein on the PVDF membrane, the molecular weight of which was similar to one of the MYTX binding proteins. The maximum (45)Ca(2+) release induced by caffeine (30 mM) was further increased in the presence of MYTX (10 microM) or DIDS (30 microM), whereas that induced by DIDS (30 microM) was not affected by MYTX (10 microM). MYTX inhibited [(3)H]DIDS binding to HSR in a concentration-dependent manner. Furthermore, [(125)I]MYTX binding to 30 kDa protein was inhibited by DIDS in a concentration-dependent manner. These results suggest that MYTX and DIDS release Ca(2+) from HSR in a common mechanism. The 30 kDa protein may be a target protein for the Ca(2+) releasing action of MYTX and DIDS.

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