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Biomedical subjects

Y Okada

Publications and source records attributed to Y Okada.

At least 19 recordsLinked to original sources
PubMed1992

Collagenase expression in the lungs of transgenic mice causes pulmonary emphysema.

Transgenic mice were generated that expressed a human collagenase transgene in their lungs under the direction of the haptoglobin promoter. Histological analysis demonstrated disruption of the alveolar walls and coalescence of the alveolar spaces with no evidence of fibrosis or inflammation. This pathology is strikingly similar to the morphological changes observed in human emphysema and therefore implicates interstitial collagenase as a possible etiological agent in the disease process. Although elastase has been proposed as the primary enzyme responsible for emphysematous lung damage, this study provides evidence that other extracellular matrix proteases could play a role in emphysema. In addition, these transgenic mice are a defined genetic animal model system to study the pathogenesis of emphysema.

Animals↗
PubMed1992

Attenuation of ischemic and postischemic damage to brain metabolism and circulation by a novel Ca2+ channel antagonist, NC-1100, in spontaneously hypertensive rats.

We investigated the effect of a newly synthesized Ca2+ channel antagonist, NC-1100, on cerebral blood flow (CBF) and metabolism in spontaneously hypertensive rats. The rats received a bolus injection of 0.2 or 1.0 mg/kg NC-1100 i.v. and 1-h cerebral ischemia was then induced by bilateral carotid artery occlusion (group 1). The rats in group 2 were continuously infused with NC-1100 0.03 or 0.1 mg/kg per min, starting immediately after bilateral carotid artery occlusion, for the 1 h of ischemia and following 3-h recirculation. Group 1: during ischemia, CBF in all rats decreased to 6-8% of the resting values. At 1 h cerebral ischemia, brain tissue lactate increased 11.5-, 10.1- and 9.8-fold of the normal control given vehicle or NC-1100, 0.2 and 1.0 mg/kg, respectively. The ATP levels were better preserved by NC-1100 administration; 0.61 +/- 0.04 (mean +/- S.E.M.), 0.80 +/- 0.09 and 0.97 +/- 0.14 mmol/kg (P < 0.05 vs. vehicle), respectively. Group 2: during recirculation, CBF in NC-1100-treated rats returned to 83-90% of the resting values, but to only 65% in the vehicle group. Postischemic brain lactate at 3 h was less well preserved and ATP was dose dependently better preserved in NC-1100- than vehicle-treated rats. It is considered that pre- as well as postischemic administration of a Ca2+ channel antagonist, NC-1100, is beneficial to attenuate and also ameliorate the metabolic and circulatory derangement in the ischemic brain.

Adenosine Triphosphate↗
PubMed1992

Crystal structure of papain-succinyl-Gln-Val-Val-Ala-Ala-p-nitroanilide complex at 1.7-A resolution: noncovalent binding mode of a common sequence of endogenous thiol protease inhibitors.

Succinyl-Gln-Val-Val-Ala-Ala-p-nitroanilide corresponding to a common sequence of endogenous thiol protease inhibitors is a noncompetitive reversible inhibitor of papain. In order to elucidate the binding mode of the inhibitor at the atomic level, its complex with papain was crystallized at ca. pH 7.0 using the hanging drop method, and the crystal structure was analyzed at 1.7-A resolution. The crystal has space group P2(1)2(1)2(1), with a = 43.09, b = 102.32, c = 49.69 A, and Z = 4. A total of 47,215 observed reflections were collected on the imaging plates using the same single crystal, and 19,833 unique reflections with Fo > sigma (Fo) were used for structure determination and refinement. The papain structure was determined by use of the atomic coordinates of papain previously reported, and then refined by the X-PLOR program. The inhibitor molecule was located on a difference Fourier map and fitted into the electron density with the aid of computer graphics. The complex structure was finally refined to R = 19.6% including 118 solvent molecules. The X-ray analysis of the complex crystal shows that the inhibitor is located at the R-domain side, not in the center of the binding site created by the R- and L-domains of papain. Such a binding mode of the inhibitor explains well the biological behavior that the inhibitor exhibits against papain. Comparison with the structure of papain-stefin B complex indicates that the structure of the Gln-Val-Val-Ala-Gly sequence itself is not necessarily the essential requisite for inhibitory activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

In vivo phosphorylation of the 30-kDa protein of tobacco mosaic virus.

The 30-kDa protein of tobacco mosaic virus, which is involved in cell-to-cell movement function, is phosphorylated in tobacco protoplasts. To investigate which portion of the protein is phosphorylated we inoculated several truncated 30-kDa protein mutants into protoplasts and determined whether or not those truncated proteins are phosphorylated. The results showed that amino acid residues 234-261 of the 30-kDa protein are required for this phosphorylation.

Amino Acid Sequence↗
PubMed1992

Matrix metalloproteinase 9 (92-kDa gelatinase/type IV collagenase) from HT 1080 human fibrosarcoma cells. Purification and activation of the precursor and enzymic properties.

Matrix metalloproteinase 9 (MMP-9) has been purified as an inactive zymogen of M(r) 92,000 (proMMP-9) from the culture medium of HT 1080 human fibrosarcoma cells. The NH2-terminal sequence of proMMP-9 is Ala-Pro-Arg-Gln-Arg-Gln-Ser-Thr-Leu-Val-Leu-Phe-Pro, which is identical to that of the 92-kDa type IV collagenase/gelatinase. The zymogen can be activated by 4-aminophenylmercuric acetate, yielding an intermediate form of M(r) 83,000 and an active species of M(r) 67,000, the second of which has a new NH2 terminus of Met-Arg-Thr-Pro-Arg-(Cys)-Gly-Val-Pro-Asp-Leu-Gly-Arg-Phe-Gln-Thr- Phe-Glu. Immunoblot analyses demonstrate that this activation process is achieved by sequential processing of both NH2- and COOH-terminal peptides. TIMP-1 complexed with proMMP-9 inhibits the conversion of the intermediate form to the active species of M(r) 67,000. The proenzyme is fully activated by cathepsin G, trypsin, alpha-chymotrypsin, and MMP-3 (stromelysin 1) but not by plasmin, leukocyte elastase, plasma kallikrein, thrombin, or MMP-1 (tissue collagenase). During the activation by MMP-3, proMMP-9 is converted to an active species of M(r) 64,000 that lacks both NH2- and COOH-terminal peptides. In addition, HOCl partially activates the zymogen by reacting with an intermediate species of M(r) 83,000. The enzyme degrades type I gelatin rapidly and also cleaves native collagens including alpha 2 chain of type I collagen, collagen types III, IV, and V at undenaturing temperatures. These results indicate that MMP-9 has different activation mechanisms and substrate specificity from those of MMP-2 (72-kDa gelatinase/type IV collagenase).

Amino Acid Sequence↗
PubMed1992

A one-step sandwich enzyme immunoassay for human matrix metalloproteinase 3 (stromelysin-1) using monoclonal antibodies.

A one-step sandwich enzyme immunoassay (EIA) for matrix metalloproteinase 3 (MMP-3; stromelysin-1) was developed. The assay system used two simultaneous immunoreactions using a solid phase monoclonal antibody and a horseradish peroxidase-labeled monoclonal antibody (Fab'). The sensitivity of the assay system was 20 micrograms/l and linearity was obtained between 31 and 500 micrograms/l. The EIA system was capable of measuring both precursor and active forms of MMP-3 as well as the forms of MMP-3 complexed with tissue inhibitors of metalloproteinases. MMP-3 levels as measured by this assay are significantly higher in the sera of patients with rheumatoid arthritis as compared to those of healthy subjects and patients with osteoarthritis. Immunoblot analyses showed that in the sera and synovial fluids of patients with rheumatoid arthritis, MMP-3 is present in the 59- and 57-kDa precursor forms.

Animals↗
PubMed1992

Excitatory effect of adenosine on neurotransmission is due to increase of transmitter release in the hippocampal slices.

Adenosine has dose-dependent biphasic excitatory and inhibitory effects on neurotransmission in the hippocampus. The mechanism of the excitatory action is not known although that of the inhibitory action has been well analyzed. Here we report on the mechanism of excitatory action of adenosine, using hippocampal slices. Studies of intracellular recordings of CA3 pyramidal neurons showed that the amplitude of EPSP was dramatically enhanced by application of adenosine at low concentration (0.1 microM) without changing resting membrane potentials, membrane conductance or the threshold for spike generation by injecting current pulses. On the other hand, the presence of adenosine at a concentration of 0.1 microM during electrical stimulation to the slices increased 1.7 times the release of glutamate, an excitatory neurotransmitter in the hippocampus. These results indicate that the excitatory action of adenosine at low doses is due to the increase of transmitter release.

Adenosine↗
PubMed1992

E4080 has a dual action, as a K+ channel opener and a Ca2+ channel blocker, in canine coronary artery smooth muscle.

To clarify the vasodilating mechanism of action of E4080, which possesses vasodilating and bradycardic effects, we investigated its effects on intracellular Ca2+ concentrations ([Ca2+]i), as measured with fura-2, and force of contraction in canine coronary artery. E4080 reduced the increase in [Ca2+]i and force of contraction induced by 30 and 90 mM KCl physiological salt solution (PSS) in a concentration-dependent manner. The effects of E4080 in 30 mM KCl-PSS were inhibited by 10(-5) M glibenclamide. In 30 mM KCl-PSS, the slope of the [Ca2+]i-force relationship in the presence of E4080 was steeper than that of control, suggesting that E4080 decreased the sensitivity of contractile elements to Ca2+, as an effect which was also inhibited by glibenclamide. However, the [Ca2+]i-force curve was not changed by E4080 in 90 mM KCl-PSS. These results suggest that E4080 is a vasodilator in canine coronary artery, having K+ channel opening and Ca2+ channel blocking actions. The membrane hyperpolarization induced by E4080 may reduce the sensitivity of contractile elements to Ca2+.

Analysis of Variance↗
PubMed1992

Exocytosis upon osmotic swelling in human epithelial cells.

Upon osmotic swelling human epithelial cells exhibited significant increases in the membrane capacitance. Evidence for exocytosis includes its dependency on temperature, cytosolic Ca2+ and ATP as well as its sensitivity to guanosine 5'-O-(3-thio)triphosphate (GTP gamma S) and N-ethylmaleimide (NEM). A role of the osmotic exocytosis in the subsequent cell volume regulation is suggested.

Adenosine Triphosphate↗
PubMed1992

Post-inhibitory excitation of adenosine on neurotransmission in guinea pig hippocampal slices.

The postsynaptic field potential (population spike potential; PS) was recorded from the granule cell layer of guinea pig hippocampal slices. Adenosine at low concentrations ranging from 10 nM to 1 microM enhanced the amplitude of PS, whereas at concentrations over 10 microM it inhibited the neurotransmission. There appeared to be a rebound phenomenon after the removal of adenosine at inhibitory concentrations and the amplitude of the PS overshot the initial amplitude (we called this post-inhibitory excitation; PIE). Neither depressants such as gamma-aminobutyric acid (GABA; 1 mM) nor sodium pentobarbital (100 microM) by itself induced PIE. After application of GABA or sodium pentobarbital together with adenosine (0.1 microM), however, removal of all agents could induce the PIE. PIE as well as the excitatory effect of adenosine at low concentrations was counteracted by application of H-7 (100 microM), melittin or polymyxin B, potent protein kinase C (PKC) inhibitors, suggesting that the excitatory effect of adenosine is mediated by a metabolic process involving PKC. These results indicate that PIE induced by adenosine at high concentrations is due to a mechanism similar to the excitatory effect induced by adenosine at low concentrations, and that during application of adenosine at high concentrations the excitation is masked by its potent inhibitory effect.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

Selective reduction of glutamate in the rat superior colliculus and dorsal lateral geniculate nucleus after contralateral enucleation.

The effects of afferent lesions on the levels of glutamate, aspartate and gamma-aminobutyric acid (GABA) in the laminae of the superior colliculus (SC) and dorsal lateral geniculate nucleus (dLGN) of the rat were studied, using microassay methods for these amino acids. The analysis was performed 12-14 days after left eye enucleation, or ablation of right visual cortical area, or both left eye enucleation and ablation of right visual cortex. Superficial gray layer (SGL) and deep layers in the SC were dissected out from the thin-sectioned, freeze-dried sample. In the dLGN, the outer and inner laminae were separately dissected. The glutamate contents in the upper half of SGL and outer lamina of dLGN contralateral to eye enucleation decreased significantly (15%). Combination of eye enucleation and visual cortical ablation further decreased the glutamate content in the upper half of the right SGL (29.3%). On the other hand, aspartate and GABA concentrations in the SC and dLGN exhibited no significant reduction after deafferentations. These results indicate that the retino-tectal and retino-geniculate pathway of the rat may be glutamatergic in nature.

Animals↗
PubMed1992

In vivo microdialysis of amino acid neurotransmitters in the hippocampus in amygdaloid kindled rat.

Extracellular concentrations of gamma-aminobutyric acid (GABA), glutamate (Glu) and aspartate (Asp) were determined by microdialysis in rat hippocampus during various amygdaloid kindled stages. The values of GABA and Glu were increased 3-4 times in C2-C3 stages in comparison with the values in control animals. After reaching the C5 stages, these values were increased 3-7 times. However, the concentration of Asp decreased depending on the kindling stage, reaching the lowest value of 33% in comparison with the normal value. The observed changes may be related to kindling induced seizures.

Amygdala↗
PubMed1992

Liquid chromatographic/atmospheric pressure chemical ionization mass spectrometric analysis of synthetic elastase inhibitor peptide.

A liquid chromatographic/atmospheric pressure chemical ionization mass spectrometric method for the determination of tert-butyloxycarbonyl-Tyr-Leu-Val-CH2Cl (Boc-YLV-CH2Cl) was investigated. Boc-YLV-CH2Cl was eluted from a Cosmosil 5C8 column in a solvent system of 0.1% acetic acid-methanol (30: 70, v/v). The positive ion spectrum of Boc-YLV-CH2Cl showed a quasi-molecular ion at m/z 526 with fragment ions which provided structural information. Boc-YLV-CH2Cl was purified from blood and tissue samples with Sep-Pak C18 cartridges. The analysis in biological samples was performed by focusing the characteristic ion at m/z 526. The calibration graphs were linear over the concentration range studied (injected amounts of 9.5-190 pmol). The method was applied to the determination of Boc-YLV-CH2Cl in biological samples.

Amino Acid Sequence↗
PubMed1992

A finding of highly selective synthetic inhibitor of plasma kallikrein; its action to bradykinin generation, intrinsic coagulation and experimental DIC.

We found a novel and highly selective synthetic inhibitor of plasma kallikrein (PK), called PKSI-527; the Ki value was 0.81 microM. PKSI-527 inhibited the bradykinin (BK) generation induced by kaolin and prolonged partial thromboplastin time (PTT). PKSI-527 prevented the decrease of fibrinogen (Fg) levels due to i.v. injection of ellagic acid in mice and ameliorated the endotoxin (ET)-induced DIC in rats.

Animals↗
PubMed1992

Membrane capacitance increases induced by histamine and cyclic AMP in single gastric acid-secreting cells of the guinea pig.

During acid secretion, gastric parietal cells undergo profound morphological changes including formation of the apical secretory membrane. To examine the mechanism of histamine-induced increases in the apical membrane area at the single cell level, we monitored the membrane capacitance by applying a time-resolved phase-sensitive detection method to singly isolated parietal cells of guinea pig. A real-time increase in the membrane capacitance was detected within several min after stimulation with histamine. An H2-blocker (cimetidine), but not an H1-blocker (pyrilamine), inhibited the histamine response. Dibutyryl cyclic AMP mimicked the histamine effect. The capacitance response to histamine was sensitive to cytosolic Ca2+, temperature and N-ethylmaleimide. The histamine response was inhibited by intracellular application of a non-hydrolyzable ATP analog (AMP-PNP) and an isoquinolinesulfonamide derivative that works as an inhibitor of protein kinase A (H-8). These results indicate that in parietal cells, elevation of intracellular cyclic AMP induces exocytotic insertion of intracellular membranes into the plasma membrane, presumably by activating protein kinase A.

Animals↗
PubMed1992

Clinicopathological study on combination therapy consisting of arterial infusion of lipiodol-dissolved SMANCS and transcatheter arterial embolization for hepatocellular carcinoma.

Combination therapy (LpTAE) consisting of arterial infusion of a lipophilic anticancer drug, SMANCS, dissolved in an oily lymphographic agent, lipiodol (LPD), and transcatheter arterial embolization (TAE) for hepatocellular carcinoma (HCC) was studied with special reference to the pathological findings. A total of 32 patients were subjected to surgical resection after LpTAE. The pattern of LPD deposition in the tumor was examined by CT scan (Lipiodol CT, LpCT) at 7 days and/or 1 month after LpTAE. The resected materials were examined radiographically with soft X-rays and histologically. LPD was deposited in tiny daughter nodules with a diameter of less than 5 mm and in tumor thrombi as well as in the main tumors, which showed necrotic change. Part of the LPD flowed out from the main tumor via the drainage vein and was deposited in the capsular invasion, resulting in necrosis. LPD accumulated almost exclusively within the blood spaces of trabecular-type HCC, creating a pattern corresponding to a cast of the tumor vessels, which showed prominent necrosis. On the other hand, LPD was not deposited in scirrhous, compact, or well-differentiated HCC, which showed little or no necrosis. It was demonstrated that LpCT images, which accurately depicted the existence and the extent of LPD deposition and necrosis in the tumor, were useful for precise evaluation of the therapeutic effect. Our findings indicate that LpTAE and LpCT are valuable for the diagnosis and treatment of HCC and should play a central role in systemic therapeutic approaches to this disease.

Adult↗
PubMed1992

Cellular variant of extraskeletal myxoid chondrosarcoma of abdominal wall--a case report with comparative immunohistochemical study on cartilaginous collagenous proteins in various myxoid mesenchymal tumors.

A rare cellular variant of recurrent extraskeletal myxoid chondrosarcoma occurring in the right lower abdominal wall of a 70-year-old man, is presented with emphasis on a characteristic distribution pattern of cartilaginous collagen proteins in the stroma. While the primary and the first recurrent tumors showed the typical histology of extraskeletal myxoid chondrosarcoma, the later tumor, which recurred 14 years after the first resection, comprised mostly compact nodules of proliferating anaplastic cells with little mucoid stroma. Some areas presented a hemangiopericytomatous pattern. A few nodules possessed abundant myxoid stroma. Immunohistochemically, type II collagen was demonstrated in the stroma of some cellular areas, and type VI collagen was intensely stained around individual tumor cells both in cellular and myxoid areas. In a comparative immunohistochemical study, the same distribution pattern of cartilaginous collagen proteins was observed only in skeletal myxoid chondrosarcomas, but not in other mesenchymal tumors with abundant myxoid stroma. These findings seem to support the cartilaginous nature of extraskeletal myxoid chondrosarcoma, and will facilitate the differential diagnosis of soft-tissue tumors with myxoid stroma.

Abdominal Muscles↗