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Biomedical subjects

Y Shibata

Publications and source records attributed to Y Shibata.

At least 595 records · Page 33Linked to original sources
PubMed1989

[Immunochemical characterization of platelet-specific alloantigen Baka].

We investigated the location of platelet-specific alloantigen Baka on platelet membrane glycoproteins. In indirect immunoprecipitation experiments, the anti-Baka antibody precipitated glycoprotein (GP) II b and a small amount of GP III a. The immunoblots using partially purified GP II b/III a complex as the target antigen indicated that GP II b alpha carried the Baka alloantigen. When the partially purified GP II b/III a complex digested with chymotrypsin was examined, the Baka alloantigen was found on a 65 kD fragment derived from GP II b alpha under reducing conditions. In addition, the immunoblots after two-dimensional nonreduced-reduced SDS-PAGE directly indicated that the 65 kD fragment had a mol. wt. of 80 kD under nonreducing conditions. The immunoblots using platelets digested in situ with chymotrypsin indicated that the 65 kD fragment of GP II b alpha was retained by the platelet membrane. We conclude, therefore, that the Baka alloantigen is located on a 65 kD fragment that represents the membrane side of the cleavage site of chymotrypsin on GP II b alpha.

Antigens, Human Platelet↗
PubMed1989

[Effect of Actinomyces viscosus on the production of prostaglandin E2 and thromboxane B2 in macrophages].

Certain species of bacteria have been implicated in the etiology and pathogenesis of periodontal diseases. It has been reported that Actinomyces viscosus (A. viscosus) is associated with gingivitis. On the other hand, it is known that prostaglandin (PG) E2 is one of potent mediators of bone resorption and macrophage is PGE2 producing cell. It has been reported that a number of macrophage is increased in inflamed gingival tissues and that A. viscosus (T14V strain) cells significantly stimulated the arachidonic acid (AA) release and the secretion of PGE2 and thromboxane (TX) B2. Furthermore, the level of PGE2 in inflamed gingival tissues was 18 times higher than that of normal gingiva. In general, it is believed that the rate-limiting step in the production of PGs and TXs is dependent on the release of AA from phospholipids in the cell membrane. However, recent papers suggested that the produced levels of PGE2 and TXB2 were not completely dependent on the amounts of released AA, and the mechanism of rate limiting step and the PGE2 production are still remains to be elucidated. It is known that glucocorticoid, anti-inflammatory steroid, inhibits the AA release from phospholipids of cell membrane. In the present study, in order to clarify the mechanism of PGE2 and TXB2 production by the A. viscosus cells, the effect of addition of glucocorticoid on the levels of PGE2 and TXB2 production were studied. The effects of ionophore A 23187 and zymosan, which were known as agents of macrophage activation but having different action manner, on the relation between the AA release and productions of PGE2 and TXB2 were also comparatively studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Actinomyces↗
PubMed1989

[Transseptal suture fixation in the management of prosthetic valve dehiscence].

Valve dehiscence resulted from prosthetic valve endocarditis and aortitis is the most common cause of the reoperation after prosthetic valve replacement. In our experience, the results of reoperation has been far from satisfactory. For the successful management of prosthetic dehiscence, we have adopted the transseptal suture technique of accurately securing the prosthetic valve. Five patients with prosthetic valve dehiscence and one patient with native valve endocarditis were operated upon using the transseptal techniques. Left ventricular-aortic discontinuity was repaired using composite valve-tube graft together with this technique in two patients. All but one patient who succumbed to multiple organ failure induced by preoperative hemodynamic deterioration have survived the operation without recurrent infective endocarditis or valve dehiscence.

Adult↗
PubMed1989

[A case of juvenile esophageal cancer with hematemesis].

We here report a case of juvenile esophageal cancer which developed with a chief complaint of hematemesis. The case was a 36-year-old male patient who was admitted to the hospital because of dysphagia and repeated hematemesis episodes. Through various imaging studies, the patient was diagnosed as having advanced esophageal carcinoma. Since it was considered to be impossible to perform a curable surgical treatment, we tried, using a Laser apparatus, to alleviate the stenosis of the esophageal lumen and to control the bleeding from the cancerous lesion. However, an operation was finally performed after observing that the Laser therapy had not been so effective. Hematemesis is an uncommon symptom among primary complaints of esophageal cancer. The present case developed a protuberant cancerous mass which considerably obstructed the esophageal lumen. It is speculated that the patient repeatedly vomited blood which had gradually originated from ruptured capillary vessels in the tumor and had accumulated in the esophageal lumen. The histological type of the cancer was poorly-differentiated squamous cell carcinoma which partially contained an undifferentiated element. This histological nature might have accelerated the growth of the esophageal cancer in the present case.

Adult↗
PubMed1988

Phospholipase A2 in macrophage plasma membrane releases arachidonic acid from phosphatidylinositol.

A high level of arachidonic acid release from [2-14C]arachidonylphosphatidylinositol (PI) was observed at neutral pH (6.0-7.0) in the presence of purified plasma membranes of guinea pig peritoneal macrophages. This activity was at least 10-fold higher than that with arachidonylphosphatidylcholine (PC) or phosphatidylethanolamine (PE) as substrate. The accumulation of [14C]diacylglycerol and [14C]phosphatidic acid was not detected at any time, and arachidonic acid release from [14C]arachidonyldiacylglycerol was not detectable either. The data suggest that arachidonic acid release from PI may not occur via the phospholipase C pathway. In this paper, we demonstrate the possibility that arachidonic acid release from PI at neutral pH in the macrophage plasma membrane is dependent on the action of phospholipase A2 (EC 3.1.1.4) -like activity. The maximum arachidonic acid release was dependent upon both pH and substrate. Particularly, the activity of arachidonic acid release from PI at neutral pH was very high compared with that from PC or PE. We suggest that phosphatidylinositol phospholipase A2 (EC 3.1.1.52) may play an important role in providing arachidonic acid for subsequent metabolic activity in the macrophages.

Animals↗
PubMed1988

1H-NMR investigation of the interaction between RNase T1 and a novel substrate analog, 2'-deoxy-2'-fluoroguanylyl-(3'-5')uridine.

The interaction between RNase T1 and a non-hydrolysable substrate analog, 2'-deoxy-2'-fluoroguanylyl-(3'-5')uridine (GfpU), was investigated using 1H-NMR spectroscopy. In the complex, the Gfp portion takes the syn form around the glycosidic bond and the 3'-endo form for the ribose moiety, similar to those found in 3'-GMP and 2'-deoxy-2'-fluoroguanosine 3'-monophosphate (Gfp). However, in contrast to the cases of these two inhibitors, the complex formation with GfpU at pH 6.0 was found to shift the His-40 C2 proton resonance of RNase T1 to high field as much as 1 ppm. At pH 6.0, this histidine residue appears to be unprotonated in the complex, but is protonated in the free enzyme (pKa of His-40 being 7.9). His-40, rather than Glu-58, is probably involved in the catalytic mechanism as a Lewis base, supporting the recent results from site-directed mutagenesis.

Aspergillus↗
PubMed1988

(NZW x BXSB)F1 mouse. A new animal model of idiopathic thrombocytopenic purpura.

A decrease in thrombocyte count was observed in (NZW x BXSB)F1 (W/B F1) mice at the age of greater than 5 mo, whereas megakaryocyte counts were found to increase in such mice. FACS analyses revealed the presence of both platelet-associated antibodies (PAA) and circulating antiplatelet antibodies. There is a correlation between the presence of these antibodies and the degree of thrombocytopenia. The transplantation of normal bone marrow cells from BALB/c nu/nu mice to W/B F1 mice was found to have preventative and curative effects on thrombocytopenia; the mice showed normal platelet counts and no evidence of circulating antiplatelet antibodies. These results indicate that thrombocytopenia in W/B F1 mice is due to the presence of antibodies to platelets. We therefore think that W/B F1 mice serve as a useful animal model of idiopathic thrombocytopenic purpura (ITP) not only for elucidating the mechanism of the development of antiplatelet antibodies, but also for characterizing autoantibodies to platelets.

Animals↗
PubMed1988

Reactivities of human urinary prokallikrein and kallikrein toward rabbit antibodies with special reference to enzyme immunoassay.

Human urinary prokallikrein and kallikrein have been analyzed by means of solid phase enzyme immunoassay (EIA) using rabbit antibodies. The anti-kallikrein antibody-immobilized EIA detected both kallikrein and prokallikrein. However, only kallikrein was detectable at concentrations below 20 micrograms/1. The anti-prokallikrein antibody-immobilized EIA detected both kallikrein and prokallikrein, but the binding maximum for kallikrein was about one-third less than that for prokallikrein. Similar difference in reactivity of kallikrein and prokallikrein toward each antibody was observed with immunoaffinity column chromatography and single radial immunodiffusion. The results show that immunochemical properties of human urinary prokallikrein and kallikrein differ distinctly, and conflicting results on detectability of kallikrein and prokallikrein in human urine with EIA or radioimmunoassay using the anti-kallikrein antibody was due to the difference in reactivity of the two forms of kallikrein toward the immobilized antibody.

Animals↗
PubMed1988

Striped structures on the cytoplasmic surface membranes of the endothelial vesicles of the rat aorta revealed by quick-freeze, deep-etching replicas.

The cytoplasmic surface of plasmalemmal vesicles in aortic endothelial cells was examined in quick-freeze, deep-etching replicas. In addition to the clathrin-coated vesicles, striped patterns were observed over the cytoplasmic surface membranes of small vesicles (60-80 nm in diameter) in the unfixed specimens. These patterns were more clearly visible in saponin-extracted specimens; the stripes were composed of several ridges or strands of 6-10 nm in width, and some were crossed. These were distinct from the characteristic pentagons or hexagons of the clathrin-coated vesicles. This striped structure was enhanced by treatment with myosin subfragment-1 or phalloidin, thereby indicating a possible relation to actin filaments. Patchy plaques with similar striped patterns appeared on the cytoplasmic surface of the plasmalemma proper and also on the cytoplasmic vacuole membranes together with clathrin. These striped structures may be involved in the formation and transport of so-called "uncoated" vesicles.

Animals↗
PubMed1988

Effects of bone marrow ablation on compartmental prostaglandin synthesis by mononuclear phagocytes.

Mononuclear phagocyte functions were studied in mice selectively deprived of bone marrow and rendered profoundly monocytopenic by the administration of the bone seeking isotope, 89Sr. Characteristics of such mice include severe impairment of monocyte-M phi elicitation, ablation of C. parvum induction of PGSM but the persistence of resident peritoneal and pulmonary alveolar M phi populations; splenic M phi increase in number concomitantly with splenic hemopoiesis. Studies on compartmental regulation in this model suggest that the capacity of splenic M phi to synthesize and release PGE2 is dependent upon a function of the bone marrow and is not wholly determined by the local environment. The relationship of blood monocytes to PGSM is uncertain. In contrast to splenic M phi, the capacity of resident peritoneal M phi for eicosanoid synthesis appears to be independent of bone marrow function. Monocyte influx, moreover, does not appear necessary for the maintenance of the resident peritoneal and alveolar M phi populations. We do not yet know whether bone marrow ablation destroys a migratory precursor of PGSM or the source of a crucial regulatory agent. In conclusion, the observations discussed show that prostaglandin metabolism within the spleen is subject to extracompartmental influence. It is clearly important to determine the regulatory characteristics of individual M phi compartments and generalizations about functional properties of mononuclear phagocytes should be made with circumspection.

Animals↗
PubMed1988

Sex chromatin analysis of lymphocytes invading host organs in transfusion-associated graft-versus-host disease.

We report a method of sex chromatin analysis of lymphocytes separated from host organs in transfusion-associated graft-versus-host disease (GVHD), which enabled the demonstration of invasion by donor lymphocytes. The lymphocytes examined were separated from deparaffinized tissue blocks of skin, spleen and bone marrow from two female patients with transfusion-associated GVHD by incubation in 0.5% pepsin. The tissues had been removed at autopsy and fixed in formalin. Sex chromatin analysis was performed by fluorescence microscopy on separated lymphocytes stained with 0.005% quinacrine dihydrochloride. By this means Y chromatin-positive (i.e. male) lymphocytes were demonstrated in the skin, spleen and bone marrow of both female patients.

Aged↗
PubMed1988

Calcium uptake into renal brush border membranes in vitamin B6 deficient rats.

The calcium uptake into renal brush border membrane vesicles, which has been purified from normal or vitamin B6 deficient rat renal cortex by calcium precipitation, was investigated. The values of Km and Vmax were determined to be 1.89 mM and 4.26 nmol of Ca2+/mg of protein per 20s in vitamin B6 deficient rats, respectively. This Vmax was lower than that of normal rats. The chemical compositions of renal brush border membranes did not display a difference in normal and vitamin B6 deficient rats. The amount of brush border membranes isolated from 1 gram of renal cortex in vitamin B6 deficient rats was less than in normal rats.

Animals↗
PubMed1988

Recognition of acidic phospholipase A2 activity in plasma membranes of resident peritoneal macrophages.

Phospholipase (PLase) activities in the plasma membrane of guinea pig peritoneal macrophages were studied, as these enzymes having such activity may be candidates for the release of arachidonic acid (AA) from phosphatidylcholine (PC). An AA release system operating at acidic pH was identified in the macrophage plasma membrane and characterized. This membrane-bound acidic PLase A2 had an optimum pH at 4.5, and enzyme activation was observed in Ca++-free medium; but the maximum activity was found at 0.5 mM Ca++ concentration. The Km value for PC of acidic PLase A2 was 4.2 microM, and a Michaelis-Menten relationship was evident. Calcium might act as a cofactor at some intermediate step during the activation of acidic PLase A2 in light of the uncompetitive manner of Ca++ action. Furthermore, the release of [3H]-AA from preradiolabelled macrophage plasma membranes occurred with the addition of Ca++ at pH 4.5. These data suggest that the acid PLase A2 is a component of the plasma membrane and is not due to lysosomal contamination since membrane-bound acidic PLase A2 properties are opposite to those found for lysosomal PLase A2.

Animals↗
PubMed1988

Purification and properties of Bacteroides heparinolyticus heparinase (heparin lyase, EC 4.2.2.7).

Heparinase (heparin lyase, EC 4.2.2.7) was isolated from the cell extract of an oral bacterium, Bacteroides heparinolyticus. It was a basic protein with an isoelectric point of 9.5. Its molecular weight was 63,000. The enzyme was the most active against heparin among the tested mucopolysaccharides. Catalytic properties may be similar to those of heparinase of Flavobacterium heparinum, since the enzymatic degradation products obtained by using the two enzymes were the same on the basis of paper chromatography.

Bacteroides↗
PubMed1988

Pituitary apoplexy manifested during a bromocriptine test in a patient with a growth hormone- and prolactin-producing pituitary adenoma.

This report describes the clinical course of pituitary apoplexy induced by a single dose of bromocriptine in a 50-year-old woman with acromegaly. The patient suddenly complained of diminished vision and headache 2 hours after the oral administration of 2.5 mg of bromocriptine. Her visual symptoms and headache persisted for several days. The basal plasma GH concentration decreased from 76.2 ng/ml to 37.2 ng/ml the day after the attack of apoplexy and to 3.0 ng/ml on the 9th day. The authors assess the changes in endocrine findings related to pituitary apoplexy and also emphasize the necessity to view with caution any symptomatic change during bromocriptine therapy.

Adenoma↗