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Biomedical subjects

K Yasui

Publications and source records attributed to K Yasui.

At least 145 records · Page 8Linked to original sources
PubMed1998

Neutralizing mechanism of a monoclonal antibody against Japanese encephalitis virus glycoprotein E.

The neutralization of Japanese encephalitis virus (JEV) was studied using JEV-specific neutralizing (NT) monoclonal antibody (MAb) 503 that recognizes the envelope glycoprotein. Analysis using radiolabeled JEV and observations by confocal laser microscopy and electron microscopy indicated that the NT and protection activities of MAb 503 did not result from the prevention of the first step of JEV infection, binding of virus to the cell surface. Treatment with MAb 503 strongly inhibited JEV-induced cell fusion and internalization of JEV into the cells, and resulted in enhanced release of JEV-RNA from the cells. These observations suggested that the NT activity of MAb 503 is involved in the later steps of JEV infection.

Adsorption↗
PubMed1998

Branches of the vagus nerve destined for the heart and the adjoining great vessels in the house shrew, Suncus murinus, with reference to the terminology of the vagal cardiac branches.

In order to help to organize the understanding of the bewildering complexities of the innervation of the mammalian heart by the vagus nerve and to clear up of confusions as regards the vagus cardiac branches, we scrutinized these branches in the adult house shrew, Suncus murinus, under a stereomicroscope. A number of branches were given off from the vagus nerve not only to the heart, but also to the adjoining great vessels, both outflowing and inflowing. When compared from the developmental viewpoint, the basic conformations of these branches on two sides were found not to differ from each other, but rather presented a symmetrical configuration, the feature which has been ascertained also in mammalian embryos. Relying on developmental criteria, we classified them into the arterial porta-related and the venous porta-related groups, formulating a new terminology by naming them on the basis of their destination. This version of terminology allowed us to define the vagus cardiac branches of the house shrew more accurately than the current terminology (e.g., Nomina Anatomica), and seems to provide us a clue for clearing up confusions concerning the terminology of the vagus cardiac branches in mammals.

Animals↗
PubMed1998

Tissue plasminogen activator (T-PA) and plasminogen activator inhibitor (PAI-1) levels in the conditioned medium of cultured porcine brain microvascular endothelial cells.

Vascular endothelial cells are known to produce tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1). However, the release kinetics of these substances by brain microvascular endothelial cells (BMEC) is less well known. BMEC prepared from porcine brains using enzymatic digestion and percoll gradient separation was exposed to culture medium containing thrombin (1.0IU/ml), histamine (10 mumol/ml), and TN-alpha (500, 1000, 2000U/ml). The supernatant obtained at respective time points was subjected to ELISA for t-PA, PAI-1 and t-PA-PAI-1 complex. The value of these substances were significantly higher than those of the controls at respective time points. It also proved that t-PA and PAI-1 production by BMEC increases in a parallel fashion. The present study suggests that t-PA production by BMEC cultured under given stimulation increases, however, it is accompanied by concomitant PAI-1 production.

Animals↗
PubMed1998

[Recent management of metastatic colorectal cancer].

The most common metastatic sites in colorectal cancer are the lung, liver, and the pelvis in rectal cancer. Systemic chemotherapy for these metastases is not effective. Our principle of treatment for metastatic colorectal cancer is as follows. Radical resection is the first choice of treatment if the metastases are localized. Radiation therapy and intra-arterial infusion of 5-FU is adopted if radical resection is impossible. Five-year survival rates of curative resection at our hospital for pulmonary metastases, hepatic metastases and local recurrences of rectal cancer are 35.3% (n = 44), 28.4% (n = 72) and 34.1% (n = 32), respectively. Intra-arterial hepatic continuous infusion of 5-FU and weekly high-dose infusion of 5-FU (WHF) are effective chemotherapy for inoperable hepatic metastases. For inoperable pelvic recurrence of rectal cancer, intraoperative radiation therapy, 192 Ir brachytherapy, interstitial hyperthermia and intra-arterial chemotherapy have seemed to be effective treatment methods.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

Theophylline accelerates human granulocyte apoptosis not via phosphodiesterase inhibition.

Theophylline, in addition to its bronchodilator effect, is reported to have an antiinflammatory action that may account for its clinical effectiveness in the reduction of inflammatory cells in the airway. In bronchial asthma, such inflammatory cytokines as GM-CSF and IL-5 are upregulated and have been proposed to cause granulocyte infiltration (neutrophils and eosinophils) in the airway by inhibition of granulocyte apoptosis. We examined the abilities of theophylline to counteract the prolongation of human granulocyte survival caused by cytokines. Theophylline was shown to shorten granulocyte survival in a dose-dependent manner. Upon incubation with a therapeutical concentration of theophylline (0.1 mM; 18 microg/ml), percentages of GM-CSF (10 ng/ml)-induced delayed apoptosis increased from 18+/-2% to 38+/-3% (p < 0.02) in neutrophils and from 21+/-2% to 35+/-2% (p < 0.02; 24-h incubation) in eosinophils. The percentage of IL-5 (5 ng/ml)-induced delayed eosinophil apoptosis also increased from 22+/-4% to 33+/-2% (P < 0. 05). In contrast, cyclic AMP (cAMP)-increasing agents (3-isobutylmethylxanthine, dibutyryl cAMP, and rolipram) inhibited granulocyte apoptosis in the control and anti-Fas antibody-treated cells. In eosinophils, the expression of bcl-2 protein decreased after incubation with theophylline. These findings suggest that theophylline accelerates granulocyte apoptosis, which may play an essential role in inflammation, and controls granulocyte longevity regardless of the elevation of intracellular cAMP levels.

1-Methyl-3-isobutylxanthine↗
PubMed1997

Nasal and pharyngeal abnormalities caused by the mouse goosecoid gene mutation.

The Goosecoid (gsc) gene is a homeobox-containing gene expressed first in the gastrula, and later during organogenesis in development. The gsc gene transcript is found in the first and second branchial arches, frontonasal mass in its late phase of expression. We have previously shown that targeted mutation of the mouse gsc gene leads to neonatal death and craniofacial defects. In this study, we performed histological studies on craniofacial phenotypes in order to elucidate the processes underlying the neonatal death of gsc mutant mice. We found that gsc mutant mice have aplastic nasal cavities and lack the Sinus Paranasalis. We also showed that secretory olfactory glands in the basal layers are aplastic. This is suggested to be essential defects for olfaction. gsc mutant mice also show several pharyngeal phenotypes, including defects in the pharyngeal muscles and the pharyngeal mucosa. It is therefore suggested that mutant mice develop lethal gastro-intestinal phenotypes caused by defects in breathing and sucking of milk as a consequence of these craniofacial disorders. These results should help elucidating the molecular genetic programs essential to the neonatal development of mammals.

Animals↗
PubMed1997

Sphingosylphosphocholine modulates the ryanodine receptor/calcium-release channel of cardiac sarcoplasmic reticulum membranes.

Sphingosylphosphocholine (SPC) modulates Ca2+ release from isolated cardiac sarcoplasmic reticulum membranes; 50 microM SPC induces the release of 70 80% of the accumulated calcium. SPC release calcium from cardiac sarcoplasmic reticulum through the ryanodine receptor, since the release is inhibited by the ryanodine receptor channel antagonists ryanodine. Ruthenium Red and sphingosine. In intact cardiac myocytes, even in the absence of extracellular calcium. SPC causes a rise in diastolic Ca2+, which is greatly reduced when the sarcoplasmic reticulum is depleted of Ca2+ by prior thapsigargin treatment. SPC action on the ryanodine receptor is Ca(2+)-dependent. SPC shifts to the left the Ca(2+)-dependence of [3H]ryanodine binding, but only at high pCa values, suggesting that SPC might increase the sensitivity to calcium of the Ca(2+)-induced Ca(2+)-release mechanism. At high calcium concentrations (pCa 4.0 or lower), where [3H]ryanodine binding is maximally stimulated, no effect of SPC is observed. We conclude that SPC releases calcium from cardiac sarcoplasmic reticulum membranes by activating the ryanodine receptor and possibly another intracellular Ca(2+)-release channel, the sphingolipid Ca(2+)-release-mediating protein of endoplasmic reticulum (SCaMPER) [Mao, Kim, Almenoff, Rudner, Kearney and Kindman (1996) Proc.Natl.Acad.Sci. U.S.A 93, 1993-1996], which we have identified for the first time in cardiac tissue.

Animals↗
PubMed1997

An estimate of divergence time of Parazoa and Eumetazoa and that of Cephalochordata and Vertebrata by aldolase and triose phosphate isomerase clocks.

Previously we suggested that four proteins including aldolase and triose phosphate isomerase (TPI) evolved with approximately constant rates over long periods covering the whole animal phyla. The constant rates of aldolase and TPI evolution were reexamined based on three different models for estimating evolutionary distances. It was shown that the evolutionary rates remain essentially unchanged in comparisons not only between different classes of vertebrates but also between vertebrates and arthropods and even between animals and plants, irrespective of the models used. Thus these enzymes might be useful molecular clocks for inferring divergence times of animal phyla. To know the divergence time of Parazoa and Eumetazoa and that of Cephalochordata and Vertebrata, the aldolase cDNAs from Ephydatia fluviatilis, a freshwater sponge, and the TPI cDNAs from Ephydatia fluviatilis and Branchiostoma belcheri, an amphioxus, have been cloned and sequenced. Comparisons of the deduced amino acid sequences of aldolase and TPI from the freshwater sponge with known sequences revealed that the Parazoa-Eumetazoa split occurred about 940 million years ago (Ma) as determined by the average of two proteins and three models. Similarly, the aldolase and TPI clocks suggest that vertebrates and amphioxus last shared a common ancestor around 700 Ma and they possibly diverged shortly after the divergence of deuterostomes and protostomes.

Amino Acid Sequence↗
PubMed1997

ATP regulates cardiac Ca2+ channel activity via a mechanism independent of protein phosphorylation.

The role of adenosine triphosphate (ATP) in the regulation of L-type Ca2+ channel activity was investigated in inside-out patches from guinea-pig ventricular cells, in which the Ca2+ channel activity had been reprimed by application of cytoplasm from bovine heart. Passing the cytoplasm through a diethylaminoethyl (DEAE)-sepharose column or heating at 60 degrees C for 20 min attenuated the induction Ca2+ channel activity to 6-13% of that in the preceding cell-attached patch. Addition of 10 mM MgATP to the cytoplasm greatly improved the potency of cytoplasm in restoring Ca2+ channel activity (to 83 +/- 22%, mean +/- SE). This effect of MgATP was also produced, although with lower potency, by K2ATP (61 +/- 20%) or 5'-adenylylimidodiphosphate (AMP-PNP, 39 +/- 7%), a non-hydrolyzable ATP analogue, suggesting that hydrolysis of ATP is not required for the stimulatory effect on channel activity. A non-specific protein kinase inhibitor H8 (50-100 microM) did not inhibit the effect of cytoplasm + MgATP on channel activity, suggesting the involvement of a pathway independent of phosphorylation. We conclude that ATP regulates Ca2+ channel activity in dual pathways: one with, and the other without, protein phosphorylation.

Adenosine Triphosphate↗
PubMed1997

Impact of 3-dimensional helical computerized tomography on selection of operative methods for ureteropelvic junction obstruction.

PURPOSE: We studied the feasibility of imaging the direct correlation between crossing vessels and obstructed ureteropelvic junction with helical (spiral) computerized tomography (CT) for selecting surgical repair of symptomatic ureteropelvic junction obstruction. MATERIALS AND METHODS: From July 1995 to December 1995, 4 select patients with symptomatic ureteropelvic junction obstruction underwent contrast enhanced helical CT. In addition to transaxial images, 3-dimensional reformatted images were used for evaluation. RESULTS: We identified 2 cases of ureteropelvic junction obstruction due to crossing vessels regarded as ureterovascular hydronephrosis, which is characterized by the spatial relationship between malrotated renal pelvis and anterior crossing vessels. Laparoscopic or open repair was performed in these 2 patients and operative findings were in agreement with prospective helical CT interpretation. Antegrade endopyelotomy was performed successfully for the remaining 2 patients. CONCLUSIONS: The 3-dimensional helical CT is reliable in detecting ureterovascular hydronephrosis preoperatively and in presenting better operative methods for ureteropelvic junction obstruction.

Adult↗
PubMed1997

Effects of colony-stimulating factors (CSFs) on neutrophil apoptosis: possible roles at inflammation site.

We found that granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) had different effects on the apoptosis of human mature neutrophils induced by anti-Fas antibody. GM-CSF suppressed this process and neutrophils retained their functions of superoxide production and enzyme release against invasion of microorganisms. In contrast, G-CSF had a weaker effect on the anti-Fas antibody-induced neutrophil apoptosis than GM-CSF, with neutrophil function suppressed in proportion to the apoptosis. GM-CSF produced by satellite cells at the inflammatory site may inhibit apoptosis and the neutrophils may maintain their primed functions to kill the invading microorganisms. G-CSF produced by fibroblasts or endothelial cells may work in another fashion by increasing the number of neutrophils more effectively than GM-CSF. GM-CSF and G-CSF may exert different effects on neutrophils at the inflammatory sites in the human body.

Antibodies, Monoclonal↗
PubMed1997

Metastatic gastric lymph node rate is a significant prognostic factor for resectable stage IV stomach cancer.

BACKGROUND: Stage IV gastric carcinoma is rarely curatively resected and almost invariably carries a poor prognosis. Several clinicopathologic factors are involved, but lymphatic spread of the cancer may significantly affect survival. STUDY DESIGN: A retrospective study was designed to evaluate whether the nodal metastatic rate (number of lymph node metastases/number of resected lymph nodes) is a parameter of lymphatic spread and could provide a significant prognostic factor. Several prognostic factors were assessed by multivariate analysis in 153 stage IV gastric carcinoma patients with histopathologic data on nodal metastasis. RESULTS: A significant difference in survival was observed in the stage IV cancer patients with total nodal or gastric nodal metastatic rates < 50% versus those with rates > 50%. Multivariate analysis revealed that a total nodal or gastric nodal metastatic rate > 50% was a highly significant prognostic factor. The gastric nodal metastatic rate can be used in patients who do not undergo an extended lymphadenectomy. CONCLUSIONS: Lymphatic spread of gastric carcinoma expressed in terms of the total nodal or gastric nodal metastatic rate is a significant prognostic factor. The latter can be calculated without pathologic data derived from extended lymphadenectomy, and so it is universally applicable.

Humans↗
PubMed1997

Spontaneous death of isolated adult rat cardiocytes in culture in association with internucleosomal cleavage of genomic DNA.

Many isolated adult cardiocytes do not survive beyond the early days of culture, but why they die has not been defined. We examined the possibility of apoptosis as the mechanism of death in cultured atrial and ventricular rat cardiocytes. Calcium-tolerant cardiocytes isolated by enzymatic dissociation were cultured with a medium containing FBS. Nucleosomal DNA fragmentation was detected by electrophoresis of DNA extracted from the cardiocytes, by immunohistochemical in situ DNA nick-end labelling of single cells, and by enzyme immunoassay for in vitro quantification in cytoplasmic fraction. Electrophoresis on the 5th to 14th day of culture revealed the ladder appearance characteristic of internucleosomal DNA cleavage in apoptosis with a consistent single peak of increased cytoplasmic DNA fragments. After the 14th day, the cytoplasmic DNA fragments decreased, and the ladder appearance could no longer be detected by electrophoresis. Cardiocytes positive with nick-end labelling were seen by the 5th day, and then increased in number over the remaining days. These results indicate that many isolated cardiocytes die spontaneously by apoptosis within the first 2 weeks of culture, suggesting a possible signal dependence for survival of adult cardiocytes. In addition to chemical signal depletion in culture, other possible explanations for this apoptosis include the absence of an electric signal during culture, lack of contractile activity, and initial loss of intercellular connections.

Journal Article↗
PubMed1997

Megakaryocytes derived from CD34-positive cord blood cells produce interleukin-8.

In a serum-free liquid culture, thrombopoietin (TPO) selectively stimulated the growth of megakaryocytic cells from CD34-positive cord blood cells. Using these cultured cells, we investigated cytokine production by human megakaryocytes. Day 10 megakaryocytes (2 x 10(5)) secreted > 1000 pg/ml of interleukin (IL)-8, in contrast to small amounts of IL-1beta and IL-6. A time-course study showed that the IL-8 production of megakaryocytes occurred at the late phase of the culture period. The megakaryocyte-conditioned medium had the chemotactic potential of polymorphonuclear leucocytes, which was abrogated by the addition of anti-IL-8 antibody, suggesting the secretion of biologically active IL-8. The combination of TPO and IL-1alpha was required for a significant augmentation of the IL-8 secretion. Direct evidence for IL-8 synthesis in megakaryocytes was provided by reverse transcription-polymerase chain reaction on purified CD41b+ cells and by the detection of intracellular IL-8 in CD41b+ cells. These results suggest that TPO stimulates not only the proliferation and differentiation of the progenitors capable of megakaryocytic lineage expression but also IL-8 release by the megakaryocytic cells with the aid of IL-1.

Cells, Cultured↗