Biomedical subjects

K Iwaki

Publications and source records attributed to K Iwaki.

At least 37 records · Page 2Linked to original sources

PubMed1997

Decrease in the amount of focal adhesion kinase (p125(FAK)) in interleukin-1beta-stimulated human umbilical vein endothelial cells by binding of human monocytic cell lines.

Monocytes in the blood circulation migrate across endothelial cell monolayers lining the blood vessels and infiltrate into the underlying tissues in inflammation. However, little is known about the mechanisms by which leukocytes migrate across the endothelial barrier after binding and what molecules participate in the process. Addition of the human monocytic cell line THP-1 to interleukin-1beta (IL-1beta)-stimulated human umbilical vein endothelial cells (HUVEC) induced a decrease in the amount of focal adhesion kinase (p125(FAK)) protein, a tyrosine kinase localized at focal contacts and essential for cell attachment to the extracellular matrix, whereas little change was observed in the amount of other molecules associated with cell adhesion such as vascular cell adhesion molecule-1, alpha-catenin, and talin. A maximum decrease in the amount of p125(FAK) was observed 15-30 min after addition of THP-1 cells to HUVEC, after which the level of p125(FAK) gradually recovered. A reduction in the density of actin stress fibers in IL-1beta-activated HUVEC was observed in parallel with the decrease in p125(FAK). The p125(FAK) decrease was partially inhibited by preventing THP-1 binding to HUVEC using a mixture of antibodies to adhesion molecules. We suggest that the decrease in p125(FAK) triggered by binding of monocytes in inflammation facilitates the transendothelial migration of the monocytes by altering the adhesiveness of endothelial cells to the extracellular matrix.

Antibodies, Monoclonal↗

PubMed1997

Pharmacological studies on a new antihypertensive agent, S-2150, a benzothiazepine derivative: 3. Hypotensive and antimyocardial-stunning effects in dogs.

The hypotensive and antimyocardial-stunning effects of a new 1,5-benzothiazepine antihypertensive agent, S-2150, were investigated in dogs. S-2150 (30 mg/kg, p.o.) decreased the blood pressure in conscious renal hypertensive dogs. Although the maximal hypotensive effect of S-2150 was observed at 5-9 h after administration, the effect of diltiazem was seen at 2.0 h. Arrhythmia was not observed as a hypotensive effects of S-2150 but was markedly induced by diltiazem. In anesthetized open-chest dogs, S-2150 (20 micrograms/kg/min, i.v.) caused by hypotensive effect similar to that of diltiazem but decreased myocardial work (double product) by much less than did diltiazem. S-2150 more promptly improved the local myocardial stunning caused by occlusion of the left anterior descending coronary artery and its reperfusion. This effect did not accompany the energy-sparing action in ischemic/reperfused myocardium, which was different from the case of diltiazem. In isolated dog mesenteric arteries, S-2150 relaxed KCl and phenylephrine contracture. These results suggest that S-2150 is a favorable hypotensive agent for hypertensive patients with ischemic heart disease. Blockage of both Ca2+ channels and alpha 1-adrenoceptors by S-2150 seems to lead to cardiovascular effects different from those of diltiazem.

Adenosine Triphosphate↗

PubMed1997

Epitope analysis of human T-cell response to MSP-1 of Plasmodium falciparum in malaria-nonexposed individuals.

BACKGROUND: MSP-1 of Plasmodium falciparum induces strong proliferative T cell responses even in malaria-nonexposed individuals. Epitopes recognized by malaria-nonimmune T cells have not been identified, and immunological mechanisms inducing such T cell responses remain to be uncovered. MSP-1 is a vaccine candidate, and it should be understood whether those epitopes have any roles in MSP-1-mediated protective immunity. The T epitopes-inducing malaria-naive T cell response was analyzed in the hope of understanding the underlying mechanisms. METHODS: Human T cell lines and clones reactive to MSP-1 of P. falciparum were established from malaria-nonexposed Japanese donors in vitro, and epitope peptides were identified. Sequences of those epitope peptides were compared to unrelated peptides in the data base. One of those peptides was tested for both binding to HLA-DR molecules and inducing proliferative responses of MSP-1-reactive T cells. RESULTS: There are at least 6 epitopes recognized by malaria-naive T cells under the restriction by HLA-DRB1*1502 or 0802. Important amino acids for the T cell recognition were identified for an MSP-1 peptide. A yeast peptide which shared those residues induced proliferative responses of MSP-1-reactive T cells. CONCLUSION: We identified T epitopes in the N-terminal region of MSP-1, some of which showed molecular similarities with unrelated environmental antigens, suggesting the presence of cross-reactive T epitopes in MSP-1. Cytokine production in response to those epitopes suggests regulatory functions of those T cells during primary infection with P. falciparum.

Amino Acid Sequence↗

PubMed1997

[The pharmacokinetics of D-lactate, L-lactate and acetate in humans].

In this study, the pharmacokinetics of D-lactate, L-lactate and acetate were investigated in 36 adult surgical patients. After induction of general anaesthesia, the subjects received intravenous injection of either 5 mmoles of D-lactate and 5 mmoles of L-lactate simultaneously (Group DL), 10 mmoles of L-lactate (Group L), or 10 mmoles of acetate (Group A). Serial arterial blood samples were obtained before the injection, and 3, 5, 7, 9 and 11 minutes after the infusion of each preparation. Plasma concentrations of D-lactate, L-lactate and acetate were measured by high performance liquid chromatography, enzymatic analysis and spectrophotometry. The pharmacokinetic parameters; distribution volume (Vd) and half-life (t1/2) were calculated with a one-compartment model from the incremental plasma concentration decay curve after administration. In Group DL, there were no differences between D-lactate and L-lactate in Vd and t1/2. Also, between L-lactate in Group DL and that in Group L, there were no differences in Vd and t1/2. The Vd and T1/2 of acetate, however, were smaller than those of L-lactate in Group L. We conclude that the pharmacokinetics of D-lactate is similar to those of L-lactate, and that acetate may be metabolized more rapidly than L-lactate.

Acetic Acid↗

PubMed1996

ICAM-1 expression on cardiac myocytes and aortic endothelial cells via their specific endothelin receptor subtype.

Endothelin-1 (ET-1) and Endothelin-3 (ET-3) increased the expression of intercellular adhesion molecule-1 (ICAM-1) on rat neonatal cultured cardiac myocytes and rat aortic endothelial cells. ET-1-induced ICAM-1 expression on cardiac myocytes was inhibited by a selective ETA receptor antagonist, S-0139, but not by a selective ETB receptor antagonist, BQ788. ET-3-induced ICAM-1 expression on endothelial cells was inhibited by BQ788 but not by S-0139. Protein kinase C (PKC) inhibitor staurosporine inhibited ETs-induced ICAM-1 expression on both cell types. Treatment of the cells with ETs increased neutrophil adhesion, which was inhibited by S-0139 and staurosporine on cardiac myocytes and by BQ788 and staurosporine on endothelial cells. These results suggest that ETs induce neutrophil adhesion to cardiac myocytes and aortic endothelial cells by increasing ICAM-1 expression, which mediate via ETA receptor on cardiac myocytes and via ETB receptor on aortic endothelial cells. ICAM-1 expression induced by activation of ETA and ETB receptors appears to be mediated through the PKC pathway.

Animals↗

PubMed1996

Pharmacological studies on a new antihypertensive agent, S-2150, a benzothiazepine derivative: 1. Antinecrotic and antiarrhythmic effects in reperfused rat hearts.

S-2150 is a new 1,5-benzothiazepine derivative that inhibits [3H]diltiazem and [3H]WB4101 bindings to the membrane of rat tissue. The effects of S-2150 on ischemia/ reperfusion injury were studied in anesthetized rats. S-2150 reduced the myocardial infarct size (IS) induced by 20-min coronary artery occlusion followed by reperfusion. To evaluate reperfusion-induced ventricular tachycardia and fibrillation (VT, VF), we occluded the coronary artery for 4 min and then reperfused it. The incidence of arrhythmia was blocked by S-2150, and this effect offered protection against cardiac death. Prazosin did not modify the IS or incidence of reperfusion arrhythmias, but combined treatment with a noneffective dose of diltiazem showed significant cardioprotective effects. We also compared the direct effects of S-2150 and diltiazem on cardiac function and coronary perfusion flow using isolated rat hearts. Both drugs decreased mechanical function and increased coronary flow, with S-2150 being less cardiodepressive and more vasodilatory. S-2150 is cardioprotective at doses comparable to hypotensive doses even though its cardiodepressant effect is much weaker than that of diltiazem. This effectiveness may be partly explained by its dual characteristics: blocking the Ca channel and the alpha 1-adrenoceptor.

Adrenergic alpha-Antagonists↗

PubMed1996

Pharmacological studies on a new antihypertensive agent, S-2150, a benzothiazepine derivative: 2. Hypotensive effects in normotensive and hypertensive rats.

S-2150 is a new 1,5-benzothiazepine derivative possessing both calcium channel-blocking and alpha 1-adrenoceptor-blocking effects. In isolated rat thoracic aorta precontracted with KCl (18 mM), the 50% inhibitory concentration (IC50) value was 190 nM for S-2150, which was similar to that of diltiazem. In aorta precontracted with phenylephrine (0.3 microM), IC50 values of S-2150 and diltiazem were 29 nM and > 10 microM, respectively. The relative contribution of calcium channel-blocking and alpha 1-adrenoceptor-blocking activities to hypotension was determined by using anesthetized rats before and after masking of the alpha 1-receptors with prazosin. The hypotensive effect of S-2150 [0.3 and 1 mg/kg intravenously (i.v.)] was attenuated by 40% after prazosin treatment, whereas that of diltiazem was not. In conscious spontaneously hypertensive rats (SHRs), renal hypertensive rats, and normotensive rats, S-2150 [10, 30, and 60 mg/kg orally (p.o.)] caused dose-dependent hypotensive effects. The effect of S-2150 was 4-7 times more potent than that of diltiazem. There were no changes in the hypotensive effects with consecutive administration of S-2150 during 6-8 weeks in SHRs and stroke-prone SHRs (SHRSPs). In SHRSPs, S-2150 reduced the mortality by stroke and small arterial hyperplasia in abdominal organs and also ameliorated renal excretory function. These results suggest that S-2150 may be a useful antihypertensive agent possessing both calcium-antagonistic and alpha 1-adrenoceptor-blocking effects.

Adrenergic alpha-1 Receptor Antagonists↗

PubMed1995

Natural human interferon-alpha inhibits the adhesion of a human carcinoma cell line to human vascular endothelium.

The adhesion of cells to the microvascular endothelium is an essential step in the inflammatory response and metastasis. We have found that pretreatment of a human epidermoid carcinoma cell line, KB, with natural human interferon-alpha (IFN-alpha) inhibited the binding of the malignant cells to human umbilical vein endothelial cells (HUVEC) in a dose- and time-dependent manner. As one of several possible mechanisms for this inhibition, the expression of some revelant adhesion molecules on KB cell surfaces was examined after IFN-alpha treatment. Apart from a slight increase in the expression of integrin alpha 4 beta 1 (very late activation antigen 4, VLA-4), no changes in the expression of other adhesion molecules, such as sialyl Lewis X, CD44, and leukocyte function-associated antigen 1 (LFA-1), which is known to be a heterodimer of CD11a and CD18, were observed after treatment with IFN-alpha. In addition, the cell viability of KB was not affected by treatment of the cells with IFN-alpha, although the cell proliferation was markedly inhibited, indicating that the inhibitory effect of IFN-alpha on KB cell binding to vascular endothelium is not a result of a cytotoxic effect of IFN-alpha. Because the metastatic process requires not only the adhesion of tumor cells to vascular endothelium during their extravasation but also proliferation at distant sites, our findings from this in vitro experimental model suggest that IFN-alpha may have a potential inhibitory effect on tumor cell metastasis.

Antineoplastic Agents↗

PubMed1995

Metastasis-promoting activity of a novel molecule, Ag 243-5, derived from mycoplasma, and the complete nucleotide sequence.

We found that mycoplasma-infected cells have a higher ability to metastasize in vivo than non-mycoplasma-infected cells. To investigate this phenomenon, we obtained a monoclonal antibody, MAb 243-5, by immunization with Mycoplasma arginini-infected RPMI 4788 cells. This MAb recognized a mycoplasmal protein with an MW of 47 kDa and completely inhibited the experimental metastasis of M. arginini-infected RPMI 4788 cells using a nude mouse model. Using this MAb, we purified a molecule called Ag 243-5 and determined the N-terminal amino acid sequence and clarified the entire nucleotide sequence of the Ag 243-5 gene. PCR analysis showed the existence of a homologous gene in Mycoplasma hyorhinis. Four sequential injections of Ag 243-5 (30 micrograms/shot) promoted the experimental metastasis of non-mycoplasma-infected RPMI 4788 cells more than 10-fold using a nude mouse model. Ag 243-5 also promoted the experimental metastasis of the non-mycoplasma-infected mouse colon cancer cell line colon 26. This metastasis-promoting effect was neutralized by MAb 243-5.

Amino Acid Sequence↗

PubMed1994

[Anesthesia for modified radical mastectomy with breast reconstruction].

We investigated the factors influencing the amount of intraoperative bleeding, the factors influencing postoperative blood transfusion and the effect of postoperative analgesia retrospectively in 71 patients who underwent modified radical mastectomy with breast reconstruction. The amount of intraoperative bleeding decreased significantly in hypotensive anesthesia using epidural anesthesia compared with that with prostaglandin E1. Patient's weight and body surface area are the factors which influenced the amount of intraoperative bleeding. No patient received intraoperative blood transfusion. The amount of postoperative bleeding was significantly greater in 14 cases with blood transfusion and the amount of intraoperative bleeding was not significantly greater in blood transfusion cases. Fifty-one patients received epidural morphine intraoperatively. The dosage of postoperative analgesic was significantly less in these patients.

Aged↗

PubMed1994

[Analgesic effects of the lumbar epidural block with the catheter placed caudad].

In 31 cases of trans-urethral resection of the prostate (TUR-P), the lumbar epidural block was carried out with the catheter placed caudad. In 23 of 31 cases, it was found that the catheters were inserted caudad with coiling, but not so distant from the puncture site. In 3 cases, the catheters were placed caudad beyond a vertebral segment, in 2 cases cephalad, in another 2 cases passed through the intervertebral foramen, and in the other case the position undetectable. However, in 24 of 31 cases, adequate analgesia was obtained by epidural block only. Hypotension during the operation was seen only in 4 cases. In 3 cases, the catheters were successfully placed caudad beyond a vertebral segment and the levels of analgesia 10 minutes after the injection were T11-T10 to S3-S5. In the anesthetic management of TUR-P, it is necessary to obtain complete analgesia in sacral segments and to avoid high thoracic epidural block. We concluded that this method was useful for the anesthetic management of TUR-P.

Aged↗

PubMed1993

Rapid determination of tetracycline antibiotics in serum by reversed-phase high-performance liquid chromatography with fluorescence detection.

A rapid and accurate determination of tetracycline antibiotics in human serum by reversed-phase high-performance liquid chromatography with fluorescence detection has been developed, based on protein precipitation in serum. Various reagents for precipitation were investigated, and 24% trichloroacetic acid in methanolic solution gave the maximum recovery (at least 94.3%) and interference-free chromatograms of different three tetracyclines. At a concentration of 0.5 micrograms/ml, the precision (relative standard deviation) ranged from 1.12 to 1.94%. In the range 0.04-10.0 micrograms/ml for oxytetracycline and chlorotetracycline and 0.01-10.0 micrograms/ml for tetracycline, linear responses were observed. The detection limits of this method were 10-35 ng/ml for all three antibiotics. The proposed method was applied to the determination of serum concentrations in subjects receiving tetracycline antibiotics.

Chromatography, High Pressure Liquid↗

PubMed1993

Induction of HSP70 in cultured rat neonatal cardiomyocytes by hypoxia and metabolic stress.

BACKGROUND: A cultured neonatal rat cardiomyocyte model is used to investigate the expression of the inducible heat shock protein 70 (HSP70i) during hypoxia/reoxygenation and metabolic stress. METHODS AND RESULTS: The major HSP70i is increased in its expression at the mRNA and protein level in myocytes exposed to hypoxia/reoxygenation and metabolic stress by the addition of 2-deoxyglucose and sodium cyanide, which are inhibitors known to block ATP production. Surprisingly, the appearance of HSP70 mRNA precedes the intracellular ATP depletion caused by hypoxia, which is contrary to what we observe when the cardiomyocytes are subjected to metabolic stress. CONCLUSIONS: It has been postulated recently that the decrease in intracellular ATP content in cells under stress may be the trigger that leads to the induction of HSP70i by reducing the pool of free HSP70, thus activating the stress response. Our results indicate that although this may be the case during metabolic stress, another route of activation must be used during the early stages of hypoxia in cardiomyocytes. The induction of HSP70i also appears to precede the onset of cellular damage as measured by the release of cytoplasmic enzymes and preincorporated arachidonic acid. This indicates that cardiomyocytes are able to respond to hypoxia/reoxygenation and metabolic stress with increased HSP70i production and points to a potential protective role of heat shock proteins during ischemia/reperfusion injury.

Adenosine Triphosphate↗

PubMed1993

[Fibromuscular dysplasia with an internal carotid artery web on the angiograms].

A 58-year-old woman experienced a transient right-sided hemianopsia. She also had difficulty finding words and trouble naming parts of objects. On admission, three days later, there were no signs of residual neurological deficit. Laboratory studies showed findings of neither diabetes mellitus, hypertension nor cardiac disease. Her serum cholesterol level was normal. No bruit was heard over the head and neck. Preoperative angiograms showed a discrete web (septum) at the left internal carotid origin (Fig. 2). 123I-IMP SPECT revealed a decreased areas of perfusion mainly in the left middle cerebral artery distribution (Fig. 3A). A reconstructive operation was performed. A firm discrete nonatherosclerotic ridge (septum) protruding into the vessel lumen was resected. Microscopic examination of the surgical specimen demonstrated intimal fibroplasia, a rare subtype of fibromuscular dysplasia (FMD). Postoperatively, hypoperfused areas in SPECT were improved (Fig. 3B). The patient has been free of symptoms to the present time (for about one year). In addition to the rarity of the lesion, the available data suggest that web-like subtype of FMD is apt to be associated with an increase in the risk of hemodynamic compromise and thromboembolism. Surgical therapy is recommended, especially for symptomatic patients.

Carotid Artery, Internal↗

PubMed1992

Determination of tetracycline antibiotics by reversed-phase high-performance liquid chromatography with fluorescence detection.

A highly sensitive method for the determination of tetracycline antibiotics (TCs) using reversed-phase high-performance liquid chromatography with fluorescence detection is presented. This method was based on the use of disodium ethylenediaminetetraacetate (EDTA) and calcium chloride as fluorescence-increasing reagents in the mobile phase. The concentrations of each reagent in the mobile phase greatly influenced the fluorescence intensity of TCs. When the concentration of EDTA and calcium chloride were 25 and 35 mM, respectively, and the pH of the mobile phase was 6.5, the maximum fluorescence intensity was obtained. The column temperature hardly influenced the fluorescence intensity. At 3.75 ng of TCs injected, the precision (relative standard deviation) ranged from 1.12 to 2.20%. In the range 0.075-37.5 ng for tetracycline and oxytetracycline and 0.225-37.5 ng for chlortetracycline, a linear response was observed. The detection limits of this method were 49-190 pg for three different TCs. The proposed method was applied to the determination of one of the TCs in pharmaceuticals by the internal standard method using other TCs as internal standards and was also applied to determination of TCs added to fish tissue.

Animals↗

PubMed1992

[Concomitant graft replacement of the total aortic root and the transverse aortic arch for type A aortic dissection associated with annuloaortic ectasia].

Between April 1988 and February 1992, eight patients with type A aortic dissection associated with annuloaortic ectasia (AAE) underwent the concomitant graft replacement of the total aortic root and the transverse aortic arch at our institution. The acuity of the aortic dissection was acute stage in 3 patients and chronic stage in 5 including 3 cases of re-do operation. All operations were performed with an aid of extracorporeal circulation, blood cardioplegia, selective cerebral perfusion and open distal anastomosis. The operative techniques employed in this series consisted of total aortic root replacement using a composite graft (Bentall, Cabrol or Piehler's technique), and total arch replacement using en bloc arch reconstruction or three vessels graft replacement. One patients underwent re-do operation for coronary anastomotic false aneurysm following Bentall operation and aneurysmal dilatation of the false lumen at the aortic arch, and died of LOS because of the prolonged myocardial ischemia. Other seven patients survived the operation, and lead the normal life at the present time. The present data suggests that type A aortic dissection associated with AAE involving aortic arch could be treated by concomitant graft replacement of the total aortic root and the transverse aortic arch.

Adult↗

PubMed1990

Alpha- and beta-adrenergic stimulation induces distinct patterns of immediate early gene expression in neonatal rat myocardial cells. fos/jun expression is associated with sarcomere assembly; Egr-1 induction is primarily an alpha 1-mediated response.

The present study was designed to determine if alpha- and beta-adrenergic stimulation of neonatal rat myocardial cells might induce common and/or distinct members of the immediate early gene program and to assess whether their induction might correlate with the differential effects of these adrenergic agonists on cardiac gene expression, sarcomere assembly, and several features of myocardial cell hypertrophy. Alpha- and beta-adrenergic stimulation of neonatal rat myocardial cells both produce an increase in the assembly of an individual contractile protein (myosin light chain-2) into organized sarcomeric units and also rapidly induce mRNAs for the immediate early genes c-fos and c-jun, thereby suggesting a potential role for these protooncogenes in sarcomerogenesis. alpha-Adrenergic stimulation results in the co-induction of mRNAs encoding a zinc finger protein gene (Egr-1). However, beta-adrenergic stimulation does not produce a significant increase in the levels of Egr-1 mRNA, providing the first evidence in any cell system that c-fos and Egr-1 expression can regulated separately. Studies with norepinephrine in combination with various adrenergic receptor antagonists revealed that the induction of Egr-1 is primarily an alpha 1-mediated, pertussis toxin-insensitive response. These studies provide the first evidence for the induction of immediate early genes following adrenergic stimulation of myocardial cells and demonstrate alpha- and beta-adrenergic stimulation can rapidly activate the expression of common and distinct subsets of these transcriptional regulators. Since alpha- and beta-adrenergic agonists have differential effects on cardiac gene expression and on the acquisition of several features of myocardial cell hypertrophy, the induction of Egr-1 provides a potential mechanism for the induction of genes that are exclusively induced during alpha-adrenergic-mediated myocardial cell hypertrophy.

Animals↗

PubMed1990

Precolumn derivatization technique for high-performance liquid chromatographic determination of penicillins with fluorescence detection.

A precolumn derivatization method was developed for the high-performance liquid chromatographic (HPLC) determination of penicillins using fluorescence detection. Penicillins were derivatized by a two-step reaction, the beta-lactam ring being opened by hydrolysis in aqueous sodium carbonate solution in the first step to give a secondary amine functionality, and the secondary amino group being reacted with 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole in the second step to give a fluorescent derivative. The resulting reaction mixture was injected directly onto a reversed-phase column and analysed by HPLC. At a penicillin concentration of 10 micrograms/ml, the precision (relative standard deviation) ranged from 1.49 to 2.20%. In the concentration range 0.2-100 micrograms/ml, a linear response was observed. The detection limits of this method were 30-85 ng/ml for five different penicillins at a signal-to-noise ratio of 3:1. The proposed method was applied to the determination of penicillins added to serum following pretreatment by deproteinization and removal of compounds containing amino functionalities with a cation-exchange resin.

Chromatography, High Pressure Liquid↗