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K Matsuzaki

Publications and source records attributed to K Matsuzaki.

At least 19 recordsLinked to original sources
PubMed1998

Magainins as paradigm for the mode of action of pore forming polypeptides.

Magainins are a class of antimicrobial peptides discovered in the skin of Xenopus laevis. The peptides kill bacteria by permeabilizing the cell membranes without exhibiting significant toxicity against mammalian cells, and are a promising candidate for a new antibiotic of therapeutic value. The main target of the peptides are considered to be the lipid matrix of the membranes. This review summarizes studies on magainin-lipid interactions in comparison with other pore forming peptides. The selective toxicity can be at least partly explained by preferential interactions of magainins with anionic phospholipids abundant in bacterial membranes. A novel mode of action is discussed in detail, i.e., the formation of a dynamic peptide-lipid supramolecular pore, which allows the mutually coupled transbilayer transport of ions, lipids, and peptides per se.

Amino Acid Sequence↗
PubMed1998

Mechanism of synergism between antimicrobial peptides magainin 2 and PGLa.

The antimicrobial peptides magainin 2 and PGLa, discovered in the skin of the African clawed frog, Xenopus laevis, exhibit marked synergism [Westerhoff, H. V., Zasloff, M., Rosner, J. L., Hendler, R. W., de Waal, A., Vaz Gomes, A., Jongsma, A. P. M., Riethorst, A., and Juretic, D., Eur. J. Biochem. 228, 257-264 (1995)], although the mechanism is not yet clear. They are believed to kill bacteria by permeabilizing membranes. In this study, we examined the interactions of these peptides in lipid bilayers. PGLa, like magainin 2, preferentially interacts with acidic lipids, forming an amphipathic helix. The peptide induces the release of a water-soluble dye, calcein, entrapped within liposomes. The coexistence of magainin 2 enhances membrane permeabilization, which is maximal at a 1:1 molar ratio. Fluorescence experiments using L18W-PGLa revealed that both peptides form a stoichiometric 1:1 complex in the membrane phase with an association free energy of -15 kJ/mol. Single amino acid mutations in magainin 2 significantly altered the synergistic activity, suggesting that precise molecular recognition is involved in complex formation. The complex as well as each component peptide form peptide-lipid supramolecular complex pores, which mediate the mutually coupled transbilayer transport of dye, lipid, and the peptide per se. The rate of pore formation rate is in the order complex >/= PGLa > magainin 2, whereas the pore lifetime is in the order magainin 2 > complex > PGLa. Therefore, the synergism is a consequence of the formation of a potent heterosupramolecular complex, which is characterized by fast pore formation and moderate pore stability.

Amino Acid Sequence↗
PubMed1998

Relationship of membrane curvature to the formation of pores by magainin 2.

Magainin 2, an antimicrobial peptide from the Xenopus skin, kills bacteria by permeabilizing the cell membranes. We have proposed that the peptide preferentially interacts with acidic phospholipids to form a peptide-lipid supramolecular complex pore, which allows mutually coupled transbilayer traffic of ions, lipids, and peptides, thus simultaneously dissipating transmembrane potential and lipid asymmetry [Matsuzaki, K., Murase, O., Fujii, N., and Miyajima, K. (1996) Biochemistry 35, 11361-11368]. In this paper, we examined the effect of membrane curvature strain on pore formation. Magainin effectively forms the pore only in phosphatidylglycerol bilayers at low peptide-to-lipid ratios, well below 1/100. In contrast, the permeabilization of phosphatidylserine, phosphatidic acid, or cardiolipin bilayers occurred at much higher peptide-to-lipid ratios (1/50 to 1/10) with some morphological change of the vesicles. The latter three classes of phospholipids are known to form hexagonal II structures under conditions of reduced interlipid electrostatic repulsions. Incorporation of phosphatidylethanolamine also inhibited the magainin-induced pore formation in the inhibitory order of dioleoylphosphatidylethanolamine > dielaidoylphosphatidylethanolamine. Addition of a small amount of palmitoyllysophosphatidylcholine enhanced the peptide-induced permeabilization of phosphatidylglycerol bilayers. Magainin greatly raised the bilayer to hexagonal II phase transition temperature of dipalmitoleoylphosphatidylethanolamine. These results suggest that the peptide imposes positive curvature strain, facilitating the formation of a torus-type pore, and that the presence of negative curvature-inducing lipids inhibits pore formation.

Amino Acid Sequence↗
PubMed1998

Osteoclast differentiation factor (ODF) induces osteoclast-like cell formation in human peripheral blood mononuclear cell cultures.

We have reported that osteoclast differentiation factor (ODF) expressed on the plasma membrane of osteoblasts/ stromal cells is a ligand for osteoclastogenesis inhibitory factor (OCIF). A genetically engineered soluble form of ODF (sODF) induced osteoclast-like multinucleated cells (OCLs) in the presence of M-CSF in mouse spleen cell cultures. Osteoblasts/stromal cells were not required in this process. To elucidate the mechanism of human osteoclastogenesis, human peripheral blood mononuclear cells (PBMCs) were cultured for 7 days with sODF and human M-CSF in the presence or absence of dexamethasone. Treatment of human PBMCs with sODF together with M-CSF induced OCLs, which expressed tartrate-resistant acid phosphatase and vitronectin receptors, produced cAMP in response to calcitonin, and formed resorption pits on dentine slices. OCLs were also formed from the adherent cell population of human PBMCs. Dexamethasone was required for human OCL formation in culture of whole PBMCs but not in culture of the adherent cell population. OCL formation was strongly inhibited by OCIF simultaneously added. These results clearly indicate that like in mouse osteoclastogenesis, ODF is a critical factor for human osteoclastogenesis. The present study also indicates that OCIF acts as a naturally occurring decoy receptor for ODF in inhibiting signal transduction in human osteoclast formation.

Animals↗
PubMed1998

Aortic dissection extending from ductus diverticulum aneurysm.

We report the case of a 28-year-old woman with type B chronic aortic dissection extending from a ductus diverticulum aneurysm. The patient was successfully treated by interposition of a Hemashield 26-mm woven Dacron graft with a left posterolateral thoracotomy approach. Circulatory arrest through profound hypothermia and short retrograde cerebral circulation were employed during proximal anastomosis of the graft.

Adult↗
PubMed1998

Immunolocalization of transforming growth factor beta during wound repair in rat retina after laser photocoagulation.

BACKGROUND: Scatter photocoagulation induces regression of retinal neovascularization, but the mechanism of its therapeutic effect is incompletely understood. To elucidate the mechanism of therapeutic effect of photocoagulation is the main focus of our research. We have already demonstrated basic fibroblast growth factor (bFGF) immunolocalization during retinal wound repair following laser photocoagulation. Transforming growth factor beta (TGF beta) reportedly inhibits endothelial cell growth and bFGF-induced cell proliferation in vitro. In the present study, we evaluated the immunohistochemical localization of TGF-beta 1 and -beta 2 during wound repair in the rat retina following laser photocoagulation. METHODS: Krypton laser photocoagulation was performed on the eyes of pigmented rats. The eyes were then enucleated on day 1, 3, 7, 14, 28 or 56 following the photocoagulation and enrolled into the analysis of immunohistochemical localization of TGF-beta 1 and -beta 2. RESULTS: Immunoreactivity for TGF-beta 1 and -beta 2 was present in the ganglion cell layer and photoreceptor outer segments of the normal adult rat retina. The cytoplasm of RPE cells at the photocoagulated lesion showed intense TGF-beta 1 and -beta 2 immunoreactivity on day 3 after laser photocoagulation. Macrophages that migrated into the lesion lacked positive staining for TGF-beta 1 and -beta 2. TGF-beta immunoreactivity in RPE cells continued to be upregulated for more than 1 month compared with that in normal RPE cells. Controls did not exhibit any positive staining. CONCLUSION: An elevated expression of TGF-beta immunoreactivity for a longer period of time than bFGF was observed in RPE cells at the photocoagulated lesion in vivo. In the late phase of retinal wound repair, TGF-beta may inhibit cell proliferation induced by mitogens, introduce an end stage of cellular events, and induce extracellular matrix induction.

Animals↗
PubMed1998

Ligand-dependent and -independent interactions with the transforming growth factor type II and I receptor subunits reside in the aminoterminal portion of the ectodomain of the type III subunit.

The type III receptor for transforming growth factor beta (TGFbeta), which exhibits no kinase activity, binds TGFbeta1 and TGFbeta2 and is involved in assembly and activity of the multi-subunit TGFbeta signal transduction complex. Recently we showed that TGFbeta receptor type III (TbetaRIII) can participate in a complex composed of the dimeric TGFbeta ligand and a type III, II, and I receptor subunit. The interaction of the TbetaRIII subunit with TbetaRII is TGFbeta-dependent, whereas interaction with TbetaRI is TGFbeta-independent. Here we use coexpression of the three types of TGFbeta receptors in baculoviral-infected insect cells to determine which parts of the unglycosylated TbetaRIII receptor participate in the binding of TGFbeta, the TGFbeta-dependent interaction with TbetaRII and the TGFbeta-independent interaction with TbetaRI. The results suggest that the first 500 amino acid residues in the aminoterminal portion of TbetaRIII exhibit all three properties.

Activin Receptors, Type I↗
PubMed1998

Androgen metabolism in cultured rat renal inner medullary collecting duct (IMCD) cells.

Although the stimulations of renal hypertrophy and renal erythropoietin production have been well-known androgen effects in the kidney, recent investigative progresses are further providing good evidences for androgen-regulated gene productions of key enzymes or local hormone substrates important to renal cell metabolisms and tubular functions in mouse or rat proximal tubules, respectively. It has been also reported that testosterone restores vasopressin receptors in medullary collecting ducts of the ageing rat and improves a urinary concentrating ability. Therefore in the present study we examined a metabolic pathway of androgens in cultured rat renal IMCD cells, which finally determine a urinary composition and volume. IMCD cells cultured from kidneys of male Wistar rats weighing about 200 g were incubated with serum-free culture media containing 4 nM [3H] testosterone or [3H] androstenedione for 2-48 h. Radioactive compounds in incubation media were then separated by reverse-phase high-pressure liquid chromatography (HPLC) and identified mainly on the basis of comparison of retention times of standard materials on HPLC. The main metabolites identified in testosterone or androstenedione incubation experiment were 5 alpha-dihydrotestosterone or 5 alpha-androstanedione, respectively. 5 alpha-Reductase inhibitor, MK 906, effectively inhibited the formations of these Ring A reduced metabolites. These results may suggest that rat renal IMCD cells possess 5 alpha-reductase activity, thereby converting androgens into their biologically active forms in vivo.

5-alpha Reductase Inhibitors↗
PubMed1998

Differential expression of transforming growth factor-beta and its receptors in hepatocytes and nonparenchymal cells of rat liver after CCl4 administration.

BACKGROUND/AIMS: Transforming growth factor-beta (TGF-beta) is a family of multifunctional proteins that regulate hepatocyte proliferation, and biosynthesis of the extracellular matrix. In this study we examined whether modulation of TGF-beta receptor expression contributes to the liver diseases. METHODS: The mRNA expression of TGF-beta1, TGF-beta type I receptor (TGFbetaRI), TGF-beta type II receptor (TGFbetaRII) and TGF-beta type III receptor (TGFbetaRIII) in rat livers injured by CCl4 administration was studied by Northern blotting. The mRNA expression patterns were confirmed by in situ hybridization. RESULT: The peak of TGF-beta1 mRNA expression was observed 48 h after acute intoxication with CCl4 in nonparenchymal cells. However, the levels of TGFbetaRI and TGFbetaRII mRNA expression decreased from 24 h to 48 h and from 12 h to 48 h, respectively, and returned to the normal level by 72 h. TGFbetaRII mRNA expression was depressed more and for longer than that of TGFbetaRI mRNA. Analysis in separated hepatocytes and nonparenchymal cells from the injured livers indicated that the mRNA changes occurred in hepatocytes. Nonparenchymal cells expressed TGFbetaRI and TGFbetaRII mRNAs at constant levels during liver regeneration. TGFbetaRIII mRNA, which also decreased after 12 h, was not apparent in hepatocytes but only in nonparenchymal cells. CONCLUSIONS: These observations suggest that: (i) whenever TGF-beta1 is increased in CCl4-treated livers, it may induce liver fibrogenesis via nonparenchymal cells; (ii) the mitoinhibitory effect of TGF-beta1 on hepatocytes is transiently relieved by down-regulation of TGF-beta receptors for 72 h post-damage; and (iii) the resistance to TGF-beta growth inhibition between 24 to 48 h may be predominantly due to down-regulation of the expression of TGFbetaRII.

Animals↗
PubMed1998

Eye socket reconstruction with free flaps in patients who have had postoperative radiotherapy.

It is difficult to fit an ocular prosthesis and correct periorbital depression deformity in a patient who has undergone radiotherapy after enucleation of the eye for retinoblastoma during infancy. Simultaneously, developmental disturbances of the eyelids and severe periorbital depression deformities develop. However, due to recent advances in microvascular surgery, free flap transplantation is increasingly used for eye socket reconstruction because of its good circulatory effects with enough volume to augment large periorbital tissue defects. In the present study, we report on our success in using a free groin flap, scapular flaps and parascapular flaps simultaneously for reconstruction of eye sockets and correction of depressed deformities.

Adult↗
PubMed1998

Repeat coronary artery bypass in a patient with liver cirrhosis.

The case of a 69-year-old man with liver cirrhosis, thrombocytopenia, unstable angina, and a history of previous coronary artery bypass grafting (CABG) is presented. The patient under-went successful repeat CABG through lateral thoracotomy on the beating heart without extracorporeal circulatory support.

Aged↗
PubMed1998

[In vitro activities of faropenem against clarithromycin resistance Helicobacter pylori isolates].

Agar dilution and semi-solid agar dilution were used to determine the MIC of faropenem (FRPM) against 24 H. pylori isolates. FRPM was active against clarithromycin resistance H. pylori isolates. And, the MICs obtained by both methods were in agreement. The results suggest that FRPM was not affected by pH and is a clinically useful oral antibiotic for the eradication therapy of H. pylori infections.

Anti-Bacterial Agents↗
PubMed1998

Clinical characteristics in Japanese patients with coexistent hypertrophic cardiomyopathy and coronary vasospasm.

There are only a few reports concerning coexistent hypertrophic cardiomyopathy (HCM) and vasospastic angina. Clinical characteristics in patients with both diseases have not been clarified yet. This study was designed to elucidate the relationship between chest pain and coronary vasospasm in HCM patients and to delineate clinical characteristics in patients with both HCM and coronary vasospasm. First, 36 patients with HCM underwent acetylcholine provocation test for coronary vasospasm and were divided into two groups on the basis of presence or absence of coronary vasospasm. Next, the following risk factors for coronary artery disease were compared between the two groups: hypertension, smoking, hyperlipidemia, diabetes mellitus, and hyperuricemia. Coronary vasospasm was induced in 10 (28%) of 36 patients with HCM. There were no significant differences in age and male gender between the two groups. Smoking was more prominent in HCM patients with than without coronary vasospasm (80% vs 35%, p<0.05), but there were no differences in the prevalence of other risk factors between the two groups. In conclusion, coronary vasospasm appears to play a significant role in the etiology of myocardial ischemia in Japanese patients with HCM, and smoking might be a major risk factor for coexistence of HCM and coronary vasospasm.

Adult↗
PubMed1998

[Acute myocardial infarction due to traumatic hemorrhagic shock with open fracture: a case report of staged amputation and CABG].

A 55-years-old man was admitted to an emergent hospital with hypovolemic pre-shock and open fracture of the right lower extremity. CPR was needed for myocardial infarction induced by hemorrhagic shock. Wound infection and bacteremia (Enterococcus SP) were noted 10 days after admission. Severe three vessel disease was demonstrated by preoperative (amputation) evaluation, he was also referred for CABG. For a control of infectious focus before using cardiopulmonary bypass, two-stage-operation (amputation and CABG) were selected. Both perioperative courses were uneventful and the patient recovered well after rehabilitation.

Amputation, Surgical↗
PubMed1998

[Partial anomalous pulmonary venous connection to the high superior vena cava: a case report of repair by modified Vargas' procedure].

A two and a half year-old boy with partial anomalous pulmonary venous connection (PAPVC) to the high superior vena cava (SVC) underwent a surgical repair by Vargas' procedure. The SVC was divided above the orifice of the anomalous pulmonary vein and the cephalad end of the SVC was anastomosed to the right atrial (RA) appendage. The anomalous pulmonary venous flow was diverted to the left atrium through the enlarged atrial septal defect using the RA wall only. Post-operative angiography showed no stenosis of pulmonary venous pathway, however, the SVC was compressed by the ascending aorta. Vargas' procedure could be useful for repair of PAPVC to the high SVC, however, care must be taken not to compress the rerouted SVC by the ascending aorta.

Child, Preschool↗
PubMed1998

[A case report of pulmonary embolectomy using an endoscope for the detection of residual emboli].

A 61-year-old woman was transferred to our hospital because of palpitation, tachypnea and repeated syncopal attack. On admission, sinus tachycardia and hypoxia were noted without deterioration of consciousness. The diagnosis of pulmonary embolism was made by pulmonary angiography and right heart catheterization showing multiple pulmonary emboli and pulmonary hypertension. An emergent pulmonary embolectomy was performed under total cardiopulmonary bypass. Residual emboli of bilateral pulmonary arteries were detected with a fiberoptic choledochoscope and removed carefully with forceps. Pulmonary angioscopic evaluation appears to be safe and useful for direct visual detection of emboli and completion of embolectomy.

Embolectomy↗