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Biomedical subjects

T Horii

Publications and source records attributed to T Horii.

At least 37 records · Page 2Linked to original sources
PubMed2001

Chemical synthesis and biological activity of the gelatinase biosynthesis-activating pheromone of Enterococcus faecalis and its analogs.

An 11-residue peptide lactone, termed the gelatinase biosynthesis-activating pheromone (GBAP), triggers the production of the pathogenicity-related extracellular proteases, gelatinase and serine protease, in Enterococcus faecalis. In this study, we synthesized GBAP and its analogs and examined their gelatinase biosynthesis-inducing activity. This study on the structure-activity relationship shows that a lactone ring was indispensable for the activity.

Amino Acid Sequence↗
PubMed2001

Natural human immunoglobulin G subclass responses to Plasmodium falciparum serine repeat antigen in Uganda.

Serum samples from Ugandan residents of a malaria-hyperendemic region were tested by enzyme-linked immunosorbent assay for reactivity against recombinant constructs of the 47 (SE47')- and 50 (SE50A)-kDa fragments of Plasmodium falciparum serine repeat antigen (SERA). Immunoglobulin (Ig) G3 and IgG1 were the predominant subclass responses to SE47' and SE50A, respectively. The geometric mean optical density (OD) for IgG3 anti-SE47' was significantly lower in children < 15 years compared with adults > or = 15 years (P < 0.0001). By contrast, the geometric mean IgG1 anti-SE50A was slightly higher in children compared with adults (P < 0.01). The proportion of high responders (ODs > 0.5) to SE47' was significantly lower in children compared with adults (P < 0.001), whereas the proportion of high responders to SE50A was comparable in children and adults (P = 0.07). This first detailed study of SERA in a malaria-hyperendemic region suggests that natural human IgG3 anti-SE47' might be associated with immunity to malaria.

Adolescent↗
PubMed2001

[Left ventriculoplasty for non-ischemic cardiomyopathy with severe heart failure in 70 patients].

OBJECTIVES: Treatment of cardiac failure due to non-ischemic cardiomyopathy by left ventriculoplasty using partial left ventriculectomy (Batista operation) or septal anterior ventricular exclusion was evaluated. METHODS: Left ventriculoplasty was performed in 70 patients (59 men and 11 women with a mean age of 51 years) from December 1996 to June 2000. Preoperative New York Heart Association (NYHA) functional class was IV in 43 patients including 29 receiving inotropic support, and class III in 27 patients. Nineteen patients required emergency surgery because of on-going shock and 51 patients were operated electively. Combined cardiac procedures were mitral valve reconstruction in 62 patients (45 replacements, 17 repairs), tricuspid annuloplasty in 37, and aortic valve replacement in 4. The initial 24 patients underwent typical Batista operation regardless of myocardial viability. The other 46 patients underwent selective ventriculoplasty to excise or exclude the weakest part according to the findings of the intraoperative echo-guided volume reduction test. RESULTS: The intraaortic balloon pump was used in 12 patients and the left ventricular assist device in 2 patients. Three (5.9%) of the 51 patients who underwent elective operation and 12 (63.2%) of the 19 patients with emergency operation died in the hospital, giving an overall hospital mortality of 21.4% (15/70). Hospital mortality was reduced from 33.3% (8/24) in the initial 24 patients to 15.2% (7/46) in the recent 46 patients with the volume reduction test. Mean ejection fraction increased from 22.2 +/- 6.7% to 29.6 +/- 6.0%. Diastolic dimension decreased from 81.1 +/- 9.5 to 69.8 +/- 19.2 mm. End-diastolic and systolic volume indices decreased from 199.0 +/- 47.9 to 124.1 +/- 34.9 ml/m2 and from 154.0 +/- 41.2 to 89.3 +/- 31.7 ml/m2, respectively, at one postoperative month in the 55 hospital survivors. The mean pulmonary capillary wedge pressure decreased from 25.6 +/- 7.8 to 13.6 +/- 4.5 mmHg. Serum brain natriuretic peptide decreased from 999 +/- 647 preoperatively to 547 +/- 362 pg/ml one month after the operation. Thirteen patients (18.6%) died in the late period mainly due to heart failure. Among the 42 survivors, 37 patients returned to NYHA functional class I-II, and cardiac events were rare after one postoperative year. Actuarial survivals at 3 years in elective and emergency operations were 71.9% and 33.3%, respectively. CONCLUSIONS: Left ventriculoplasty is acceptably safe for elective operation and clinical improvement can be obtained by proper surgical procedures and careful postoperative medical treatment.

Adolescent↗
PubMed2000

Identification of a novel prostaglandin f(2alpha) synthase in Trypanosoma brucei.

Members of the genus Trypanosoma cause African trypanosomiasis in humans and animals in Africa. Infection of mammals by African trypanosomes is characterized by an upregulation of prostaglandin (PG) production in the plasma and cerebrospinal fluid. These metabolites of arachidonic acid (AA) may, in part, be responsible for symptoms such as fever, headache, immunosuppression, deep muscle hyperaesthesia, miscarriage, ovarian dysfunction, sleepiness, and other symptoms observed in patients with chronic African trypanosomiasis. Here, we show that the protozoan parasite T. brucei is involved in PG production and that it produces PGs enzymatically from AA and its metabolite, PGH(2). Among all PGs synthesized, PGF(2alpha) was the major prostanoid produced by trypanosome lysates. We have purified a novel T. brucei PGF(2alpha) synthase (TbPGFS) and cloned its cDNA. Phylogenetic analysis and molecular properties revealed that TbPGFS is completely distinct from mammalian PGF synthases. We also found that TbPGFS mRNA expression and TbPGFS activity were high in the early logarithmic growth phase and low during the stationary phase. The characterization of TbPGFS and its gene in T. brucei provides a basis for the molecular analysis of the role of parasite-derived PGF(2alpha) in the physiology of the parasite and the pathogenesis of African trypanosomiasis.

Amino Acid Sequence↗
PubMed2000

Vacuolar H(+)-ATPase localized in plasma membranes of malaria parasite cells, Plasmodium falciparum, is involved in regional acidification of parasitized erythrocytes.

Recent biochemical studies involving 2',7'-bis-(2-carboxyethyl)-5, 6-carboxylfluorescein (BCECF)-labeled saponin-permeabilized and parasitized erythrocytes indicated that malaria parasite cells maintain the resting cytoplasmic pH at about 7.3, and treatment with vacuolar proton-pump inhibitors reduces the resting pH to 6.7, suggesting proton extrusion from the parasite cells via vacuolar H(+)-ATPase (Saliba, K. J., and Kirk, K. (1999) J. Biol. Chem. 274, 33213-33219). In the present study, we investigated the localization of vacuolar H(+)-ATPase in Plasmodium falciparum cells infecting erythrocytes. Antibodies against vacuolar H(+)-ATPase subunit A and B specifically immunostained the infecting parasite cells and recognized a single 67- and 55-kDa polypeptide, respectively. Immunoelectron microscopy indicated that the immunological counterpart of V-ATPase subunits A and B is localized at the plasma membrane, small clear vesicles, and food vacuoles, a lower extent being detected at the parasitophorus vacuolar membrane of the parasite cells. We measured the cytoplasmic pH of both infected erythrocytes and invading malaria parasite cells by microfluorimetry using BCECF fluorescence. It was found that a restricted area of the erythrocyte cytoplasm near a parasite cell is slightly acidic, being about pH 6.9. The pH increased to pH 7.3 upon the addition of either concanamycin B or bafilomycin A(1), specific inhibitors of vacuolar H(+)-ATPase. Simultaneously, the cytoplasmic pH of the infecting parasite cell decreased from pH 7.3 to 7.1. Neither vanadate at 0.5 mm, an inhibitor of P-type H(+)-ATPase, nor ethylisopropylamiloride at 0.2 mm, an inhibitor of Na(+)/H(+)-exchanger, affected the cytoplasmic pH of erythrocytes or infecting parasite cells. These results constitute direct evidence that plasma membrane vacuolar H(+)-ATPase is responsible for active extrusion of protons from the parasite cells.

Acids↗
PubMed2000

Production of shiga toxin by Escherichia coli measured with reference to the membrane vesicle-associated toxins.

Production of Shiga toxin (Stx) 1 and 2 from Stx-producing Escherichia coli (STEC) was measured with reference to the membrane vesicle (MV)-associated toxins. An immunoblot analysis method using specific antibodies for Stx1 and Stx2 was developed for the detection of the extracellular toxins. All 46 STEC isolates, studied including 30 O157 and 16 other O-antigenic isolates, released Stx1 and Stx2 as MV-associated and MV-removed fractions under aerobic and anaerobic conditions. Treatment of vesicles with polymyxin B that disrupted MVs increased the release of Stx1 and Stx2. Therefore, delivery of Stx1 and Stx2 by MVs is a general mechanism in STEC. Stx1 remained within MVs rather than in the MV-removed fraction under an aerobic culture condition. On the other hand, a larger proportion of Stx2 was detected in the MV-removed fraction. The kinetic patterns of the release of the toxins from STEC strains showed that both Stx1 and Stx2 were released into the growth medium during the exponential growth phase. An rpoS-deficient mutation did not have altered levels of extracellular Stx1 and Stx2, supporting the idea that Stx1 and Stx2 are produced during exponential growth phase.

Aerobiosis↗
PubMed2000

Rapid isolation and identification of staphylococcal exoproteins by reverse phase capillary high performance liquid chromatography-electrospray ionization mass spectrometry.

The isolation of staphylococcal extracellular toxins and enzymes (exoproteins) usually requires time-consuming purification steps such as repeated chromatographic separations and isoelectric focusing. We performed rapid isolation, quantification and identification of staphylococcal exoproteins by reverse phase capillary high performance liquid chromatography-electrospray ionization mass spectrometry (LC-ESI/MS) followed by the determination of N-terminal amino acid sequences of separated peaks. We identified two novel exoproteins as well as previously reported antigens ORF-1 and ORF-2, glutamyl endopeptidase in Staphylococcus aureus NCTC8325 and protein A, staphylococcal enterotoxin C3 (SEC3), toxic shock syndrome toxin-1 (TSST-1) and alpha-toxin in a clinical isolate methicillin-resistant S. aureus (MRSA) 3543. MRSA3543 secreted 5.33 and 1.45 microg of SEC3 and TSST-1 per 20 microg total exoproteins ml(-1), respectively. The capillary LC treatment of the exoprotein fraction separated at least 12 peaks, indicating its high-resolution power. We found that when a protein was once determined by its N-terminal sequence, its mass spectrum and the obtained molecular mass was applicable for the assignment of the protein.

Amino Acid Sequence↗
PubMed2000

The staphylokinase gene is located in the structural gene encoding N-acetylmuramyl-L-alanine amidase in methicillin-resistant Staphylococcus aureus.

The nucleotide sequence of a 15600-bp DNA fragment containing the staphylokinase gene (sakNU3-1) of methicillin-resistant Staphylococcus aureus (MRSA) NU3-1 was determined. The sak gene was found within the ply gene encoding N-acetylmuramyl-L-alanine amidase and thus the ply gene should be inactivated. In the flanking region of the sak gene, the tandem repeat sequences (GAAGTGTT and GAATGGTT) were present as possible junction points between the sak and ply genes. No sequences characteristic of the presence of an IS-like element were found. Upstream from the ply gene, the kdpA, kdpB and kdpC homologues were present. Downstream from the ply gene, the tagA, tagH and tagG homologues were present. The sak gene was inserted into the same position of ply in 5/6 of sak(+) MRSA isolates with different genotypes. In all of these sak(+) isolates, Sak was detected in the culture supernatant.

Cloning, Molecular↗
PubMed2000

Neutral sphingomyelinase activity dependent on Mg2+ and anionic phospholipids in the intraerythrocytic malaria parasite Plasmodium falciparum.

Sphingolipid metabolism and metabolites are important in various cellular events in eukaryotes. However, little is known about their function in plasmodial parasites. Here we demonstrate that neutral sphingomyelinase (SMase) involved in the sphingomyelin (SM) catabolism is retained by the intraerythrocytic parasite Plasmodium falciparum. When assayed in a neutral pH buffer supplemented with Mg(2+) and phosphatidylserine, an activity for the release of the phosphocholine group from SM was detected in parasite-infected, but not in uninfected, erythrocyte ghosts. The SMase activity in the parasite-infected erythrocyte ghosts was enhanced markedly by anionic phospholipids including unsaturated but not saturated phosphatidylserine. Mn(2+) could not substitute for Mg(2+) to activate SMase in parasite-infected erythrocyte ghosts, whereas both Mn(2+) and Mg(2+) activated mammalian neutral SMase. The specific activity level of SMase was higher in isolated parasites than in infected erythrocyte ghosts; further fractionation of lysates of the isolated parasites showed that the activity was bound largely to the membrane fraction of the parasites. The plasmodial SMase seemed not to hydrolyse phosphatidylcholine or phosphatidylinositol. The plasmodial SMase, but not SM synthase, was sensitive to scyphostatin, an inhibitor of mammalian neutral SMase, indicating that the plasmodial activities for SM hydrolysis and SM synthesis are mediated by different catalysts. Our finding that the malaria parasites possess SMase activity might explain why the parasites seem to have an SM synthase activity but no activity to synthesize ceramide de novo.

Amides↗
PubMed2000

Medium compositions and culture conditions for the assay of fosfomycin susceptibility by Etest.

The Etest (AB Biodisk, Solna, Sweden), a susceptibility testing method, was used for fosfomycin and was evaluated by comparison with the agar dilution method for 73 clinical isolates of Escherichia coli, including two resistant strains, and an optimal Etest method for fosfomycin was determined. Media and culture conditions greatly affected the minimum inhibitory concentrations (MICs) determined by the Etest for fosfomycin, as shown for the agar dilution methods. Our results showed that the most favorable conditions for the Etest for fosfomycin were with Mueller-Hinton agar (Becton-Dickinson Japan, Tokyo, Japan) under aerobic conditions. However, the MICs for the resistant strains were much higher than those determined by agar dilution methods, using Nutrient agar (Becton-Dickinson Japan) under anaerobic conditions. The addition of glucose-6-phosphate did not significantly affect the Etest results.

Agar↗
PubMed2000

Intraoperative coronary artery imaging with infrared camera in off-pump CABG.

To achieve high quality off-pump coronary artery bypass grafting (CABG), thermal coronary artery imaging using a new generation infrared camera was used and anastomotic status was assessed intraoperatively. In 12 patients who underwent off-pump CABG, 18 grafts (11 internal thoracic, 2 radial, 2 gastroepiploic arteries, and 3 saphenous veins) were evaluated following completion of anastomoses. All grafts were clearly visualized and anastomotic and flow status were observed with local epicardial cooling by CO2 blower in the normothermic heart. Seventeen grafts had no problems and one internal thoracic artery graft showed anastomotic failure that was successfully revised. All grafts were restudied by conventional catheter angiography postoperatively, and all were patent. Intraoperative coronary imaging with a highly sensitive infrared camera is noninvasive and effective for real time evaluation in the operating room. This results in more successful off-pump CABG.

Aged↗
PubMed2000

Coronary artery bypass grafting with gastroepiploic artery composite graft.

BACKGROUND: To achieve better results after coronary artery bypass grafting (CABG), arterial conduits are the first choice in multiple CABG for younger patients. We present here the early results of CABG with gastroepiploic artery (GEA) composite graft with free radial artery (RA) to revascularize right coronary artery or left circumflex artery in addition to internal thoracic artery to left anterior descending artery. METHODS: Between July 1997 and June 1998, 13 patients received CABG with GEA (larger caliber than 2.0 mm) composite graft. We have assessed the early results. RESULTS: There was no postoperative death or major morbidity. Postoperative angiogram was performed in 11 patients and all conduits were patent. Postoperative exercise stress test was done in 13 cases and showed no ischemia. CONCLUSIONS: Multiple CABG with arterial conduit can be performed by this procedure. The free RA functioned from secondary branches derived from proximal GEA. In conclusion, this procedure seems to be safe and effective, and both long-term patency and better quality of life may be expected.

Abdominal Muscles↗
PubMed2000

Partial left ventriculectomy, ventriculoplasty or valvular surgery for idiopathic dilated cardiomyopathy - the role of intra-operative echocardiography.

BACKGROUND: The partial left ventriculectomy (PLV) is known to work in some patients with dilated cardiomyopathy (DCM), although this procedure does not work well in all patients and the operative mortality is higher than the other cardiac surgeries. In addition to PLV, left ventriculoplasty to exclude antero-septal wall or valvular surgery without left ventricle (LV) surgery can be also effective in patients with DCM. To improve the surgical results for dilated cardiomyopathy, we introduced echo-guided volume reduction test and evaluated the surgical procedures and the results on the surgery for DCM. METHODS: Between December 1996 and July 1999, 56 patients with DCM (50 with idiopathic DCM, six with dilated hypertrophic cardiomyopathy) were surgically treated. Under the standard cardiopulmonary bypass, left ventricular motion was determined with color kinesis of echocardiogram and the lesion of akinetic wall was removed or excluded. RESULTS: After the initial PLV in 18 patients (initial group), operative procedures were selected in 21 with PLV, five with LV plasty, or 12 with valve surgery without LV surgery according to the findings of the LV wall motion by intraoperative echogram (select group). There were six hospital deaths and late follow-up deaths within 1 year in initial group, however, the mortality decreased significantly after the selection of the operative procedures; three hospital deaths and two late deaths in the select-group (P<0.05). Significant decrease of left ventricular diameter, the LV ejection fraction and endosystolic volume index were demonstrated after the LV surgery. The survival rate improved significantly after the selection of the operative procedures; 14 months survival rates was 50.0% in initial group and 73.1% in select group (P<0.05). CONCLUSION: Operative mortality decreased and late follow-up results improved after the selection of operative procedures according to the intraoperative volume reduction test.

Adolescent↗
PubMed2000

Lincomycin-induced endotoxin release in Escherichia coli sepsis: evidence for release in vitro and in vivo.

OBJECTIVE: To evaluate the propensity of lincomycin and clindamycin to induce release of endotoxin, the authors investigated endotoxin release in Escherichia coli isolated from a patient who developed septic shock following lincomycin treatment. METHODS: Endotoxin release from the E. coli isolate exposed to lincomycin, clindamycin, and ceftazidime were determined in vitro and in vivo. RESULTS: In vitro, this E. coli released significantly larger amounts of endotoxin after exposure for 6 hours to lincomycin or clindamycin versus no antibiotic; however, endotoxin release with these antibiotics was significantly less than with ceftazidime. There was no significant difference in in vitro endotoxin release between small (8 mg/L) and large (0.5 minimum inhibitory concentration [MIC]) doses of these antibiotics, and 0.5 MICs of lincomycin and clindamycin were 1024 and 256 mg/L, respectively. These results were supported by scanning electron microscopic observations, which demonstrated that lincomycin, clindamycin, and ceftazidime induced formation of filamentous cells. In addition, plasma endotoxin concentrations after treatment for 4 hours with lincomycin, clindamycin, and ceftazidime (5 mg/kg) were at least 20-fold higher than with no antibiotic in an E. coli sepsis rat model. CONCLUSION: Results of this study suggest that the bacteriostatic antibiotics, lincomycin and clindamycin, induce endotoxin release in the treatment of E. coli infections.

Animals↗