Biomedical subjects

Y Todo

Publications and source records attributed to Y Todo.

At least 19 recordsLinked to original sources

PubMed2003

Inductance of rf-wave-heated plasmas.

The inductance of rf-wave-heated plasmas is derived. This inductance represents the inductance of fast electrons located in a plateau during their acceleration due to electric field or deceleration due to collisions and electric field. This inductance has been calculated for small electric fields from the two-dimensional Fokker-Planck equation as the flux crossing the surface of critical energy mv(2)(ph)/2 in the velocity space. The new expression may be important for radio-frequency current drive ramp-up, current drive efficiency, current profile control, and so on in tokamaks. This inductance may be incorporated into transport codes that study plasma heating by rf waves.

Journal Article↗

PubMed2001

In vitro and in vivo efficacies of T-3811ME (BMS-284756) against Mycoplasma pneumoniae.

T-3811, the free base of T-3811ME (BMS-284756), a new des-F(6)-quinolone, showed a potent in vitro activity (MIC at which 90% of the isolates tested are inhibited [MIC(90)], 0.0313 microg/ml) against Mycoplasma pneumoniae. The MIC(90) of T-3811 was 4-fold higher than that of clarithromycin but was 4- to 8-fold lower than those of trovafloxacin, gatifloxacin, gemifloxacin, and moxifloxacin and was 16- to 32-fold lower than those of levofloxacin, ciprofloxacin, and minocycline. In an experimental M. pneumoniae pneumonia model in hamsters, after the administration of T-3811ME (20 mg/kg of body weight as T-3811, once daily, orally) for 5 days, the reduction of viable cells of M. pneumoniae in bronchoalveolar lavage fluid was greater than those of trovafloxacin, levofloxacin, and clarithromycin (20 and 40 mg/kg, orally) (P < 0.05).

Animals↗

PubMed2001

Circulating matrix metalloproteinases and their inhibitors in premature coronary atherosclerosis.

To investigate the clinical significance of circulating matrix metalloproteinases (MMPs) and their tissue inhibitos (TIMPs) in patients with premature coronary atheroscrelosis, we studied 53 consecutive male patients with angiographically defined premature (<65 years) and stable coronary artery disease. Plasma levels of MMP-2, MMP-3, MMP-9, TIMP-1, and TIMP-2 were determined in peripheral blood by a sandwich enzyme immunoassay, and the results were compared with those from 133 age-matched control males. There were significant differences in all the MMPs and TIMPs (p<0.001) between patients and controls. In the patient group, the levels of MMP-9 (mean +/- SD (ng/ml) 27.2 +/- 15.2/21.8 +/- 15.2) and TIMP-1 (130.4 +/- 55.7/94.5 +/- 26.3) were significantly higher, and the levels of MMP-2 (632.5 +/- 191.6/727.6 +/- 171.4), MMP-3 (53.1 +/- 31.2/79.6 +/- 29.9), and TIMP-2 (24.7 +/- 15.2/35.4 +/- 16.4) were significantly lower than those of controls. We found significant positive correlation between plasma MMP-9 levels and low-density lipoprotein (LDL)-cholesterol levels (Rs = 0.168, p = 0.022), and significant negative correlation between plasma MMP-9 levels and high-density lipoprotein (HDL)-cholesterol levels (Rs = -0.164, p = 0.026) by Spearman rank correlation test. In contrast, plasma MMP-2 (Rs = 0.181, p = 0.014) and MMP-3 (Rs = 0.260, p = 0.0004) levels were positively correlated with HDL-cholesterol levels. TIMP-2 levels were negatively correlated with total cholesterol (Rs = -0.197, p = 0.007) and LDL-cholesterol (Rs = -0.168, p=0.022) levels. These results suggest that the circulating levels of MMPs and TIMPs are altered in patients with premature coronary atherosclerosis and that plasma lipoprotein cholesterol levels correlate with these, possibly as a result of the lipoprotein-vessel wall interactions.

Biomarkers↗

PubMed2000

A multivariate analysis of blood vessel and lymph vessel invasion as predictors of ovarian and lymph node metastases in patients with cervical carcinoma.

BACKGROUND: To the authors' knowledge there are few available data regarding the influence of lymphovascular space invasion, which has been examined separately as two components (lymphatic vessel invasion [LVI] and blood vessel invasion [BVI]), in the metastasis of cervical carcinoma. METHODS: LVI and BVI, which include capillary vessel invasion, were reviewed retrospectively based on the histopathologic slides of 239 women with cervical carcinoma who were treated with radical hysterectomy. The correlation between lymph node and/or ovarian metastases and LVI, BVI, and other histopathologic factors was investigated by multiple logistic regression analysis. The influence of LVI and BVI on survival was examined by Cox regression analysis. RESULTS: The rate of incidence of LVI was higher than that of BVI in all stages of cervical carcinoma (P < 0.0001 for International Federation of Gynecology and Obstetrics Stage IB and Stage II disease and P < 0.05 for Stage III disease). The incidence rate of BVI increased as LVI became more prominent and there was a significant correlation between the two findings (P < 0.0001). BVI was more frequent in adenocarcinoma/adenosquamous carcinoma than in squamous cell carcinoma (P < 0.05). LVI (P < 0.0001) and parametrial invasion (P < 0.0001) were significantly related to lymph node metastasis on multivariate analysis. Conversely, BVI (P < 0.05) and parametrial invasion (P < 0.0025), as well as adenocarcinoma or adenosquamous carcinoma (P < 0.0005), were significantly related to ovarian metastasis on multivariate analysis. With regard to the prognostic significance of these components, it was found that BVI (hazards ratio [HR] = 2.0), ovarian metastasis (HR = 6.5), and lymph node metastasis (HR = 5.5) were significantly related to a poor prognosis in women with cervical carcinoma. CONCLUSIONS: Ovarian metastasis may occur via hematogenous spread of cervical carcinoma. The results of the current study suggest that BVI, including capillary vessels, that is diagnosed separately from LVI using hematoxylin and eosin stained sections may be an important prognostic factor for patients with cervical carcinoma.

Carcinoma, Adenosquamous↗

PubMed2000

Prognostic significance of serous and clear cell adenocarcinoma in surgically staged endometrial carcinoma.

BACKGROUND: The serous adenocarcinoma (SA) and clear cell adenocarcinoma (CCA) of endometrium have been shown to be associated with high relapse rate and poor survival. It is not clear whether prognostic significance of these specific cell types of tumor is independent of retroperitoneal lymph node metastasis and other histopathologic prognostic factors in endometrial carcinoma. METHODS: We examined 240 consecutive patients with clinical stage I to stage III endometrial carcinoma who were treated prospectively with radical surgery and/or platinum-based chemotherapy. Surgery included extended hysterectomy, bilateral salpingo-oophorectomy, and systematic pelvic and paraaortic lymph node dissection. Prognostic significance of various histopathologic factors was determined by Cox regression analysis. RESULTS: SA/CCA were more frequently associated with deep myometrial invasion, high nuclear grade (G3), lymph-vascular space invasion (LVSI), and pelvic lymph node metastasis when compared to endometrioid adenocarcinoma (EMA). Of 216 clinically staged stage I or II disease, seven of 12 cases of SA/CCA had extrauterine disease. This incidence was much higher than that for EMA (46/204) (p<0.01). A multivariate Cox regression analysis revealed that cell type, grade, LVSI, and paraaortic node metastasis (PANM) were independent prognosticators. CONCLUSIONS: Prognosis of patients with endometrial carcinoma depends on cell type, grade, LVSI, and PANM. Poor prognosis for patients with SA/CCA is independent of lymph node metastasis and other histopathologic prognostic factors. The SA/CCA should be strictly discriminated from EMA.

Adenocarcinoma, Clear Cell↗

PubMed2000

Prevention of lymphocyst formation following systematic lymphadenectomy.

BACKGROUND: The occurrence of pelvic lymphocysts is an important complication following systematic lymphadenectomy for gynecological malignancies. We employed a procedure to prevent vaginal shortening following radical hysterectomy and we examined whether this procedure could be effective in preventing pelvic lymphocyst formation. METHODS: We studied the incidence of lymphocysts in 190 patients with 84 cervical cancers, 74 endometrial cancers and 32 ovarian cancers, using computed tomographic examination at 3 and 6 months subsequent to the surgery. The surgery included radical hysterectomy and a procedure to prevent vaginal shortening (101), modified radical hysterectomy (79) and simple hysterectomy (7), with systematic lymphadenectomy. RESULTS: There was a significant difference in the incidence of pelvic lymphocysts between cervical cancer (4.8%) and ovarian cancer (18.8%). The postoperative incidence of lymphocyst formation in patients undergoing radical hysterectomy with the procedure to prevent vaginal shortening (5.9%) was significantly lower than in those who underwent modified radical hysterectomy (15.2%). CONCLUSION: Our procedure to prevent vaginal shortening could be effective in preventing not only the shortening of the vagina but also the occurrence of pelvic lymphocysts in patients undergoing radical hysterectomy with systematic lymphadenectomy for gynecological malignancies.

Adolescent↗

PubMed1999

In vitro and in vivo antimicrobial activities of T-3811ME, a novel des-F(6)-quinolone.

The in vitro and in vivo activities of T-3811ME, a novel des-F(6)-quinolone, were evaluated in comparison with those of some fluoroquinolones, including a newly developed one, trovafloxacin. T-3811, a free base of T-3811ME, showed a wide range of antimicrobial spectra, including activities against Chlamydia trachomatis, Mycoplasma pneumoniae, and Mycobacterium tuberculosis. In particular, T-3811 exhibited potent activity against various gram-positive cocci, with MICs at which 90% of the isolates are inhibited (MIC90s) of 0.025 to 6.25 microgram/ml. T-3811 was the most active agent against methicillin-resistant Staphylococcus aureus and streptococci, including penicillin-resistant Streptococcus pneumoniae (PRSP). T-3811 also showed potent activity against quinolone-resistant gram-positive cocci with GyrA and ParC (GrlA) mutations. The activity of T-3811 against members of the family Enterobacteriaceae and nonfermentative gram-negative rods was comparable to that of trovafloxacin. In common with other fluoroquinolones, T-3811 was highly active against Haemophilus influenzae, Moraxella catarrhalis, and Legionella sp., with MIC90s of 0.0125 to 0.1 microgram/ml. T-3811 showed a potent activity against anaerobic bacteria, such as Bacteroides fragilis and Clostridium difficile. T-3811 was the most active agent against C. trachomatis (MIC, 0.008 microgram/ml) and M. pneumoniae (MIC90, 0.0313 microgram/ml). The activity of T-3811 against M. tuberculosis (MIC90, 0.0625 microgram/ml) was potent and superior to that of trovafloxacin. In experimental systemic infection with a GrlA mutant of S. aureus and experimental pneumonia with PRSP in mice, T-3811ME showed excellent therapeutic efficacy in oral and subcutaneous administrations.

Administration, Oral↗

PubMed1998

Pharmacological properties of T-3762, a novel fluoroquinolone antimicrobial agent in parenteral use. III. Chemical structures and dermovascular permeability-increasing activities.

Fluoroquinolone antibiotics and chemically related compounds including the pazufloxacin methanesulfonate named T-3762 were examined for their ability to increase cutaneous vascular permeability following intradermal injection in dogs. A positive skin reaction was produced by the injection of a compound with a substituent of the piperazinyl, 4-piperizyl, 3-aminopyrolizinyl or 3-aminocyclobutyl group at the 7-position (C-7) of the quinolone skeleton at a minimum concentration of 101.8 microg/ml or less. Substitution at position 1, 6 or 8 of the ring nucleus hardly affected the activity of the compounds with the C-7 substituted piperazinyl group. The compounds with 7-positioned substituents other than the piperazinyl group showed relatively weak activity, and in particular those with the 1-aminocyclopropyl group including T-3762 were barely positive in concentrations of more than 500 microg/ml. An analysis of the three-dimensional models of the compounds with the C-7 substituted, nitrogen-containing groups revealed that the range of the geometrically optimum distance between the nitrogen and the carbon atoms was from 2.98 to 4.98 A for highly active compounds and from 2.47 to 2.65 A for weakly active compounds. In conclusion, the C-7 substituted piperazine moiety of the molecules of already-known fluoroquinolone antibiotics may be responsible for the ability to increase cutaneous vascular permeability, whereas T-3762 is practically inactive because the free amino nitrogen of the 1-aminocyclopropyl group is conformationally present at a shorter distance from the carbon atom at position 7 of the ring nucleus.

Animals↗

PubMed1997

Characteristics of quinolone-induced small colony variants in Staphylococcus aureus.

Exposure of Staphylococcus aureus to 1 x MIC of the quinolone antibiotic pazufloxacin for 24 h, followed by plating on drug-free media, led to the emergence of small colony variants (SCVs) in addition to large colony variants (LCVs). However, following incubation with 0.25 or 4 x MIC of pazufloxacin, only LCVs were obtained. The SCVs were half as susceptible to pazufloxacin or ciprofloxacin as wild-type S. aureus, while the susceptibilities of LCVs were essentially unchanged. The reduced susceptibilities of SCVs did not result from mutations in the quinolone-resistance-determining regions of DNA gyrase and topoisomerase IV, since the sequences of these genes were identical to those of the wild-type. However, the SCVs accumulated pazufloxacin and ciprofloxacin to a lesser degree than did wild-type. Furthermore, their susceptibility to quinolones was almost unaffected by reserpine or verapamil, suggesting that the reduced uptake resulted from decreased permeability, rather than from an active efflux pump. The ability of various quinolones to induce emergence of SCVs in S. aureus, correlated with the presence of carbon-bonded substituents at the C-7 position of a quinoline or naphthyridine nucleus, or with the presence of a benzoxazine nucleus. In conclusion, pazufloxacin-induced SCVs represent a mutant that one might expect to be rapidly eliminated in vivo and, hence, not to survive as a quinolone-resistant pathogen. This finding suggests a novel approach for development of future quinolones.

Animals↗

PubMed1995

A new cognition-enhancing agent, (R)-(-)-1-(benzo[b]thiophen-5-yl)- 2-[2-(N,N-diethylamino)ethoxy]ethanol hydrochloride. Effects on memory impairment in rats generated by cerebral embolization and basal forebrain lesions.

The title compound (T-588) has been evaluated for its ameliorating effect on memory impairment generated by cerebral embolization and by a basal forebrain (BF) lesion in male Wistar rats. The memory and learning deficits induced by injection of carbon-microspheres into the internal carotid artery were significantly improved by T-588 at oral dose of 3-10 mg/kg, as determined by an active avoidance response assay, whereas the reference drugs (tacrine, idebenone and indeloxazine) proved almost inactive in the same assay procedure. As far as the embolization was concerned, a significant decrease in cerebral acetylcholine and monoamines was observed. The effect on the memory impairment caused by an electrolytic lesion of the BF was assessed by a passive avoidance task. T-588 exhibited a bell-shaped dose-response curve and was most active at 1 mg/kg (oral dose), while tacrine showed equal activity at 10 mg/kg.

Animals↗

PubMed1995

Studies on cognitive enhancing agents. I. Antiamnestic and antihypoxic activities of 2-dimethylaminoethyl ethers and related compounds.

N-(2-Dimethylaminoethyl)carboxamide (1a-d), 2-dimethylaminoethyl alkyl ether (2a, b), and 2-dimethylaminoethyl 2-hydroxy-2-phenethyl ether (3a-c) and its amino and methylene analogues (3d, 4) have been screened for antiamnestic and antihypoxic activities in mice. A clear reversing effect on electroconvulsive shock-induced amnesia was found with 1a-d, 2a,b, and 2-dimethylaminoethyl 2-hydroxy-2-phenylethyl ether (3a). However, a protective effect against hypoxia was only observed with 3a. Compound 3a, which displayed the dual activity, was further investigated for ameliorating effect on CO2-induced memory impairment, and it was found to be more potent than indeloxazine and bifemelane. In addition, the acute toxicity of 3a in mice was significantly lower than that of tacrine, but its serum-to-brain penetration ability in rats was less than that of the reference drugs.

Amnesia↗

PubMed1995

Studies on cognitive enhancing agents. II. Antiamnestic and antihypoxic activities of 1-aryl-2-(2-aminoethoxy)ethanols.

A series of 2-(2-aminoethoxy)-1-phenylethanols having a variety of N- and phenyl-substitution patterns as well as 5- and 6-membered heteroaryl counterparts of our prototype compound 1 (2-(2-dimethylaminoethoxy)-1-phenylethanol) have been prepared and evaluated for antiamnestic and antihypoxic activities. Compound 3b, the 3-methylphenyl analogue of 1, proved to be significantly more potent than 1 in reversing electroconvulsive shock-induced amnesia as well as CO2-induced learning-impairment in mice. It exhibited low acute toxicity in mice and afforded a greater brain/serum concentration ratio than 1 after oral administration to rats.

Amnesia↗

PubMed1995

Studies on cognitive enhancing agents. III. Antiamnestic and antihypoxic activities of a series of 1-bicycloaryl-2-(omega-aminoalkoxy)ethanols.

2-(2-Aminoethoxy)-1-hydroxyethyl derivatives of bicyclic arenes (naphthalene, thianaphthene, benzofuran, and indole) were prepared and screened for antiamnestic (AA) and antihypoxic (AH) activities which were evaluated by measuring the reversing potency in electroconvulsion-induced amnesia and the protective effect against hypoxia, respectively, in mice. Compound 3o, 1-(benzo[b]thiophen-5-yl)-2- (2-diethylaminoethoxy)ethanol, showed the best AA and AH activity profile, being superior to our prototype compound, 2-(2-dimethylaminoethoxy)-1-phenylethanol (1). Elongation of the ethylene linkage in the side chain of 3o to 3- and 4-carbon moieties brought about a significant decrease in AH activity. Compound 3o was further investigated for its protective effect against CO2-induced memory impairment and for acute toxicity in mice. It is ten-fold more potent than tacrine in the amnesia-reversal assay and is considerably less toxic than tacrine.

Amnesia↗

PubMed1995

[Studies on structure of light degradation products of (-)-(S)-10-(1-aminocyclopropyl)-9-fluoro-3-methyl-7-oxo-2,3-dihyd ro-7H- pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid (T-3761) in aqueous solution and solid state].

The structures of light degradation products of (-)-(S)-10-(1-aminocyclopropyl)-9-fluoro-3-methyl-7-oxo-2,3-dih ydr o-7H- pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid (T-3761) in aqueous solution and in the solid state were investigated. In aqueous solution, ten products were detected using HPLC and in the solid state, one main product was detected. All these light degradation products were isolated and their structures were elucidated. It was revealed that in almost all light degradation products only the 1-aminocyclopropyl side chain at the 10-position of T-3761 is changed to various structures by light oxidation. Surprisingly we found a unique light degradation product, in which carboxylic acid at the 6-position of T-3761 is changed to the hydroxy moiety.

Anti-Infective Agents↗

PubMed1994

Pyridonecarboxylic acids as antibacterial agents. VI. Synthesis and structure-activity relationship of 7-(alkyl, cycloalkyl, and vinyl)-1-cyclopropyl-6-fluoro-4-quinolone-3-carboxylic acids.

The title compounds (1a-i) have been synthesized starting with ethyl 1-cyclopropyl-6,7-difluoro-4-quinolone-3-carboxylate (2). The 7-cyclopropyl and 7-vinyl derivative (1e and 1i) exhibited potent in vitro antibacterial activities against both gram-positive and gram-negative bacteria, being equipotent with ciprofloxacin (CPFX) except for the activity against Pseudomonas aeruginosa. The two compounds were significantly less toxic than CPFX in terms of convulsion-induction as determined by intracerebral administration to mice, but showed lower urinary recoveries on intravenous administration.

4-Quinolones↗

PubMed1994

Pyridonecarboxylic acids as antibacterial agents. VII. Synthesis and structure-activity relationship of amino- and hydroxyl-substituted 7-cycloalkyl and 7-vinyl derivatives of 1-cyclopropyl-6-fluoro-4-quinolone-3- carboxylic acid.

Novel C(7)-derivatives of 1-cyclopropyl-6-fluoro-4-quinolone carboxylic acid (3a-o) have been synthesized and evaluated for in vitro antibacterial activity. Compounds 3e (3-aminocyclobutyl), 3g (1-aminocyclopropyl), 3m ((2-aminomethyl)vinyl), and 3o ((1-aminomethyl)vinyl) showed significant inhibitory activity, comparable to that of ciprofloxacin, against gram-negative bacteria including P. aeruginosa. A good pharmacokinetic profile (serum and brain concentrations and urinary recovery) was obtained for the two cyclic compounds (3e and 3g), but that of the vinylic compounds (3m and 3o) was less favorable. Compound 3g was less toxic than 3e, ciprofloxacin, or ofloxacin in terms of acute toxicity and convulsion-induction.

4-Quinolones↗

PubMed1994

Pyridonecarboxylic acids as antibacterial agents. VIII. Synthesis and structure-activity relationship of 7-(1-aminocyclopropyl)-4-oxo-1,8-naphthyridine-3-carboxylic acids and 7-(1-aminocyclopropyl)-4-oxoquinoline-3-carboxylic acids.

4-Oxo-1,8-naphthyridine- and 4-oxoquinoline-3-carboxylic acids (2a, b and 3a-1) possessing a 1-amino-cyclopropyl group at the 7-position have been synthesized and evaluated for in vitro antibacterial activities. The three quinolones (3d, h, i) exhibited potent antibacterial activities against both gram-positive and gram-negative bacteria, which are comparable to those of ciprofloxacin (CPFX) and ofloxacin (OFLX). Among the three compounds, the best pharmacological and pharmacokinetic profile was obtained with 3i, an OFLX analogue, which was considerably less toxic than three reference quinolones (1, CPFX and OFLX).

4-Quinolones↗

PubMed1994

Pyridonecarboxylic acids as antibacterial agents. IX. Synthesis and structure-activity relationship of 3-substituted 10-(1-aminocyclopropyl)-9-fluoro-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de]- 1,4-benzoxazine-6-carboxylic acids and their 1-thio and 1-aza analogues.

A series of the title compounds listed in Chart 1 have been synthesized to study the effects of 3-alkyl substituents on the antibacterial potency and in vivo efficacy of 10-(1-aminocyclopropyl)-9-fluoro-7-oxo-2,3-dihydro-7H-pyrido[1,2,3 -de]-1,4-benzoxazine-6-carboxylic acid and its 1-thio and 1-aza variants. Compound (S)-1, which proved most active in vitro against five representative gram-positive and gram-negative organisms, was assayed in vivo using Staphylococcus aureus and Pseudomonas aeruginosa mouse infection models. It exhibited an excellent in vivo efficacy, being superior to ofloxacin and ciprofloxacin, and was then assayed for convulsion-inducing activity, mammalian cell cytotoxicity, and topoisomerase II inhibition. The biological results showed that (S)-1 displayed antibacterial and toxicological advantages over ofloxacin and ciprofloxacin. Compound (S)-1 and its methanesulfonate showed high serum concentrations after oral and intravenous administrations to mice.

Animals↗