The Experts below are selected from a list of 60 Experts worldwide ranked by ideXlab platform
A Arpini - One of the best experts on this subject based on the ideXlab platform.
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comparative ototoxicity of Dibekacin and netilmicin in guinea pigs
Pharmacology & Toxicology, 2009Co-Authors: L Parravicini, A Forlani, M Marzanatti, A ArpiniAbstract:The cochleo- and vestibulotoxicity of Dibekacin and netilmicin were compared in a guinea pig model. Both aminoglycosides were administered subcutaneously for 21 days at the dose level of 150 mg/kg/day. Control animals were injected with saline. Dibekacin-treated animals showed a significant (P less than 0.05) increase in the thresholds of the Preyer pinna reflex and the VIIIth nerve compound action potential in response to sound click stimulation. Moreover, a deterioration of the electrophysiologic auditory response and an almost complete suppression of the post-rotatory nystagmus were detected. In contrast, netilmicin did not induce any significant change in auditory and vestibular functions as compared to the control group. Our results demonstrated that netilmicin was devoid of ototoxicity in the guinea pig, while Dibekacin provoked mild cochlear and severe vestibulotoxicity.
Yokoyama Takashi - One of the best experts on this subject based on the ideXlab platform.
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Susceptibility of Methicillin-resistant Staphylococcus aureus Clinical Isolates to Various Antimicrobial Agents. III. Novel, Inducible Resistance to Macrolide-lincosamides-treptogramin B (MLS) Antibiotics.
Hiroshima University Medical Press, 1993Co-Authors: Inouye Yoshio, Morifuji Kazuo, Masumi Noriko, Takesue Yoshio, Sugiyama Masanori, Kodama Takashi, Yokoyama TakashiAbstract:Resistance patterns against 25 antimicrobial agents consisting of β-lactams, aminoglycosides, tetracyclines, fluoroquinolones, macrolides and etc. were examined for 69 strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated at Hiroshima University Hospital from July 1991 to April 1992. Regarding overall resistance (the percentage of highly and moderately resistant strains), the following antimicrobial agents were no more effective chemotherapeutics for MRSA infections (%resistance): methicillin (100), flomoxef (100), kanamycin (100), tobramycin (100), amikacin (100), isepamicin (100), gentamicin (78), Dibekacin (100), ofloxacin (99), levofloxacin (99), temafloxacin (99), erythromycin (100), clarithromycin (100), tetracycline (93), minocycline (93) and fosfomycin (100). Further spread of arbekacin-resistant strain, which was isolated in April 1991, into a clinical environment could not be recognized during the period covered in the present study. All the MRSA strains were resistant either constitutively (26 strains) or inducibly (43 strains) to macrolide-lincosamide-streptogramin B (MLS) antibiotics. When expression is constitutive, the strains are resistant to all MLS antibiotics. In contrast, 16-membered macrolide (i.e., jasamycin), lincomycin and mikamycin B escape resistance in the strains with a typical inducible resistance overcome in the presence of 14-membered macrolides by a translational attenuation mechanism. Three of 4β-lactamase-positive strains, however, can not be classified in these two resistance groups, being exclusively resistant to mikamycin B. The strains grown in the presence of any inducing MLS antibiotic became susceptible to mikamycin B even in the inducer-free culture
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Susceptibility of Methicillin-resistant Staphylococcus aureus Clinical Isolates to Various Antimicrobial Agents. IL Isolation of Arbekacin-resistant Strain.
Hiroshima University Medical Press, 1992Co-Authors: Inouye Yoshio, Morifuji Kazuo, Masumi Noriko, Nakamura Shoshiro, Takesue Yoshio, Santou Takahiro, Yokoyama TakashiAbstract:Resistance patterns against 24 antimicrobial agents were examined for 50 strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated at Hiroshima University Hospital during the period October 1990 and July 1991. Overall resistance (the percentage of highly and moderately resistant strains) to the antimicrobial agents is summarized as follows: methicillin 100%, flomoxef 100% (β-lactams); kanamycin 94%, tobramycin 94%, amikacin 100%, isepamicin 94%, gentamicin 80%, Dibekacin 94%, arbekacin 2% (basic oligosaccharide group/aminocyclitols); ofloxacin 96%, temafloxacin 96%, levofloxacin 96% (fluoroquinolones); erythromycin 98%, clarithromycin 98%, josamycin 30% (macrolides); vancomycin 0% (glycopeptide); tetracycline 94%, minocycline 94% (tetracyclines); fosfomycin 100%; mikamycin B 30%, nosiheptide 0% (peptide); rifampicin 2% (ansamycin); streptomycin 2% (basic oligosaccharide group); chloramphenicol 2%. Arbekacin resistance was observed in one case: the cross resistance was complete among the aminocyclitol antibiotics tested in this study and streptomycin, probably due to the ribosomal alteration
Tsutomu Tsuchiya - One of the best experts on this subject based on the ideXlab platform.
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synthesis of 2 oxidized derivatives of 5 deoxy 5 epi 5 fluoro Dibekacin and arbekacin and study on structure chemical shift relationships of urethane or amide type nh protons in synthetic intermediates
Carbohydrate Research, 1997Co-Authors: Yoshihiko Kobayashi, Tsutomu TsuchiyaAbstract:Abstract Three 2″-modified Dibekacin-analogs have been prepared as potential compounds active against resistant bacteria producing 2″- O -phosphotransferases; one is 5-deoxy-5,2″-diepi-5-fluoroDibekacin ( 9 ) prepared from a suitably protected 2″- O -triflyl derivative through the 2″,3″-cyclic carbamate, and the others are 2″-oxo derivatives ( 12 and 22 , both as the hydrate) of 5-deoxy-5-epi-5-fluoro-Dibekacin and -arbekacin prepared through oxidation at C-2″ of suitably protected derivatives. Relationships between the t -butoxycarbonyl(= Boc)-N H -shifts of per- N -Boc synthetic intermediates and their structures were studied. It was found that the shifts, measured in pyridine- d 5 at 80 °C, which spread over a close range (δ 6–7 ppm), are sensitively influenced by nearby and surrounding groups around the BocNH group in respect of electron-withdrawing character, hydrogen bonding (BocN H … acceptor), and also solvent effects (BocN H … N C 5 H 5 ).
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synthesis of Dibekacin analogs containing 3 oxa and 3 aza 2 3 4 trideoxy d glycero hexopyranose
Carbohydrate Research, 1996Co-Authors: Ryuji Kuwahara, Tsutomu TsuchiyaAbstract:6-O-(3-Oxa-2,3,4-trideoxy-alpha-D-glycero-hexopyranosyl) derivatives (10 and 17) of both 3',4'-dideoxyneamine and 5-epifluoro-5,3',4'-trideoxyneamine have been prepared by coupling ethyl 6-O-benzyl-3-oxa-2,3,4-trideoxy-1-thio-D-glycero-hexopyranoside (5) with suitable aglycons. The corresponding 3"-aza derivative (19) of Dibekacin (6) was prepared by oxidation of 1,3,2',6'-tetra-N-tosylDibekacin (7) with Pb(OAc)4 followed by treatment with NH4OAc and reduction with NaBH3CN. Related ring-opening compounds (11 and 25) were also prepared.
Inouye Yoshio - One of the best experts on this subject based on the ideXlab platform.
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Susceptibility of Methicillin-resistant Staphylococcus aureus Clinical Isolates to Various Antimicrobial Agents. III. Novel, Inducible Resistance to Macrolide-lincosamides-treptogramin B (MLS) Antibiotics.
Hiroshima University Medical Press, 1993Co-Authors: Inouye Yoshio, Morifuji Kazuo, Masumi Noriko, Takesue Yoshio, Sugiyama Masanori, Kodama Takashi, Yokoyama TakashiAbstract:Resistance patterns against 25 antimicrobial agents consisting of β-lactams, aminoglycosides, tetracyclines, fluoroquinolones, macrolides and etc. were examined for 69 strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated at Hiroshima University Hospital from July 1991 to April 1992. Regarding overall resistance (the percentage of highly and moderately resistant strains), the following antimicrobial agents were no more effective chemotherapeutics for MRSA infections (%resistance): methicillin (100), flomoxef (100), kanamycin (100), tobramycin (100), amikacin (100), isepamicin (100), gentamicin (78), Dibekacin (100), ofloxacin (99), levofloxacin (99), temafloxacin (99), erythromycin (100), clarithromycin (100), tetracycline (93), minocycline (93) and fosfomycin (100). Further spread of arbekacin-resistant strain, which was isolated in April 1991, into a clinical environment could not be recognized during the period covered in the present study. All the MRSA strains were resistant either constitutively (26 strains) or inducibly (43 strains) to macrolide-lincosamide-streptogramin B (MLS) antibiotics. When expression is constitutive, the strains are resistant to all MLS antibiotics. In contrast, 16-membered macrolide (i.e., jasamycin), lincomycin and mikamycin B escape resistance in the strains with a typical inducible resistance overcome in the presence of 14-membered macrolides by a translational attenuation mechanism. Three of 4β-lactamase-positive strains, however, can not be classified in these two resistance groups, being exclusively resistant to mikamycin B. The strains grown in the presence of any inducing MLS antibiotic became susceptible to mikamycin B even in the inducer-free culture
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Susceptibility of Methicillin-resistant Staphylococcus aureus Clinical Isolates to Various Antimicrobial Agents. IL Isolation of Arbekacin-resistant Strain.
Hiroshima University Medical Press, 1992Co-Authors: Inouye Yoshio, Morifuji Kazuo, Masumi Noriko, Nakamura Shoshiro, Takesue Yoshio, Santou Takahiro, Yokoyama TakashiAbstract:Resistance patterns against 24 antimicrobial agents were examined for 50 strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated at Hiroshima University Hospital during the period October 1990 and July 1991. Overall resistance (the percentage of highly and moderately resistant strains) to the antimicrobial agents is summarized as follows: methicillin 100%, flomoxef 100% (β-lactams); kanamycin 94%, tobramycin 94%, amikacin 100%, isepamicin 94%, gentamicin 80%, Dibekacin 94%, arbekacin 2% (basic oligosaccharide group/aminocyclitols); ofloxacin 96%, temafloxacin 96%, levofloxacin 96% (fluoroquinolones); erythromycin 98%, clarithromycin 98%, josamycin 30% (macrolides); vancomycin 0% (glycopeptide); tetracycline 94%, minocycline 94% (tetracyclines); fosfomycin 100%; mikamycin B 30%, nosiheptide 0% (peptide); rifampicin 2% (ansamycin); streptomycin 2% (basic oligosaccharide group); chloramphenicol 2%. Arbekacin resistance was observed in one case: the cross resistance was complete among the aminocyclitol antibiotics tested in this study and streptomycin, probably due to the ribosomal alteration
Doris Hernandez - One of the best experts on this subject based on the ideXlab platform.
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effects of bekanamycin and Dibekacin on the electrical activity of cardiac pacemaker cells
Archives of Medical Research, 1993Co-Authors: Miguel A Morales, Jose Luis Castrillon, Doris HernandezAbstract:In spontaneously beating sinus venosus of the frog Caudiverbera caudiverbera the effects of bekanamycin and Dibekacin, two aminoglycoside antibiotics, on action potentials of cardiac primary pacemaker cells were studied by intracellular recording. Bekanamycin and Dibekacin induced a concentration-dependent decrease of the amplitude, overshoot and the rate of rise of the action potential. Both also flattened the slow diastolic depolarization leading to a marked decrease in beat rate. At the highest concentration used (1 x 10(-3) M), the aminoglycosides produced a complete inhibition of primary cells action potentials. It was preceded by the appearance of subthreshold oscillations of the membrane potential which were observed for a few minutes until the electrical activity of pacemaker cell ceased. During absence of impulse initiation a stable membrane potential about -40 mV was observed. Aminoglycoside effects, excepting those on SCL, were completely suppressed when external calcium was increased to 3.6 mM. The results support the conclusion that bekanamycin and Dibekacin depress the electrical activity of pacemaker cells. It is suggested that this effect is induced by aminoglycosides blockade of the slow calcium current involved in both upstroke and slow diastolic depolarization and through modification of potassium outward current. Bekanamycin at a lower concentration than that needed to induce electrophysiological effects potentiated verapamil 1 x 10(-8) effects on cardiac pacemaker cells.