Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Haemophilus influenzae Rf 232, showing the phenomena of restriction and modification, contains an endonuclease that inactivates in vitro the biological activity of DNAs lacking the strain-specific modification. This specific restriction endonuclease has been purified to near homogeneity by a procedure that includes DNA-agarose chromatography. This highly purified enzyme requires ATP and Mg2+ for activity and is stimulated by S-adenosylmethionine. The enzyme seems to cleave DNA at well-defined sites, since it produces a specific pattern of bands upon agarose gel electrophoresis. The enzyme has no ATPase activity. A methylase activity is observed in the course of the endonucleolytic reaction, which probably protects some of the DNA sites from cleavage.
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PMID:Purification and properties of a new restriction endonuclease from Haemophilus influenzae Rf. 3 45

EndoR . NgoII, a class II restriction endonuclease isolated from Neisseria gonorrhoeae, was purified to electrophoretic homogeneity. We were able to separate it from another restriction endonuclease of N. gonorrhoeae, NgoI, by phosphocellulose chromatography. NgoII is an isoschizomer of HaeIII, a restriction endonuclease of Haemophilus aegyptius, and was found to recognize the deoxyribonucleic acid nucleotide base sequence GGCC. NgoII was able to digest phage lambda deoxyribonucleic acid over a wide pH range, with optimal activity at pH 8.5. The enzyme has an absolute requirement for Mg2+; maximal enzyme activity was observed at 1 mM Mg2+. The active enzyme has a molecular weight of 65,000 and appears to be composed of six subunits of identical molecular weight (11,000). No methylase activity could be detected in the purified enzyme preparation.
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PMID:NgoII, a restriction endonuclease from Neisseria gonorrhoeae. 3 16

A DNA-relaxing enzyme capable of concerted nicking and closing of DNA backbone bonds has been purified from Haemophilus gallinarum by two chromatographic steps and gel filtration. The enzyme efficiently catalyzes the removal of superhelical turns from a negatively twisted DNA and requires Mg2+ for this activity. Slight removal of superhelical turns from a positively twisted DNA generated by binding of ethidium bromide is found, but only at high enzyme concentrations. The DNA-relaxing activity is inhibited markedly with heat-denatured DNA, whereas native DNA and RNA have almost no affect on this activity.
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PMID:Purification and characterization of DNA-relaxing enzyme from Haemophilus gallinarium. 22 61

During bacteriophage studies on Haemophilus influenzer, it was observed that encapsulated type b and unencapsulated Rb strains released a bactericidal substance acitve against types a, c, d, e, and f H. influenzae, non-typable H. influenzae strains, other Haemophilus species, and certain members of the Enterobacteriaceae. The bactericidal activity was assayed by a plaque test utilizing an Rd strain as an indicator lawn and was also demonstrated in mixed broth cultures of a producer strain and an indicator strain. Immediately lysis of sensitive bacteria by the factor was not evident. The factor is sensitive to trypsin but resistant to deoxyribonuclease, treatment with 2-mercaptoethanol, lipase, alpha-amylase, and heating in a 100 degrees C water bath for 20 min. The activity is not dependent upon increased Ca2+ or Mg2+ concentration as is necessary for HP1C1 and S2 phage propagation. The bactericidal factor is not pelleted by high-speed centrifugation at 150,000 X g for 6 h. Treatment with ultraviolet light or mitomycin C does not result in observable phage, phage-like particles, or increased bactericidal activity. T-HE BACTERICIDAL FACTOR IS NOT A TYPICAL SMALL MOLECULAR WEIGHT "COLICIN-LIKE" BACTERiocin in that it is not inducible, has a wider range of activity, and does not kill by "single-hit" kinetics. On preliminary characterization, it is a thermostable protein toxic to certain bacterial strains.
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PMID:Bactericidal substance produced by Haemophilus influenzae b. 108 28

The rate of production of acid-soluble material during degradation of duplex DNA by Hemophilus influenzae ATP-dependent DNAse (Hind exonuclease V) has been shown to be directly dependent upon the Mg2+ concentration in the reaction mixture. At high concentrations of Mg2+ (5 to 20 mM), DNA degradation to acid-soluble products is rapid and the rate of ATP hydrolysis is slightly depressed. At low concentrations of Mg2+ (0.1 to 0.5 mM), the enzyme rapidly hydrolyzes ATP and converts up to 35% of linear duplex DNA to single-stranded material while degrading less than 0.2% of the DNA to acid-soluble products. We refer to this enzymatic production of single-stranded DNA as the "melting" activity. Under the conditions of our assay, the initial melting reaction is processive, lasting about 70s on phage T7 DNA. Using DNAs with several different lengths, we have established that the duration of the initial reaction is dependent upon DNA length, requiring approximately 1 s per 0.18 mum. The products of the initial reaction on phage T7 DNA are somewhat heterogeneous, consisting of short duplex fragments approximately 0.5 mum long, purely single-stranded products up to 7 mum long, and longer duplex fragments 3 to 11 mum in length, some of which have single-stranded tails. Nearly half of the single-stranded material remains linked to a duplex segment of DNA after the inital processive reaction. We propose that Hind exo V initiates attack at the DNA termini and then acts in a processive manner, migrating along the DNA molecule, converting some regions to single-stranded material by the combined action of the melting activity and limited phosphodiester cleavage, while leaving other regions double-stranded. At the completion of its processive movement through a single DNA molecule, it is released and then recycles onto either intact molecules or the partially degraded products, continuing in this manner until the DNA is finally reduced to oligonucleotides.
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PMID:Mechanism of DNA degradation by the ATP-dependent DNase from Hemophilus influenzae Rd. 108 72

The in vitro activity of OPC-17116, a new C-5 methyl fluoroquinolone, was compared with the activities of other fluoroquinolones. OPC-17116 inhibited 50% of the members of the family Enterobacteriaceae tested and 90% of Haemophilus influenzae, Neisseria species, and Moraxella catarrhalis isolates at less than or equal to 0.25 microgram/ml. At less than or equal to 2 micrograms/ml, 90% of the Enterobacteriaceae were inhibited, which was comparable to or better than the activities of fleroxacin, ofloxacin, and lomefloxacin but less than the activity of ciprofloxacin. OPC-17116 inhibited 90% of the staphylococci tested at less than or equal to 0.25 micrograms/ml, but it did not inhibit methicillin-resistant, ciprofloxacin-resistant Staphylococcus aureus or Staphylococcus epidermidis. Group A, B, C, F, and G streptococci and Streptococcus pneumoniae were inhibited by less than or equal to 0.5 microgram/ml, being four-fold more active than ciprofloxacin and ofloxacin. Tosufloxacin was the most active agent tested against gram-positive cocci. OPC-17116 inhibited Bacteroides fragilis at 4 micrograms/ml. There was a minimal effect of inoculum size on MIC, and the MBCs were within 1 dilution of the MICs. The activity of OPC-17116 was decreased at pH 6 and in the presence of high Mg2+ concentrations, but it was unaffected by human serum. OPC-17116 showed a postantibiotic effect against Pseudomonas aeruginosa and Staphylococcus aureus similar to the postantibiotic effects reported for other fluoroquinolones. The frequency of spontaneous single-step resistance was low (less than 10(-9)), but repeated passage of organisms in the presence of OPC-17116 resulted in the selection of resistant isolates.
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PMID:In vitro activity of OPC-17116. 132 20

The in vitro antibacterial activity of OPC-17116, a new fluoroquinolone, against a wide variety of clinical isolates was evaluated and compared with those of ciprofloxacin, ofloxacin, and norfloxacin. OPC-17116 showed potent broad-spectrum activity against gram-positive and -negative bacteria. The activity of this compound against gram-positive bacteria was higher than those of other quinolones, and its activity against gram-negative and anaerobic bacteria was roughly comparable to those of other quinolones. OPC-17116 had potent activity against important pathogens of respiratory tract infections such as Staphylococcus aureus, Streptococcus pneumoniae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Haemophilus influenzae, and Branhamella catarrhalis. The MICs of this compound against 90% of these organisms, except for methicillin-resistant S. aureus, ranged from less than or equal to 0.006 to 3.13 micrograms/ml. OPC-17116 at more than one-half the MICs was bactericidal against clinical isolates of S. aureus, Escherichia coli, K. pneumoniae, and P. aeruginosa. The activity of OPC-17116 was decreased by several culture conditions such as acidic pH, high concentration of Mg2+ ions, and inoculum size of 10(7) CFU/ml. OPC-17116 inhibited the supercoiling activity of DNA gyrases from E. coli KL-16 and S. aureus SA113 (50% inhibitory concentrations, 0.19 and 23.0 micrograms/ml, respectively). The amount of OPC-17116 accumulation was higher than that of other quinolones in S. aureus.
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PMID:Comparative in vitro activities of a new quinolone, OPC-17116, possessing potent activity against gram-positive bacteria. 133 89

Sparfloxacin (AT-4140, CI-978, PD 131501) was tested against over 800 recent bacteremic strains and compared with ciprofloxacin and six other fluoroquinolones. The 90% minimum inhibitory concentration (MIC90) ranges for the Enterobacteriaceae species were (a) sparfloxacin, 0.03-1 microgram/ml and (b) ciprofloxacin, 0.015-0.25 microgram/ml. Moraxella catarrhalis, Haemophilus influenzae, and Neisseria gonorrhoeae were very susceptible to sparfloxacin (MIC90s, 0.004- less than or equal to 0.03 microgram/ml) and the other comparison drugs. Staphylococcus aureas and other staphylococci were generally susceptible to the tested fluoroquinolones but very susceptible to sparfloxacin and WIN 57273. All beta-hemolytic streptococci, enterococci, and pneumococci had sparfloxacin MICs of less than or equal to 1 microgram/ml. Sparfloxacin was quite active against anaerobic bacteria including Bacteroides fragilis gr. and Gram-positive strains (MIC90s, less than or equal to 2 micrograms/ml). The most resistant enteric bacilli were among Serratia marcescens and the Proteae, especially the Providencia spp. (two- to eightfold higher MICs). Pseudomonas aeruginosa strains were also susceptible to sparfloxacin (MIC90, 2 micrograms/ml). Magnesium ions, CO2 incubation, and low pH had some adverse effect on sparfloxacin MICs, and resistance development was documented among current clinical isolates of staphylococci, pseudomonas, and some enteric species.
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PMID:In vitro antimicrobial activity of sparfloxacin (AT-4140, CI-978, PD 131501) compared with numerous other quinolone compounds. 190 15

The in vitro activity of a new quinolone, AM-1091 [7-(3-amino-1-pyrrolidinyl)-8-chloro-1-cyclopropyl-6-fluoro-1,4-dihydro- 4-oxo- 3-quinoline carboxylic acid hydrochloride], was compared with those of ciprofloxacin, ofloxacin, beta-lactams, and gentamicin. AM-1091 inhibited 90% of the isolates of the family Enterobacteriaceae at less than or equal to 0.12 micrograms/ml. For many species AM-1091 was 2-fold more active than ciprofloxacin and 2- to 32-fold more active than ofloxacin. It inhibited Enterobacter, Citrobacter, and Klebsiella species resistant to ceftazidime and gentamicin. Ninety percent of Pseudomonas aeruginosa isolates were inhibited by 0.5 micrograms/ml, so for this species AM-1091 was twofold less active than ciprofloxacin. AM-1091 was more active against Pseudomonas cepacia and Xanthomonas maltophilia, inhibiting isolates resistant to imipenem and gentamicin. Most Haemophilus influenzae, Neisseria gonorrhoeae, Neisseria meningitidis, and Branhamella catarrhalis isolates were inhibited by less than or equal to 0.06 micrograms/ml. The MICs for 90% of Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus faecalis isolates were 0.06, 0.06, and 2 micrograms/ml, respectively. AM-1091 inhibited hemolytic streptococci and Streptococcus pneumoniae at 0.25 micrograms/ml and was more active than ciprofloxacin or ofloxacin against gram-positive species. AM-1091 inhibited 90% of the Bacteroides species at 0.5 micrograms/ml. The frequency of spontaneous resistance was less than 10(-10) for most organisms, but resistant strains could be selected by repeated subculturing. Although AM-1091 had lower in vitro activity at pH 5.5 and in the presence of high concentrations of Mg2+, it still inhibited most organisms at </= 0.5 micrograms/ml under these conditions. AM-1091 rapidly killed Escherichia coli and P. aeruginosa and had a prolonged postantibiotic suppressive effect on these bacteria.
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PMID:Comparative in vitro activity of a new quinolone, AM-1091. 267 53

The in vitro activity of a new quinolone, QA-241, 9-fluoro-6,7-dihydro-5-methyl-8(4-methyl-1-piperazinyl) -1,7-dioxo-1 H,5H-benzo[ii]quinolizine-2-carboxylic hydrochloride, was compared with those of ciprofloxacin, ofloxacin, ceftazidime, imipenem, and gentamicin. QA-241 inhibited 90% of isolates of Enterobacteriaceae at a concentration of less than or equal to 2 micrograms/ml. It was two-fold and four- to 16-fold less active than ofloxacin and ciprofloxacin, respectively. QA-241 was less active against Pseudomonas aeruginosa and other Pseudomonas species than ciprofloxacin. Most Haemophilus influenzae and Neisseria gonorrhoeae isolates were inhibited at concentrations of less than or equal to 0.03 microgram/ml. The MIC for 90% of Staphylococcus aureus isolates, including methicillin-resistant S. aureus, was 1 microgram/ml, as was that for S. epidermidis. For streptococci, including Streptococcus faecalis, the MIC90 was 4 micrograms/ml. QA-241 had minimal activity against anaerobic species. The frequency of spontaneous resistance was less than 10(-9) for members of the Enterobacteriaceae. However, resistant strains could be isolated by repeated subculture. Similar to other quinolones, its activity was less at an acid pH and in the presence of high Mg2+ concentrations. QA-241 showed a good postantibiotic suppressive effect on Escherichia coli.
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PMID:Comparative in vitro activity of a new fluorinated 4-quinolone, QA-241. 279 86


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