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)

We describe here a new method for the electron microscopic mapping of sequence homology in nucleic acids. Specific segments of the T7 chromosome have been isolated following digestion with the restriction endonuclease from Hemophilus aegyptious (Haey). Denatured segments are annealed to the l-strand of T7 DNA; treatment of the hybrid with glyoxal allows only guanosine residues in the single-chain region to the reacted, producing an adduct which will no longer hydrogen bond with its complement on the r-strand. When the segment is displaced and the glyoxalated l-strand allowed to renature with the r-strand, "H" shaped structures are produced in which the duplex region corresponds to the position of sequence homology with the segment. The conditions employed for glyoxalation do not detectably disrupt duplex regions as small as 400 base pairs. This procedure should be generally useful for observing sequence homology in more complex DNA molecules containing duplex regions which can be specifically enriched for and their arrangement determined by electron microscopy.
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PMID:A new method for mapping nucleic acid sequence homology by electron microscopy. 113 34

The interactions between bovine polymorphonuclear leukocytes (PMNs) and the bacterium Haemophilus somnus are known to be complex. In this paper, we evaluated the effect of H. somnus on PMN function using a flow cytometric (FC) technique that simultaneously determined the extent of phagocytosis and hydrogen peroxide production by PMNs, as well as using conventional techniques, such as the nitroblue tetrazolium (NBT) and chemiluminescence assays, to analyse the PMN respiratory burst. Results from the FC and chemiluminescence assays demonstrated that in vitro exposure of PMNs to logarithmically growing H. somnus reduced the respiratory burst of PMNs obtained from healthy calves. However, this reduction was not detected by the NBT assay. A decrease in phagocytosis by PMNs could also be shown using the FC assay. In addition, PMNs from calves with acute Hemophilosis (i.e. exposed to H. somnus in vivo) showed reduced activity when compared to PMNs from healthy calves. These in vitro and in vivo observations indicate that the modulation of bovine PMN function by H. somnus may contribute significantly towards the pathogenesis of the disease.
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PMID:Effect of Haemophilus somnus on phagocytosis and hydrogen peroxide production by bovine polymorphonuclear leukocytes. 129 42

Haemophilus somnus is a catalase-negative, gram-negative pathogen of cattle which is refractory to killing by bovine neutrophils. In this report, we showed that H. somnus rapidly inhibited Luminol-dependent chemiluminescence of bovine neutrophils costimulated with opsonized zymosan or phorbol myristate acetate. We have postulated that this inhibition resulted in part from H. somnus preventing the accumulation of hydrogen peroxide (H2O2) during the oxidative burst. In support of this hypothesis, we have demonstrated that when stimulated with viable H. somnus, bovine neutrophils accumulate lower levels of H2O2 than did neutrophils stimulated with heat-killed H. somnus or opsonized zymosan. We have presented evidence that four separate strains of H. somnus, despite being catalase negative by conventional criteria, removed H2O2 from solution. Viable cells of H. somnus were required for the removal of H2O2 from solution; little or no activity was observed when suspensions of heat-killed, formalin-killed, or sonicated cells of H. somnus were incubated with H2O2. In addition, the elimination of H2O2 occurred only in the presence of carbon sources that could be utilized by H. somnus, indicating that elimination of H2O2 was an energy-dependent process. The amount of H2O2 that could be eliminated by 10(7) cells of H. somnus was greater than 10 nmol, an amount comparable to that produced by a similar number of stimulated bovine neutrophils. Thus, we suggest that the ability of H. somnus to remove H2O2 from solution may be an important virulence mechanism that contributes to the survival of the organism following ingestion by bovine neutrophils.
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PMID:Elimination of hydrogen peroxide by Haemophilus somnus, a catalase-negative pathogen of cattle. 164 67

We examined the killing of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus by oxygen metabolites generated by the xanthine-xanthine oxidase (X-XO) system. This system generates a mixture of oxidants, including superoxide radical, hydrogen peroxide, hydroxyl radical, and possibly singlet oxygen. Differential sensitivity to the X-XO system was observed among strains of A. actinomycetemcomitans; notably, 2 catalase-deficient strains and 2 strains representative of serotypes b and c were the most susceptible. H. aphrophilus was not sensitive. The amount of oxidants produced by the X-XO system more closely correlated with killing than the ratio of oxidant production. Cytochrome c, superoxide dismutase, catalase, dimethyl sulfoxide, and desferrioxamine were used to determine the role of superoxide radical, hydrogen peroxide and hydroxyl radical in the bactericidal process. Hydrogen peroxide was the major bactericidal agent against A. actinomycetemcomitans. Superoxide anion participated in killing of A. actinomycetemcomitans to varying but lesser degrees. The intracellular generation of hydroxyl radical was implicated in the killing of several strains. We conclude that (i) strains of A. actinomycetemcomitans are differentially sensitive to the bactericidal effects of the X-XO system and (ii) of the oxidants produced by the X-XO system, hydrogen peroxide is the most bactericidal against A. actinomycetemcomitans.
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PMID:Sensitivity of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus to oxidative killing. 166 50

Copper-zinc superoxide dismutase ([Cu,Zn]-SOD) is widely found in eukaryotes but has only rarely been identified in bacteria. Here we describe sodC, encoding [Cu,Zn]-SOD in Haemophilus influenzae and H. parainfluenzae, frequent colonists and pathogens of the human respiratory tract. In capsulate H. influenzae, sodC was found in only one division of the bacterial population, and although the protein it encoded was clearly [Cu,Zn]-SOD from its deduced sequence, it lacked enzymatic activity. In H. parainfluenzae, in contrast, active enzyme was synthesized which appeared to be secreted beyond the cytoplasm when the gene was expressed in Escherichia coli minicells. The origin of gene transcription differed between the Haemophilus species, but protein synthesis from cloned genes in vitro was comparable. A C-T transition was found in the H. influenzae sequence compared with the H. parainfluenzae sequence, leading to a histidine, known to be crucial in eukaryotic [Cu,Zn]-SOD for copper ion coordination and so for enzymatic activity, to be changed to tyrosine. This is speculated to be the cause of inactivity of the H. influenzae enzyme. Secreted SODs have only been described in a few bacterial species, and this is the first identification of [Cu,Zn]-SOD in a common human upper respiratory tract colonist. The role of secreted bacterial SODs is unknown, and we speculate that in Haemophilus species the enzyme may confer survival advantage by accelerating dismutation of superoxide of environmental origin to hydrogen peroxide, disruptive to the normal mucociliary clearance process in the host.
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PMID:Copper-zinc superoxide dismutase of Haemophilus influenzae and H. parainfluenzae. 193 42

Neutrophil myeloperoxidase (MPO) adsorbs to bacteria as a pre-requisite for killing by the MPO/hydrogen-peroxide/chloride system. Three chromatographically distinct isoforms of MPO (MPO I, MPO II, and MPO III) have been isolated from human neutrophils. The purpose of this study was to determine whether oral bacteria--including Actinobacillus actinomycetemcomitans, Capnocytophaga sputigena, Haemophilus aphrophilus, and Eikenella corrodens--differentially adsorb the three major isoforms of MPO from a mixture of MPO I, II, and III, and to assess the effect of pH and normal human serum (NHS) on MPO adsorption. MPO III adsorbed preferentially (i) at high bacterial concentrations, (ii) in the pH range of 6.0-8.0, and (iii) in the presence and absence of NHS. These results support the role of MPO III in the killing of oral bacteria.
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PMID:Preferential adsorption of human neutrophil myeloperoxidase isoform III by oral bacteria. 217 41

Fluoranthene, a non-carcinogenic polycyclic aromatic hydrocarbon, inactivates Escherichia coli cells in the presence of near-ultraviolet light (NUV; 300-400 nm). E coli cells carrying defects in the uvrA6 or katF genes are sensitized to inactivation by the simultaneous treatment with fluoranthene and NUV, suggesting that DNA is a target and that hydrogen peroxide is generated. Haemophilus influenzae transforming DNA can be inactivated by the simultaneous treatment with fluoranthene and NUV confirming DNA as a target. Using the photooxidation of imidazole and histidine as probes, fluoranthene was found to generate singlet oxygen in organic and aqueous media. In water, it participated in electron transfer reactions, reducing nitro blue tetrazolium as well as ferricytochrome C. This reduction took place both in the presence of air, where superoxide anion was formed, and under argon. Simultaneous treatment with fluoranthene and NUV was incapable of inducing histidine-independent mutations. Simultaneous treatment with fluoranthene and NUV was incapable of inducing the uvrA gene product as evidenced by the absence of the induction of beta-galactosidase in an E coli operon fusion strain [uvrA215::Mud(Ap,lac)].
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PMID:Phototoxic effects of fluoranthene, a polycyclic aromatic hydrocarbon, on bacterial species. 282 96

Previously we showed that guinea pig alveolar macrophages (AMs) incubated with serum obtained from Haemophilus influenzae-treated animals had detrimental effects on airway smooth muscle beta-adrenergic receptor function. In the present study the influence of H. influenzae treatment on several functions of guinea pig AMs was examined. Sera obtained from animals 4 days after intraperitoneal administration of H. influenzae or from control guinea pigs possessed similar opsonic capacities. No effects of these sera on hydrogen peroxide release by AMs were observed as compared to the basal hydrogen peroxide release of AMs. Interestingly, stimulation of AMs with serum from control animals resulted in a diminished cyclo-oxygenase product formation, which was potentiated after incubating AMs with serum from H. influenzae-treated guinea pigs. No differences in phagocytic activity of AMs isolated from control or H. influenzae-treated animals were observed. When AMs were incubated with phorbol myristate acetate or zymosan, the cells produced superoxide anion and released hydrogen peroxide. However, the amounts of superoxide and hydrogen peroxide released did not differ between AMs isolated from control or H. influenzae-treated animals.
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PMID:Phagocytosis and metabolism of alveolar macrophages of guinea pigs treated with Haemophilus influenzae. 282 54

The topical application of hydrogen peroxide (H2O2) and sodium bicarbonate (NaHCO3), individually and in combination, has been used empirically in the treatment of periodontal diseases. In this study, we examined both minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of these disinfectants individually and in combination against selected facultative, Gram-negative oral bacteria in a microtiter dilution assay. The bacteria studied included Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, Eikenella corrodens, and Capnocytophaga gingivalis. These bacteria exhibited MBC (one hr) values ranging from 75 mumol/L to greater than 10 mmol/L and MIC from less than 5 to 500 mumol/L for H2O2. The tested bacteria exhibited MIC values for NaHCO3 of from 23 to 182 mmol/L, and the MBC (one hr) exceeded 728 mmol/L for most of the strains examined. At sublethal (sub-MIC) concentrations, sodium bicarbonate antagonized the ability of H2O2 to inhibit bacterial growth in MIC assays, but sublethal concentrations of H2O2 had no effect on the MIC values of NaHCO3. Lethal concentrations of H2O2 and NaHCO3 exhibited synergistic antimicrobial activity in combination in one-hour bactericidal assays. Since the bactericidal properties of these antimicrobial agents are synergistic, we conclude that it may be rational to use them in combination to treat certain forms of periodontal disease. Also, lower and perhaps safer concentrations of H2O2 can be used in combination with NaHCO3 when oxidative antimicrobial chemotherapy is indicated.
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PMID:Antimicrobial properties of hydrogen peroxide and sodium bicarbonate individually and in combination against selected oral, gram-negative, facultative bacteria. 301 51

Actinobacillus actinomycetemcomitans and the genetically-related oral haemophili (Haemophilus segnis, Haemophilus aprhophilus and Haemophilus paraphrophilus) exhibit a range of sensitivities to the lethal effect of hydrogen peroxide (H2O2), A. actinomycetemcomitans being the most resistant. To extend this information, susceptibility to a range of H2O2 concentrations (10(-6)-10(-3) M) was assessed by incubating bacterial suspensions for 1 h at 37 degrees C in the presence of H2O2 and spreading the suspensions on chocolate agar plates to determine the concentration of H2O2 producing a 50 per cent reduction in colony-forming units (LD50). Catalase activity was quantified with a Clark-type oxygen electrode, which polarographically monitored the formation of dissolved oxygen in bacterial suspensions or sonicates following addition of reagent H2O2. Sensitivity to H2O2 did not correlate with catalase activity, either in intact cells or in bacterial sonicates. Specifically, some bacterial strains with undetectable catalase activity were highly resistant to H2O2. Micromolar concentrations of sodium azide which completely inhibited cell-associated catalase activity did not affect the resistance of A. actinomycetemcomitans to H2O2. Thus, the endogenous catalase activity of A. actinomycetemcomitans and certain oral haemophili is not an important determinant of resistance to the bactericidal effects of H2O2.
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PMID:Influence of endogenous catalase activity on the sensitivity of the oral bacterium Actinobacillus actinomycetemcomitans and the oral haemophili to the bactericidal properties of hydrogen peroxide. 386 73


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