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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The natural product 2-chloro-3,11-tridecadiene-5,7,9-triyn-1-ol (1) photosensitized the inactivation of Escherichia coli in the presence of near-ultraviolet light (320-400 nm; NUV) under both aerobic and anaerobic conditions. A series of E. coli strains differing in DNA repair capabilities and catalase proficiency exhibited indistinguishable inactivation kinetics following treatment with the chemical plus NUV. The presence of carotenoids did afford some protection to E. coli against inactivation under aerobic conditions, consistent with the involvement of singlet oxygen. The photosensitized hemolysis of human erythrocytes occurred more rapidly in the absence than in the presence of oxygen. Aerobically, the onset of hemolysis was partially inhibited by NaN3 and by 2,6-di-t-butyl-4-methylphenol (BHT) but not by superoxide dismutase (SOD). The aerobic lipid peroxidation observed in the membranes of erythrocyte ghosts was completely inhibited by BHT, and partially by NaN3, but not by SOD. These results suggest that either lipid peroxidation of the membrane is not the main cause of photohemolysis or that BHT has insufficient access to intact erythrocyte lipids to protect them. Aerobically, crosslinking of membrane proteins was also observed; it was not affected by SOD, but was partially inhibited by BHT and NaN3. The anaerobic photosensitized hemolysis of erythrocytes was more rapid; a radical mechanism was suggested since BHT inhibited the hemolysis to a greater extent than under aerobic conditions. Neither lipid peroxidation nor protein crosslinking was observed under conditions believed to be anaerobic. A light-dependent electron transfer to cytochrome c was obtained under argon but not under oxygen. Although induced mutations were not observed in the experiments with E. coli, 1 was capable of damaging both supercoiled pBR322 and Haemophilus influenzae transforming DNA in a manner that seemed to be equivalent under aerobic and anaerobic conditions. In conclusion, 1 can behave as typical photodynamic molecule under aerobic conditions but, in contrast to most photodynamic molecules, it is also phototoxic under anaerobic conditions. The extent to which the radical reactions detected under anaerobic reactions compete with the photodynamic processes when oxygen is present is not known.
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PMID:Photosensitization by 2-chloro-3,11-tridecadiene-5,7,9-triyn-1-ol: damage to erythrocyte membranes, Escherichia coli, and DNA. 160 51

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

Branhamella catarrhalis, previously named Neisseria catarrhalis was known as a saprophytic inhabitant of the human respiratory tract. The importance as a facultative pathogen has increased during the last years. This study demonstrates the presence of B. catarrhalis in sputa and bronchial secretions of adults as well as children with bronchopulmonary diseases in a part of Berlin. From March 1989 to July 1990 in routine examinations in the bacteriological laboratory of a lung hospital 46 isolates (from 32 patients) of B. catarrhalis were identified. B. catarrhalis was found in pure culture and in mixed culture usually in association with Haemophilus sp. 75% were positive for beta-lactamase. B. catarrhalis is oxidase- and catalase positive and does not produce acidification of sugars. The strains reduce nitrate and hydrolyze tributyrin. The tributyrin hydrolysis proved to be useful for differentiation Branhamella from Neisseria.
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PMID:[Branhamella (Moraxella) catarrhalis--a clinically relevant pathogen of bronchopulmonary diseases?]. 180 57

alpha-Terthienyl photosensitizes single strand breaks in pBR322 DNA. Almost identical results were observed under oxygen and under argon. In the presence of oxygen, this DNA nicking was enhanced by histidine and was not affected by superoxide dismutase, catalase, or the antioxidant BHT. Although chemical damage to DNA treated with alpha-terthienyl plus near-UV was clearly demonstrated in vitro, transformation in E. coli with this damaged pBR322 DNA still took place. Likewise, Haemophilus influenzae DNA transforming activity was not significantly decreased by photosensitization with alpha-terthienyl.
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PMID:alpha-Terthienyl photosensitizes damage to pBR322 DNA. 185 40

Anthracene is a photodynamic compound in vitro. In the presence of oxygen, it is known to generate singlet oxygen and participate in Type II reactions. In aqueous solution, it also participates in Type I reactions, such as in the photoreduction of cytochrome c, which can be suppressed by superoxide dismutase. In argon, direct photoreduction of cytochrome c also takes place. Anthracene induces the photodynamic hemolysis of human erythrocytes and inactivates Escherichia coli cells photodynamically. By using a series of E. coli strains differing in DNA repair capabilities and catalase proficiency, sensitivity to inactivation by anthracene plus NUV was correlated with catalase deficiency rather than with particular repair deficiencies. The fact that carotenoid genes cloned and expressed in E. coli offered partial protection suggests that the membrane may be one possible target for inactivation by anthracene plus NUV. Anthracene plus NUV inactivated Haemophilus influenzae transforming DNA and led to nicking of supercoiled pBR322 DNA in vitro. In vivo, therefore, anthracene is a phototoxic molecule whose cytotoxicity could be the result of damage to more than one target.
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PMID:Light-dependent cytotoxic reactions of anthracene. 196 59

Cellular, colonial, cultural, and biochemical characteristics of 25 field strains of gram-negative pleomorphic bacilli from rams with epididymitis were compared with Actinobacillus actinomycetemcomitans American Type Culture Collection (ATCC) strain 29522 and Actinobacillus seminis ATCC strain 15768. Three field strains were identified as A. actinomycetemcomitans, 15 as A. seminis, and 2 as Haemophilus agni; however, 5 strains (3 in group A and 2 in group B) were not identified as species in the genera Actinobacillus, Haemophilus, or Pasteurella based on the taxonomic criteria in Bergey's manual of systematic bacteriology. The 5 Actinobacillus-like organisms in groups A and B were predominantly gram-negative coccobacilli and exhibited less pleomorphism than the 2 Actinobacillus species. The colonial morphologies of groups A and B were similar to the 2 Actinobacillus species but were smaller in diameter and had a pale yellow color. Groups A and B, like the actinobacilli, were facultative anaerobic and capnophilic, did not grow on MacConkey agar, and were catalase-positive and oxidase-positive. Group A reduced nitrate but group B did not. The A. seminis strains utilized ornithine, and group A utilized arginine; but group B did not utilize either ornithine or arginine. All strains failed to utilize lysine or tryptophane. All strains produced acid but no gas from glucose, and the utilization of other carbohydrates varied markedly both between and within the 5 groups of bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cultural and biochemical characterization of Actinobacillus and Actinobacillus-like species from ram lambs with epididymitis. 248 12

In vitro, the photodynamic compound benzo[a]pyrene (BAP) generates singlet oxygen efficiently when irradiated in organic solvents. It also photogenerates superoxide anion radical in water and can act as a photoreducing agent in the absence of oxygen. In vivo, the hemolysis of human erythrocytes, the inactivation of Escherichia coli cells representing a series of strains differing in excision repair and catalase proficiency, and the inactivation of Haemophilus influenzae transforming DNA activity were used to characterize the phototoxicity of BAP in the presence of near-UV light (290-400 nm). The results are consistent with BAP behaving as a photosensitizer that generates both superoxide and singlet oxygen, and that damages chiefly membranes. DNA does not seem to be a major target in the phototoxic reactions investigated.
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PMID:The light-dependent cytotoxicity of benzo[a]pyrene: effect on human erythrocytes, Escherichia coli cells, and Haemophilus influenzae transforming DNA. 255 8

Although Haemophilus influenzae requires heme for growth, the source of heme during invasive infections is not known. We compared heme, lactoperoxidase, catalase, cytochrome c, myoglobin, and hemoglobin as sources of heme for growth in defined media. The minimum concentration of heme permitting unrestricted growth of strain E1a, an H. influenzae type b isolate from cerebrospinal fluid, was 0.02 micrograms/ml. Using molar equivalents of heme as lactoperoxidase, catalase, cytochrome c, myoglobin, and hemoglobin, we determined that myoglobin and hemoglobin permitted unrestricted growth at this concentration. To determine the ability of host defenses to sequester heme from H. influenzae, we used affinity chromatography to purify human haptoglobin and hemopexin, serum proteins which bind hemoglobin and heme. Plate assays revealed that 12 strains of H. influenzae acquired heme from hemoglobin, hemoglobin-haptoglobin, heme-hemopexin, and heme-albumin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of outer membrane proteins of strain E1a grown in heme-replete and heme-restricted conditions revealed a heme-repressible outer membrane protein with an apparent molecular mass of 38 kilodaltons. These results demonstrated that, unlike Escherichia coli, H. influenzae may acquire heme from hemoglobin-haptoglobin. H. influenzae also may acquire heme from hemopexin and albumin, which have not been previously investigated. The role of outer membrane proteins in the acquisition of heme is not yet clear.
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PMID:Protein sources of heme for Haemophilus influenzae. 302 98

Actinobacillus (Haemophilus) actinomycetemcomitans is a facultatively anaerobic, gram-negative coccobacillus which is a possible etiological agent in juvenile periodontitis (JP). In this study, bacterial flora, especially the occurrence of A. actinomycetemcomitans, in the periodontal pockets of one juvenile with gingivitis (G), one JP patients, five rapidly progressive periodontitis (RP) patients and one adult periodontitis(AP) patient, and one adult with healthy periodontium was investigated using a blood agar medium and a selective medium for A. actinomycetemcomitans. Eight hundred and sixty-five bacteria were isolated from the periodontal pockets, examined for their gram-stain, cell morphologies, relations to O2 and CO2 and catalase reaction, and divided into 21 groups on the basis of these characters. Among the isolates, 604 isolates were further characterized biochemically and identified. A. actinomycetemcomitans was found as 0.2% of the flora of a site in the JP patient, as 9% of the flora of a site in the G patient, and as 19% and 1%, respectively, of the flora of a site in the two RP patients. However, the organism was not detected in another lesion site of the JP patient. In our JP and RP patients, Fusobacterium, Wolinella, Streptococcus, and obligately anaerobic, gram-positive cocci were frequently found at high levels. The bacterial flora of the G and AP patients were more heterogeneous and included Bacteroides at relatively high proportions. These results indicate that A. actinomycetemcomitans is not always associated with JP but occurred in some patients with RP and G.
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PMID:Actinobacillus (Haemophilus) actinomycetemcomitans in periodontal disease. 377 88


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