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 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

This report emphasizes new clinical information about bacterial meningitis in infants and children. Important elements of diagnosis include examination for the presence of shock and increased intracranial pressure. In such cases, initial treatment should focus on appropriate fluid therapy, administration of oxygen, reduction of intracranial pressure and use of corticosteroids. Currently, antibiotics of choice include ampicillin plus either cefotaxime or ceftriaxone in young infants, and one of these cephalosporins in older patients (beyond 3 months of age). Shorter durations of therapy (5 to 7 days for meningococcus, 7 days for haemophilus and 7-10 days for pneumococcus) are now commonly employed. In many centers, dexamethasone is started before the first dose of antibiotic and continued for 4 days to reduce neurologic and audiologic sequelae. Future trends will include studies of endotoxin neutralizers and non-steroidal anti-inflammatory drugs to reduce further tissue injury in meningitis. Prevention of meningitis is the ultimate goal. Since Haemophilus influenzae vaccination can now begin at 2 months, this approach may bring important results soon.
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PMID:Bacterial meningitis--an update. 176 75

The profound decline in death rates from respiratory infections in recent decades in the developed countries of the world is a complex phenomenon that probably results from a combination of socioeconomic and environmental change and modern medical care. Death rates from respiratory infections in the developing world are very variable, and there is evidence that they can decrease dramatically when effective health services are engrafted onto a social environment in which mothers are literate and trained to observe their children's health. A worldwide case management program aimed at making lifesaving antibiotics and oxygen available for treatment of children in deprived areas is currently being spearheaded by the World Health Organization and rests on simplified approaches to diagnosis that are widely disseminated to parents and primary health workers. These guidelines have been shown in field studies to contribute to changes in child mortality. The epidemiology of pneumonia in childhood seems similar worldwide. Most children suffer five to eight respiratory infections annually if they live in the cities and fewer if they live in rural areas but, in deprived circumstances, pneumonia complicates the infection much more often and the principal organisms are pneumococcus and Haemophilus influenzae. A vaccine approach to these two organisms is attractive and needs further field testing. Meanwhile, a case management approach, making antibiotics available on a rational basis worldwide, is capable of saving lives. Until mothers in the developing world have confidence in the survival of their children, they are unlikely to be attracted to control of their fertility.
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PMID:Acute respiratory infections in children in the developing world. 181

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

The lethal effect of polychromatic near-UV light (325-400 nm) on Haemophilus influenzae was 8 times higher under aerobic than anaerobic irradiation. This light increased the frequency of mutation to novobiocin resistance and ability to utilize protoporphyrin IX. The slope of mutagenic effect at low doses appeared greater for the aerobic than for the anaerobic group. We concluded that polychromatic near-UV mutation of H. influenzae under anaerobic irradiation was caused by direct oxygen-independent action on DNA.
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PMID:Mutagenic and lethal action of polychromatic near-ultraviolet (325-400 nm) on Haemophilus influenzae in the presence of nitrogen. 235 36

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

In the past decade, significant progress has been made in understanding structure-function relationships of the new quinolones, which have a N-1-substituted, 1,4-dihydro-4-oxo-pyridine-3-carboxylic acid moiety as the basic nucleus. Modification of the groups affixed to positions C-6, C-7, and C-8 has made a major change in the antimicrobial activity, pharmacokinetic, and metabolic properties of the quinolones as have changes in the moieties affixed to the N-1 nitrogen. The new quinolones have a carboxyl group at position 3 and a keto group at C-4. The presence of a fluorine atom at C-6 enhances the deoxyribonucleic acid (DNA) gyrase inhibitory activity as well as the ability of the compounds to inhibit staphylococci. Position C-7 has been one of the most modified sites. Addition of a piperazinyl group markedly increased gram-positive activity, primarily antistaphylococcal activity; lowered the minimal inhibitory concentrations against Enterobacteriaceae, Haemophilus spp., and Neisseria spp.; and added activity against Pseudomonas aeruginosa compared with nalidixic acid. Methyl derivatives of the piperazine group or of the pyrroles have longer half-lives than do unsubstituted moieties. At the N-1 position, a cyclopropyl group appears to be most potent with respect to minimal inhibitory concentrations against Enterobacteriaceae and Pseudomonas. Ofloxacin is unique in that it has an oxygen substituted at C-8 with the substituent part of the ring system formed by fusion to the N-1 position. This has produced excellent in vitro activity against gram-positive species comparable with that of ciprofloxacin, excellent activity against the Enterobacteriaceae, and antipseudomonal activity superior to agents with an ethyl substitution at position N-1. The oxazine ring of ofloxacin provides excellent oral absorption with virtually 95 percent bioavailability; this modification also has prevented metabolism and has provided a long half-life of seven to eight hours.
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PMID:Chemical evolution of the fluoroquinolone antimicrobial agents. 255 62

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

The Gram-negative bacterium Haemophilus influenzae has been shown to cause a deterioration of the guinea pig pulmonary beta-adrenergic receptor system. In the present study we investigated further the mechanisms behind this effect. To this extent we evaluated the involvement of pulmonary macrophages (PM). Treatment of guinea pigs with killed H. influenzae bacteria resulted in the accumulation of a factor in the serum which could specifically stimulate PM. Thus stimulated, PM from nontreated animals caused a decrease of tracheal beta-adrenergic receptor function in vitro. This effect was evident by a decrease of the maximal response of the dose-response curves to isoprenaline, whereas the EC50 values did not change. Catalase and thiourea abolished the PM-induced effects, whereas superoxide dismutase did not, indicating that oxygen-centered radicals, in particular the highly reactive hydroxyl radical, may be responsible for the observed effects. In addition, dexamethasone also inhibited the decrease of tracheal beta-adrenergic receptor function. When activated PM, taken from animals that had been pretreated with killed H. influenzae bacteria 4 days beforehand, were stimulated with serum from a H. influenzae-treated animal, a potentiation of tracheal beta-adrenergic receptor function was observed.
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PMID:Dual effects of Haemophilus influenzae on guinea pig tracheal beta-adrenergic receptor function: involvement of oxygen-centered radicals from pulmonary macrophages. 303 75


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