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

Strains of Haemophilus influenzae isolated from patients in N.E. Scotland between 1983 and 1986 have been subtyped by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of whole-cell polypeptides. Gels were stained with Coomassie blue and polypeptide profiles were analysed using the Dice coefficient of similarity. Type b strains were all closely related, the 19 strains analysed being grouped at a 90% similarity level into one large (13 strains) and one small (3 strains) cluster with 3 strains being ungrouped. Thirty-six non-typable, epidemiologically unrelated strains were subtyped; one pair of strains had indistinguishable polypeptide profiles. The polypeptide profiles of the remaining strains showed much heterogeneity, although groups of strains isolated from the same patient over short periods showed indistinguishable profiles.
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PMID:Haemophilus influenzae subtyping by SDS-PAGE of whole-cell polypeptides. 349 48

A Haemophilus influenzae strain (T-1,3) possessing clinical beta-lactam resistance due to altered penicillin-binding protein 3 was used to construct a recombinant cosmid gene bank in Escherichia coli. Three of the recombinant cosmids were capable of transforming a susceptible H. influenzae strain (Rdnov) simultaneously to moxalactam resistance and altered the binding of penicillin-binding proteins 3a and 3b to [35S]penicillin G. Restriction endonuclease mapping of one of the recombinant cosmids, pLB100, was performed to facilitate subsequent subcloning of the gene(s) responsible for the altered penicillin-binding protein 3 (a and b) binding phenotype. Subcloning of individual fragments derived from pLB100 indicated that two adjacent fragments of DNA were both capable of transforming a susceptible Haemophilus strain to moxalactam resistance and altered penicillin-binding protein 3 binding. Expression of plasmid-coded proteins in minicells indicated that one fragment coded for a major 55,000-molecular-weight polypeptide and that the second contained a C-terminal coding region that expressed a 28,000-molecular-weight polypeptide when fused to the N-terminal region of the tetracycline resistance gene. Initial attempts at labeling the plasmid-coded proteins expressed in minicells with [35S]penicillin G were unsuccessful.
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PMID:Cloning and expression of genes responsible for altered penicillin-binding proteins 3a and 3b in Haemophilus influenzae. 355 33

We compared several rapid techniques used for extraction of outer membrane proteins from gram-negative enteric bacteria to Haemophilus influenzae type b. After lysis of cells with a French press, the inner and outer membranes were separated by isopycnic centrifugation. Each membrane was identified by density, morphology, enzymatic activity, and susceptibility to solid-phase iodination of intact cells. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis, we identified 10 polypeptides which were enriched in the outer membrane band compared to the inner membrane band. Using these proteins, we compared the polypeptide pattern of outer membranes with that obtained by (1) selective solubilization with sodium dodecyl-beta-D-maltoside, octyl-beta-D-glucopyranoside, Triton X-100, sodium, or cholamidopropyl dimethylaminopropanesulfonate; (2) extraction with chaotropic agents and heat; and (3) differential centrifugation of vesicles shed during transition from log growth phase to stationary growth phase. There were definable differences between the polypeptide pattern of membranes obtained with each rapid technique compared to the polypeptide pattern of isolated outer membranes. The polypeptide pattern of lithium extracts and the Triton X-100 insoluble fractions of total membranes most closely approximated the polypeptide pattern of isopycnically isolated outer membranes. Depending on the outer membrane protein sought, one of these rapid techniques can be utilized when a rapid method of outer membrane protein isolation is required.
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PMID:A comparison of techniques for isolation of the outer membrane proteins of Haemophilus influenzae type b. 387 12

Three derivatives of oleandomycin in which the C"-4 hydroxyl moiety was replaced for the first time with a nitrogen functionality have been compared with erythromycin base and oleandomycin base. The minimum inhibitory concentrations of these derivatives for 90% of a group of clinical isolates of Staphylococcus aureus were one-half to one-fourth those of erythromycin. The minimum inhibitory concentrations of the experimental macrolides for 50% of a group of S. aureus isolates resistant to greater than 12.5 micrograms of erythromycin per ml ranged from 0.2 to 0.39 micrograms/ml. The activities of these experimental compounds were equivalent to the activities of erythromycin against Staphylococcus epidermidis, Bacteroides fragilis, and Haemophilus influenzae isolates. In general, erythromycin was more active against Streptococcus species. Each experimental macrolide was superior to erythromycin in inhibiting RNA-directed, cell-free polypeptide synthesis. The three experimental compounds were markedly more active than erythromycin base after oral administration to mice infected with S. aureus. The 50% protective doses of the experimental compounds ranged from 27.4 to 45.7 mg/kg; that of erythromycin was approximately 100 mg/kg.
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PMID:Evaluation of three 4"-deoxy-4"-sulfonamido-oleandomycin derivatives with erythromycin-like antibacterial potency. 670 75

Morphological differences were observed in competent and noncompetent Haemophilus parainfluenzae and Haemophilus influenzae when thin sections of these cells were examined by electron microscopy. The membranous extensions present on the surface of competent H. parainfluenzae cells disappeared on treatment with transforming DNA, while vacuole-like structures appeared in the periplasm. Noncompetent cells had 1/5th as many extensions on their surface as competent cells, and no vacuoles were observed after treatment with homologous DNA. Competent cells treated with radiolabeled DNA were disrupted and the clarified lysate was centrifuged on CsCl density gradients. Material having a density of 1.34 g/ml was found to contain the majority of the DNase-resistant radioactive DNA recovered from the bacteria and was shown by electron microscopy to be composed of membrane vesicles. The polypeptide composition of this dense membrane fraction was similar to that of H. parainfluenzae outer membrane.
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PMID:Possible mechanism for donor DNA binding and transport in Haemophilus. 695 25

A method has been developed to separate the cell envelope of encapsulated (type b) Haemophilus influenzae into its outer and inner membrane components with procedures that avoided two problems encountered in fractionation of this envelope: (i) the tendency of the outer and inner membranes to hybridize and (ii) the tendency of the apparently fragile inner membrane to fragment into difficulty sedimentable units. Log phage cells, whose lipids were radioactively labeled, were lysed by passage through a French press. The lysate was applied to a discontinuous sucrose gradient, and envelope-rich material was collected by centrifugation onto a cushion of dense sucrose under carefully controlled conditions. This material was then further fractionated by isopycnic centrifugation in a sucrose gradient to yield four membrane fractions which were partially characterized. On the basis of their radioactivity, buoyant density, ultrastructure, polypeptide composition, and content of phospholipid, protein, lipopolysaccharide, and succinic dehydrogenase, these fractions were identified as follows: fraction 1, outer membrane vesicles with very little inner membrane contamination (less than 4%); fraction 2, outer membrane vesicles containing entrapped inner membrane; fraction 3, a protein-rich fraction of inner membrane; fraction 4, a protein-poor fraction of inner membrane. Fractions 3 and 4 contained about 25% outer membrane contamination.
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PMID:Isolation and partial characterization of outer and inner membranes from encapsulated Haemophilus influenzae type b. 697 Jan 93

Polypeptides that appear to be involved in competence development and deoxyribonucleic acid (DNA) uptake by Haemophilus influenzae were detected with a surface-specific iodinating reagent 1,3,4,6,-tetrachloro-3 alpha, 6 alpha-diphenylglycoluril. As shown on electrophoretograms, a number of polypeptides became sensitive to 125I protein labeling with the ability of these cells to bind DNA. Of these polypeptides, nine were reduced in their ability to be labeled (ral polypeptides) extensively after the incubation of competent cells with homologous, but not with heterologous, DNA. Iodination of many of these ral polypeptides was reduced in competence-deficient mutants compared with wild-type competent cells. One 125I-labeled polypeptide corresponding to a molecular weight of 29,000 was present at reduced levels in mutants reduced in the ability to bind DNA. Our results suggest that the 29,000-molecular-weight polypeptide corresponds with the ability of H. influenzae to take up DNA and that a complex of proteins is involved in DNA uptake and transformation.
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PMID:Haemophilus influenzae polypeptides involved in deoxyribonucleic acid uptake detected by cellular surface protein iodination. 697 28

Protein H (B. Lugtenberg, R. van Boxtel, D. Evenberg, M. de Jong, P. Storm, and J. Frik, Infect. Immun. 52:175-182, 1986) is the major polypeptide of the outer membrane of Pasteurella multocida, a bacterium pathogenic for humans and animals. We have purified this protein to homogeneity by size exclusion chromatography after selective extraction with surfactants and demonstrated its pore-forming ability after reincorporation into planar lipid bilayers. In these experiments, the current through the pores was a linear function of the applied voltage in the range of -50 to +50 mV. Voltages beyond +/- 50 mV tended to partially close the channels, giving rise to apparent negative resistances. These observations suggest that protein H channels are probably not voltage regulated in vivo. With the patch clamp technique, single-channel conductance fluctuations of 0.33 nS were recorded in 1 M KCl. Electrophoretic and circular dichroism analyses showed that protein H forms homotrimers stable in sodium dodecyl sulfate at room temperature, with a high content of beta-sheet secondary structure. Upon boiling, the trimers were fully dissociated into monomers with an increase of alpha helix and irregular structure, at the expense of beta sheets. The apparent molecular mass of fully denatured monomers ranged between 37 and 41.8 kDa, depending on the electrophoretic system used for analysis. The trimeric arrangement of protein H was confirmed by image analysis of negatively stained, two-dimensional crystal arrays. This morphological study revealed, in agreement with electrophoretical data, a trimeric structure with an overall diameter of 7.7 nm. Each monomer appeared to contain a pore with an average diameter of 1 nm. Quantitative comparisons revealed that the amino acid composition (hydropathy index of -0.40) and the N-terminal sequence (determined over 36 residues) of protein H are similar to those of bacterial general porins, notably porin P2 of Haemophilus influenzae. We conclude from this set of structural and functional data that protein H of P. multocida is a pore-forming protein related to the superfamily of the nonspecific bacterial porins.
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PMID:Purification and characterization of protein H, the major porin of Pasteurella multocida. 767 92

DNA sequencing, RNA mapping, and protein expression experiments revealed the presence of a gene, tfoX+, encoding a 24.9-kDa polypeptide, that is transcribed divergently from a common promoter region with the Haemophilus influenzae rec-1+ gene. H. influenzae strains mutant for tfoX failed to bind transforming DNA and were transformation deficient. Primer extension experiments utilizing in vivo total RNA from precompetent and competent H. influenzae cells demonstrated that transcription of tfoX+ increased immediately upon competence induction, suggesting that tfoX+ is an early competence gene. Similar experiments showed that the expression of the late competence-specific gene, com101A+, was tfoX+ dependent. Moreover, expression of plasmid-borne tfoX+ in H. influenzae resulted in constitutive competence. The addition of cyclic adenosine monophosphate (cAMP) to strains carrying a tfoX::lacZ operon fusion resulted in an immediate increase in beta-galactosidase activity that correlated with an increase in genetic transformability. Collectively, our results suggest that TfoX may play a key role in the development of genetic competence by regulating the expression of late competence-specific genes.
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PMID:Identification of a DNA transformation gene required for com101A+ expression and supertransformer phenotype in Haemophilus influenzae. 772 7

The 80-kDa D15 antigen (D-15-Ag) has previously been shown to be a target for protective immunity and conserved amongst typeable and nontypeable Haemophilus influenzae. Here, the gene encoding D-15-Ag is shown to encode a 797-aa polypeptide which, after cleavage of the predicted signal peptide, would have a molecular mass of 85,632 Da.
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PMID:The sequencing of the 80-kDa D15 protective surface antigen of Haemophilus influenzae. 773 23


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