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Biomedical subjects

A Ingold

Publications and source records attributed to A Ingold.

12 recordsLinked to original sources
PubMed1994

Analysis of coreceptor versus accessory molecule function of CD8 as a correlate of exogenous peptide concentration.

Substitution in the alpha 3 domain of class I molecules can ablate the recognition of target cells by CD8 dependent cytotoxic T lymphocytes. This effect has been attributed to a destruction of the CD8 alpha binding site on the class I molecule, a hypothesis which is consistent with results obtained in conjugate binding assays. To assess the relative contribution to CTL activation of CD8 functioning as either a coreceptor or an accessory molecule, we have compared the ability of H-2Kb ovalbumin reactive CTL to lyse M12.C3 or T2 cells transfected with an H-2Kb gene encoding a wild type or mutant (CD8 nonbinding) alpha 3 domain. To establish that the substitution in the alpha 3 domain does not alter the ability of the H-2Kb molecule to bind the antigenic peptide, we have compared the binding of the ovalbumin derived H-2Kb restricted peptide (SIINFEKL) to T2 cells expressing either the CD8 binding or the CD8 nonbinding form of H-2Kb. This peptide conjugated with FITC bound equally well to T2 cells expressing either form of H-2Kb. Upon binding of this peptide, both forms of the H-2Kb molecule underwent the same conformational change as revealed by increases in the expression of particular serological epitopes. Furthermore, inhibition of the binding of the SIINFEKL peptide to both the wild type and mutant H-2Kb was observed following pretreatment of the cells with similar amounts of other H-2Kb restricted peptides derived from Sendai and Vesicular Stomatitis viruses. When the transfected M12 cells were tested for their ability to serve as targets for an anti-H-2Kb ovalbumin CTL clone, cells expressing the mutant H-2Kb molecule required the addition of 100-fold more exogenous peptide than did cells expressing the wild type molecule in order to obtain significant lysis. These data strengthen the previous hypothesis that CD8 functions much more efficiently as a coreceptor than as an accessory molecule for T cell effector function.

Amino Acid Sequence↗
PubMed1987

Phylogenetic relationships between chlorophytes, chrysophytes, and oomycetes.

The phylogenetic relationships among the chlorophyte Chlamydomonas reinhardtii, the chrysophyte Ochromonas danica, and the oomycete Achyla bisexualis were explored by comparing the sequences of their small-subunit ribosomal RNA coding regions. Comparisons of similarity values or inspection of phylogenetic trees constructed by distance matrix methods reveal a very close relationship between oomycetes and chrysophytes. The separation of chrysophytes from chlorophytes is comparable to that of plants from animals, and both separations are far antedated by the divergence of a number of other protist groups.

Animals↗
PubMed1986

Phylogenetic evidence for the acquisition of ribosomal RNA introns subsequent to the divergence of some of the major Tetrahymena groups.

Previous work has demonstrated the presence of a self-splicing intron in the large subunit ribosomal RNA coding region in some strains of the ciliate protozoan Tetrahymena. Sequence comparisons of the intron regions from six Tetrahymena species showed these to fall into three homology groups. In an attempt to evaluate the evolutionary origins of the intervening sequences, we have now determined complete small subunit ribosomal RNA gene sequences from 13 species of Tetrahymena and the absolute number of nucleotide differences between the sequences was used to construct a phylogenetic tree. This phylogeny was consistent with the groupings suggested by comparisons of other biochemical characters including cytoskeletal proteins, isozyme analyses, and restriction maps of complete rRNA transcription units. The homology groupings that were based upon the intron sequence data do not agree with the relationships inferred from the small subunit rRNA sequence data. These observations are taken to indicate that the intron character has been acquired independently in different species at a stage later than the branching out of the species.

Animals↗
PubMed1976

Conversion of benzylpenicillin to penicilloic acid in patients with chronic bronchial infections.

A colorimetric method was modified to estimate the levels of benzylpenicillin and its penicilloic acid in urine. When benzylpenicillin was given orally to healthy volunteers, both it and its penicilloic acid were detected in the urine. When benzylpenicillin was given by intramuscular injections to these volunteers, only benzylpenicillin was detected in the urine. Patients suffering from chronic bronchial infections that exhibited beta-lactamase producing gram-negative bacteria in their sputum were given benzylpenicillin intramuscularly. It was found that both benzylpenicillin and penicilloic acid were recovered from the urine of such patients.

Administration, Oral↗
PubMed1975

Sputum and serum levels of amoxycillin in chronic bronchial infections.

A study of 11 patients suffering from acute exacerbations of chronic bronchial infection, all with purulent (Mp+++) sputum, showed that good penetration of amoxycillin into such sputum occurs. The levels of amoxycillin in sputum doubled proportionally with the oral dose, at least up to dosages of 2 g. High dosages or oral amoxycillin may therefore, be advantageous in the treatment of chronic bronchial infection. In a study of 30 chronic bronchitic patients, whose sputum varied in purulence from mucoid to purulent (Mp+++) the concentration of amoxycillin in sputum containing approximately 50% pus (Mp++) was significantly higher than that in any other degree of purulence. These results indicate that amoxycillin penetrates best into sputum at an intermediate degree of purulence.

Adult↗
PubMed1974

Osmotically stable L forms of Haemophilus influenzae and their significance in testing sensitivity to penicillins.

The sensitivity of Haemophilus influenzae to penicillins in vitro, determined either by serial antibiotic dilution in broth or by the disc method on agar, is apparently profoundly influenced by inoculum size if the results are read by macroscopic inspection. Microscopic inspection of the growth, however, reveals that the turbidity in heavily inoculated broth containing concentrations higher than the minimal inhibitory concentration is the product of L forms which have failed to succumb to osmotic lysis. Similarly, minute colonies appearing in the ;inhibition zone' of disc tests are composed of L forms. In both broth and agar tests reduction of the osmolality of the medium from 340 to 144 mOsm per kg failed to bring about lysis of organisms exposed either to ampicillin or amoxycillin. The significance of this remarkable osmotic stability of haemophilus L forms is discussed in relation both to testing of sensitivity of this organism to penicillins and to persistence of chronic haemophilus infections of the lower respiratory tract.

Ampicillin↗