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Biomedical subjects

D B Murphy

Publications and source records attributed to D B Murphy.

138 records · Page 8Linked to original sources
PubMed1975

Cross reactivity between H-2K and H-2D products. III. Effect of H-2K-H-2D cross sensitization on skin graft survival.

Cross sensitization between the products of the H-2K and H-2D loci has been demonstrated by an experimental design in which recipients were sensitized with tissue bearing determinants controlled by one locus (e.g., H-2K), and then challenged with skin grafts expressing determinants controlled by the other locus (e.g., H-2D). In one combination, experimental grafts were rejected faster than first-set control grafts. Cellular rather than humoral mechanisms appeared to mediate this effect. In a second combination, prolonged survival of experimental grafts were observed. This enhanced survival may have been influenced by serum antibody, either to H-2 or Ia determinants.

Animals↗
PubMed1975

Cross reactivity between H-2K and H-2D products. II. Identification of the cross reacting specificities.

Absorption analyses were conducted on antisera which had previously been shown to detect cross reactivity between the H-2K and H-2D gene products. These analyses revealed that the cross reactions were due to known public H-2 specificities. Identification of cross reactive anti-H-2.3 and anti H-2.5 antibodies confirmed earlier predictions that genes controlling these specificities should be localized at opposite ends of the H-2 complex. The finding of H-2.29 activity on both sides of the S region clarified ambiguities encountered in assigning this specificity to certain recombinant types. Results with H-2.36 support the suggestion that this determinant may also be specified by both H-2K and H-2D genes.

Absorption↗
PubMed1975

Use of urease test disks in the identification of mycobacteria.

Use of commercially available urea differentiation disks is a rapid and convenient means of determining the urease activity of mycobacteria. In the study performed, paper disks containing Ewing's Urea R Broth were compared with two other methods of testing for urease production. Over 1,500 tests were performed with recent patient isolates from which at least 15 different species of mycobacteria were identified. The tests were read at intervals for 72 h, and a comparison of test results as to rapidity and accuracy for each species was tabulated. The urea disks showed a faster reaction time when compared with the other two methods. They also showed a high percentage (79 to 100%) of reliability for each species on the first run, based on the expected response.

Classification↗
PubMed1975

Serologic and biochemical studies of the Ia system of the mouse H-2 gene complex. Further evidence for I-C subregion.

Three antisera were made against B10.A(5R) tissues to show the presence of an I-Cd subregion in that strain: 1) B10 anti-B10.A(5R) [anti-Dd, I-Cd]; 2) (B10 times C3H.9L) F1 anti-B10.A(5R) [anti-Ddi1; 3) (B10 times HTI)F1 anti-B10.A(5R) [anti-I-Cd]. Serologic analyses of the antisera clearly showed the presence of an Id segment in B10.A(5R) and provided further evidence for the existence of a new I-C subregion. These anti-I-Cd sera define the Ia.7 specificity and analyses of several recombinants map Ia.7 within the I-C subregion. Ia.7 is present in I-Ck, I-Cd and Ip strains. Biochemical analyses showed that the Ia.7 molecule has a molecular weight of 31,000 and is distinct from the 46,000 m.w. H2K or D molecules. The possible roles of the I-C region in immune response, mixed lymphocyte reaction, and graft-vs-host reaction are discussed.

Absorption↗
PubMed1974

The role of microtubules in the movement of pigment granules in teleost melanophores.

When microtubules in teleost melanophores are disrupted with antimitotic agents, colchicine, high hydrostatic pressure, low temperature, and vinblastine, the alignment and movement of the pigment granules in these cells disappear; during recovery, the return of alignment and movement corresponds in both time and space with the repolymerization of microtubules. Furthermore, analysis of nearest neighbor distances in untreated melanophores reveals that pigment granules are closely associated with microtubules. Other structures such as microfilaments, the endoplasmic reticulum, and the cytoplasmic matrix do not appear to be involved. Thus we conclude that microtubules determine the alignment and are essential for the selective movements of the pigment granules in these cells. Investigations of the mechanism of movement show that microtubules are required for both centrifugal and centripetal migrations and that they do not change in number or location during redistribution of pigment. Our results further indicate that microtubules in melanophores behave as semistable organelles as determined by investigation with colchicine and hydrostatic pressure. These observations and others rule out a push-pull mechanism based on the polymerization and depolymerization of microtubules or one which distinguishes two operationally different sets of microtubules. We propose instead that particles move by sliding along a fixed array of microtubules.

Animals↗
PubMed1973

Microtubules: evidence for 13 protofilaments.

When microtubules are fixed in glutaraldehyde in the presence of tannic acid and thin sections cut, the subunit structure of the microtubule is readily observed without the need of image reinforcement. Seven types of microtubules were analyzed: those in the heliozoan axoneme, the mitotic apparatus, the contractile axostyle, repolymerized microtubules derived from the chick brain, the central pair in flagella, and the A tubules of flagella and the basal body. In all cases microtubules were composed of 13 equally spaced protofilaments. The B tubules in flagella and the basal body appear to be composed of 11 subunits. The connections of the B to the A and the C to the B are described. A model of a microtubule is presented.

Animals↗
PubMedDate not supplied

Efficiency of antigen presentation differs in mice differing at the Mls locus.

In the mouse, potent primary in vitro proliferation of T cells can be induced by allelic variants of cell-surface glycoproteins, Ia antigens, the genes for which are located in the I region of the major histocompatibility complex (MHC) on chromosome 17. The only other potent primary proliferative response known is induced by mixing MHC-identical lymphocytes from strains that differ at the locus termed Mls (ref. 1) (for mixed lymphocyte stimulating), which has been mapped to chromosome 1. While it is relatively easy to raise antibodies against Ia antigens, and thus determine both their chemical nature and their role in T-cell stimulation, the nature of the product of the Mls locus has remained obscure. It has been proposed that the Mls locus product is a minor antigen recognized in association with self-Ia antigens, a translocated Ia-like element, or a mitogenic molecule found on the surface of antigen presenting cells (APC). Here, we demonstrate that APCs from mice carrying stimulatory Mls locus alleles present antigen more efficiently to cloned, antigen-specific, Ia-restricted T cells than APCs from mice carrying nonstimulating Mls locus alleles. We propose that the Mls locus does not encode a unique cell-surface antigen at all; we suggest instead that the T-cell proliferative response induced by Mls-locus disparate cells reflects recognition of self-Ia molecules on APCs. If our interpretation is correct, it provides further evidence both for the quantitative nature of self tolerance and for the existence of a distinct recognition site for self-Ia molecules on antigen-specific T lymphocytes.

Animals↗