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Biomedical subjects

D C Morrison

Publications and source records attributed to D C Morrison.

193 records · Page 11Linked to original sources
PubMed1973

Relationship of the structure of bacterial lipopolysaccharides to its function in mitogenesis and adjuvanticity.

The ability of bacterial lipopolysaccharides to induce lymphocyte mitogenesis and to act as an adjuvant of antibody formation was attributable to the lipid-A region of the molecule. Measured by induction of DNA synthesis, lipid A was mitogenic for bone marrow-derived lymphocytes obtained from spleens of congenitally athymic mice but not for thymocytes obtained from thymuses of normal mice. Adjuvanticity was demonstrated by the ability of lipid A to convert a tolerogenic regimen of antigen into one eliciting an immune response and by its ability to markedly enhance the antibody response to a weak antigen.

Adjuvants, Immunologic↗
PubMedDate not supplied

A motion artefact in real-time ultrasound scanners.

Motion observed in real-time ultrasound images may be very misleading. The speckle pattern in images of soft tissue is an artefact and it may move in a way which bears no simple relationship to the motion of the tissues. The physical origin of this anomaly is described.

Biophysical Phenomena↗
PubMedDate not supplied

Bacterial endotoxins and pathogenesis.

Recent advances in endotoxin biochemistry, cell biology, and immunopathology are reviewed. Discussion is focused on the endotoxin-unresponsive C3H/HeJ mouse and the contributions the studies of this mouse have made to current concepts of the mechanisms of endotoxin action. The extension of the observations documented with this experimental model provide a firm foundation for productive future research into the precise role of bacterial endotoxins in the protection against, and exacerbation of, gram-negative bacterial sepsis.

Animals↗
PubMedDate not supplied

A two-step mechanism for the interaction of Re lipopolysaccharide with erythrocyte membranes.

In this report, a unique model system that allows the investigation of the interaction of lipopolysaccharide (LPS) with erythrocyte membranes is described. Rabbit red blood cells exposed to S. minnesota (Re mutant) R595 LPS were rendered sensitive to the cationic antibiotic polymyxin B in a manner independent of the temperature of incubation of erythrocytes with LPS (subsequent addition of polymyxin B induced hemolysis of erythrocytes sensitized with LPS). Following sensitization of red blood cells with R595 LPS, a time-dependent decrease in susceptibility of the cells to polymyxin B-mediated hemolysis occurred, which was shown not to be the result of dissociation of LPS from rabbit erythrocytes. The demonstration that the decrease in sensitivity of red blood cells to polymyxin B was dependent on the temperature of incubation of LPS with red blood cells is not inconsistent with the proposal that the decrease in sensitivity is attributable to a hydrophobic rearrangement of lipid-rich R595 LPS within the lipid bilayer of the erythrocyte membrane. The importance of this putative rearrangement of LPS within cell membrane in cellular triggering of LPS is unknown.

Animals↗
PubMedDate not supplied

Selective interaction between lymphocytes and lipid A subunits in lipopolysaccharide macromolecular aggregates.

The interaction between bacterial lipopolysaccharides (LPS) and murine spleen cells was examined. The results indicate that lipid A-rich subunits, contained within the heterogeneous LPS macromolecule, associated selectively with spleen cells. In the LPS not associated with spleen cells, the relative amounts of lipid A-rich subunits were reduced; however, this reduction was not of a sufficient magnitude to be reflected in the stimulation of B cells. By constructing hybrid LPS macromolecules with various amounts of lipid A-rich subunits it was documented that mitogenic activity of B cells was relatively refractory to lipid A subunit composition. Furthermore, the presence of polysaccharide-rich subunits regulated downward the expression of lipid A-dependent activity.

Animals↗
PubMedDate not supplied

Lipid A-dependent lymphocyte proliferation in "endotoxin-nonresponder" mice.

Lipopolysaccharides (LPS) with a subunit composition reduced in heterogeneity were prepared by gel-filtration chromatography of detergent-dissociated LPS from the smooth strain of Escherichia coli 055:B5. The splenocyte mitogenic activity of reassociated column-fraction pools was markedly dependent on the ratio of O-antigen polysaccharide to lipid A, where the activity of the fraction richest in lipid A (F5 LPS) was approximately three orders of magnitude greater than the least active fraction (F1 LPS). The F5 LPS, which contains only a trace of O-antigen polysaccharide, induces a spleen-cell proliferative response in C3H/HeJ "LPS nonresponder" spleen cells. This mitogenic activity is not present in either unfractionated LPS or the other column fractions. These latter findings indicate that LPS macromolecular aggregates of the appropriate physico-chemical structure and/or compositions have the capacity to elicit C3H/HeJ spleen-cell proliferative responses.

Animals↗
PubMedDate not supplied

Procedure for assessment of neurodevelopmental delay in young children: preliminary report.

This report describes the development of a new procedure for assessing neurodevelopmental delay in young children. The Primitive Reflex and Postural Adjustment Assessment procedure is designed to measure degrees of occurrence of remnants of primitive reflexes and immature postural adjustment. Preliminary findings show that the Primitive Reflex and Postural Adjustment Assessment procedure can successfully identify degrees of neurodevelopmental delay in young children, and that the procedure differentiates normal children from mentally retarded and emotionally disturbed children. Additional work is needed to assess the validity and reliability of this procedure.

Affective Symptoms↗