PubMed Health⌕ Search

Biomedical subjects

D J Pihlaja

Publications and source records attributed to D J Pihlaja.

5 recordsLinked to original sources
PubMed1977

Gradionation: hypothesis for positioning and patterning.

The interaction of contiguous proteins is explored in microtubules, rosettes, and membranes based on the well established molecular phenomena of cooperativity and allosterism. It is proposed that conformational gradients in protein arrays cause the formation of gradions by nearest-neighbor interactions. Gradions are repeating functional molecular sequences that contain several conformational forms of one or more proteins, with the result that different reactive sites can exist in the same molecular architecture at any one time. Gradionators are small controlling molecules that may be microscopically visible as layers of linkages, but could alse be smaller. Some of the presently available supporting evidence and its functional implications are discussed, including the possibility that the raison d'etre for membrane-particle arrays is to enhance the regulation and amplification capabilities of cell systems.

Allosteric Regulation↗
PubMed1976

Surface ultrastructure in alkali-burned rabbit corneas.

The scanning electron microscope was used to follow morphologic events after alkali burn of rabbit corneas. Immediately after a burn there was extensive destruction and shrinkage of the epithelial cells. In subsequent healing, the regenerated superficial cells were morphologically abnormal and possed multiloculated cysts; three months later the normal polygonal packing of cells was not observed. Although the shape of these cells was irregular, microprojections were present on the cell surface. Basal cells were usually observed at the edge of an epithelial defect, an area where the epithelium was easily detached from the basement membrane. In long-standing epithelial defects, the basement membrane became eroded in a spot-like manner after about two weeks. Eventually, when a frank stromal ulcer had formed, bundles of collagen fibrils were visible in a meshwork-like fashion. These changes did not seem to be caused by the direct action of alkali but rather by latent secondary factors that took days or weeks to activate.

Alkalies↗