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P Knox

Publications and source records attributed to P Knox.

29 records · Page 2Linked to original sources
PubMed1982

The abnormal morphology of polyoma-transformed baby hamster kidney cells is due to a failure to respond to 70K spreading factor.

The typical elongated bipolar morphology of baby hamster kidney (BHK) cells is not shown by polyoma-transformed BHK (Py-BHK) cells. Instead, the transformed line adheres poorly to tissue-culture plastic and cells have a more rounded morphology than the parent line. Plasma fibronectin is known to mediate the spreading of BHK cells, but when human serum is subjected to Sephacryl S-300 chromatography two peaks of spreading activity are eluted; the first is fibronectin and the second, which is quantitatively more significant, is a 70 K protein that is not related to fibronectin and stimulates spreading by a different mechanism. Py-BHK cells spread well in low concentrations of purified fibronectin but will not spread well in levels of serum that contain similar or greater concentrations of fibronectin. This is because fibronectin-mediated spreading of both BHK and Py-BHK cells occurs only in the presence of low concentrations of other proteins; albumin and other serum proteins inhibit fibronectin-mediated spreading. BHK cells spread under routine culture conditions in response to the 70 K factor rather than fibronectin. The altered morphology that results from viral transformation is due to a failure of the cells to respond to the 70 K spreading factor.

Animals↗
PubMed1981

The effect of human peripheral lymph on cell growth in vitro.

Peripheral lymph is similar in composition to the interstitial fluid that surrounds most cells in vivo. Gel filtration is used to show that the protein composition of such lymph is considerably different from that of plasma. Primary cell cultures fail to survive in adult human plasma or serum but grow well in adult peripheral lymph collected from the dorsum of the foot. The different effects on cell cultures may be because toxic components such as low-density lipoproteins are partially filtered out by the capillary endothelium.

Animals↗
PubMed1980

Isolation of a serum component that stimulates the spreading of cells in culture.

A foetal-calf-serum component has been isolated that stimulates cells in culture to adopt typical fibroblast morphology. This "spreading" factor is a glycoprotein with a mol. wt. of approx. 62000 and contains 12% carbohydrate; it has an isoelectric point of 4.8. The method described allows purification to homogeneity as judged by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and analytical isoelectric focusing. Under cell-culture conditions the factor is active at 18 micrograms/ml.

Amino Acids↗
PubMed1980

The distribution of cell-spreading activities in sera: a quantitative approach.

Sephacryl S-300 gel filtration of animal sera is used to demonstrate that there are at least 2 components that promote the 'spreading' of cells in culture. A morphometric technique is described to quantitate the spreading process. For a number of cell strains and established cell lines the more quantitatively significant spreading factor is not fibronectin. Rather it is a component with fibronectin and seems to cause spreading via a different mechanism from that stimulated by fibronectin. Thus fibronectin will cause spreading in the absence of protein synthesis, whereas the smaller component requires protein synthesis. The kinetics of spreading are also different at all concentrations of the factors that are effective. By comparing the spreading promoted by whole sera with that promoted by separate serum fractions following chromatography we conclude that under normal conditions plasma fibronectin plays little part in initial cell spreading. This view is supported by the fact that fibronectin-depleted serum will stimulate cell spreading.

Animals↗
PubMed1979

Cell adhesion and proteoglycans. I. The effect of exogenous proteoglycans on the attachment of chick embryo fibroblasts to tissue culture plastic and collagen.

Proteoglycan was isolated from cartilage and freed from contaminating glycoproteins and hyaluronic acid. The macromolecule consists of a protein core covalently linked to a number of glycosaminoglycan side chains, namely chondroitin sulphate and keratan sulphate. This proteoglycan retards the attachment of a variety of cell types to tissue culture plastic and to collagen. Glycosaminoglycans alone, have no significant effect on rates of attachment. Similarly, trypsinized proteoglycan is without effect. It is concluded that the structural integrity of the proteoglycan macromolecule is essential for its effect on cell adhesion.

Animals↗
PubMedDate not supplied

The FRAME multicentre project on in vitro cytotoxicology.

An in vitro method for assessing the relative acute toxicities of chemicals was developed through the collaboration of four tissue culture laboratories. Cytotoxicity was measured by using a dye-binding method to determine inhibition of the proliferation of BCL-D1 cells 72 hr after addition of the test chemical. A blind trial with 50 chemicals showed that the test procedure gave results with a high degree of interlaboratory reproducibility.

Biotransformation↗