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Biomedical subjects

P F Davison

Publications and source records attributed to P F Davison.

At least 37 records · Page 2Linked to original sources
PubMed1982

Immunological, biochemical, ultrastructural, and electrophysiological characteristics of a human glioblastoma-derived cell culture line.

This report presents the results of a study using multiple techniques of the established human cell line, LM, which has been developed in culture medium from a patient with a right temporoparietal glioblastoma. This cell line has human subtetraploid karyotype and has several features of a transformed line in culture. These include continuous propagation for 10 years, ability to form tumor nodules when transplanted into immunologically suppressed hamsters, and pleomorphic appearance. Ultrastructurally, it is characterized by multiple nuclei, few actin cables, and numerous surface-membrane microvilli, as well as abundant 9- to 10-nm cytoplasmic filaments. By its immunological reactivity, the line can be shown to contain glial fibrillary acidic protein at low levels, consistent with its glial origin and continued nature. Dibutyryl cyclic adenosine monophosphate (db-cAMP) induces formation of long astrocytic-like processes as well. Its membrane electrical characteristics include a low resting membrane potential and short time constant. Used in a microtiter antiglioma antibody cytotoxicity assay, LM yields a positive reaction to antibodies in the sera of 80% of patients with astrocytomas and only 9% of normal blood-bank donors, suggesting that it shares common antigens with other astrocytic tumor lines. The varied characteristics of this glioblastoma-derived line emphasize the "multiforme" nature on the neoplasm and suggest that for characterization of any such line, multiple parameters are necessary to allow comparison with other long-term glioblastoma lines in the literature. The usefulness of the LM line in in vitro cell biological, immunological, chemotherapeutic, and radiobiological studies of gliomas makes such efforts very worthwhile.

Brain Neoplasms↗
PubMed1982

The healing of linear nonperforating wounds in rabbit corneas of different ages.

Linear nonperforating incisions were made in the corneas of 2-week-old and 2-year-old rabbits. The resulting wounds were examined by light microscopy and transmission and scanning electron microscopy. A corneal incision of a 2-week-old rabbit produced a wide gaping wound caused by retraction of the cut stromal lamellae away from the incision. The wound became wider with time as the developing eye enlarged and the cut lamellae retracted further. Polymorphonuclear leukocytes, presumably from the tear film, penetrating into the wound area before it was covered over by the sliding epithelium. Most of the leukocytes disappeared by 3 days after wounding. Three to six layers of fibroblasts appeared beneath the epithelial plug. The tissue eventually rebuilt approximately one third of the corneal depth lost to the wound. The stroma of the wounded region did not return to its normal width, but the epithelium was thicker than that of the unwounded cornea. An incision in a 2-year-old rabbit cornea produced a narrow V-shaped wound that did not change shape with time. This wound was repaired by fibroblasts resulting in collagenous repair tissue being the same depth as the normal stroma. There appears to be no evidence for wide gaping wounds in humans in the literature, as was found in this study in rabbits.

Age Factors↗
PubMed1981

Isolation and characterization of a soluble, immunoactive peptide of glial fibrillary acidic protein.

A soluble immunoactive peptide with a molecular weight of 16 000 was isolated and purified from the cyanogen bromide digest of the insoluble 50 000 dalton glial fibrillary acidic protein by Sephacryl S-200 gel filtration followed by DEAE-Bio-gel A chromatography. The homogeneity of the peptide was established by SDS-polyacrylamide gel electrohporesis and isoelectric focusing. The peptide from several species showed immunocrossreaction with rabbit antibody to intact glial fibrillary acidic protein. The peptide has a pI value of 5.32. The amino acid sequence of 28 residues from the amino terminus of the calf peptide has been determined.

Amino Acid Sequence↗
PubMed1981

Filament proteins in central, cranial, and peripheral mammalian nerves.

Several classes of 10-nm filaments have been reported in mammalian cells and they can be distinguished by the size of their protein subunit. We have studied the distribution of these filaments in nerves from calves and other mammals. From the display on polyacrylamide electrophoretic gels of proteins in extracts from fibroblast and central, cranial and peripheral nerves, we cut the appropriate stained bands and prepared iodinated peptide maps. The similarities between the respective maps provide strong evidence for the presence of vimentin in cranial and peripheral nerves. The glial fibrillary acidic protein was found in axon preparations from the central nervous system, but was not identified in distal segments of some cranial nerves, nor in peripheral nerve.

Animals↗
PubMed1980

Mechanisms of development and aging.

The view is expressed that an inappropriate emphasis and research is currently directed towards simplistic approaches to the problem of aging; it is concluded that an understanding of the biochemical mechanisms underlying the aging process must be sought using a SYSTEMS analysis, at a level of complexity and integration much greater than that encompassed by any theory thus far considered.

Aging↗
PubMed1980

Comparison of specific activities of enzymes from young and old dogs and mice.

Aldolases A and B (EC 4.1.2.13) and liver cytoplasmic superoxide dismutase (EC 1.15.1.1) have been purified from young and old dogs and mice. The specific activities of these enzymes were measured and show no diminution with age. In addition, dog aldolase B, dog liver superoxide, and mouse liver aldolase were titrated in crude extracts with specific antisera. No accumulation of cross-reacting material with age was detected. The electrophoretic mobilities of these enzymes and the susceptibilities of dog aldolases A and B to trypsin digestion were also unchanged. These results are additional evidence that the accumulation of inactive enzymes is not an invariable concomitant of aging.

Aging↗
PubMed1978

Bovine tendons. Aging and collagen cross-linking.

The level of cross-linking between the polypeptide chains of the collagen molecules in bovine tendons of different ages has been assessed by measuring quantitatively through densitometry the changes in the ratios of individual cyanogen bromide peptides separated on polyacrylamide gels. An increase in the number of cross-links in mature, as compared to young, tendons correlates with a depletion in the proportion of the free, COOH-terminal peptides alpha1-CB6 and alpha2-CB3,5 and with an increase in a broad distribution of peptides moving slowly in the gels: these peptides are not seen in digests of acid-soluble collagen. Some of these peptides which are presumably cross-linked migrate more slowly than beta components and collagen alpha chains and are apparently of a higher molecular weight. No increase in cross-linked peptides is detectable beyond the age of maturation; this analysis refutes, at least in this tissue, the common presumption that progressive cross-linking occurs in collagen through an animal's lifetime.

Aging↗
PubMed1977

Sturctural homologies in mammalian neurofilament proteins.

Antibody has been prepared to purified neurofilament protein extracted from calf brain. This antibody crossreacts with brain and nerve extracts from all mammals tested but fails to crossreact with frog, cod and chicken nerve extracts. Thus the serologic homology of these neurofilament proteins appears to be restricted to the mammals. Structural similarities between the mammalian neurofilament protein are also indicated by the strong resemblance between iodinated peptide maps prepared from the electrophoretically purified neurofilament proteins.

Amino Acids↗