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Biomedical subjects

F W Keeley

Publications and source records attributed to F W Keeley.

At least 73 records · Page 4Linked to original sources
PubMed1984

Characterization of collagen from normal human sclera.

Human scleral tissue contains approximately 50% collagen by weight, consisting predominantly of type I collagen. There is little or no evidence for the presence of substantial quantities of type II, type III or other collagen types. There appears to be no difference in either collagen content or genetic type in sclera between adult and juvenile tissues or between anterior and posterior segments of the sclera, although, with increased age there is a marked increase both in the extent of glycosylation of the collagen and its resistance to solubilization by treatment with pepsin.

Adult↗
PubMed1983

Characterization of proteins from the calcified matrix of atherosclerotic human aorta.

The nature of proteins occluded in the mineralized matrix of calcified areas of atherosclerotic human aortic tissue has been investigated. In spite of their reported presence in atherosclerotic lesions, neither plasma lipoproteins, immunoglobulin G or fibrinogen could be detected among the proteins specifically trapped in the mineralized matrix and released by decalcification. However, human serum albumin was present in the decalcifying extract in a persistent complex with a more acidic protein component. Also present in the decalcifying extract was an acidic protein component with a molecular weight between 6000 and 10000 which contained both serine phosphate and gamma-carboxyglutamic acid. This component closely resembled in amino acid composition the non-albumin moiety of the serum albumin complex, suggesting that this low molecular weight, gamma-carboxyglutamic acid-containing protein component was present in the calcified matrix both in the free form and in association with human serum albumin.

Amino Acids↗
PubMed1983

Measurement of the absolute synthesis of soluble and insoluble elastin by chick aortic tissue.

The rate of in vitro synthesis of soluble and insoluble elastin by thoracic aorta of 2-day-old chicks has been measured in absolute terms. In the absence of beta-aminopropionitrile (beta APN), the steady state level of soluble elastin was 120 pmol/100 mg of aortic tissue or 3.7 micrograms/whole aorta segment. The rate of synthesis of elastin in vitro was approximately 130 micrograms/day per whole aorta segment. This is three- to four-fold lower than the estimated rate of in vivo synthesis for a comparable segment of aortic tissue at the same stage of development. Pulse-chase experiments suggested that this difference was not due to in vitro proteolysis of a significant proportion of the newly synthesized soluble elastin, but rather that the conversion of soluble to insoluble elastin was both rapid and efficient. These experiments also indicated the presence in aortic tissue of a substantial pool of elastin of intermediate solubility. Although inclusion of beta APN in the incubation medium resulted in an increase in the amount of soluble elastin in aortic tissue, the rate of accumulation of newly synthesized soluble elastin in the presence of this inhibitor of cross-linking was not linear, but decreased with incubation time. Furthermore, although beta APN effectively suppressed the appearance of insoluble elastin for at least 2 h, some escape from the effect of this inhibitor was seen with further incubation. In general, beta APN significantly depressed elastin synthesis.

Amino Acids↗
PubMed1981

Identification of elastin in developing aortic tissue by immunological methods.

Antibodies raised in rabbits to tropoelastin isolated from lathyritic chick aorta were conjugated with ferritin and used to identify and locate elastin-containing elements in sections of aortic tissue from developing chicks. The ferritin-antibody conjugate was associated with a network of fine filaments with a diameter of 3-5 nm which, in the 8-10 day old chick embryo aorta, was distributed between and around small but recognizable elastic fibers. In older aortic tissue this ferritin-labelled material was seen principally in loose association with the periphery of developing elastic fibers. The microfibrils did not interact with the ferritin-antibody conjugate. Treatment of chicks with beta aminopropionitrile did not interfere with the accumulation of ferritin-labelled filaments on these small elastic fibers, suggesting that the mechanism of addition of new material onto growing fibers may be independent of cross-linking.

Amino Acids↗
PubMed1980

Biochemical identification of elastin in periosteum and pericranium.

Histologic observations of elastic in periosteum have never been confirmed biochemically. Elastins were isolated, quantitated and characterized from human periosteal and pericranial tissues. Periosteum contains approximately 2.1% elastin by weight and does not appear to vary between skeletally mature and immature donors. Pericranium contains approximately 2.7% elastin by weight. These elastin contents are comparable to that reported for human skin. Amino acid analyses of the elastin from periosteum and pericranium showed the characteristic, non-polar amino acid composition of elastin. Proportions of the polar amino acids were somewhat elevated compared with elastins from the ligamentum and the aorta but were similar to those isolated from cartilaginous sources. The desmosine contents of the periosteal and pericranial elastins were comparable to those of elastins from other sources.

Adolescent↗
PubMed1977

The extraction and partial characterization of proteins released by decalcification from calcified human aortic plaques.

Tissue from severely atherosclerotic human aortas was divided into heavily calcified (plaque) and less calcified (non-plaque) areas. After defatting and thorough extraction with neutral salt solutions, further proteinaceous material was released from plaque than non-plaque areas. Although organic phosphorous was associated with the EDTA-solubilized protein from both plaque and non-plaque areas, the phosphorous to protein ratio of extracts from plaque areas was 2 to 3 times that from non-plaque areas. Analysis of the major protein component of the extract of plaque areas indicated an acidic glyco-protein which appeared to be associated with an organic phosphorous moiety as well as cholesterol and cholesterol esters.

Amino Acids↗
PubMed1976

A convenient method for the identification and estimation of soluble elastin synthesis in vitro.

A method is described by which newly synthesized soluble elastin can be routinely and conveniently identified and estimated in vitro without the need for unlabelled carrier tropoelastin. Aortic tissue from 11 day old chick embryos is incubated in the presence of [14C] L-proline and [3H] L-valine and the distributions of [14C] proline-, [14C] hydroxyproline-and [3H] valine-labelled proteins on SDS-polyacrylamide gels are determined. Soluble elastin is identified as a [14C] hydroxyproline-labelled peak of molecular weight approximately 70,000 daltons which also incorporates large quantities of [3H] valine and has a [14C] hydroxyproline/[14C] proline ratio of about 0.2. Whereas the hydroxyproline label can be used to estimate newly synthesized soluble elastin even after several hours of incubation, similar use of the [3H] valine label is limited to short incubation times. Paradoxically, the quantity of [14C] hydroxyproline-labelled soluble elastin detected by the assay decreases with increased incubation time. This fall-off in labelled soluble elastin is not due to an increase in the rate of crosslinking of the protein over the course of the incubation. Soluble elastin is detectable both in tissue extract and medium fractions. The presence of hydroxyproline-labelled protein fragments in the medium fraction is evidence of proteolytic breakdown of collagen or elastin or both proteins. This proteolytic activity is augmented by the inclusion of serum in the incubation medium and is not inhibited by phenylmethylsulfonylfluoride. The method provides a convenient assay by which factors affecting the synthesis and secretion of soluble elastin may be studied.

Aminopropionitrile↗