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Biomedical subjects

E Crouch

Publications and source records attributed to E Crouch.

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

Ferruginous bodies and the histologic evaluation of dust exposure.

Ferruginous bodies are frequently observed in histologic sections of lung from individuals with occupational or environmental exposure to asbestos and other mineral dusts. Analysis of large numbers of such ferruginous bodies has demonstrated that the types with asbestos cores can be differentiated by light microscopy from several chemically and morphologically distinct classes of nonasbestos ferruginous bodies, including those formed on sheet silicates (talc and mica), carbon, rutile, and fly ash. Light-microscopic screening of lung tissue sections for ferruginous bodies is a reliable, convenient, and economical method for documenting exposure to a variety of mineral dusts and can assist in determining the etiology of pneumoconiotic lesions. Because tissue sections are relatively insensitive detectors of particles, the finding of ferruginous bodies in section implies heavy dust exposure.

Asbestos↗
PubMed1984

Malakoplakia mimicking carcinoma metastatic to lung.

Malakoplakia is a rare inflammatory disorder which infrequently involves sites outside of the lower genitourinary or gastrointestinal tract. We report a case of malakoplakia in which the patient presented with a left renal mass and bilateral pulmonary nodules suggestive of metastatic renal carcinoma. Postmortem cultures of the lesions grew E. coli; macrophages at both sites contained gram-negative bacilli and numerous Michaelis-Gutmann bodies. X-ray spectroscopic analysis of the bodies showed wide variation in calcium, phosphorus, and iron content, suggesting that Michaelis-Gutmann bodies were formed in part by the deposition of amorphous salts.

Diagnosis, Differential↗
PubMed1983

Progressive massive fibrosis of the lung secondary to intravenous injection of talc. A pathologic and mineralogic analysis.

We present a patient with a history of heroin addiction and 19 years of methadone maintenance who died of respiratory failure following nine years of slowly progressive dyspnea. During this nine-year period, chest x-rays consistently had revealed large, bilateral densities having the appearance of progressive massive fibrosis (PMF). At autopsy the lungs exhibited corresponding areas of dense, gritty consolidation, which microscopically showed an active granulomatous reaction with associated vascular obliteration. Throughout the lesions were refractile and birefringent plates of particulate material. Interstitial, perivascular, and vascular granulomas also were noted in the periphery of the lung. X-ray energy spectroscopy and diffraction studies of the particulates confirmed the presence of talc at levels of 540 X 10(6) particles/g of dried tissue in the mass lesion and 96 X 10(6)/g in the peripheral lung. Smaller numbers of silica particles also were identified. Approximately 30% of the talc particles were greater than 5 mu in maximum dimension, a finding consistent with intravenous delivery. Particles larger than 15 mu were only found in the mass lesion. We conclude that massive granulomatous lesions with the radiographic appearance of PMF can occur in association with intravenous injection of talc. We suggest that particle size and cumulative particle load are important in the pathogenesis of these lesions.

Electron Probe Microanalysis↗
PubMed1982

Extreme scenarios for nuclear waste repositories.

Two extreme scenarios for release of radioactive waste have been constructed. In the first, a volcanic eruption releases 1 km2 of an underground nuclear waste repository, while in the second, waste enters the drinking water reservoir of a major city. With pessimistic assumptions, upper bounds on the number of cancers due to radiation are calculated. In the volcano scenario, the effects of the water are smaller than the effects of natural radioactivity in the volcanic dust if the delay between emplacement and eruption exceeds 2000 yr. The consequences of the waste in drinking water depend on the survival time of the canisters and the rate of leaching of the nuclides from the waste matrix. For a canister life of 400 yr and a leach time of 6300 yr the cancer rate in the affected area would increase by 25%.

Air Pollution, Radioactive↗
PubMed1981

Therapeutic factors in group psychotherapy. A review.

This is a review of theoretical, empirical, and clinical research on therapeutic factors (TFs) in group psychotherapy covering the period 1955 to 1979. Therapeutic factors are processes that contribute to improvement in the patient's condition; they are different from conditions for change and from techniques. The following TFs are examined: self-disclosure, interaction, acceptance (cohesiveness), insight, catharsis, guidance, altruism, vicarious learning, instillation of hope, and an existential factor. Criteria for adequate experimental design in group research are proposed. About 40% of the works reviewed contain empirical studies; the quality of these studies is variable both conceptually and methodologically. It is difficult to assess the extent to which clinical practice has actually been influenced by this work on TFs.

Catharsis↗
PubMed1980

Structural basis for apparent heterogeneity of collagens in human basement membranes: type IV procollagen contains two distinct chains.

Fetal cells isolated from human amniotic fluid synthesize type IV procollagen when grown in monolayer culture. The procollagen, which contains two biochemically distinct chains, was found to be structurally and immunologically related to type IV collagen chains and collagenous fragments isolated from human placenta. Limited pepsin digestion of the intact procollagen that was deposited in the cell layer during culture produced a heterogeneous population of collagenous peptides comparable to that obtained during isolation of type IV collagens from human tissues. These studies support the hypothesis that basement membranes contain at least two genetically distinct type IV procollagen chains and suggest that the heterogeneity of collagenous components obtained after pepsin digestion of tissues and isolated basement membranes can result from degradative cleavage of the procollagen at a limited number of protease-sensitive sites.

Amniotic Fluid↗
PubMed1979

Collagen synthesis by bovine aortic endothelial cells in culture.

Endothelial cells isolated from bovine aorta synthesize and secrete type III procollagen in culture. The procollagen, which represents the major collagenous protein in culture medium, was specifically precipitated by antibodies to bovine type III procollagen and was purified by diethyl-aminoethylcellulose chromatography. Unequivocal identification of the pepsin-treated collagen was made by direct comparison with type III collagen isolated by pepsin digestion of bovine skin, utilizing peptide cleavage patterns generated by vertebrate collagenase, CNBr, and mast cell protease. The type III collagen was hydroxylated to a high degree, having a hydroxyproline/proline ratio of 1.5:1.0. Pulse-chase studies indicated that the procollagen was not processed to procollagen intermediates or to collagen. Pepsin treatment of cell layers, followed by salt fractionation at acidic and neutral pH, produced several components which were sensitive to bacterial collagenase and which comigrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with alpha A, alpha B, and type IV collagen chains purified from human placenta by similar techniques. Bovine aortic endothelial cells also secreted fibronectin and a bacterial collagenase-insensitive glycoprotein which, after reduction, had a molecular weight of 135,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (using procollagen molecular weight standards) and which was not precipitable by antibodies to cold-insoluble globulin or to alpha 2-macroglobulin. Collagen biosynthesis by these cells provides an interesting model system for studying the polarity of protein secretion and the attachment of cells to an extracellular matrix. The presence of type III collagen in the subendothelium and the specific interaction of this protein with fibronectin and platelets suggest the involvement of this collagen in thrombus formation following endothelial cell injury.

Animals↗
PubMed1979

Characterization of a type IV procollagen synthesized by human amniotic fluid cells in culture.

Fetal epithelioid cells, isolated from human amniotic fluid, synthesize and secrete a type IV-like procollagen characterized by a unique pattern of cyanogen bromide (CNBr)-produced peptides. The procollagen is disulfide-bonded and, after reduction, migrates on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a doublet between collagen beta components and pro-alpha 1(I) chains. No conversion of the procollagen to collagen or to procollagen intermediates is observed in cell culture. The procollagen was purified by salt fractionation and ion exchange chromatography; its amino acid composition resembles that of collagenous proteins extracted from basement membranes, with a high 3- and 4-hydroxyproline and hydroxylysine content and low levels of alanine and arginine. The major products obtained after limited proteolytic digestion of the protein retain interchain disulfide bonds and, after reduction, migrate on sodium dodecyl sulfate-polyacrylamide gel electrophoresis near intact pro-alpha 1(I) chains. The procollagen is secreted efficiently by amniotic fluid cells despite almost complete inhibition of peptidyl hydroxylation but, unlike type I procollagen, the secreted underhydroxylated chains lack interchain disulfide bonds. Since these cells also secrete fibronectin and elaborate an extensive extracellular matrix, the system should prove useful in the study of cell-matrix interactions.

Amino Acids↗
PubMed1979

Isolation of a collagen-binding fragment from fibronectin and cold-insoluble globulin.

Limited proteolytic cleavage of fibronectin and plasma cold-insoluble globulin with cathepsin D produced two major fragments. The smaller, Mr = 72,000 fragment bound to collagen and contained most of the cysteine in the molecule. This region contains intrachain disulfide bonds which maintain a conformation that is necessary for interaction with collagen. Cleavage of the intact protein and the 72,000-dalton fragment with plasmin localized the collagen-binding region in cold-insoluble globulin to a sequence of about 42,000 daltons. This region is located approximately two-thirds of the linear distance from the NH2 terminus of each chain in the dimeric molecule.

Amino Acids↗
PubMed1979

Comparison of the structures of human fibronectin and plasma cold-insoluble globulin.

Human amniotic fluid fibronectin and plasma fibronectin (cold-insoluble globulin) are indistinguishable both immunologically and by amino acid composition. Cyanogen bromide and tryptic peptides also suggest substantial structural homology. However, carbohydrate analysis has demonstrated additional saccharides in fibronectin and an overall increase in carbohydrate content relative to cold-insoluble globulin. Furthermore, limited proteolytic cleavage of the two proteins indicates differences in primary structure or in conformation. Using affinity-purified antibodies to cold-insoluble globulin, a glucosamine-labeled pronase-resistant component, probably proteoglycan, was found to coprecipitate with fibronectin, suggesting an association between these two macromolecules in the connective tissue matrix.

Amino Acids↗
PubMed1979

Interspecies comparison of carcionogenic potency.

For guidance in decisions on how to safeguard humans from carcinogens, it is necessary to use data on carcinogenesis in animals. This paper disucsses how such data, combined with human experience, may be used quantitatively in such decisions. It is demonstrated empirically that good correlations exist between different species for suitably defined carcinogenic potencies for various chemicals. This allows sufficient accuracy in extrapolating form animal data to human risk to support a logical scheme for the evaluation of such risks. Some recommendations for future research are given.

Animals↗
PubMed1979

A method for the study of therapeutic factors in group psychotherapy.

A method is described for the study of therapeutic factors in group therapy in which patients and their therapists prepare brief reports at regular intervals about those events in treatment which they regard as important; these reports are then assigned by independent judges to a classification of therapeutic factors which has been specifically devised for this purpose. The feasibility, validity and reliability of the method are discussed and its potential application to group therapy research and training briefly mentioned.

Adult↗
PubMed1978

Collagen synthesis by human amniotic fluid cells in culture: characterization of a procollagen with three identical proalpha1(I) chains.

Second trimester human amniotic fluid cells synthesize and secrete a variety of collagenous proteins in culture. F cells (amniotic fluid fibroblasts) are the most active biosynthetically and synthesize predominantly type I with smaller amounts of type III procollagen. Epithelioid AF cells (the predominating clonable cell type) synthesize a type IV-like procollagen and a procollagen with three identical proalpha chains, structurally and immunologically related to the proalpha1 chains of type I procollagen. The latter procollagen, when cleaved with pepsin and denatured, yields a single non-disulfide-bonded alpha chain that migrates more slowly than F cell or human skin alpha1(I) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis but coelutes with these chains from carboxymethyl-cellulose. The major cyanogen bromide produced peptides demonstrate a similar behavior relative to peptides derived from alpha1(I). The collagen is characterized by an increased solubility at neutral pH and high ionic strength, relative to type I collagen. The amino acid composition of the pepsin-resistant alpha chain is essentially identical with that of human alpha1(I), except for marked increases in the content of 3- and 4-hydroxyproline and hydroxylysine. Preliminary experiments suggest that these increased posttranslational modifications are responsible for the unusually slow migration of this collagen and its cyanogen bromide peptides on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The procollagen has, therefore, been assigned the chain composition [proalpha1(I)]3. Like type I procollagen, [proalpha1(I)]3 undergoes a time-dependent conversion, in the medium and cell layer, to procollagen intermediates and alpha chains. The production of [proalpha1(I)]3 probably reflects the state of differentiation and/or embryologic derivation of AF cells rather than a characteristic of the fetal phenotype, since F cells do not synthesize significant amounts of the procollagen.

Amino Acids↗
PubMed1978

Organization of extracellular proteins on the connective tissue cell surface: relevance to cell-matrix interactions in vitro and in vivo.

A model has been developed that proposes a cell surface-associated protein meshwork, composed in part of fibronectin and collagen, for a connective tissue cell attached to a substratum. In support of this model are the observations that collagen and fibronectin interact and that these proteins are similarly distributed on the fibroblast cell surface. We suggest that this external meshwork interacts directly or indirectly with the internal cytoskeleton and with the extracellular matrix and thereby mediates several cellular properties, including adhesion, shape, and motility. Loss of cell surface fibronectin as a result of viral transformation, or due to treatment of normal cells with tunicamycin, an inhibitor of protein glycosylation, may contribute to the reduced adhesion and altered morphology observed in these circumstances. We therefore predict that the changes in these properties observed with virally transformed cells, mitotic cells, and cells treated with proteolytic enzymes are related to alterations in the external protein meshwork.

Animals↗
PubMed1978

Amniotic fluid fibronectin. Characterization and synthesis by cells in culture.

A glycoprotein immunologically related to plasma cold-insoluble globulin (CIG) and fetal skin fibroblast fibronectin has been purified from second-trimester human amniotic fluid. This protein (amniotic fluid fibronectin) migrated more slowly than CIG on sodium dodecyl sulfate gel electrophoresis and showed greater polydispersity which could result, at least in part, from heterogeneity in glycosylation. Cloned human amniotic fluid epithelioid and fibroblastic cells synthesized and secreted a protein with similar properties into the culture medium. Fibronectin was shown to be associated with the pericellular and extracellular matrix of cultured amniotic fluid cells by immunofluorescence, lactoperoxidase-catalyzed iodination, and labeling with ferritin-conjugated antibodies. The kinetics of secretion of the protein were consistent with its role as a matrix protein. We anticipate that amniotic fluid fibronectin will prove to be the same protein which elsewhere in the body is incorporated into connective tissues and basement membranes. Amniotic fluid could, therefore, serve as a convenient source of in vivo synthesized fibronectin for biological and structural studies.

Amniotic Fluid↗
PubMed1978

Regulation of growth and gene activity in euploid hybrids between human neonatal fibroblasts and epithelioid amniotic fluid cells.

Pure populations of proliferating synkaryons were obtained from polyethylene glycol-mediated crosses between diploid human foreskin fibroblasts and epithelioid amniotic fluid cells. These hybrids proved to be chromosomally stable tetraploids. They continuously produced heteropolymeric G6PD and showed strictly additive patterns of silver staining of both parental sets of nucleolar organizing chromosomes. Collagenous proteins characteristic of the fibroblast parent were synthesized, while fibronectin production appeared to be directed by the epithelioid portion of the genome. Even though these heterotypic hybrids proliferated at a reduced rate and achieved fewer population doublings relative to homotypic (fibroblast X fibroblast) crosses, they survived passage by trypsinization better than pure populations of epithelioid cells. These observations suggest a concerted action of both parental genomes with respect to proteins responsible for "household" functions, but complementation and possibly modulation of gene action with respect to "luxury" protein synthesis and cell growth.

Amniotic Fluid↗