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Biomedical subjects

N L Thompson

Publications and source records attributed to N L Thompson.

At least 73 records · Page 4Linked to original sources
PubMed1990

Binding of a monoclonal antibody and its Fab fragment to supported phospholipid monolayers measured by total internal reflection fluorescence microscopy.

The association of an anti-dinitrophenyl monoclonal antibody and its Fab fragment with supported phospholipid monolayers composed of a mixture of dipalmitoylphosphatidylcholine and dinitrophenyl-conjugated dipalmitoylphosphatidylethanolamine has been characterized with total internal reflection fluorescence microscopy. The surface densities of bound antibodies were measured as a function of the antibody and Fab solution concentrations, and as a function of the solution concentration of dinitrophenylglycine. The apparent association constant of Fab fragments with surface-associated haptens was approximately 10-fold lower than the association constant for haptens in solution, and the apparent surface association constant for intact antibodies was only approximately 10-fold higher than the constant for Fab fragments. Data analysis with simple theoretical models indicated that, at most antibody surface densities, 50-90% of membrane-associated intact antibodies were attached to the surface by two antigen binding sites.

Antibodies, Monoclonal↗
PubMed1990

Effects of newborn screening of cystic fibrosis on reported maternal behaviour.

Screening for cystic fibrosis is highly controversial. Concerns have been expressed that newborn screening may cause mothers, who had considered their child to be healthy before diagnosis, to overprotect their child. Some critics of screening also suggest that a period of delay from onset of symptoms to diagnosis may help a mother adjust to the reality of the child's lethal condition. This study compared the strength of overprotective child rearing attitudes of 29 mothers whose children were screened (13 had symptomatic children and 16 asymptomatic children) with the attitudes of 29 mothers whose children were diagnosed after the onset of symptoms. Results indicate that newborn screening had not increased a mother's tendency to overprotect her child with cystic fibrosis and in some cases the tendency had decreased. Further, delay in diagnosis when screening was not conducted usually caused mothers considerable personal distress.

Anxiety↗
PubMed1990

Transforming growth factor-beta expression in fibropapillomas induced by bovine papillomavirus type 1, in normal bovine skin, and in BPV-1-transformed cells.

There is substantial evidence to suggest that transforming growth factor-beta (TGF-beta) plays an important role in wound healing and tissue repair as well as in carcinogenesis. It has also been observed that naturally occurring bovine papillomavirus type 1 (BPV-1)-induced bovine fibropapillomas occur predominantly at traumatized sites of the body, suggesting that humoral factors released in wounds might be important for papillomavirus infection. We have therefore investigated the possible role of TGF-beta 1 in BPV-1 infections. Two antipeptide antibodies which recognize different epitopes in the N-terminus of TGF-beta 1 were used to localize TGF-beta 1 in bovine fibropapillomas and normal bovine skin using immunohistochemical methods. Staining by anti-LC(1-30) is intracellular in suprabasal keratinocytes of the epidermis as well as the hair follicles and sebaceous glands and correlates with known sites of TGF-beta 1 mRNA synthesis. Anti-CC(1-30) staining is extracellular in the immediately underlying dermis. Neither the pattern nor intensity of TGF-beta 1 staining was affected by BPV-1 infection. C127 cells and BPV-1-transformed C127 cells were compared for TGF-beta 1 mRNA expression and secretion of TGF-beta 1 peptide. Although the levels of messenger RNA and secreted TGF-beta 1 peptide were similar in both cell types, five- to six-fold greater amounts of TGF-beta-like activity per cell was detected in media conditioned by the uninfected cells. TGF-beta 1 treatment had no effect on the growth rate of either cell type or on BPV-1 gene expression in the transformed cells.

Animals↗
PubMed1990

Accelerated aging and male homosexuality: Australian evidence in a continuing debate.

The evidence of research looking at accelerated aging among gay men is contradictory. In this study the issue of accelerated aging is addressed by accounting for the duality of the gay man's lifestyle as he interacts in both the homosexual community and the larger society where heterosexuality is the presumed norm. The onset of middle and old age as self-perceived by gay men and as perceived by other gay men in the homosexual subculture is contrasted. The results indicate that existing contradictions and debates about gay men and accelerated aging are largely a function of their referent perceptual worlds.

Adaptation, Psychological↗
PubMed1989

Transforming growth factor-beta production by synovial tissues from rheumatoid patients and streptococcal cell wall arthritic rats. Studies on secretion by synovial fibroblast-like cells and immunohistologic localization.

The growth of synovial fibroblast-like cells from patients with rheumatoid arthritis and rats with streptococcal cell wall (SCW)-induced arthritis in vitro under anchorage-independent conditions is inhibited by transforming growth factor-beta (TGF-beta). Because this growth factor is present in rheumatoid synovial fluids, we studied whether this cytokine might be secreted by cells in rheumatoid synovial tissue. We show that synovial tissues from patients with rheumatoid arthritis and osteoarthritis, and rats with SCW-induced arthritis, contain TGF-beta-1 mRNA. TGF-beta, predominantly type 1, was spontaneously secreted in vitro by synovial tissue explants and synovial fibroblast-like cells. In addition, TGF-beta could be detected immunohistochemically in cells throughout rheumatoid and SCW-induced arthritic rat synovial tissues. Finally, exogenous TGF-beta induced collagen and inhibited collagenase mRNA levels by cultured synoviocytes. These data support an autocrine role for TGF-beta in the regulation of synoviocytes in rheumatoid arthritis and, in light of its demonstrated effects on the immune system, suggest that TGF-beta might also have important paracrine effects on infiltrating inflammatory cells.

Animals↗
PubMed1989

Fluorescence correlation spectroscopy for detecting submicroscopic clusters of fluorescent molecules in membranes.

The formation of cell surface receptor clusters has been implicated or confirmed in the mechanism of signal transduction across biological membranes for a variety of processes, including receptor-mediated phagocytosis and endocytosis and cellular response to hormones and neurotransmitters. Fluorescence correlation spectroscopy (FCS) is one technique that may provide insight into the kinetics and extent of receptor aggregation. Recent theoretical and experimental developments in FCS for the investigation of submicroscopic clusters of fluorescent molecules are described and the potential applications of the technique to receptor aggregation are reviewed.

Cell Membrane↗
PubMed1989

High-order fluorescence fluctuation analysis of model protein clusters.

The technique of high-order fluorescence fluctuation autocorrelation for detecting and characterizing protein oligomers was applied to solutions containing two fluorescent proteins in which the more fluorescent proteins were analogues for clusters of the less fluorescent ones. The results show that the model protein clusters can be detected for average numbers of observed subunits (free monomers plus monomers in oligomers) equal to 10-100 and for relative fluorescent yields that correspond to oligomers as small as trimers. High-order fluorescent fluctuation analysis may therefore be applicable to cell surface receptor clusters in natural or model membranes.

Macromolecular Substances↗
PubMed1989

Transforming growth factor-beta 1: histochemical localization with antibodies to different epitopes.

We have localized transforming growth factor-beta (TGF-beta) in many cells and tissues with immunohistochemical methods, using two polyclonal antisera raised to different synthetic preparations of a peptide corresponding to the amino-terminal 30 amino acids of TGF-beta 1. These two antibodies give distinct staining patterns; the staining by anti-CC(1-30) is intracellular. This differential staining pattern is consistently observed in several systems, including cultured tumor cells; mouse embryonic, neonatal, and adult tissues; bovine fibropapillomas; and human colon carcinomas. The extracellular staining by anti-CC(1-30) partially resembles that seen with an antibody to fibronectin, suggesting that extracellular TGF-beta may be bound to matrix proteins. The intracellular staining by anti-LC(1-30) is similar to that seen with two other antibodies raised to peptides corresponding to either amino acids 266-278 of the TGF-beta 1 precursor sequence or to amino acids 50-75 of mature TGF-beta 1, suggesting that anti-LC(1-30) stains sites of TGF-beta synthesis. Results from RIA and ELISAs indicate that anti-LC(1-30) and anti-CC(1-30) recognize different epitopes of this peptide and of TGF-beta 1 itself.

Animals↗
PubMed1989

Expression of transforming growth factor-beta 1 in specific cells and tissues of adult and neonatal mice.

We have used immunohistochemical techniques to detect transforming growth factor-beta 1 (TGF-beta 1) in many tissues of adult and neonatal mice. Each of two antibodies raised to the amino-terminal 30 amino acids of TGF-beta 1 selectively stained this molecule in either intracellular or extracellular locations. Strong intracellular staining was found in adrenal cortex, megakaryocytes and other cells of the bone marrow, cardiac myocytes, chondrocytes, renal distal tubules, ovarian glandular cells, and chorionic cells of the placenta. Marked staining of extracellular matrix was found in cartilage, heart, pancreas, placenta, skin, and uterus. Staining was often particularly intense in specialized cells of a given tissue, suggesting unique roles for TGF-beta within that tissue. Levels of expression of mRNA for TGF-beta 1 and its histochemical staining did not necessarily correlate in a given tissue, as in the spleen. The present data lend further support to the concept that TGF-beta has an important role in controlling interactions between epithelia and surrounding mesenchyme.

Adrenal Glands↗
PubMed1988

Inhomogeneous translational diffusion of monoclonal antibodies on phospholipid Langmuir-Blodgett films.

The translational mobility of fluorescent-labeled monoclonal antibodies specifically bound to supported phospholipid bilayers containing hapten-conjugated phospholipids has been measured as a function of the surface concentration of bound antibodies using fluorescence recovery after photobleaching. Fluorescence recovery curves are fit well by a model that assumes the presence of two populations of antibodies with different lateral diffusion coefficients. The larger diffusion coefficient equals 3.5 x 10(-9) cm2/s, the smaller diffusion coefficient ranges from 1.5 x 10(-9) cm2/s to 2.5 x 10(-10) cm2/s, and the fractional fluorescence recovery associated with the smaller coefficient increases from approximately 0 to approximately 0.7 with increasing concentration of bound antibody. These results suggest that complexes of haptenated phospholipids and antibodies in phospholipid Langmuir-Blodgett films form clusters or domains in a concentration-dependent fashion.

Antibodies, Monoclonal↗
PubMed1988

Transforming growth factor-beta: possible roles in carcinogenesis.

TGF-beta is the prototype of a large family of multifunctional regulatory proteins. The principal sources of the peptide, platelets and bone, suggest that it plays a role in healing and remodeling processes. In vitro, TGF-beta is chemotactic for monocytes and fibroblasts and can greatly enhance accumulation of extracellular matrix components by fibroblasts. Its ability to stimulate the formation of granulation tissue locally and the demonstration of specific time- and tissue-dependent expression in embryogenesis suggest that similar mechanisms are operative in vivo. By analogy to its effects in wound healing and embryogenesis, it is proposed that TGF-beta, secreted by tumour cells, can augment tumour growth indirectly by effects on the stromal elements. These effects include suppression of the immune response, and enhancement of both angiogenesis and formation of connective tissue. Many tumour cells have escaped from direct growth inhibitory effects of TGF-beta by a variety of mechanisms including inability to activate the latent form of the peptide, loss of cellular receptors for TGF-beta, and loss of functional intracellular signal transduction pathways.

Animals↗
PubMed1988

Transforming growth factor beta-1 in acute myocardial infarction in rats.

TGF-beta 1 has been examined in the heart during myocardial infarction caused by ligation of the left coronary artery. Infarcted and uninfarcted myocardium have been compared by immunohistochemical staining of TGF-beta 1 and by Northern blot analysis of mRNA. Normal ventricular myocytes are strongly stained by an antibody to TGF-beta 1. Progressive loss of staining of these myocytes begins within 1 hr after coronary ligation. However, by 24-48 hr after ligation, intense staining of myocytes at the margin of infarcted areas is seen. Northern blots of infarcted myocardium 48 hr after ligation show a 3- to 4-fold increase in the principal 2.4 kb TGF-beta 1 mRNA; there is also a marked increase in a minor 1.9 kb transcript. In the same tissue samples, there is a 2-fold decrease in the mRNA for the glycolytic enzyme, glyceraldehyde-3-phosphate dehydrogenase. The results indicate a significant role for TGF-beta in the response of the heart to injury.

Animals↗
PubMed1988

Increased expression of growth factor mRNAs accompanies viral transformation of rodent cells.

Transforming growth factors-alpha and beta (TGF-alpha and -beta) and platelet-derived growth factor (PDGF), three distinct peptide hormones, acting together, are able to potentiate the phenotypic transformation of normal rat kidney (NRK) cells. Cells transformed by retroviruses have been shown to secrete increased levels of TGF-alpha, TGF-beta and PDGF. We report here that Harvey sarcoma virus-transformed NIH-3T3 cells and Moloney sarcoma virus-transformed NRK cells show increased expression of the mRNAs for TGF-alpha, TGF-beta, PDGF A-chain and nerve growth factor (NGF) compared to their untransformed counterparts. No amplification or rearrangement in the genomic DNA is seen in the transformed cells. In tumor tissue formed by subcutaneous injection of Ha-3T3 cells, this enhanced level of TGF-beta mRNA returns to the control level of the untransformed cells. The increase in TGF-beta mRNA in the transformed cells is paralleled by an increase in the level of TGF-beta protein as shown by immunoprecipitation and Western blotting procedures using specific TGF-beta antibodies.

Animals↗
PubMed1987

Growth in culture and tumorigenicity after transfection with the ras oncogene of liver epithelial cells from carcinogen-treated rats.

Two epithelial cell lines designated LE/2 and LE/6 were established from cells isolated by centrifugal elutriation from the livers of carcinogen-treated rats. Both cell lines exhibit some characteristics of fetal liver cells, such as the expression of the 2.3-kilobase alpha-fetoprotein mRNA, aldolase A, and lactate dehydrogenases 4 and 5. Primary cultures contain gamma-glutamyl transferase-positive cells which do not proliferate in vitro. After the first passage, the LE/2 and LE/6 cell lines are uniformly gamma-glutamyl transferase negative. Neither cell line is transformed as assayed by morphology, anchorage-independent growth, or tumor formation in nude mice. By the 50th passage, LE/6 cells form numerous colonies in soft agar in the presence of epidermal growth factor, while no colonies grow in medium lacking this growth factor. Clonal cell populations derived from five epidermal growth factor-induced soft agar colonies were not tumorigenic in nude mice. This indicates that, although epidermal growth factor-responsive late passage cells had acquired some of the phenotypic properties commonly associated with tumor cells, these cells were not fully transformed. Transformation of LE/6 cells was accomplished by transfection of the rasH oncogene (EJ). Subcutaneous inoculation of rasH (EJ)-transfected LE/6 cells produced tumors at the site of injection with histological features of moderate to well-differentiated trabecular hepatocellular carcinomas. Tumor cell lines derived from the nude mouse tumors are gamma-glutamyl transferase positive and express alpha-fetoprotein mRNA. One clonal cell line expresses both alpha-fetoprotein and albumin mRNA. These results show that nonparenchymal liver epithelial cells transfected with an activated oncogene can give rise to differentiated hepatocellular tumors similar to those induced in livers of rats fed a carcinogenic diet.

Animals↗
PubMed1987

Molecular aggregation characterized by high order autocorrelation in fluorescence correlation spectroscopy.

The use of high order autocorrelation in fluorescence correlation spectroscopy for investigating aggregation in a sample that contains fluorescent molecules is described. Theoretical expressions for the fluorescence fluctuation autocorrelation functions defined by gm,n(tau) = [(delta fm(t + tau)delta fm(t] - (delta Fm(t] (delta Fn(t]]/(F)m+n, where delta F(t) is the fluorescence fluctuation at time t, (F) is the average fluorescence, and m and n are integers less than or equal to 3, are derived. Methods for determining the number densities and relative fluorescence yields of aggregates of different sizes from a series of Gm,n(0) values are outlined. The method is applied to 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate suspended in solutions of water and ethyl alcohol. The technique presented may prove useful in detecting and characterizing aggregates of fluorescent-labeled biological molecules such as cell surface receptors.

Carbocyanines↗