Biomedical subjects

S Lyons

Publications and source records attributed to S Lyons.

At least 19 recordsLinked to original sources

PubMed1996

An anti-cytokine bioactivity assay for interferons-alpha, -beta and -omega.

Interferons-alpha and -beta (IFN-alpha and -beta) are cytokines that are widely known to induce potent anti-viral activity. However, it has become increasingly apparent that IFN-alpha and -beta exert a variety of other biological effects, including anti-tumour and immunomodulatory activities and are increasingly used clinically to treat a range of malignancies, myelodysplasias and autoimmune diseases, e.g., IFN-beta for multiple sclerosis. The most widely used bioassays for the IFNs are based on their anti-viral activity, but these do not predict the biological activity of the IFNs in anti-tumour and immunomodulatory therapies. Thus, we have developed anti-cytokine-based bioassays that may be more reflective of such activity and which have several advantages over existing anti-viral bioassays. The anti-cytokine bioassay is based on the ability of IFN-alpha, -beta and -omega to inhibit granulocyte-macrophage-colony-stimulating factor (GM-CSF) induced proliferation of the erythroleukaemic cell line TF-1. This assay can take only 24 h, is sensitive to 200 fg (0.04 IU) IFN-alpha or -beta and 100 fg (0.02 IU) IFN-omega and is able to detect down to these levels in serum or plasma samples. The usefulness of anti-cytokine bioassays for IFN-alpha, -beta and -omega is not restricted to the GM-CSF/TF-1 cell format and other alternatives are available, such as erythropoietin (EPO)/TF-1 cells and EPO/UT-7-EPO cells. These assays can be made specific for each of the IFNs by including neutralising antibodies in the bioassay.

Humans↗

PubMed1995

Effect of the carbon dioxide laser on viability of ear cartilage in a rabbit model.

The carbon dioxide (CO2) laser can be used for rapid, detailed sculpting of cartilage for creation of an ear framework for reconstruction of microtia. Clinical and animal studies of the effect of the CO2 laser have noted good healing with little evidence of a zone of tissue injury adjacent to the laser incisions. The current study has investigated the longer term effect of CO2 on chondrocyte viability in a rabbit ear model in which the laser has been used to incise autogenous cartilage segments for implantation into subcutaneous pockets. Over a 3-month period, the conformational integrity of the segments, when compared to segments incised with a scalpel, was no different. However, radioactive sulfur uptake studies to assess the viability of chondrocytes indicated a decrease in chondrocyte density in those specimens that have been subjected to laser incisions. Although other studies of acute cellular injury indicate that the CO2 laser may be beneficial for cartilage incision and sculpting, the current study indicates that resorption over longer periods of time might be encountered as a consequence of decreased chondrocyte viability in the vicinity of the laser incisions.

Analysis of Variance↗

PubMed1994

A forced choice procedure for evaluation of contrast sensitivity function in preschool children.

BACKGROUND: The ability to clinically use Contrast Sensitivity Function (CSF) in adults for detection of visual pathway disorders has been demonstrated. The results of CAF testing would be especially meaningful clinically for young children for earlier diagnosis and treatment of visual disorders. In preschool children (ages 3-5 years), CSF assessment has been more laborious and less practical clinically and has met with limited use or success when dealing with preschool children. The purpose of this study was to evaluate the effectiveness of a modified two-alternative forced choice (2AFC) procedure in testing the CSF in preschool children. METHODS: The subjects in this study consisted of 26 children between the ages of 35 and 60 months of age. The children were free of any detectable visual deficits, illness, and neurological or developmental abnormalities. A Vistech Vision Contrast Sensitivity System (CTS 6500) chart was modified and applied in a two-alternative forced choice procedure to determine the contrast sensitivity threshold for five spatial frequencies (1.5, 3.0, 6.0, 12.0, and 18.0 cycles/degree). RESULTS: All 26 children completed the testing at all five spatial frequency levels with both eyes under monocular testing conditions. The average actual testing time required less than 7.0 minutes for the combined right and left eye test time for all subjects. The results suggest that as the age increased, there was a tendency for an overall increase in the child's ability to detect lower contrast levels. The results indicate that this modified procedure yielded values proximal to adult CSF values, especially in the higher spatial frequencies. CONCLUSIONS: We have demonstrated that a modified forced-choice procedure using Vistech CSF gratings could be used in a preschool population. The two alternative forced choice method used in this study was found to be an effective and clinically efficient technique for evaluating the CSF levels in preschool children and makes it possible to screen for a variety of visual and neurological conditions in the preschool child.

Aging↗

PubMed1990

Autoimmune hemolytic anemia and rheumatoid arthritis.

The incidence of AIHA in patients with rheumatoid arthritis has not been shown to exceed that in the general population. The prevalence of rheumatoid arthritis in patients with AIHA approximates that in the general population. On the basis of these data, it is extremely difficult to establish a relationship between AIHA and rheumatoid arthritis. The patient we have described had the unusual presentation of AIHA with rheumatoid arthritis. We believe the two remain distinct entities.

Aged↗

PubMed1989

Isolation of self-recognizing IgG2a monoclonal rheumatoid factors.

Hybridoma cell lines were produced by fusing spleen cells from 11 mice that expressed the lpr mutation to nonsecreting SP2/0 myeloma cells. Five to 20% of the hybridoma cell lines so derived were found to secrete antibodies that recognized autologous IgG2a. Out of 168 anti-IgG2a clones tested, 4 clones produced anti-IgG2a rheumatoid factor (RF) that was itself IgG2a. Two clones recognized self IgG2a while the other two clones each recognized a nonself IgG2a allotypic determinant. These findings indicate that self-recognizing antibodies are a component, albeit a minor one, of the RF repertoire of lpr/lpr mice.

Animals↗

PubMed1988

Transcription of HLA class II genes in the absence of B-cell-specific octamer-binding factor.

HLA-DR and other human class II histocompatibility genes are expressed by Epstein-Barr virus-transformed B-lymphocyte cell lines but not by most T-cell leukemia lines. We determined by transcriptional run-on experiments that regulation of class II expression in these cells is at the level of gene transcription; nuclei isolated from B-cell lines actively transcribe class II mRNA, whereas nuclei from non-class II-expressing T-cell lines and from the class II transactive factor-deficient B-cell mutant 6.1.6 do not. In searching for DNA-binding proteins which might regulate transcription, we found both a ubiquitous (B1) and a B-cell-specific (B2) factor which bind to the octamer sequence ATTTGCAT 52 base pairs 5' of the cap site in the DR alpha gene. We examined the relationship of these factors to DR alpha transcription. HUT-78, a T-cell line which expresses class II mRNA constitutively, contains only the ubiquitous B1 octamer-binding factor also found in non-class II-expressing T-cell leukemias. Human fibroblast, HeLa, and melanoma cell lines similarly contain only the ubiquitous factor, even when these cells are induced to express class II mRNA by treatment with gamma interferon. Both B1 and B2 binding factors are present in the B-cell mutant 6.1.6, which nevertheless fails to transcribe class II mRNA. Although we have not ruled out the requirement of B-cell-specific octamer-binding factor B2 for class II expression in B cells, it is clear that in other cells substantial DR alpha transcription occurs in the absence of this factor.

B-Lymphocytes↗

PubMed1985

An indirect fluorescent antibody test for antibodies against HTLV-III.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗

PubMed1984

An immunological method for detecting gene expression in yeast colonies.

A method for detection of cloned, expressed genes in yeast colonies has been developed. The 70-kilodalton (kDa) mitochondrial outer membrane protein of yeast was used as a model protein. Transformation of a strain deficient in the gene for the 70-kDa protein was performed, and transformed colonies were detected with the antibody decoration technique. This technique is based upon gentle lysis of yeast colonies that have been grown on nitrocellulose filters such that the yeast proteins remain bound in discrete spots after lysis. The lysis is carried out by alkaline conditions in the presence of 2-mercaptoethanol and sodium dodecyl sulfate. After lysis, empty sites on the nitrocellulose filter are blocked to eliminate nonspecific binding of proteins by either 0.5% bovine serum albumin or 0.05% Tween 20. Decoration with antibody is visualized by using 125I-labeled protein A or peroxidase-conjugated second antibody. Antigens amounting to less than 0.1% of the total protein in the cell can be readily detected by the assay. The sensitivity of the assay enables detection of 1 positive colony per plate containing about 1000 colonies.

Antigen-Antibody Complex↗

PubMed1983

Bragg peak proton beam therapy for arteriovenous malformation of the brain.

Explore the source record for details and available documents.

Adult↗

PubMed1979

Modulation of T cells and macrophages by cholera toxin treatment in vivo and in vitro.

Cholera Toxin influences the antibody response to SRBC. Enhanced responses occur in vivo and in vitro when CT is added together with antigen. However, CT depresses antibody formation when given in vivo before antigen but enhances in vitro responses under the same conditions. Modulation of antibody formation appeared due to effects of T lymphocytes as well as macrophages. Co-cultivation of immunologically impaired spleen cells from CT pretreated animals with macrophage-rich peritoneal cells or educated T cells increased the antibody response.

Animals↗

PubMed1974