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Biomedical subjects

R C Newton

Publications and source records attributed to R C Newton.

At least 55 records · Page 3Linked to original sources
PubMed1990

The production of human interleukin-1 beta by blood monocytes.

Human peripheral blood monocytes can produce interleukin-1 (IL-1) beta following the addition of picogram amounts of bacterial lipopolysaccharides (LPS). The activation of IL-1 production by these cells can be mimicked by manipulation of specific biochemical pathways which appear to be independent of, and synergistic with, the pathways activated by LPS. Such pathways may be used by other physiological systems to modulate the production of IL-1. Both negative and positive modulation of IL-1 production can be described. Selected chemical antagonists of the arachidonic acid cascade have been shown to inhibit IL-1 production. The activity of such compounds does not appear to be related to their activity as inhibitors of cyclooxygenase or lipooxygenase enzymes or to activity as antioxidants. The intracellular form of IL-1 beta is limited to the precursor, which is found cytoplasmically. The release of IL-1 by activated cells appears to be regulated, in part, by the integrity of the microtubule system of the cells.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1989

Identification of IL-1 receptors on human monocytes.

The expression and functional analysis of IL-1 beta R on human monocytes were investigated. Binding of 125I-IL-1 to human monocytes was found to be specific and saturable. Scatchard plot analysis revealed a single class of receptors with a binding constant of 600 pM and a receptor density of approximately 100 binding sites per cell. At 37 degrees C 54% of the labeled ligand was internalized over 2 h of incubation. Addition of 0.2% sodium azide to the cells reduced ligand internalization to 9% of total bound. Cross-linking studies revealed that the IL-1R in human monocytes had a Mr of 80 kDa. The addition of IL-1 to monocytes caused changes in membrane Ag expression as assessed by flow cytometric analysis. The results of this study identify IL-1 receptors on monocytes and suggest that IL-1 may act as an effector molecule for monocytes by enhancing expression of Ag correlated with cell differentiation and immune function.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1989

Systemic interleukin I administration suppresses arachidonic acid-induced ear oedema in the mouse.

Recombinant human interleukin 1 beta (IL-1 beta), given intraperitoneally to mice as a single injection, significantly suppressed the development of arachidonic acid (AA)-induced ear oedema. This effect was noted 2 h after administration and for at least 5 days afterwards. IL-1 beta was effective in the dose range of 250 ng-20 micrograms/mouse. Injection of IL-1 beta per se resulted in erythema of the ears, and thus, IL-1 beta has the capacity not only to induce and augment but also to suppress inflammatory responses. Indomethacin administered as subcutaneously-implanted pellets did not influence the IL-1 beta induced-ear erythema, but suppressed to some extent the effect of IL-1 beta on the AA-induced ear oedema.

Animals↗
PubMed1989

A surgical treatment for vitiligo: autologous cultured-epithelial grafts.

Medical treatment of vitiligo has been disappointing; therefore surgical treatments using autologous grafts have been tried. We investigated a new technique in which normally pigmented epidermal cells from a vitiligo patient were cultured on a collagen-coated membrane in MCDB-153, a media that supports melanocytes and keratinocytes. The cell/collagen-coated membrane was used to cover a superficially dermabraded vitiliginous area. Clinical repigmentation, though incomplete, was evident in three of four patients in 4 weeks. Immunofluorescence and electron microscopy were performed on the grafted areas (involved and uninvolved controls). These studies demonstrate the reappearance of melanocytes and melanosomes within the grafted area. All three patients who were successfully repigmented retained their pigment at 1 year follow-up. Further investigation of this promising treatment for vitiligo is warranted.

Adult↗
PubMed1989

Flow cytometric analysis of the effect of interleukin-1 administration on bone marrow populations in mice.

We have examined the effect of administration of human interleukin-1 (IL-1) beta on bone marrow populations in mice. The bone marrow population was characterized by flow cytometric analysis of cell volume, right angle light scatter, and cell surface markers. The bone marrow population demonstrated significant alterations following the injection of a single dose of IL-1. The earliest response was a loss of granulocytes, which was followed by an expansion of cells in this population. There was also an accumulation of kappa chain positive B cells 24 h following administration. These cells were lost from the marrow over the next 48 h, accompanied by an expansion of precursor cells. The changes in cell populations were not due to contaminating lipopolysaccharide (LPS), although the effects could be mimicked by injection of high doses of LPS. Significant effects could be detected with single dose administration of 10 micrograms to 10 ng of IL-1 per animal. The effects of a single high dose (10 micrograms) were mimicked with multiple injections of low doses (5 x 10 ng), suggesting that the intensity of the response is related to the pharmacokinetics of IL-1. These results indicate a potent effect of IL-1 administration on murine bone marrow granulocyte and B lymphocyte populations. The studies described offer a means for the analysis of the effects of IL-1 in vivo.

Animals↗
PubMed1989

The thyroid.

The integument contains many components whose function is influenced by thyroid hormone. Thus, an increase or decrease in hormone levels results in a variety of cutaneous, hair, and nail changes. These changes are important to recognize, as they may aid in the early diagnosis of thyroid disorders. Other cutaneous disorders are more prevalent in patients with thyroid disease, and their recognition may likewise be helpful. Finally, several syndrome complexes occur with which thyroid disorders are regularly associated.

Hair Diseases↗
PubMed1988

Interleukin 1-induced, T cell-mediated regression of immunogenic murine tumors. Requirement for an adequate level of already acquired host concomitant immunity.

Intraperitoneal injection of human rIL-1 in a dose of 0.5 microgram daily for 5 d, or 1 microgram daily for 3 d, was capable of causing complete regression of immunogenic SA1 sarcoma growing subcutaneously in syngeneic or semisyngeneic mice. Higher doses of IL-1 were not more therapeutic against the SA1 sarcoma, but needed to be given to cause complete regression of the immunogenic L5178Y lymphoma. On the other hand, the P815 mastocytoma was much less responsive to IL-1 therapy, in that it failed to undergo complete regression in response to doses of IL-1 capable of causing regression of the L5178Y lymphoma. IL-1 caused regression of the SA1 sarcoma when given on days 6-8 of tumor growth, but not when given on days 1-3. This refractoriness of a small tumor to IL-1 therapy suggests that the antitumor action of IL-1 is based on an underlying host-immune response that is not generated until after day 3 of tumor growth. Direct evidence for the participation of host immunity in IL-1-induced tumor regression was supplied by results showing that IL-1 was not therapeutic against the SA1 sarcoma growing in T cell-deficient (TXB) mice, unless these mice were first infused with Ly-2+ and L3T4+ T cells from donor mice bearing an established SA1 sarcoma. In contrast, normal T cells, or T cells from donor mice bearing a YAC-1 lymphoma, failed to provide TXB recipients with the ability to cause regression of their SA-1 sarcoma in response to IL-1 treatment. The results are in keeping with the interpretation that exogenous IL-1, by augmenting the production of tumor-sensitized T cells, converts a subtherapeutic level of host immunity to a therapeutic level. The results suggest, in addition, that IL-1 only stimulates the replication of T cells that are already engaged in the antitumor immune response.

Animals↗
PubMed1988

Characterization of murine IL-1 beta. Isolation, expression, and purification.

One cDNA clone encoding a truncated murine IL-1 beta (M IL-1 beta) sequence was isolated from a murine macrophage cDNA library. We reconstituted the coding sequence of the 152-residue mature protein and expressed it in Escherichia coli. rM IL-1 beta was purified to homogeneity and characterized by oligonucleotide and NH2-terminal sequence analysis. Purified rM IL-1 beta exhibited biologic activity equivalent to 7.8 x 10(7) units/mg in the murine thymocyte proliferation assay and 9.9 x 10(3) units/mg in the human gingival fibroblast PGE2 production assay, indicative of species specificity. The isoelectric point of rM IL-1 was found to be 8.85. The circular dichroism spectrum revealed that the secondary structure of M IL-1 is indistinguishable from that of the human protein. Receptor binding studies indicated the rM IL-1 bound to murine EL-4.1 thymoma cells in a specific and dose-dependent fashion with an affinity of 32 pM. Competition binding data suggested that murine and human IL-1 compete for a single class of receptor. Antisera were generated in rabbits against both murine and human IL-1. Results of ELISA binding and antisera neutralization assays indicated that there are common antigenic sites between the two IL-1 beta molecules. These domains are of functional importance because they are capable of mediating the neutralization of biologic activity.

Amino Acid Sequence↗
PubMed1988

Quantitation of related proteins by Western blot analysis.

A spectrophotometric assay for quantitation of related proteins following Western blot analysis is described. Proteins were separated by polyacrylamide gel electrophoresis and electrophoretically transferred to nitrocellulose. In the system utilized in this study, immobilized interleukin-1 (IL-1) proteins were identified by ELISA reaction using a rabbit antibody specific for IL-1 beta. Subsequently, the membrane was probed with goat anti-rabbit antibody conjugated to horseradish peroxidase and IL-1 proteins were detected by incubation with 4-chloro-1-naphthol and hydrogen peroxide. The stained IL-1 bands were cut out, exposed to the peroxidase chromogenic substrate, o-phenylenediamine (OPD), and hydrogen peroxide and the rate of reaction was determined spectrophotometrically at 490 nM. A linear relationship between enzyme activity and IL-1 concentration was observed from 10 to 1000 ng/lane. Thus, this represents a sensitive and specific method for quantitating small amounts of IL-1 in complex protein mixtures.

Chromogenic Compounds↗
PubMed1988

The need for a do-not-resuscitate policy in a public city hospital.

Data were collected over a six-month period from in-hospital cardiopulmonary resuscitation (CPR) patients (aged 18 years and older) who were admitted to a public hospital. The sample population was mostly male (55.4 percent), primarily black (90.6 percent), with a mean age of 61 years. Medical expenses for these patients were largely covered by public funds or medical charities, reflecting the predominately low socioeconomic status of the population. The proportion of patients discharged alive after in-hospital CPR was 6.1 percent. The CPR sample contains a large proportion of patients in the terminal phase of diseases such as metastatic cancer, acquired immune deficiency syndrome (AIDS), and end-stage liver disease. Chart reviews revealed that do-not-resuscitate (DNR) orders were not presented as a therapeutic option to either patient or family in the majority of instances. These findings indicate a need to develop standards and strategies for decision making about the use of CPR specific to this population.

Adolescent↗
PubMed1988

The distribution and clearance of radiolabeled human interleukin-1 beta in mice.

Mice were injected with radiolabeled human interleukin-1 beta (IL-1) and monitored for tissue localization and route of clearance. IL-1 was labeled with no apparent loss of in vitro biological activity. Mice were injected by intravenous (i.v.), intraperitoneal (i.p.), and subcutaneous (s.c.) routes with either low dose (10 ng radiolabeled) or high dose (10 ng radiolabeled with 10 micrograms unlabeled) IL-1. Blood and urine were monitored and various tissues were counted for radioactivity after 2, 24 or 48 hours. Injection of either dose of IL-1 by i.v. route demonstrates a rapid initial loss of IL-1 from the circulation followed by a slower loss over the next hour. Injection by i.p. or s.c. routes gives an initial peak in circulating IL-1 after 10 minutes which is sustained over at least the next 7 hours with the high dose. Circulating IL-1 is associated with the plasma fraction and is not cell associated. Two hours after injection, most tissues examined were found to contain an equal amount of IL-1 on a weight basis with the exception of bone, which contains half the level found in other tissues, and kidney, which contains 4-8 fold more IL-1. The major route of clearance is the kidney with 10-20% of label found in the urine within hours of injection. IL-1 found in the urine contains intact 17 kD IL-1.

Animals↗
PubMed1987

A biochemical and kinetic analysis of the interleukin-1 receptor. Evidence for differences in molecular properties of IL-1 receptors.

This study describes the biochemical characterization and kinetic analysis of the interleukin-1 (IL-1) receptor in Raji human B-lymphoma and EL4 murine T-lymphoma cells. The internalization of 125I-IL-1 was studied in both cell types by an acid extraction technique which removes surface bound ligand. At 37 degrees C, binding to Raji IL-1 receptors was almost entirely cell surface (91%). EL4 cells, in contrast, internalized 59% of ligand at this temperature and this was almost totally inhibited by sodium azide. Receptor binding studies showed that the B-cells had a lower binding affinity but much higher receptor density per cell (KD = 2.1 nM, Ro = 7709) than the T-cells (KD = 0.4 nM, Ro = 241). The receptor binding affinity of two IL-1 analogs, Glu-4 and clone 18, was determined in competitive binding studies. In the B-cells the analogs had binding affinities of 25 and 90%, respectively, whereas in the T-cells the affinities were 0.2 and 200%, respectively. Chemical cross-linking studies showed that the IL-1 receptor in B-cells had a lower molecular weight than that in T-cells (68 kDa compared to 80 kDa). In summary these studies demonstrate that structural differences exist between IL-1 receptors in Raji and EL4 cells.

Animals↗
PubMed1987

Muteins of human interleukin-1 that show enhanced bioactivities.

Using recombinant DNA techniques, we have made a series of amino-terminal muteins of human interleukin-1 (IL-1). Two of the muteins demonstrated 4-7-fold increase in bioactivity as compared to that of the native IL-1. The enhanced biological potency coincides with an increase in both receptor binding affinity and in vivo tumor inhibitory activity. By site specific mutagenesis, we have shown that the arginine at the fourth position of IL-1 is one of the key residues in the function of IL-1. Circular dichroism studies of the amino-terminus analogs showed little structural rearrangement. The change in bioactivity might be due to a change in the stability of the muteins, in the side chain interactions with receptors or in the minor change in folding near the receptor binding site.

Amino Acid Sequence↗
PubMed1987

Lack of a central role for calcium in the induction and release of human interleukin-1.

This study examines the potential role of calcium in the activation of human monocytes by bacterial lipopolysaccharide (LPS) to produce interleukin-1 (IL-1). Monocytes cannot be triggered to produce IL-1 through addition of calcium ionophores. Triggering of IL-1 production by LPS cannot be blocked by depletion of extracellular calcium, blockade of calcium channels, or addition of agents which antagonize the effects of intracellular calcium. Finally, the addition of LPS does not induce the mobilization of intracellular free calcium as measured by quin-2 fluorescence.

Calcimycin↗
PubMed1987

Effect of antiinflammatory drugs on human interleukin-1-induced cartilage degradation.

Human monocyte IL-1 stimulated the release of proteoglycans from cartilage in organ culture in a concentration-related manner. This stimulation required protein synthesis as shown by inhibition with cycloheximide. The metal chelator, 1,10-phenanthroline, inhibited breakdown, suggesting the involvement of a metalloproteinase. Various nonsteroidal anti-inflammatory drugs (100 microM), and the corticosteroids, dexamethasone and hydrocortisone (1-10 microM), were not effective in blocking proteoglycan release. Of the disease modifying agents tested, levamisole was ineffective while the antimalarials, chloroquine (100 microM) and hydroxychloroquine (100 microM), inhibited the action of IL-1. The free-radical inhibitor SOD (5000 U/ml but not 1000 U/ml) was effective while catalase (8000 U/ml) was not. The protective effects of SOD and the antimalarials suggest that oxygen reactive species may play a role, while lack of inhibition with NSAIDs and corticosteroids indicate that arachidonic acid metabolites may not be important in this degradative process.

Animals↗