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Biomedical subjects

H S Shin

Publications and source records attributed to H S Shin.

At least 163 records · Page 9Linked to original sources
PubMed1986

Direct evidence for the existence of nominal antigen binding sites on T cell surface Ti alpha-beta heterodimers of MHC-restricted T cell clones.

The binding of nominal antigen to Ti alpha-beta heterodimers on MHC-restricted human T cell clones specific for fluorescein-5-isothiocyanate (FL) was detected by flow cytometry and affinity chromatography. The FL-Ti interaction is of physiologic significance, since T cell activation is induced by cross-linked arrays of FL in the absence of the specific MHC recognition. High antigen valence is required to achieve stable binding to cells and subsequent activation, which is consistent with estimated Ti-FL association constants of less than 3 X 10(5) l/mol. In addition to providing direct evidence that the Ti alpha-beta heterodimer is the receptor for antigen, these data suggest that nominal antigen binding sites exist on the Ti molecules of at least some MHC-restricted clones.

Antigens↗
PubMed1986

Release of arachidonic acid and formation of oxygenated derivatives after complement attack on macrophages: role of channel formation.

Treatment of [3H]arachidonic acid ([3H]C20:4)-labeled, antibody-sensitized mouse resident peritoneal macrophages with rabbit serum complement, or C6-deficient rabbit serum + C6, caused hydrolytic release of incorporated [3H]C20:4 from phospholipids, followed by conversion to oxygenated derivatives. The C6 dose-response curve for release of C20:4 plus its metabolites was monotonic, which indicates dependence on channel formation, whereas the dose-response curve for lysis displayed multi-hit behavior. High-performance liquid chromatography demonstrated that the major radiolabeled products in the aqueous phase co-eluted with C20:4, 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), and prostaglandin E2. Kinetic studies of the release of 6-keto-PGF1 alpha, the major metabolite, displayed biphasic characteristics; a moderate amount of this prostaglandin was released before the onset of cell lysis. Experimental evidence obtained by freeze-thaw or by incubation of these cells with melittin or A23187 indicated that cell lysis does not necessarily result in the production of inflammatory mediators. Furthermore, when macrophages were treated with serum complement, it was apparent that the major part of the release was due to C5b-9 and not to the action of C5a. We conclude that release of C20:4 and its derivatives from complement-treated macrophages does not depend on cytolysis, but is a consequence of insertion and channel formation.

Animals↗
PubMed1986

Clinical significance of unilateral sinusitis.

In general, the etiologic factors of chronic paranasal sinusitis are systemic conditions such as nutrition, predisposition, allergy, and local factors such as nasal anatomic conditions. Among these factors, the development of unilateral sinusitis is a model case verifying the influence of local factors. In my study of 640 cases over a certain period of time, a comparison was made between 161 cases of unilateral sinusitis and 479 cases of bilateral sinusitis in order to verify the effects of local factors in the development of this disease. Patients with a history of previous sinus surgery or tumors were eliminated from the cases. 1. The male-female incidence rate, and the age distribution of the patients at the initial visit showed no prominent differences between unilateral and bilateral cases. 2. It was found that a larger number of cases of unilateral sinusitis had a duration of less than one year as compared to bilateral sinusitis which were longer than and year. Therefore it can be said that the duration of unilateral sinusitis is usually shorter than that of bilateral sinusitis. 3. In unilateral cases the patients with moderate to severe nasal septal deviation, one number of patients with septal deviation towards the diseased side was twice as high as that on the non-affected side. 4. The incidence rate of polyps occurring in the middle meatus was shown to be about twice as high in bilateral cases as in unilateral cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Antigen valence determines the binding of nominal antigen to cytolytic T cell clones.

We have shown that cytotoxic T cell clones specific for the nominal antigen FL will bind high molecular weight (600,000 to 2,000,000) polyacrylamide and Ficoll polymers conjugated with 200-600 FL groups per molecule. Low molecular weight polymers (40,000) with the same epitope density did not give stable binding. A high molecular weight polymer with a lower epitope density also failed to bind. Taken together, these results suggest that a substantial degree of multivalence is a necessary factor in the stable binding of nominal antigen to T cell clones.

Acrylic Resins↗
PubMed1985

Analysis of major histocompatibility complex haplotypes of t-chromosomes reveals that the majority of diversity is generated by recombination.

t-chromosomes are natural polymorphisms in feral populations of mice that are thought to be descended from a single ancestral chromosome. They carry an inversion of at least 10 cM surrounding the major histocompatibility complex (MHC) that effectively prevents recombination between a t-bearing chromosome and wild type chromosomes. However, on the rare occasion when two different t-chromosomes meet in a wild female, recombination occurs at an apparently normal rate. Since they contain the highly polymorphic MHC, their limited origin and restricted chances for recombination make t-chromosomes a valuable tool for studying the relative contributions of mutation and recombination to the generation of diversity. Using 13 different serological reagents to class I antigens, and studying restriction enzyme polymorphisms detected with three molecular probes for class II genes examined with three endonucleases, we present data indicating that the major factor responsible for the diversity of class I antigens is recombination, but that for class II genes, mutation must play an important role in addition to recombination.

Animals↗
PubMed1985

A biological clock in Drosophila.

The per locus plays a central role in the organization and function of the Drosophila biological clock. The gene has been mapped to a 7-kb DNA segment by physically locating the breakpoints of several chromosomal rearrangements that disrupt per function. This DNA contains a single transcription unit which produces a 4.5-kb poly(A)+ RNA. No oscillation in the synthesis of this transcript is detected when per expression is followed over a 24-hour cycle of light and dark. When wild-type DNA containing only this transcription unit is transferred to the genome of a per0 (arrhythmic) fly by P-element-mediated transformation, the 4.5-kb RNA is produced and rhythmic behavior is restored with high penetrance of the rhythmic phenotype. This transforming DNA will also complement chromosomal deletions that include the per locus and adjoining transcription units, indicating that only one gene in this chromosomal interval plays a measureable role in the production of circadian rhythms. Transformed flies having rhythms with longer than wild-type periodicity underproduce the 4.5-kb RNA. We suggest that the periodicity of circadian rhythms in Drosophila is determined by the level of expression of a per locus protein encoded by the 4.5-kb transcript. We have found DNA homologous to the per locus in several species of vertebrates. DNA exhibiting very high homology to a portion of the per locus has been cloned from the mouse and the DNA sequence of the conserved segment has been determined. Mouse and fly DNAs both appear to code for long protein segments composed exclusively of alternating threonine and glycine or serine and glycine residues.

Animals↗
PubMed1985

The interaction of nominal antigen with T cell antigen receptors. I. Specific binding of multivalent nominal antigen to cytolytic T cell clones.

In this report, we describe an experimental strategy for analyzing the interaction of nominal antigen with antigen-specific T cell clones. Our approach was based on the notion that low affinity interactions between nominal antigen and T cell antigen receptors might be detected by using a highly multivalent form of the antigen in which a large number of identical, appropriately spaced epitopes are attached to a polymer backbone. Antigens of this kind should be capable of multivalent binding to receptors on the T cell, resulting in a marked enhancement of the overall avidity of the interaction. To examine this possibility, we established a series of murine cytolytic T cell (Tc) clones specific for the readily detectable hapten fluorescein isothiocyanate (FL). These clones lysed FL-conjugated target cells in an antigen-specific fashion and also showed specificity for target cell MHC gene products. The interaction of these clones with the nominal antigen FL was assessed by flow cytometry, using a series of water-soluble FL-conjugated polymers varying in polymer backbone and FL isomer. High m.w. (600 to 2000 Kd) polymers of acrylamide, dextran, or Ficoll conjugated with 300 to 800 FL groups/molecule bound specifically to anti-FL Tc clones. There was little binding to syngeneic spleen cells, thymocytes, noncytolytic T cell clones, or T cell clones specific for other haptens such as NIP. Polymer concentrations in the 1 to 10 micrograms/ml range produced readily detectable binding within minutes at 20 degrees C, and the binding approached plateau levels at polymer concentrations of between 100 and 300 micrograms/ml. Studies with closely related FL isomers showed that the same antigen fine specificity was operative in both lysis of FL-conjugated target cells and in binding of FL-conjugated polymers. The functional significance of the observed binding was assessed by measuring the effect of FL-conjugated polymers on lymphokine secretion by the clones. High m.w. FL-conjugated polymers caused a dose-dependent increase in the production of macrophage activation factor (MAF) by anti-FL Tc clones, but did not increase MAF production by an NIP-specific clone. In contrast, concanavalin A induced MAF production by both FL-specific and NIP-specific clones. Thus, the observed binding is both specific and functionally significant. These results suggest that soluble nominal antigen, in an appropriately multivalent form, can bind specifically to antigen receptors on Tc clones.

Animals↗
PubMed1985

Role of endogenous complement in monoclonal IgM antibody-dependent leukemia suppression in vivo: participation of C3b.

The mechanism by which McAb of the IgM isotype causes prolonged survival of leukemic rats was investigated. The participation of endogenous C in the suppression of IgM-sensitized leukemia cells was demonstrated by the observations that a) suppression was abrogated in CVF-treated rats, and b) the CVF effect was partially reversed if C3b was provided on the surface of IgM-sensitized leukemia cells.

Animals↗
PubMed1984

Gene mapping within the T/t complex of the mouse. IV: The inverted MHC is intermingled with several t-lethal genes.

Using a combination of classical genetics, serology, and molecular genetics, we have mapped as many as possible of the MHC components in t haplotypes. Results indicate that the whole MHC is included in a simple inversion with the relative positions of its genes being intact. Furthermore, some of the t-lethal mutations map very near to, or are intermingled with, components of the MHC. At the centromeric end the t12 lethal maps between TL and H-2D in the Qa region, and distally the tw5 lethal is inseparable from H-2K.

Alleles↗
PubMed1984

Inhibition of T cell-mediated cytotoxicity by anti-inflammatory steroids.

We have tested the capacity of glucocorticoids to modulate the effector function of splenic cytotoxic T lymphocytes (CTL) obtained after i.p. immunization with allogeneic cells. Although acute exposure to glucocorticoids did not inhibit the activity of freshly obtained splenic CTL, preincubation of these CTL for several hours with subnanomolar concentrations of several different glucocorticoids caused marked inhibition. The relative inhibitory potency of the steroids tested correlated with their reported activity both in glucocorticoid receptor binding assays and in assays of anti-inflammatory potency in man. The inhibitory effects of low concentrations (10(-10) M to 10(-9) M) of dexamethasone were reversed by human or mouse interleukin 2 (IL 2)-containing supernatants, but were not reversed by IL 1-containing supernatants. The inhibitory effects of higher concentrations (10(-8) M to 10(-7) M) of dexamethasone could not be reversed even by very high doses of mouse IL 2. In contrast to previous reports of minimal direct glucocorticoid effects on CTL activity, the present results suggest that after preincubation, splenic CTL from in vivo-immune mice are sensitive to inhibition by glucocorticoids, and that the glucocorticoids may act both indirectly (on IL 2 production) and directly on the CTL.

Administration, Topical↗
PubMed1984

Induction of interleukin 1 messenger RNA and translation in oocytes.

Macrophages and P388D1 murine cultured cells produce interleukin 1 (lymphocyte-activating factor) when stimulated with lipopolysaccharide or other agents. Poly A+ RNA extracted from either type of stimulated cells and injected into Xenopus oocytes causes synthesis of material with the biologic and biochemical properties of interleukin 1. It potentiates lectin-mediated thymocyte proliferation, and it has the molecular dimensions of interleukin 1, as determined by gel exclusion chromatography. RNA from either cell type causes the synthesis of interleukin 1 with an isoelectric point of 4.8 to 5.0. RNA prepared from unstimulated macrophages or P388D1 cells does not cause interleukin 1 production by oocytes. We conclude that the amount of interleukin 1 mRNA increases greatly after stimulation of either cell type, and oocytes carry out any modifications of the polypeptide necessary for activity. The kinetics of interleukin 1 mRNA accumulation and of interleukin 1 production by macrophages and P388D1 cells are compared.

Animals↗
PubMed1983

Cis-trans test shows a functional relationship between non-allelic lethal mutations in the T/t-complex.

Recessive lethal mutations in the T/t-complex of the mouse characteristically show defective genetic complementation, even when they affect very different stages of embryogenesis and are known to be nonallelic. To address the question of their genetic or functional relationship, we have applied the cis-trans test, using several well defined recombinant t-chromosomes that carry two or more lethal mutations, and others that are devoid of specific lethals. We show here that the defective complementation that occurs between different t-lethals is a specific result of the trans configuration; thus these genes, which may map as much as 15 cM apart, constitute a functional unit. Some speculations are presented to interpret this enigma in terms of DNA plasticity.

Alleles↗
PubMed1983

Macrophage-mediated cytotoxicity: role of a soluble macrophage cytotoxic factor similar to lymphotoxin and tumor necrosis factor.

Guinea pig peritoneal macrophages, when activated for cytotoxicity by the calcium ionophore A23187 or lipopolysaccharide, produce a cytotoxic factor [macrophage cytotoxic factor (M phi-CF)] that is not blocked by catalase or protease inhibitors. Fractionation of culture supernates containing M phi-CF by gel filtration revealed one peak of cytotoxic activity of Mr approximately 45,000, the same as guinea pig lymphotoxin (LT). Antiserum prepared against purified guinea pig LT completely neutralized the cytotoxic activity of M phi-CF. In addition, the cytotoxic factor in guinea pig tumor necrosis serum was found to have a Mr of 45,000 and was neutralized by anti-LT. Thus, M phi-CF is physicochemically and immunochemically similar to LT and tumor necrosis factor, if not identical. To investigate the role of M phi-CF in macrophage-mediated cytotoxicity, anti-LT was added to A23187- or lipopolysaccharide-activated macrophages before addition of L-929 target cells. In 10 of 16 experiments, the inhibition of macrophage-mediated cytotoxicity was 100%. In the others, cytotoxicity was blocked partially, the lowest inhibition being 49%. The effectiveness of inhibition appeared to be inversely related to the intensity of macrophage activation. These results indicate that M phi-CF plays a significant role in macrophage-mediated cytotoxicity but involvement of another mechanism cannot be excluded.

Animals↗
PubMed1983

The diversity of T cell receptors specific for self MHC gene products.

Cytolytic and helper T cells exhibit, in addition to their specificity for foreign antigen, a restriction specificity for self MHC gene products. The present study was designed to assess the degree of diversity within the repertoire of receptors that are involved in T cell recognition of self MHC gene products. For this purpose, we generated a series of murine cytolytic T lymphocyte (CTL) clones specific for a hapten antigen and restricted to the self MHC gene product H-2Kb. An analysis of the hapten fine specificity of these clones by using hapten analogues revealed the presence of substantial diversity within the repertoire of CTL receptors specific for the hapten. The degree of diversity within the repertoire of self H-2 recognition structures on these clones was assessed by testing clones on panels of syngeneic, congenic H-2K disparate, and H-2Kb mutant target cells bearing varying amounts of antigen. A striking degree of heterogeneity in H-2K recognition was found among these H-2Kb restricted CTL. We estimate that there are probably a minimum of 65 different patterns of H-2K recognition among these clones. Our results suggest a high degree of diversity exists within the repertoire of self MHC recognition structures on antigen-specific T cells restricted to a single self MHC gene product.

Animals↗
PubMed1983

Thrombin-induced gap formation in confluent endothelial cell monolayers in vitro.

When thrombin is incubated with confluent monolayers of human umbilical vein endothelial cells in vitro, there is a change in the shape of the endothelial cells that results in gaps in the monolayer, disrupting the integrity of the endothelium and exposing the subendothelium. Using a grid assay to measure this phenomenon, we observed that up to 80% of the surface area once covered by cells was uncovered after a 15-min incubation with 10(-2) U/ml (10(-10)M) thrombin. The effect was apparent within 2 min and did not remove cells from the surface of the culture dish. The gaps in the monolayer completely disappeared within 2 hr after exposure to thrombin. The effect of thrombin was inhibited by preincubation of thrombin with hirudin or antithrombin III plus heparin or by preincubation of the monolayers with dibutyryl cyclic adenosine monophosphate (dbcAMP). Histamine also induced gap formation in endothelial cell monolayers. Both pyrilamine and cimetidine prevented the histamine-induced effect, but they had no effect on thrombin-induced gap formation. Intact monolayers were not disrupted by bradykinin, serotonin, C5a, or C3a. Our results suggest that small amounts of thrombin can induce repeated and transient exposure of the subendothelium, a situation believed to be conducive to atherogenesis and thrombosis.

Antithrombin III↗
PubMed1983

Monoclonal antibody against a differentiation antigen on human leukemia cells: cross-reactivity with rat leukemia and suppression of rat leukemia in vivo.

We produced a McAb against a normal differentiation antigen on human ANLL that cross-reacts with a rat ANLL. The McAb reacted with all ANLL cells tested as well as normal undifferentiated myelomonocytic cells. This McAb, of the IgM isotype, in the presence of C mediated lysis of human and rat leukemic cells in vitro. In addition, it mediated complete tumor suppression in rats engrafted with 10(2) to 10(3) rat leukemic cells in vivo. No significant side effects were observed in McAb-treated rats. McAb of this type may be useful in the treatment of human ANLL after conventional therapy, which often eliminates most leukemic cells, leaving a small number of residual cells. The ultimate utility of this McAb for human therapy or McAb directed against the same or other differentiation antigens remains to be determined.

Acute Disease↗
PubMed1983

Mechanism of macrophage-mediated cytotoxicity: production of a soluble cytotoxic factor.

Peritoneal macrophages from C3HeB/FeJ mice became cytotoxic for 6C3HED lymphosarcoma cells, P815 mastocytoma cells, and L-929 fibroblasts when treated with the calcium ionophore, A23187, at concentrations ranging from 1.0 to 20 microM. The effect of A23187 on other activation processes was also tested. It was found that A23187 and lipopolysaccharide (LPS) acted synergistically, but no consistent synergy with macrophage-activating factor (MAF) was observed. Cytotoxic activity (M phi-CF) was found in cellfree supernatants from M phi activated by A23187 or LPS. Furthermore, these two activating agents synergize in the production of M phi-CF. The cytotoxic activity of the crude material was not blocked by catalase or protease inhibitors. Fractionation of supernatants by high pressure liquid chromatography has shown that there was a peak of cytotoxic activity with a m.w. of approximately 45,000. Interestingly, L-929 cells were 30-fold more sensitive to M phi-CF than a lymphotoxin-resistant subline of L-929.

Animals↗