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Biomedical subjects

A Munck

Publications and source records attributed to A Munck.

At least 109 records · Page 6Linked to original sources
PubMed1981

T cell growth factor receptors. Quantitation, specificity, and biological relevance.

To examine directly the hypothesis that T cell growth factor (TCGF) interacts with target cells in a fashion similar to polypeptide hormones, the binding of radiolabeled TCGF to various cell populations was investigated. The results indicate that TCGF interacts with activated T cells via a receptor through which it initiates the T cell proliferative response. Internally radiolabeled TCGF, prepared from a human T leukemia cell line and purified by gel filtration and isoelectric focusing, retained biological activity and was uniform with respect to size and charge. Binding of radiolabeled TCGF to TCGF-dependent cytolytic T cells occurred rapidly (within 15 rain at 37 degrees C) and was both saturable and largely reversible. In addition, at 37 degrees C, a receptor- and lysosome-dependent degradation of TCGF occurred. Radiolabeled TCGF binding was specific for activated, TCGF-responsive T cells. Whereas unstimulated lymphocytes of human or murine origin and lipopolysaccharide-activated B cell blasts expressed few if any detectable binding sites, lectin- or alloantigen-activated cells had easily detectable binding sites. Moreover, compared with lectin- or alloantigen-activated T cells, long-term TCGF-dependent cytolytic and helper T cell lines and TCGF-dependent neo-plastic T cell lines bound TCGF with a similar affinity (dissociation constant of 5-25 pM) and expressed a similar number of receptor sites per cell (5,000-15,000). In contrast, a number of TCGF-independent cell lines of T cell, B cell, or myeloid origin did not bind detectable quantities of radiolabeled TCGF. Binding of radiolabeled TCGF to TCGF-responsive cells was specific, in that among several growth factors and polypeptide hormones tested, only TCGF competed for binding. Finally, the relative magnitude of T cell proliferation induced by a given concentration of TCGF closely paralleled the fraction of occupied receptor sites. As the extent of T cell clonal expansion depends on TCGF and on the TCGF receptor, the dissection of the molecular events surrounding the interaction of TCGF and its receptor that these studies permit, should provide new insight into the hormonelike regulation of the immune response by this lymphokine.

Animals↗
PubMed1981

[Duodenal ulcer - multicenter double-blind study with proglumide].

In a randomised multicenter double blind study we investigated the healing-rate with proglumid and an antacid drug, studying 70 in- and outpatients with florid duodenal ulcer. We evaluated the size and depth of 59 chronic duodenal ulcers in 52 patients with endoscopic and x-ray-investigations before and after four-week-treatment. Inpatients of the proglumid-group had a significant higher healing-rate than inpatients in the antacid-group (95% against 70%, p less than 0.05). As found in endoscopy the outpatients in the proglumid-group had a higher healing-rate, but because of the smaller number of patients the difference was not significant. Summarized the in- and outpatients, the proglumid-group had a healing-rate of 83%, the antacid-group of 60% (p less than 0.05). Bigger ulcers with a size more than 120 mm2 at the beginning showed a significant better healing with proglumid than with the antacid-drug (t/2 = 14.6 resp. 24.6 days). With x-ray-examination we could not find differences of healing between the two groups, but younger patients often were not examined. The symptoms of patients did not show a significant difference during the healing-course. We could not find any side-effects. Proglumid is an effective drug for the healing of chronic duodenal ulcers.

Adult↗
PubMed1981

MLC-conditioned media stimulate an increase in Fc receptors on human macrophages.

Macrophage Fc receptors (FcR) are essential for antibody-dependent cellular cytotoxicity and for optimal phagocytosis of opsonized particulate antigens. Culture in the presence of conditioned medium from mixed leukocyte cultures (MLC-CM) resulted in a dose- and time-dependent increase (up to 10-fold) in FcR-dependent binding of 125I-labeled IgG1 to promyelocytic HL-60 cells, macrophage-like U-937 cells, and normal cultured human monocytes. FcR increase in HL-60 cells was blocked by cycloheximide (100 microM) and was accompanied by a slight decrease in binding affinity. Since cell volume did not change, the increase in FcR probably represents an increase in the surface density of FcR sites. MLC-CM prepared with or without serum were equally effective in augmenting FcR sites, whereas only serum-containing MLC-CM caused morphologic change of U-937 and HL-60 cells.

Antibody Specificity↗
PubMed1981

Glucocorticoid receptors in adult acute lymphoblastic leukemia.

Glucocorticoid receptors were studied in leukemic cells from 14 newly diagnosed adults with acute lymphoblastic leukemia. Receptors were found in all cases; total receptor levels ranged from 1,348 to 18,697 sites per cel (median, 7,553). To determine the utility of glucocorticoid receptor levels for predicting response to glucocorticoid therapy, lymphoblasts were studied for receptors on nine occasions, and the patients were then treated with dexamethasone as a single agent. Response to glucocorticoid therapy appeared to correlate with lymphoblast receptor level. Five of six patients with greater than 4,500 total receptor sites per cell responded; all three patients with less than 4,500 receptors failed to respond. Glucocorticoid receptor level did not correlate with response to combination chemotherapy, duration of remission, or survival. Glucocorticoid receptors were studied at the initial presentation and following relapse in five patients. In two patients, the receptor level did not change following therapy; both patients at diagnosis had leukemias resistant to glucocorticoids. Three patients at relapse developed leukemias with lower receptor levels; these patients had leukemias sensitive to glucocorticoids at diagnosis. Our data suggest that the glucocorticoid receptor levels of lymphoblasts may be useful in predicting response to glucocorticoid therapy in adult acute lymphoblastic leukemia. They also suggest that, following relapse, cases initially sensitive to glucocorticoid may develop resistance by selection of cells with fewer receptors.

Acute Disease↗
PubMed1981

The effects of glucocorticoid therapy on glucocorticoid receptors in leukemia and lymphoma.

Measurement of glucocorticoid receptors appears to be useful for selecting which patients with leukemia and lymphoma should receive glucocorticoid therapy. To determine the effect of recent or concurrent glucocorticoid therapy on the number of measured tumor glucocorticoid receptor sites, 18 patients with leukemia and lymphoma were studied. Baseline determinations of numbers of glucocorticoid receptors were performed on the malignant cells circulating in the patients' peripheral blood. Glucocorticoid therapy was then instituted consisting of dexamethasone 4 mg p.o. every 6 hr. Repeat determinations of the number of glucocorticoid receptor sites were performed within 24 hr and at various subsequent times from the start of therapy. When compared to baseline receptor numbers, 16 of 18 patients demonstrated a decrease in receptor number (median decrease 1651 sites/cell) after the start of glucocorticoid therapy. The magnitude of the change in receptor number was independent on the initial number of receptors. Our results suggest that in order accurately interpret glucocorticoid receptor numbers in patients with leukemia and lymphoma, glucocorticoid should not be administered for 3 wk prior to determinations of receptor levels.

Adult↗
PubMed1981

Glucocorticoid receptors and in vitro responses to glucocorticoid in acute nonlymphocytic leukemia.

Early clinical studies in which glucocorticoids were used alone in the treatment of acute nonlymphocytic leukemia (ANLL) reported a wide range of responses from remission in some patients to dramatic aggravation of the disease in others. In the hopes of identifying those patients likely to derive therapeutic benefit from glucocorticoids, we have studied glucocorticoid receptors and in vitro responses to glucocorticoids in 36 previously untreated adults with ANLL. The leukemic blasts of all patients contained glucocorticoid receptors (range, 4,300 to 28,400 total receptor sites per cell; median, 8,800). These receptors were similar in all respects studied to those from a variety of other normal and malignant tissues. There was little difference between receptor levels among the various French-American-British categories. In vitro responses to glucocorticoid were observed in leukemic blasts of 26 of 28 cases studied. These responses varied from near complete cell killing to stimulation of proliferation. Since the cells of patients with ANLL have about the same number of receptors as do cells from patients with acute lymphoblastic leukemia and these receptors are capable of mediating physiological responses in vitro, it is unlikely that qualitative or quantitative receptor defects underlie the relative resistance to glucocorticoid therapy of ALL compared to acute lymphoblastic leukemia. However, the broad range of in vitro responses and receptor levels suggests that these studies might be useful in identifying those patients with ANLL likely to derive benefit from steroid therapy.

Acute Disease↗
PubMed1980

Differential solubilization of nuclear glucocorticoid receptors by DNAase I and DNAase II.

This study analyzes the sensitivity of nuclear bound glucocorticoid receptors to solubilization from nuclei by DNAase I and DNAase II. Thymocytes were incubated with 10(-8) M [3H]dexamethasone, [3H]cortisol or [3H]triamcinolone acetonide, without or with 10(-6) M unlabelled dexamethasone, for 30 min at 37 degrees C and nuclei from these cells were digested with either DNAase I and DNAase II. DNAase I for 2 h at 3 degrees C leads to solubilization of 60% of the nuclear DNA and release of 10--20% triamcinolone acetonide-receptor, 30--40% dexamethasone-receptor and 85--90% cortisol-receptor. DNAase II at the same enzymatic concentration solubilizes only 10--20% of the nuclear DNA, but releases 40--50% triamcinolone-receptor, 60--70% dexamethasone-receptor and 100% cortisol-receptor. Release of nuclear bound dexamethasone-receptor by DNAase I parallels the solubilization of DNA, reaching maximum values by 2 h at 3 degrees C, whereas maximal release by DNAase II is obtained within 45 min when DNA solubilization is not complete. When nuclei initially extracted with DNAase I are re-extracted with DNAase II, greater than 65% of the DNAase I residual dexamethasone-receptors are solubilized, whereas DNAase I is ineffective in solubilizing DNAase II residual dexamethasone-receptors. DNAase I solubilizes only 30% of the 0.4 M KCl residual dexamethasone-receptor whereas DNAase II digests over 90% of this fraction. DNAase I extracts of nuclear dexamethasone-receptor chromatograph on G-100 Sephadex as a single radioactive peak just after the void volume, whereas DNAase II extracts of nuclear dexamethasone-receptor chromatograph as two peaks of radioactivity, one which is similar to the DNAase I solubilized receptor and a second broad peak of macromolecular bound radioactivity which is smaller in size.

Animals↗
PubMed1980

In-vitro glucocorticoid studies for predicting response to glucocorticoid therapy in adults with malignant lymphoma.

Neoplastic tissues from 28 adults with malignant lymphoma were examined for glucocorticoid receptors and in-vitro sensitivity to glucocorticoids. The patients were then treated with desamethasone for 5--14 days. 13 patients achieved at least a partial remission, and 15 had no significant tumour response. Lymphoma cells from patients who responded had more glucocorticoid-receptor sites per cell and greater in-vitro sensitivity as measured by glucocorticoid inhibition of incorporation of leucine and uridine than did tumour cells from non-responders. Study of tumour glucocorticoid receptors and glucocorticoid sensitivity in vitro may allow selection of those patients with lymphoma who should receive glucocorticoids as part of combination chemotherapy.

Adolescent↗
PubMed1980

Glucocorticoids and lymphocytes. I. Increased glucocorticoid receptor levels in antigen-stimulated lymphocytes.

Recently a 2- to 3-fold increase in the number of glucocorticoid receptors in human peripheral lymphocytes has been noted after in vitro mitogen stimulation. Here, we extend these observations to in vivo immunization. After unilateral immunization of adrenalectomized male rats, a 50% increase in glucocorticoid receptor sites per cell, determined by binding of dexamethasone, was observed in cell suspensions of homolateral lymph nodes over those from the contralateral nonimmunized side of the same animal. The association constant for dexamethasone was similar in both groups, as was the stereospecificity for various steroids, the time course of cytoplasmic and nuclear association, and cytoplasmic-to-nuclear translocation. Despite a 50% increase in the number of glucocorticoid receptor sites per cell, the cells from the homolateral and controlateral lymph nodes were equally sensitive to the inhibitory effects of dexamethasone, as determined by measurements of the incorporation of radiolabeled precursors of protein, RNA, and DNA, or measurements of in vitro cell survival.

Animals↗
PubMed1980

Glucocorticoids and lymphocytes. II. Cell cycle-dependent changes in glucocorticoid receptor content.

To study variations in glucocorticoid receptor levels during the cell cycle, we have separated mitogen-stimulated human peripheral lymphocytes and rat lymph node cells by unit gravity sedimentation and measured glucocorticoid binding in the resultant fractions. By morphologic criteria and thymidine incorporation, the fractions were separated into populations of G0 and G1 phase and S and post-S phase cells. A 2- to 3-fold increase in glucocorticoid receptor sites per cell, for cells in the S and post-S phase over those in G0 and G1, was observed with both nonstimulated rat lymph node cell suspensions and concanavalin A-stimulated human peripheral lymphocytes. These observations together with those from other studies indicate that formation of new glucocorticoid receptors near the S phase may be a general phenomenon in proliferating cells. We propose that this increase in glucocorticoid receptors during the cell cycle may explain the increase in glucocorticoid receptors in mitogen-stimulated lymphocytes.

Animals↗