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Biomedical subjects

D G Payan

Publications and source records attributed to D G Payan.

119 records · Page 7Linked to original sources
PubMed1984

A basophil-activating factor from human T lymphocytes.

Human T lymphocytes stimulated with phytohaemagglutinin (PHA) or streptokinase-streptodornase (SK-SD) generate an activity which elicits non-cytotoxic histamine release from human basophils. Filtration of the T lymphocyte-derived activity on columns of Sephadex G-100 and Fractogel 55F sequentially revealed one predominant basophil-activating factor of mol. wt. 70,000-90,000, that was designated BAF-T. BAF-T was composed of two acidic proteins of approximate pI 4.4 and 5.2-5.5, as assessed by isoelectric focusing. The distinction of BAF-T from IgE was confirmed by the failure of BAF-T to bind to an anti-IgE affinity column and the capacity of BAF-T to release histamine maximally from basophils desensitized to IgE-dependent stimuli. The inability of BAF-T to release histamine from human lung mast cells and dog cutaneous mastocytoma cells suggests target cell specificity. The source and activity of BAF-T are consistent with a specific contribution of this mediator to human cellular immune and hypersensitivity responses involving T lymphocytes and basophils.

Basophils↗
PubMed1984

Inhibition by somatostatin of the release of mediators from human basophils and rat leukemic basophils.

The release of mediators from unpurified human basophils challenged with anti-human myeloma IgE serum was suppressed significantly by somatostatin at respective concentrations of 3 x 10(-13) M to 10(-9) M for histamine and 10(-13) M to 10(-11) M for leukotriene D4, which had no effect on release elicited by ionophore A23187. A direct effect of picomole-nanomole concentrations of somatostatin on basophils predominated, as shown by the significant inhibition of immunologically stimulated mediator release from monocyte-free human basophils of 15 to 32% purity and from rat basophil leukemia cells. The dependence of basophil inhibition on the conformation of somatostatin was suggested by the lower potency of reduced and alkylated somatostatin and the lack of inhibitory activity of [D-Trp8] somatostatin. Somatostatin thus may mediate suppressive effects of sensory nerves in some basophil-dependent hypersensitivity reactions.

Animals↗
PubMed1984

Generation of a unique fibroblast-activating factor by human monocytes.

Purified human monocytes incubated with phytohemagglutinin (PHA), bacterial lipopolysaccharide (LPS), or serum-opsonized zymosan particles (OZ) generate human dermal fibroblast-activating activity, as assessed by increased fibroblast incorporation of [3H]-thymidine. A maximum concentration of fibroblast-activating activity was attained within 4 hr with OZ, whereas similar maximum levels required 12 hr with LPS and PHA. Sonicates of unstimulated monocytes had only minimal activity and the protein synthesis inhibitor cycloheximide suppressed significantly the appearance of fibroblast-activating activity, suggesting that the factors are generated prior to release. Filtration of supernates from OZ-stimulated monocytes on Sephadex G-75 yielded polydisperse fibroblast-activating activities, of which the major factors exhibited a mol. wt. of approximately 60,000 and 10,000. The supernates from PHA-stimulated monocytes had one predominant factor, termed fibroblast-activating factor of monocytes (FAF-M), with an apparent mol. wt. of 38,000 and a minor activity with a mol. wt. of 10,000. FAF-M was composed of two principles with isoelectric points of 5.1-5.2 and 4.0-4.2 and was free of interleukin-1, as determined by the absence of thymocyte-activating activity. FAF-M and other fibroblast-activating factors may contribute to wound healing and fibrosis in lesions characterized by mononuclear phagocyte infiltrates.

Adult↗
PubMed1983

Specific stimulation of human T lymphocytes by substance P.

Substance P (SP) and SP(4-11) stimulated significantly the proliferation of human T lymphocytes in vitro at respective concentrations of 10(-11) M to 10(-7) M and 10(-9) M to 10(-7) M, as assessed by the uptake of [3H]thymidine and [3H]leucine. The proliferative response of human T lymphocytes to PHA was augmented by 10(-9) M to 10(-8) M SP and 10(-10) M to 10(-7) M SP(4-11). The inactive analogue [D-Pro2, D-Phe7, D-Trp9]-SP inhibited the effects of SP on T lymphocytes. The specific stimulation of T lymphocytes by SP suggests a unique mechanism for the regulation of immunologic responses by peripheral nerve-derived factors.

Blood Proteins↗
PubMed1982

Modulation of human lymphocyte function by C3a and C3a(70-77).

Human C3a and the synthetic octapeptide C3a (70-77), which retains the activities of an anaphylatoxin, inhibit in a concentration-dependent manner the generation of leukocyte inhibitory factor (LIF) activity by human mononuclear leukocytes and T lymphocytes cultured with the mitogens phytohemagglutinin (PHA) or concanavalin A (Con A) or the antigen streptokinase-streptodornase (SK-SD). The generation of LIF activity was inhibited by 50% by 10(-8) M C3a or C3a(70-77) with PHA or Con A as the stimulus, whereas a more than 10-fold higher concentration of C3a(70-77) than C3a was required to achieve the same level of suppression with SK-SD as the stimulus. Similar concentrations of C3a(70-77) inhibited to the same extent the migration of T lymphocytes stimulated by alpha-thioglycerol of Con A. Neither C3a nor C3a(70-77) altered significantly the uptake of [3H]thymidine by human mononuclear cells exposed to PHA, Con A, or SK-SD. The capacity of C3a(70-77)-Sepharose,m but not Sepharose alone, to adsorb or inactivate mononuclear leukocytes required for the generation of LIF activity established a direct interaction. Analysis of the lymphocytes in the effluent from C3a(70-77)-Sepharose columns, using monoclonal antibodies to surface antigens, showed a selective depletion of the helper/inducer population of lymphocytes. C3a might represent an important mediator of the functionally selective regulation of human T lymphocyte activities by the complement system.

Cell Division↗
PubMed1981

Infection of a brain abscess of Mycoplasma hominis.

Persistent fever in a young man after evacuation of a subdural hematoma caused by a depressed skull fracture made it necessary to carry out a computerized tomographic exam of the head that demonstrated a left frontal lobe brain abscess. Mycoplasma hominis was recovered from this abscess as the sole infecting organism. Serial computerized tomographic scans showed resolution after aspiration and antibiotic therapy.

Adult↗
PubMed1975

The antagonistic effect of an inhalation anesthetic and high pressure on the phase diagram of mixed dipalmitoyl-dimyristoylphosphatidylcholine bilayers.

Several workers have shown that phase transition-related changes in membrane lipids have a profound effect on membrane-solvated protein function. This phase transition temperature dependence has been explained as resulting from the formation of lateral phase separations within the membrane bilayer. The present study demonstrates that a clinical concentration of an inhalation anesthetic produces changes in both the phase transition temperature of pure lipid bilayers and the lateral phase separation temperature of mixed dipalmitoyl- and dimyristoylphosphatidylcholine bilayers of a magnitude sufficient to influence protein function. It is further shown that pressure is able to antagonize the effect of the anesthetic on these transition temperatures. It is proposed that anesthetic action within nerve membranes may be the result of changes in the lateral phase separation-controlled environment of the membrane-solvated proteins essential to nerve function.

Anesthesia, Inhalation↗
PubMedDate not supplied

Stimulation of transcriptional regulatory activity by substance P.

The neuropeptide substance P (SP) is one of the principal mediators of neurogenic inflammation as well as a neurotransmitter in nociceptive affect neurons. The mechanisms by which binding of SP to its receptor stimulates diverse downstream biologic effects remain unknown. In order to elucidate this process we have established stably transfected cell lines expressing functional rat SP receptors (KNRK-SPR). When stimulated by SP, KNRK-SPR cells respond by simultaneously mobilizing intracellular Ca2+ and increasing cAMP levels. To determine if SP stimulation activates downstream transcriptional regulatory factors, we transfected KNRK-SPR cells with plasmids containing the activator protein 1 (AP-1) and cAMP-responsive (CRE) enhancer elements coupled to the chloramphenicol acetyltransferase (CAT) reporter gene. Stimulation with SP 1-1,000 nM caused a 1.5- to 2-fold increase in CAT activity in both AP-1-CAT- and CRE-CAT-transfected KNRK-SPR cells. Northern and Western blot analyses demonstrate that the mechanism by which SP stimulates AP-1 enhancer activity involves increases in both c-jun mRNA and protein. Moreover, gel retardation assays with oligomers containing the AP-1 and CRE binding sites showed that SP induces specific retardation bands consistent with increases in AP-1 and CRE complexes. These experiments suggest that SP-mediated stimulation of cells involves the participation of two signaling pathways resulting in several transcriptional regulatory mechanisms being activated.

Animals↗