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Biomedical subjects

M Ernst

Publications and source records attributed to M Ernst.

At least 271 records · Page 15Linked to original sources
PubMed1981

Measurement of chemiluminescence in freshly drawn human blood. I. Role of granulocytes, platelets, and plasma factors in zymosan-induced chemiluminescence.

The present investigations were undertaken to find out whether chemiluminescence measurements of stimulated granulocytes can be carried out in freshly drawn blood and -- because of the ease of the method -- be introduced into routine diagnostics. Blood was drawn from the cubital vein of healthy volunteers at various times and under various conditions. Subsequently the zymosan induced and luminol amplified chemiluminescence was recorded and analyzed. It could be demonstrated that variations existed between individuals which can, however, be minimized when photon counts obtained under standard conditions were related to the number of granulocytes present in the blood samples. It could be further demonstrated that also platelets are activated by zymosan as well an that they, contribute to the total chemiluminescence by a share of about 5%. Platelet chemiluminescence can effectively be suppressed by aspirin. Opsonising factors in plasma (presumably antibodies and/or complement) play a decisive role in the intensity and kinetics of blood chemiluminescence. Measurements of zymosan induced chemiluminescence in freshly drawn unfractionated and fractionated blood seem to be especially suited to monitor and analyze deviations and defects of the cellular and humoral defence mechanisms.

Aspirin↗
PubMed1981

Regulation of passive potassium transport of normal and transformed 3T3 mouse cell cultures by external calcium concentration and temperature.

Regulation of passive potassium ion transport by the external calcium concentration and temperature was studied on cell cultures of 3T3 mouse cells and their DNA-virus transformed derivatives. Upon lowering of external calcium concentration, passive potassium efflux generally exhibits a sharp increase at about 0.1 mM. The fraction of calcium-regulated potassium efflux is largely independent of temperature in the cases of the transformed cells, but shows a sharp increase for 3T3 cells upon increasing temperature above 32 degrees C. In the same range of temperature, the 3T3 cells exhibit the phenomenon of high-temperature inactivation of the residual potassium efflux at 1 mM external calcium. At comparable cellular growth densities, the transformed cell lines do not show high-temperature inactivation of "residual" potassium efflux. These results are consistent with the notion of a decisive role of the internal K+ concentration in the cell-density dependent regulation of cell proliferation. In particular, the growth-inhibiting effect of lowering the external Ca2+ concentrations is considered as largely due to a rise of passive K+ efflux and a subsequent decrease of internal K+ concentration. The experimental data on the Ca2+ dependence of passive K+ flux are quantitatively described by a theoretical model based on the constant field relations including negative surface charges on the external face of the membrane, which cooperatively bind Ca2+ ions and may concomitantly undergo a lateral redistribution. The present evidence is consistent with acidic phospholipids as representing these negative surface charges.

Animals↗
PubMed1981

Activation of bone marrow-derived macrophages by repeated zymosan phagocytosis leads to enhanced prostaglandin synthesis.

Bone marrow-derived macrophages were stimulated by the addition of zymosan. Phagocytic activity and prostaglandin release were taken as a measure of the activation state of the macrophages. Repeated stimulation with zymosan of macrophages which had been freed from extracellular zymosan led to further phagocytosis and prostaglandin formation. Very low amounts of prostaglandins were synthesized after the second phagocytic stimulus if the time interval between the first and second stimulation was one or two hours. In contrast, however, if the second phagocytic stimulation occurred 9 hours after the first stimulation there was a doubling of the number of phagocytosed zymosan particles and a fifteen fold increase in prostaglandin synthesis. These findings are explained as the consequences of internalized membrane material which provides additional substrates for the generation of prostaglandins.

Animals↗
PubMed1981

Superoxide release by zymosan-stimulated rat Kupffer cells in vitro.

Kupffer cells were isolated from pronase-perfused rat livers and were maintained as a monolayer culture in a state of high purity and viability. Immediately after contact with zymosan particles, O2 uptake of the Kupffer cells increased fivefold; about 50% of the net oxygen consumed was accounted for as superoxide released into the medium. Concomitantly, a transient burst of luminol-dependent chemiluminescence, an increased activity of NAD(P)H oxidase and a stimulation of the flow of glucose through the hexose monophosphate shunt were observed. Chemiluminescence and O2- production were almost completely inhibited by superoxide dismutase and iodoacetate. Zymosan-induced chemiluminescence was not inhibited in the presence of the non-penetrating thiol reagents, 5,5'-dithio-bis-2-nitrobenzoate and iodoacetyl-sepharose. Iodoacetate acted on the cytosolic glucose-6-phosphate dehydrogenase rather than on NAD(P)H oxidase of the cell membrane.

Animals↗
PubMed1980

Thymic nurse cells. Lymphoepithelial cell complexes in murine thymuses: morphological and serological characterization.

We describe a new cellular component of normal mouse thymuses, which is isolated by fractionated trypsin dissociation of minced thymus tissue followed by repeated unit gravity sedimentation. These cells are of unusually large size, with diameters of 30 mum and more. They represent cellular complexes of single large cells filled with high numbers of lymphoid cells. The majority of the engulfed lymphoid cells is not only fully intact, as judged by morphological criteria, but, moreover, includes a high proportion of mitotic figures. Electron microscopic investigations reveal the epithelial character of the large thymic nurse cells (TNC). The peripherally situated cytoplasmic tonofilament streams, and characteristic vacuoles filled with coarse, unidentified material, closely resemble cytoplasmic organelles found in the cortical reticuloepithelial cells described in situ. The internalized lymphocytes are located within caveolae lined by plasma membranes. These TNC caveolae are completely sequestered, and have lost any communication with the extracellular space, as demonstrated by the inability of an electrondense marker, cationized ferritin, to diffuse into the perilymphocytic clefts. The structural interactions between the membranes of the engulfed thymocytes with the surrounding TNC caveolar membranes were investigated both in ultrathin sections and in freeze-etch preparates. Two distinct contact types between both membranes were discerned: (a) complete, close contact along the entire lymphocyte circumference, and (b) more frequently, contact restricted to discrete, localized areas. Judging from their size and distribution, the localized contacts could correspond particle aggregates of freeze-etch preparates, which morphologically resemble certain stages of gap junction. Furthermore, we regularly found square arrays of particles of uniform size, which so far have been thought to be typical for cell membranes actively engaged in ion exchange. Tight junction-like particle arrays, which were present on TNC outer membranes, and probably represented disrupted contacts between adjacent TNC in the intact tissue, could not be found on caveolar or lymphocyte membranes. Finally, one of the most conspicuous specializations of the TNC caveolar membrane were membrane invaginations, which were arranged mainly in groups, and which probably reflect endo- or exocytotoxic events. We investigated the surface antigen phenotype of TNC by indirect immunofluorescence, with monoclonal antibodies against determinants of H-2- complex subregions as well as against lymphocyte differentiation markers. Semiquantification was reached with flow cytofluorimetry, followed by morphological control by fluorescence microscopy. The surface antigen formula of TNC is: Ig(-), Thy-l(-), H-2K(++), I-A (++), I-E/C(+), H-D(++), Ly-1(-), Ly-2(-), Qat-4(-), Qat-5(-), and peanut agglutinin (PNA)(-). Thymic macrophages, which were identified by double fluorescence, with rhodamine- coupled zymosan as a phagocytosis marker, were serologically identical with TNC. Free thymocytes, in contrast, had the following antigen formula: Ig(-), Thy-1(++), H-2K(+/-), I-A(-), I-E/C(-), H-2D(+/-), Ly-1(+/-), Ly-2(+), Qat- 4(-), Qat-5(-), and PNA(+). The unprecedented finding of high numbers of dividing thymocytes sojourning within thymic epithelial cells, and the particular specializations of the TNC caveolar membranes surrounding these engulfed thymocytes is the basis of a hypothesis that postulates that an intraepithelial differentiation cycle is one essential step in, intrathymic T lymphocyte generation.

Animals↗
PubMed1980

Does PGE1 induce modifications at the membrane level of bone marrow macrophages? A fluorescence study.

The effect of prostaglandin E1 (PGE1), and F2 alpha (PGF2 alpha) on the surface membrane configuration of bone marrow macrophages was studied. We measured the fluorescence intensity of membrane bound ANS in prostaglandin pretreated cells. The effect on fluorescence intensity of a blocker of the prostaglandin binding site (SC19220) and inhibitors of prostaglandin synthesis (aspirin, indomethacin, diclophenate, Eicosa 5,8,11,14 tetraynoic acid) also were studied. Enhancement of the fluorescence intensity of bound ANS in cells pretreated with PGE1 indicates a conformational change localized at the membrane surface. That those changes are confined to the cell surface was shown by the failure of PGE1 or PGF2 alpha to alter the fluorescence polarization of bound DPH used as indicator of membrane core viscosity. Our data indicate that PGE1 could act at the surface of the membrane and that its action causes rapid structural perturbation at strategic points in the molecular organization of the membrane of bone marrow macrophages.

Anilino Naphthalenesulfonates↗
PubMed1980

Biochemical Characterization of an Acetylcholine-hydrolyzing Enzyme from Bean Seedlings.

An acetylcholine hydrolyzing enzyme was prepared and purified (40 times) from dwarf bean hypocotyl hooks. The purity of the enzyme was proved by polyacrylamide gel electrophoresis. The molecular weight of the enzyme was determined to be 65,000 daltons. Enzyme activity was the highest at pH 8.0 and between 30 and 36 C. The enzyme had an apparent affinity constant (K(m)) for acetylcholine of 460/micromolar. The affinity for substrate analogs increased from butyrylthiocholine to propionylthiocholine to acetylthiocholine. The enzyme activity was inhibited by choline, neostigmine, physostigmine, manganese, and calcium. Magnesium had no influence on the enzyme activity. We conclude that the enzyme from dwarf beans is an acetylcholinesterase (EC 3.1.1.7).

Journal Article↗
PubMed1980

Chemiluminescence and immune cell activation: general features of the thymocyte chemiluminescent responses to plant lectins.

Rat thymocytes respond to exposure to plant lectins by a burst of oxidant generation as detected by chemiluminescence (CL) (CL) in presence of luminol. All lectins tested were capable of evoking CL as long as sufficiently high concentration was used. There was no correlation between the capacity of a given lectin to evoke CL on one hand and its ability to cause mitogenic transformation or thymocyte agglutination on the other. During the first few minutes following exposure to Con A, cells in the thymocyte pool become committed to CL but once commitment is induced, removal of cell bound ligand by addition of excess methyl-alpha-D-mannoside does not significantly alter the response. Succinylated Con A is as effective as native Con A at lower concentrations but is much more effective at higher concentrations in evoking CL. Thymocyte CL can occur in absence of extracellular calcium but this calcium-independent CL is reduced by the addition of magnesium. In presence of calcium, CL response is greatly augmented and the calcium dependent response is not inhibited in presence of magnesium. The response is relatively radiosensitive. Thymocyte CL response is inhibitable by catalase and scavengers of oxidative radicals but is relatively resistant to the effects of superoxide dismutase, requiring high concentrations of significant effect.

Animals↗
PubMed1979

Dependence of intracellular alkali-ion concentrations of 3T3 and SV 40-3T3 cells on growth density.

Intracellular contents of potassium and of sodium are determined for 3T3 and SV 40-3T3 cells in dependence of growth density. In parallel, total cell volume and volume of intracellular water is determined for these cells suspended in physiological buffer. Intracellular potassium concentration thus evaluated for suspended 3T3 cells exhibits a sharp decrease at cellular growth densities which lead to density dependent inhibition of cell proliferation. In the case of SV 40-3T3 cells, this drop of potassium concentration with increasing cellular growth density is not observed, which correlates well with the absence of cell density dependent inhibition of cell growth in the transformed cell line. These results support the notion that processes of stimulation of quiescent 3T3 cells or of cell density dependent inhibition of their proliferation are mediated by processes including changes of potassium transport characteristics leading to increase or decrease respectively of their intracellular potassium concentration. Furthermore, these and other results suggest, that a difference between normal and transformed cells most relevant to their different proliferation behaviour might reside in different transport characteristics for potassium of the plasma membranes of these cells.

Animals↗
PubMedDate not supplied

Activation of human monocytes by interleukin 2: role of T lymphocytes.

The effect of interleukin 2 (IL2) on the capability of human monocytes to secrete reactive oxygen species triggered via Fc-gamma receptor (Fc-gamma R) function had been investigated by measurement of chemiluminescence (CL). IL 2 did not activate highly purified (hp) monocytes to respond to Fc-gamma R mediated phagocytic stimulation with an enhanced respiratory burst activity unless low numbers of T cells had been co-cultured with hp monocytes. Supernatants from IL 2 treated PBMC contained interferon-gamma (IFN-gamma) and monocyte activating factor (MAF) activity. The secretion of both cytokine activities was strongly enhanced by cooperative function of monocytes. The correlation of IL 2 induced secretion of IFN-gamma and MAF activity was striking, however, monoclonal antibody (mAb) anti-human IFN-gamma failed to abrogate IL 2 stimulated and lymphocyte dependent monocyte activation. Although IL 2 had no direct monocyte activating effect, pretreatment of hp monocytes with IL 2 led to monocyte priming: subsequent co-culture with autologous control T cells enhanced the monocyte Fc-gamma R mediated CL response. The priming of monocytes by IL 2 was dependent on the interaction of IL 2 with the monocytic IL 2 receptor as shown by inhibition experiments with anti IL 2 R monoclonal antibody. Thus the IL 2 driven monocyte/T-cell interaction leads to an increased Fc-gamma R mediated monocytic respiratory burst activity and to the secretion of a soluble MAF activity, but there were no detectable amounts of IFN-gamma.

Antibodies, Monoclonal↗
PubMedDate not supplied

Development of a graphic psychiatric self-rating scale.

This report describes the development of a clinical instrument that is intended to assess general inpatient psychopathology among patients who cannot communicate directly with the clinician, either due to a language barrier or other problems with verbal communication. Reliability and validity of the instrument indicate that it can serve a useful purpose as a self-rating scale that obviates the need for extensive verbal communication. The scale also appears to be sensitive to changes in symptom intensity over time.

Adolescent↗
PubMedDate not supplied

Cardiopulmonary responses to HCl infusion are mediated by thromboxane A2 but not by serotonin.

Intravenous infusion of HCl has been shown to elicit the release of thromboxane A2 (TxA2) which alters blood pressure and breathing independent of reductions in circulating blood pH. The present experiments were designed to determine if the release of serotonin (5-HT) in the anesthetized cat contributed to cardiorespiratory responses during acid infusion and, furthermore to define the source of TxA2, viz. blood or other tissues. To infuse HCl into the bloodstream without reducing circulating blood pH (= neutral acid-base infusion), an extracorporeal arteriovenous shunt (20 ml/min) between the femoral artery and femoral vein was installed. Into this loop, acid (0.25 M HCl), and approximately 10 cm downstream, base (0.25 M NaOH) could be infused whereby blood pH could be locally reduced in the blood within the loop. This procedure was performed in three groups of cats: one group which received no drugs, a second group that was pretreated with indomethacin (2.5 mg/kg) and a third group that received the 5-HT2 receptor antagonist, ketanserin (0.75 mg/kg), prior to the infusion. During neutral acid-base infusion in the nontreated animals, right ventricular blood pressure (PRV) increased and systemic arterial blood pressure (Pa) decreased. Respiratory frequency was increased, but total ventilation was not elevated because of a concomitant fall in tidal volume (VT). The response was transient and could not be evoked with repetitive infusions of HCl and NaOH. These responses were significantly attenuated in the indomethacin-treated animals, but persisted in the cats pretreated with ketanserin. In addition, TxB2, the stable degradation metabolite of TxA2, was elevated during the acid/base infusion, but there were no measurable changes in plasma 5-HT concentration. The source of TxA2 was likely to be the blood since TxB2 was increased in plasma when acid and base were added to blood in vitro. We conclude from these experiments that transient cardiorespiratory responses to HCl infusion are mediated by the release of TxA2 from the blood and do not involve serotonin.

Animals↗