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Biomedical subjects

S Hering

Publications and source records attributed to S Hering.

At least 91 records · Page 5Linked to original sources
PubMed1988

[Free fatty acids in the serum in critical diseases: do they play a role in the protein binding of thyroid hormones?].

As a contribution to the question if the elevated concentrations of free fatty acids in sera of critically ill patients described in literature play a role in the decrease of thyroid hormone levels in these patients, serum levels of the important free fatty acids were measured in 31 patients of our intensive care unit in the course of their disease using gas chromatography. After admission to the ward, only palmitoleic acid was significantly increased compared with 174 control persons, arachidonic acid was not different from the controls, palmitic, stearic, linoleic and linolenic acid were significantly decreased. In the course of the disease, no relevant changes were observed. The 21 patients not surviving their disease showed significantly lowered levels of palmitic, stearic and linoleic acid before death compared with the surviving patients at the end of the observation period. The hypothetical role of single free fatty acids as inhibitors of the binding of thyroid hormones to their transport proteins must be questioned because of the results.

Adolescent↗
PubMed1988

Action of nifedipine or BAY K8644 is dependent on calcium channel state in single smooth muscle cells from rabbit ear artery.

The actions of nifedipine or BAY K 8644 were studied on barium currents recorded from single, collagenase- and elastase-dispersed, smooth muscle cells from the rabbit ear artery using the whole-cell configuration of the patch-clamp technique. Nifedipine (3 microM) caused a reduction in the barium current (IBa) evoked by steps to potentials positive of -10 mV. This was characterized by a pronounced 'initial' block, an increase in the rate of current decay during the voltage-clamp step, but by no increase in block if pulses were repeated every 600 ms. Rapid extracellular application of nifedipine (1 microM) during the sustained current component (using a new concentration-jump technique) was found to have no effect on IBa over 4s at +20 mV, but after returning to the holding potential (-60 mV) for 10s, sustained IBa was subsequently abolished. BAY K 8644 (1 microM) increased IBa at all potentials, and on rapid application during the sustained current component markedly potentiated IBa. The results suggest that nifedipine binds with high affinity to the closed, available state of the Ca++ channels but they do not suggest binding to the open or inactivated states. The effect of BAY K 8644 is consistent with high affinity binding to the open or inactivated and to the closed, available states.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1988

[Calcium current effects in the presence and absence of propranolol on cloned neuroblastoma and glioma hybrid cells].

The action of the (-)- and (+)-enantiomers of the beta-adrenoceptor blocking drug propranolol on the inward calcium current (ICa) was studied in single mouse neuroblastoma x rat glioma hybrid cells of clone 108CC5 by suction pipette technique for intracellular perfusion and voltage clamp. ICa was recorded after internal cell perfusion with Tris phosphate buffer and suppression of sodium and potassium currents in Na+-free external solution. Extracellularly applied (-)- and (+)-propranolol (10(-7) to 10(-3) M) inhibited ICa in a similar dose-dependent manner. The IC50 values for both substances were approximately 5 . 10(-6) to 10(-5) M. Two other beta-blockers, alprenolol and talinolol, investigated as reference compounds, also depressed the ICa, but in a significantly higher dose-range of 10(-4) to 10(-3) M. The results provide further evidence that propranolol, besides its known effect on sodium inward current, also possesses marked inhibitory actions on the ICa in mammalian nerve cell membranes at relatively low concentrations.

Alprenolol↗
PubMed1988

Raji-K562 hybrids and their use for trioma production.

Cells from the B lymphoblastoid cell line Raji (Burkitt lymphoma) and from the myeloid-erythroid cell line K562 (subline AB5), stained by two different fluorochromes, were fused in vitro by means of PEG. Hybrid cells exhibiting heterofluorescence were isolated in a cell sorter (FACS III). They were cloned and analyzed for both Raji and K562 derived antigens. Hybrid cells retained the excellent growth behaviour of AB5 cells while expressing also Raji antigens. One of the hybrids (BD7) was used for trioma production when fused with human stimulated spleen cells. Trioma cells representing a fusion product of three parental cells may be useful for studying problems of gene regulation and expression.

Antibodies, Monoclonal↗
PubMed1987

A simple method of fast extracellular solution exchange for the study of whole-cell or single channel currents using patch-clamp technique.

A new concentration-jump technique was devised for the rapid application of drugs to single, isolated cells attached to the base of the experimental chamber while recording from them with patch-clamp technique. Cells were placed in a micro-drop (less than 0.1 microliter) in a small inner bath which was separated from an outer bath by a ring of "Sylgard" polymer. Stable whole-cell recordings were made in the micro-drop and rapid solution exchange took place when a much larger volume of test solution from the outer bath was flooded over the Sylgard ring and mixed with the micro-drop. Complete equilibration occurred within less than 10 ms.

Adenosine Triphosphate↗
PubMed1987

Cell-attached patch clamp measurement of macroscopic rapid inward sodium current in cultured heart cell reaggregates.

A megaohm seal, cell-attached patch clamp technique utilizing plastic suction pipettes for measuring macroscopic rapid inward sodium current (INa) was applied to cell membrane patches 30 to 100 micron2 in area at the periphery of reaggregates of myocardial cells from newborn rats cultured for 3 to 7 days. The reaggregates were composed of about 20 to several thousand of electrically well-coupled cells, the latter forming spheroidal reaggregates with a diameter of maximally 300 microns. This system was shown to guarantee satisfactory voltage-clamp control during ionic current measurements. The time and voltage dependence of the INa recorded during periods of up to 90 min was similar to that observed in single cardiac cell preparations from adult rats. INa inactivation was described by two time constants (tau h1, and tau h2). For maximal INa tau h1 and tau h2 had values of 1.5 +/- 0.25 ms and 8.7 +/- 3.9 ms (n = 4), respectively. The time course for recovery of INa from inactivation at the reaggregate resting potential exhibited also two time constants (tau re1 = 9.8 +/- 3 ms, tau re2 = 193 +/- 50 ms, n = 5). Estimated current density was about 10 pA/micron2. The concentration of tetrodotoxin needed to reduce maximal INa by 75% was 85 times lower in the reaggregates than it was in freshly isolated heart muscle cells from adult rats. The present system offers a combination of features that should make it well-suited for the study of both short- and long-term effects on the sodium channels in neonatal heart cells: Easy handling of the object, great electric stability, high time and amplitude resolution during ionic current measurements, and viability for at least one week.

Animals↗
PubMed1987

Voltage dependence of the actions of nifedipine and BAY K 8644 on barium currents recorded from single smooth muscle cells from the rabbit ear artery.

The voltage dependence of the actions of nifedipine and BAY K 8644 were studied on whole-cell barium currents recorded from single, collagenase- and elastase- dispersed, smooth muscle cells from the rabbit ear artery using standard patch clamp techniques (Hamill et al., 1981). The results showed that nifedipine (3 x 10(-7)M) reduced the inward current in response to depolarizations positive of -10mV but in the threshold range, -40mV to -20mV, that it increased the amplitude of the peak barium current. Subsequent application of BAY K 8644 (1.5 x 10(-7)M) enhanced this latter effect but decreased the inhibition induced by nifedipine at more positive potentials.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1986

A patch clamp study of the action of ethacyzine on the rapid inward sodium current in single rat heart muscle cells.

The effect of ethacyzine (a diethylamine analogue of ethmozine) on the rapid inward sodium current (INa) was studied in single rat ventricular muscle cells by a patch clamp technique. Extracellular application of 3 microM ethacyzine depressed the INa in a use-dependent fashion. Rest recovery from the use-dependent block by ethacyzine followed an exponential time course with a time constant of about 215 +/- 40 s (n = 4, mean +/- S.E.).

Animals↗
PubMed1986

[Frequency-dependent blockade of sodium channels in isolated rat myocardial cells by the anti-arrhythmia agent ethmozine].

A patch-clamp method was used to study the effects of the phenotiazine antiarrhythmic drug ethmozine (E) on the fast sodium inward current (INa) in freshly isolated heart muscle cells of adult rats. At a concentration of 10(-5) M E caused INa inhibition that could be enhanced by increasing the frequency of depolarization. This inhibition was reversible. After the termination of repetitive depolarization the amplitude of INa recovered with a time constant of about 10 sec. These findings may help to explain the therapeutic efficiency of E in high frequency cardiac rhythm disturbances.

Animals↗
PubMed1986

Differences of K562 leukemia cell clones in the pattern of monoclonal antibody binding and NK cell susceptibility.

Fifty-three K562-clones were tested against three monoclonal anti-K562-antibodies (MoAbs). The individual NK-cell sensitivity of thirty-one K562-clones was evaluated simultaneously. It was found that considerable differences exist in the antibody binding between single clones and the parental cell line indicating antigenic heterogeneity in the K562 line. Some K562-clones showed increased NK-cell sensitivity in comparison with the uncloned cell line. However, no correlation was observed between both investigated parameters.

Antibodies, Monoclonal↗
PubMed1985

Sodium and calcium currents in neuroblastoma x glioma hybrid cells before and after morphological differentiation by dibutyryl cyclic AMP.

Sodium and calcium inward currents (INa and ICa) were measured in neuroblastoma X glioma hybrid cells of clones 108CC5 and 108CC15 by a single suction pipette method for internal perfusion and voltage clamp. Morphologically undifferentiated, exponentially growing cells were compared with cells differentiated by cultivation with 1 mmol/l dibutyryl cyclic AMP. Outward currents were eliminated by perfusing the cells with a K+-free solution. Voltage dependence and ion selectivity as well as steady state inactivation characteristics of INa and ICa resembled those of differentiated mouse neuroblastoma cells, clone N1E-115 (Moolenaar and Spector 1978, 1979). These parameters were identical in undifferentiated and differentiated cells of both clones. After differentiation the average density of the peak sodium and calcium currents was increased two and four-fold, respectively, in both cell lines. Our data indicate that exponentially growing, morphologically undifferentiated 108CC5 and 108CC15 neuroblastoma X glioma hybrid cells possess functional Na+ and Ca2+ channels undistinguishable from those of non-proliferating cells of these clones differentiated morphologically by treatment with dibutyryl cyclic AMP. That Na+ and Ca2+ spikes were not detected by other authors in these cells prior to morphological differentiation by dibutyryl cyclic AMP may be attributed to the fact that at the low resting membrane potential measured the Na+ and Ca2+ channels are inactivated.

Animals↗
PubMed1985

A kinetic analysis of the inward calcium current in 108CC15 neuroblastoma x glioma hybrid cells.

The kinetics of activation and inactivation of the inward calcium current (ICa) in morphologically undifferentiated and differentiated neuroblastoma X glioma hybrid cells of the clone 108CC15 were studied by the suction pipette technique for internal perfusion and voltage clamping. Potassium currents were eliminated by internal perfusion of the cells with a K+-free solution. Activation of ICa followed a sigmoidal time course and could reasonably be fitted by a m2 relation. The kinetics of ICa inactivation were studied by analyzing the current inactivation during long depolarizing steps and by measuring the peak ICa as a function of the length of a prepulse. Both methods gave comparable results indicating that the ICa inactivation cannot be fitted by a single exponential. The ICa inactivation was fitted by a biexponential function. Neither the activation nor the inactivation of ICa were changed after morphological cell differentiation induced by treatment with dibutyryl cyclic AMP.

Animals↗
PubMed1985

Trapidil and other 5-triazolo-(1, 5-alpha)-pyrimidine derivatives as calcium channel blockers in 108CC5 cells.

The action of trapidil (RocornalR) and its derivatives AR 12-456 and AR 12-160 on the inward calcium current (ICa) was studied in mouse neuroblastoma x rat glioma hybrid cells of the line 108CC5 under voltage clamp conditions by means of a suction pipette method. A dissociation constant of the calcium channel-trapidil complex of 277 microM was estimated for the initial inhibition of ICa by trapidil. Half maximal block of ICa was produced by 80 +/- 20 microM AR 12-456 and 500 +/- 150 microM AR 12-160.

Animals↗
PubMed1985

Calcium channel block by phenytoin in neuroblastoma x glioma hybrid cells.

The action of phenytoin on the inward calcium current (ICa) was studied in cells of the clonal mouse neuroblastoma X rat glioma hybrid line 108CC5 by the suction pipette technique for internal perfusion and voltage clamp. The ICa was recorded after suppression of Na+ and K+ currents. Phenytoin, applied externally in concentrations of 50 to 500 microM, depressed the ICa in the investigated potential range of -60 to +30 mV in a concentration-dependent manner. When the cells were stimulated by depolarizing clamp steps, the extent of the ICa depression increased with the frequency and duration of the activating pulses. ICa was also inhibited on intracellular application of phenytoin.

Action Potentials↗
PubMed1985

Monoclonal antibodies against the human leukemia cell line K 562.

Three monoclonal antibodies raised against K 562, a cell line originally established from a patient with chronic myeloid leukemia (CML) in terminal blast crisis, were selected according to their distinct reaction pattern. Whereas two antibodies (ZIK-C1-A/C5 and ZIK-C1-A/H5 also designated C and H) recognized antigens, present on K 562 cells and other immature and mature hematopoietic cells (cell lines and normal blood and bone marrow cells), antibody ZIK-C1-A/D9 also designated Y showed an exclusive binding to K 562 cells. The results obtained (here and in the following paper) indicate, that antibody ZIK-C1-A/D9 defines an early differentiation antigen of hematopoiesis or a leukemia-associated antigen.

Antibodies, Monoclonal↗
PubMed1985

Reactivity of monoclonal anti-K 562 antibodies with cells of leukemia- and lymphoma-patients.

For further characterization, monoclonal anti-K 562 antibodies (1) were tested against blood or bone marrow cell samples of patients with various leukemias and lymphomas. One antibody, ZIK-C1-A/D9 (also designated Y) reactive in previous tests exclusively with K 562 cells, but not with normal blood cells, exhibited a selective binding to cells of most AML-patients and CML-patients in myeloid blast crisis. Cells of patients with other hematopoietic malignancies were negative, except three single cases (one lymphosarcoma, one AUL and one hairy cell leukemia). Antibody ZIK-C1-B/H5 (short name H) detected an antigenic determinant, preferentially expressed on cells of AML and CML patients, but also on normal granulocytes and some mononuclear cells. Two additional monoclonal anti-K 562 antibodies, ZIK-C1-A/F5 (short name C) and 2B7, yielded specificities shared by a variety of normal and malignant hematopoietic cells.

Antibodies, Monoclonal↗