Search PubMed⌕ Search

Biomedical subjects

K Hartung

Publications and source records attributed to K Hartung.

At least 91 records · Page 5Linked to original sources
PubMed1989

[The appearance of subchondral cystoid defects in the joints of the distal extremities of the horse].

Subchondral bone cysts or cyst like lesions are an important hint in the radiographic diagnosis of degenerative joint disease. In this study we set artificial lesions of different size in the subchondral bone of different joint surfaces of horses, and we then tried to determine from which size on these lesions could be made visible on radiographs in different projections. It shows that the possibility of visualization of such lesions is frequently overestimated, cyst like lesions have to be quite large, before they can be seen on routine radiographs.

Animals↗
PubMed1989

MX homologous protein in mononuclear cells from patients with systemic lupus erythematosus.

The 76-kd human interferon (IFN)-induced MX protein is the homolog to the murine protein, which is necessary and sufficient to provide adequate resistance to influenza virus infection in murine cells and in mice. Fifty-one patients with systemic lupus erythematosus (SLE) were screened for the presence of the MX homolog in mononuclear cells and for IFN and anti-IFN antibodies in serum. In 47 of 51 patients, significant levels of the MX homolog were found, while only 15 of 51 patients had measurable alpha-IFN in their serum. The IFN activity found in these sera was characterized as a partially acid-labile alpha-IFN, by means of acid-stability cross-reactivity on heterologous cells, trypsin sensitivity, and neutralization by homologous or heterologous antisera. Four of the patients had no detectable MX homolog in their leukocytes; 3 of these 4 possessed an anti-alpha-IFN antibody that was able to neutralize both a natural alpha-IFN preparation and the acid-labile IFN in SLE sera. Also, acid-labile alpha-IFN-containing SLE sera induced the MX homolog in vitro in mononuclear cells from healthy donors. These observations suggest that endogenously produced alpha-IFN is responsible for the observed induction of the MX homolog in SLE and that the IFN system is activated in more than 90% of SLE patients.

Antibodies↗
PubMed1988

[Severe chronic Epstein-Barr virus infection with natural killer cell defect].

Chronic Epstein-Barr virus infection was confirmed serologically in a 27-year-old man with pneumonia, splenomegaly, pancytopenia, arthritis, neuropathy and psychological changes. Immunological tests revealed a defect in the cytotoxic activity of the natural killer cells. Treatment with high doses of acyclovir intravenously and of antimycotic drugs dramatically and lastingly improved the patient's condition.

Acyclovir↗
PubMed1988

Identification of synaptophysin as a hexameric channel protein of the synaptic vesicle membrane.

The quaternary structure and functional properties of synaptophysin, a major integral membrane protein of small presynaptic vesicles, were investigated. Cross-linking and sedimentation studies indicate that synaptophysin is a hexameric homo-oligomer, which in electron micrographs exhibits structural features common to channel-forming proteins. On reconstitution into planar lipid bilayers, purified synaptophysin displays voltage-sensitive channel activity with an average conductance of about 150 picosiemens. Because specific channels and fusion pores have been implicated in vesicular uptake and release of secretory compounds, synaptophysin may have a role in these processes.

Animals↗
PubMed1988

Presence of interferon and anti-interferon in patients with systemic lupus erythematosus.

Sera from 61 patients with systemic lupus erythematosus (SLE) were serially screened over a period of at least 2 years for IFN and anti-IFN antibodies. IFN concentrations were measured both with a cytopathic effect assay and a more sensitive radioimmunoassay. Of the patients 15% (9/61) had IFN in their serum at one or more occasions as measured in the bioassay (greater than or equal to 6 IU/ml); employing a RIA (greater than or equal to 1 IU/ml) 28% (17/61) of the patients studied were positive for IFN-alpha. Fifteen patients had a measurable interferonemia over 2-16 months; only two patients had detectable IFN in their serum at only one occasion. In five patients, hourly and daily variations of the IFN titer as measured by RIA were found to amount to less than 80%. The IFN activity found in these sera was characterized as IFN-alpha by means of acid stability, cross-reactivity on heterologous cells, trypsin sensitivity, and neutralization by homologous and heterologous antisera. IFN antibodies were quantified with a neutralization bioassay, an ELISA, and a radioimmunoassay. Of the 61 patients 5% (3) possessed high titers of anti-IFN antibodies which persisted over 2 years. The IFN-alpha antibody positive patients had an inactive form of the disease over years without visceral involvement but decreased serum complement levels (C4, C3, CH50) and repeated episodes of Quincke-like edema.

Antibodies↗
PubMed1987

Differential effects of pentylenetetrazole on ion currents of Aplysia neurones.

The effect of the convulsant drug pentylenetetrazole (PTZ) on separated membrane current components has been studied in identified voltage-clamped Aplysia neurones. External PTZ blocks the voltage-dependent Na+, Ca2+ currents and the delayed rectifier current (INa, ICa and IK,V, respectively). The amplitude of the Ca2+-activated K+ current (IK,Ca) is increased. The amplitude of the fast inactivating K+ current (IA) is transiently increased at low concentrations of PTZ but is depressed at higher concentrations or after long-lasting application of the drug. The effect of PTZ on leakage current (IL) seems to depend on the cell type. In some cells (R-15, L-7, LP-1) IL is decreased while it is increased in other cells (L-11, BL-1, BR-1). PTZ accelerates the inactivation of IK,V and IA and shifts the current-voltage relation of ICa to negative voltages by 5-8 mV. Pressure injection of PTZ into the neurone did not affect IK,V or IK,Ca. Thus PTZ seems to act on the outside of the plasma membrane. The effect of external PTZ on INa, ICa, IK,V and IL is also observed if the internal Ca2+ activity is buffered with EGTA suggesting that an increase in the internal Ca2+ activity is not involved. At -40 mV PTZ induces a tetrodotoxin-insensitive inward current carried by Na+ ions. PTZ transforms the beating pacemaker cell L-11 into a bursting pacemaker and the bursting pacemaker cell R-15 exhibits 'square-wave'-like oscillations of the membrane potential.

Action Potentials↗
PubMed1987

Electrical pump currents generated by the Ca2+-ATPase of sarcoplasmic reticulum vesicles adsorbed on black lipid membranes.

Sarcoplasmic reticulum vesicles adsorbed on a black lipid membrane generate an electrical current after a fast increment of the concentration of ATP. This demonstrates directly that the sarcoplasmic Ca2+-ATPase from skeletal muscle acts as an electrogenic ion pump. The increment of the concentration of ATP is achieved by the photolysis of caged ATP (P3-1-(2-nitro)phenylethyl adenosine 5'-triphosphate) a protected analogue of ATP (Kaplan, J.H. et al. (1978) Biochemistry 17, 1929-1935), which is split into ATP and 2-nitroso acetophenone. The release of ATP leads to a transient current flow across the lipid membrane indicating that the vesicles are capacitatively coupled to the underlying lipid membrane. In addition to this transient signal, a stationary current flow is obtained in the presence of ionophores which increase the conductance of the bilayer system and prevent the accumulation of Ca2+ in the lumen of the vesicles. The direction of the transient and the stationary current is in accordance with the concept that Ca2+ is pumped into the lumen of the vesicles. The transient current depends on the concentration of ATP, Ca2+ and Mg2+ as would be the case for a current generated by the sarcoplasmic Ca2+-ATPase. Its amplitude is half-maximal at 10 microM ATP and 1 microM Ca2+. At Ca2+ concentrations above 0.1 mM the amplitude of the current signal declines again. The Mg2+ concentration dependence of the current amplitude at a constant ATP concentration indicates that the MgATP complex is the substrate for the activation of the current. The pump current is inhibited by vanadate and ADP. No current signal is observed if caged ATP is replaced by caged ADP. However, the release of ADP from caged ADP generates a pump current in the presence of an ATP generating system such as creatine phosphate and creatine kinase.

Adenosine Diphosphate↗
PubMed1987

Fluctuations of the Ca2+-activated K+ current in Aplysia neurones.

Fluctuations of the Ca2+-activated K+ current were measured in identified Aplysia neurones under voltage clamp conditions. The amplitude of IK,Ca was manipulated by ionophoretic injections of Ca2+. At small amplitudes of Ca2+-activated outward currents the variance of the Ca2+-activated current fluctuations increases linearly with the mean outward current. The single-channel conductance estimated from the variance of the fluctuations and the mean outward current is 11 +/- 3 pS at -30 mV. Power spectra of the Ca2+-activated K+ current can be fitted by the sum of two Lorentzian components with corner frequencies of about 10 Hz and 120 Hz.

Animals↗
PubMed1987

[X-ray diagnosis of the abdominal cavity].

Radiography is a very important part of the diagnostic procedure in many small animal diseases. Technically perfect X-rays are essential for the exact diagnosis. The general appearance of the abdominal cavity should be evaluated at first, e.g. the overall contrast and the definition of the visualized organs. Then particular attention should be paid, if there is any peritoneal effusion or free air in the peritoneal cavity. Subsequently each radiographically visible organ has to be evaluated for its position, size, shape and radiographic density.

Animals↗
PubMed1987

[The correct position for X-ray exposure].

Radiographs should always be viewed and published in the same direction. The essential comparison of the patient's radiograph with the one of a normal animal is only possible in two pictures positioned the same way. This applies to viewing films on a screen as well as to publications of radiographs in journals and handbooks and to the demonstration of slides in presentations.

Animals↗
PubMed1986

[Radiologic diagnosis of internal diseases in dogs (2)].

Many veterinarians use radiography mainly as a diagnostic aid in surgical cases. However, internal diseases are at least as important an indication for radiography. For the optimal evaluation of internal radiographs the veterinarian should have a very good knowledge about the normal structures as well as the abnormal patterns which may be seen in diseases. Some important points for the evaluation of thoracic radiographs of the dog are given in this study.

Animals↗
PubMed1985

Secretion of colony-stimulating factors by human monocytes and bone marrow cells after in vitro treatment with biological response modifiers.

The results of this study indicate that human interferons (hIFNs) may have bimodal effects in vitro on human myelopoiesis. Low concentrations of hIFN alpha (1-10 U/ml), hIFN beta (1-100 U/ml), and hIFN gamma (1 U/ml) stimulated in vitro increased secretion of colony-stimulating factors (CSF) by human blood monocytes, which induced growth and differentiation of granulocyte-macrophage progenitor cells. High concentrations of hIFNs alpha, beta, gamma (greater than 100 U/ml), however, had direct antiproliferative effects on granulocyte-macrophage progenitors. Both effects could be blocked by monoclonal antibodies against hIFN alpha and hIFN gamma, as well as by heteroantiserum against hIFN beta. Human IFNs did not appear to be involved in mediating the response to the chemically defined biological response modifiers (BRMs) poly ICLC (polyriboinosinic-polycytidylic acid poly-L-lysine) and BM 41.332 (2-cyano-1-[(2-methoxy-6-methyl-pyridin-3yl)-methyl]-aziridine), since neutralizing antibodies against the human IFNs (anti-IFN alpha, beta, gamma) did not block the poly ICLC and BM 41.332-induced secretion of CSF by human blood monocytes. In contrast to hIFNs, poly ICLC and BM 41.332 also stimulated adherent human mononuclear bone marrow cells to secrete CSF, which induced growth and differentiation of nonadherent granulocyte-macrophage progenitors. The studies presented here thus support the concept that selected BRMs might be useful to stimulate in vivo secretion of myelopoietic growth factors and thereby promote granulocyte and monocyte/macrophage functions.

Antigen-Antibody Complex↗
PubMed1985

Potentiation of a transient outward current by Na+ influx in crayfish neurones.

In voltage-clamped "motor-giant" neurones of the crayfish Orconectes limosus a depolarizing voltage step elicits a transient inward current carried by Na+ which is followed by an early and a delayed outward current. The early outward current is reduced if the Na+ current is suppressed by tetrodotoxin or the removal of external Na+. It is also abolished if the K+ channel blocking agents tetraethylammonium and 3,4-diaminopyridine are applied to the neurone. The outward current was not depressed if Li+ was substituted for Na+ in the external solution or if the Na-K pump was inhibited by ouabain or the removal of external K+. Ionophoretic injections of EGTA did not depress the early outward current. Short ionophoretic injections of Na+ into the neurone increased the outward current elicited by a depolarization but did not affect the leakage current. It is suggested that the influx of Na+ leads to a transient increment of the Na+ concentration near K+ channels and that internal Na+ ions exert an activating or modulating effect on K+ channels.

4-Aminopyridine↗
PubMed1985

Anemonia sulcata toxins modify activation and inactivation of Na+ currents in a crayfish neurone.

The effects of three toxins (ATX I, II, III) isolated from the sea anemone Anemonia sulcata were studied in the soma membrane of a crustacean neurone under voltage-clamp conditions. All three toxins affected the action potentials and the Na+ currents in a similar manner. The lowest concentrations tested (10 nM, 20 nM and 50 nM for ATX I, II and III, respectively) had pronounced selective effects on the Na+ current. No effect on K+ or Ca2+ currents was observed with concentrations up to 5 microM. In the presence of ATX the Na+ inactivation was incomplete even with pulses of 700 ms length or strong depolarizing prepulses. Besides the effects on the inactivation process ATX affected also the activation of the Na+ current. In cells treated with ATX the negative resistance branch of the peak Na+ current voltage relation was shifted by -5 mV to -20 mV. The time to peak was increased for small depolarizations (up to -30 mV) and the rate of rise (delta I/delta t) was enlarged by ATX. A slow activating current component was also observed after depolarizing prepulses or if the Na+ current was outward. The decay of the Na+ tail currents was considerably prolonged after the application of ATX if the membrane was repolarized to potentials more positive than about -60 mV. Repetitive stimulation led to a shortening of the action potential in ATX II treated neurones. A simultaneous and parallel decrement of the peak and plateau current was observed with depolarizing voltage steps.

Action Potentials↗
PubMed1985

Modulation of myelopoiesis by CSF or CSF-inducing biological response modifiers.

We have compared the effects on number and function of bone marrow progenitors and peripheral effector cells of the myelomonocytic lineage of treatment with the 2-cyanaziridine compounds Azimexone and BM 41.332 to those of maleic anhydride divinyl ether copolymer (MVE-2) or granulocyte-macrophage colony stimulation factor (GM-CSF). Within a few hours after i.p. injection of either Azimexone or BM 41.332, there was a dose-dependent increase in serum CSF levels, CSF secretion by mononuclear bone marrow cells (BMC) and macrophages (M phi), which was followed by an increase in granulocyte-M phi committed stem cells (GM-CFU-C), nucleated BMC, and peripheral blood leukocytes. Optimal effects occurred 3 days after 50 mg/kg Azimexone or 25 mg/kg BM 41.332. Three i.p. injections of 50 mg/kg Azimexone into mice pretreated with cyclophosphamide (CY) (150 mg/kg) were able to significantly restore suppressed bone marrow cellularity (GM-CFU-C and nucleated BMC). Azimexone also increased the number of peripheral M phi in normal or CY-treated mice, without inducing detectable tumoricidal activity. These M phi, however, retained their capacity to become fully activated (cytotoxic) by appropriate activation signals such as IFN or LPS. Analogous to the 2-cyanaziridines. MVE-2 (at 25 mg/kg) had similar stimulatory effects on myeloid functions in normal mice. MVE-2 induced, in addition, a significant augmentation of cytoxicity by both M phi and NK cells. In contrast, single or multiple injections of semipurified GM-CSF into normal mice (1000 U or 5000 U per mouse) failed to detectably stimulate myelopoietic growth and differentiation. 2-cyanaziridine compounds thus offer the potential of selectively augmenting growth and differentiation of myelomonocytic cells in normal and bone marrow-depressed mice without appreciably affecting their immunological status.

Adjuvants, Immunologic↗
PubMed1985

[Internal medicine roentgen diagnosis in the dog (1)].

Many veterinarians use radiography mainly as a diagnostic aid in surgical cases. However, internal diseases are at least as important an indication for radiography. For the evaluation of internal radiographs the veterinarian should have extremely good knowledge about the normal structures as well as the abnormal patterns which may be seen in diseases. Some important points for the evaluation of thoracic radiographs are given.

Animals↗