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H Kühne

Publications and source records attributed to H Kühne.

At least 19 recordsLinked to original sources
PubMed2001

Use of EPR spectroscopy to study macromolecular structure and function.

Electron paramagnetic resonance (EPR) spectroscopy is now part of the armory available to probe the structural aspects of proteins, nucleic acids and protein-nucleic acid complexes. Since the mobility of a spin label covalently attached to a macromolecule is influenced by its microenvironment, analysis of the EPR spectra of site-specifically incorporated spin labels (probes) provides a powerful tool for investigating structure-function correlates in biological macromolecules. This technique has become readily amenable to address various problems in biology in large measure due to the advent of techniques like site-directed mutagenesis, which enables site-specific substitution of cysteine residues in proteins, and the commercial availability of thiol-specific spin-labeling reagents (Figure 1). In addition to the underlying principle and the experimental strategy, several recent applications are discussed in this review.

Animals↗
PubMed2000

Distinct effects of LDL apheresis by hemoperfusion (DALI) and heparin-induced extracorporeal precipitation (HELP) on leukocyte respiratory burst activity of patients with familial hypercholesterolemia.

Hypercholesterolemia and oxidative stress are major risk factors in atherogenesis. In the last years, lipid apheresis has been established as an effective clinical therapy by lowering not only elevated plasma low-density lipoprotein (LDL) levels but also by reducing the incidence of cardiovascular events. The aim of the present study was to investigate peripheral leukocyte oxidant generation in patients with familial hypercholesterolemia (FH) undergoing regular LDL apheresis. The activity state of leukocytes was estimated prior to, immediately after, and 2 days after LDL apheresis carried out by two distinct techniques: hemoperfusion with the DALI system and heparin-induced extracorporeal LDL precipitation (HELP). Oxidant generating activity was measured by chemiluminescence (CL) in whole blood and isolated polymorphonuclear leukocytes (PMNL). The results of our study show increased baseline respiratory burst activities in FH patients as compared to healthy controls. Apheresis with the HELP system was followed by increases in leukocyte count, zymosan-induced whole blood CL, and plasma PMNL elastase levels. The DALI technique caused no changes in leukocyte count and elastase levels and decreased whole blood CL activity. Two days after lipid removal the observed changes returned to pre-apheresis levels. Leukocyte activity parameters before and after apheresis did not correlate with the corresponding plasma levels of triglycerides, total cholesterol, and LDL cholesterol, suggesting that different handling in the framework of both apheresis techniques rather than lipid profile changes during therapy accounted for leukocyte activity modulation.

Adult↗
PubMed2000

[Contribution of Berlin clinics and especially the Charité to the development of modern anesthesia in Germany].

Soon after announcement of the first American ether anesthesias in 1846 one started to anesthetize with ether in Europe. The first ether anesthesia in Germany took place on January 24th, 1947, and was given by Johann Ferdinand Heyfelder in Erlangen. Two weeks later the first ether anesthesia in Berlin was given on February 6th, 1847, by the orthopaedic surgeon Heimann-Wolff Berend. On February 12th, 1847, the surgeon Johann Friedrich Dieffenbach used ether to anesthetize a patient in the Berlin university hospital. Still in 1847 he published his book "The Ether against Pain" which used to be the standard textbook of anesthesia in Germany for many years to come. On February 15th, 1847, Johann Christian Jüngken operated his first patient under ether anesthesia in the surgical department of the Charité hospital assisted by Rudolf Virchow. Since then several famous Berlin surgeons influenced the development of modern anesthesia until the middle of the 20th century. The nitrous oxide bottle was introduced into practice by the Barth company in cooperation with the dentist Carl Sauer and Kurt Schimmelbusch introduced his mask for ether anesthesia. Carl Ludwig Schleich reported at the German congress of surgery in 1894 about his first experience with infiltration anesthesia. Spinal anesthesia developed by August Bier in Kiel was improved during his time in Berlin.

Anesthesia↗
PubMed2000

[Otto J"ungling--the first "specialist in anesthesiology" in Berlin].

Compared to English-speaking countries, anaesthesiology in Germany developed into an independent field relatively late. German doctors were sent abroad to other European countries to learn modern anaesthetic techniques. At the beginning of the fifties, colleagues from East Germany had increasing problems to travel abroad. Otto Jüngling, who specialised in anaesthesiology in Vienna under Otto Mayrhofer, came with a work permit to the small town of Quedlinburg in the Harz mountains in November 1952. One year later, in September 1953, he went to Berlin to set up a new department of anaesthesiology at Friedrichshain Hospital. After recognition of his speciality by the Austrian General Medical Council in Linz, Otto Jüngling became the first specialist for anaesthesiology to practise in Berlin. Scientifically he worked on the development of new anaesthetics and anaesthetic machines. A transportable suction unit was one of his excellent ideas. Furthermore, he rendered outstanding services to the training of anaesthesists in Berlin. Otto Jüngling resigned in February 1959 due to unsatisfactory cooperation with public authorities and went back to Austria were he lives today as a pensioner.

Anesthesiology↗
PubMed1999

Competitive binding of acetate and chloride in photosystem II.

The binding of chloride and acetate to photosystem II (PSII) was examined to elucidate the mechanism of acetate inhibition. The mode of inhibition was studied, and individual binding sites were assigned by steady-state O2 evolution measurements in correlation with electron paramagnetic resonance (EPR) results. Two binding sites were found for acetate, one chloride-sensitive on the electron donor side and one chloride-insensitive on the electron acceptor side. The respective binding constants were as follows: KCl = 0.5 +/- 0.2 mM (chloride binding to the donor side), KI = 16 +/- 5 mM (acetate binding to the donor side), and KI' = 130 +/- 40 mM (acetate binding to the acceptor side). When acetate was bound to the acceptor side of PSII, 200 K illumination induced a narrowed form of the QA-FeII EPR signal, the yield of which was independent of the chloride concentration. When acetate was bound to the donor side, room-temperature illumination produced the S2YZ* state. EPR measurements showed that both the yield and formation rate of this state increased with acetate concentration. Increasing chloride concentrations slowed the rate of formation of the S2YZ* state, but did not affect the steady-state yield of the S2YZ* state. These findings indicate that the light-induced reactions in acetate-inhibited PSII are modulated by both donor side and acceptor side binding of acetate, while the steady-state yield of the S2YZ* state at the high PSII concentrations used for EPR measurements depends primarily on acceptor side turnover. Our data further support a close proximity of chloride to YZ*, indicating a possible role for chloride in the electron-transfer mechanism at the O2-evolving complex.

Acetates↗
PubMed1999

Mapping RNA-protein interactions in ribonuclease P from Escherichia coli using electron paramagnetic resonance spectroscopy.

Ribonuclease P (RNase P) is a catalytic ribonucleoprotein (RNP) essential for tRNA biosynthesis. In Escherichia coli, this RNP complex is composed of a catalytic RNA subunit, M1 RNA, and a protein cofactor, C5 protein. Using the sulfhydryl-specific reagent (1-oxyl-2,2,5, 5-tetramethyl-Delta3-pyrroline-3-methyl)methanethiosulfonate (MTSL), we have introduced a nitroxide spin label individually at six genetically engineered cysteine residues (i.e., positions 16, 21, 44, 54, 66, and 106) and the native cysteine residue (i.e., position 113) in C5 protein. The spin label covalently attached to any protein is sensitive to structural changes in its microenvironment. Therefore, we expected that if the spin label introduced at a particular position in C5 protein was present at the RNA-protein interface, the electron paramagnetic resonance (EPR) spectrum of the spin label would be altered upon binding of the spin-labeled C5 protein to M1 RNA. The EPR spectra observed with the various MTSL-modified mutant derivatives of C5 protein indicate that the spin label attached to the protein at positions 16, 44, 54, 66, and 113 is immobilized to varying degrees upon addition of M1 RNA but not in the presence of a catalytically inactive, deletion derivative of M1 RNA. In contrast, the spin label attached to position 21 displays an increased mobility upon binding to M1 RNA. The results from this EPR spectroscopy-based approach together with those from earlier studies identify residues in C5 protein which are proximal to M1 RNA in the RNase P holoenzyme complex.

Amino Acid Sequence↗
PubMed1998

Characterization of the interaction between manganese and tyrosine Z in acetate-inhibited photosystem II.

When acetate-inhibited photosystem II (PSII) membranes are illuminated at temperatures above 250 K and quickly cooled to 77 K, a 240 G-wide electron paramagnetic resonance (EPR) signal is observed at 10 K. This EPR signal arises from a reciprocal interaction between the spin 1/2 ground state of the S2 state of the Mn4 cluster, for which a multiline EPR signal with shifted 55Mn hyperfine peaks is observed, and the oxidized tyrosine residue, YZ*, for which a broadened YZ* EPR spectrum is observed. The S2YZ* EPR signal in acetate-inhibited PSII is the first in which characteristic spectral features from both paramagnets can be observed. The observation of distinct EPR signals from each of the paramagnets together with the lack of a half-field EPR transition indicates that the exchange and dipolar couplings are weak. Below 20 K, the S2YZ* EPR signal in acetate-inhibited PSII is in the static limit. Above 20 K, the line width narrows dramatically as the broad low-temperature S2YZ* EPR signal is converted to a narrow YZ* EPR signal at room temperature. The line width narrowing is interpreted to be due to averaging of the exchange and dipolar interactions between YZ* and the S2 state of the Mn4 cluster by rapid spin-lattice relaxation of the Mn4 cluster as the temperature is increased. Decay of the S2YZ* intermediate at 200 K shows that the g = 4.1 form of the S2 state is formed and that a noninteracting S2-state multiline EPR signal is not observed as an intermediate in the decay. This result shows that a change in the redox state of YZ induces a spin-state change in the Mn4 cluster in acetate-inhibited PSII. The interconversion between spin states of the Mn4 cluster in acetate-inhibited PSII supports the idea that YZ oxidation or YZ* reduction is communicated to the Mn4 cluster through a direct hydrogen-bonding pathway, possibly involving a ligand bound to the Mn4 cluster.

Electron Spin Resonance Spectroscopy↗
PubMed1998

Hypochlorite-modified low-density lipoprotein stimulates human polymorphonuclear leukocytes for enhanced production of reactive oxygen metabolites, enzyme secretion, and adhesion to endothelial cells.

Hypochlorite-oxidized low-density lipoprotein ((-)OCl-LDL) has been shown to stimulate various functions of human polymorphonuclear leukocytes (PMNLs). Incubation of PMNLs with (-)OCl-LDL (produced by incubation of 0.4 mM LDL cholesterol with 1 mM NaOCl for 40 min at 37 degrees C) but not native or copper-oxidized LDL induced a substantial generation of reactive oxygen species (ROS) as measured by means of chemiluminescence with one peak at 10-12 min. Upon stimulation with (-)OCl-LDL about 70% of ROS (hydrogen peroxide and superoxide anion) were released from the cells into the extracellular environment. The (-)OCl-LDL-induced increase of the respiratory burst was dependent upon the dose, exposure time, and extent of LDL oxidation. Cytochalasin B, an inhibitor of phagocytosis, markedly diminished the LDL-induced ROS generation to nearly 40% of control values. (-)OCl-LDL enhanced the adhesion of PMNLs to human umbilical venous endothelial cells 2.5-fold as compared to native LDL and promoted the secretion of the active granule enzymes lysozyme and beta-glucuronidase. Together, the results suggest a potential role of LDL-activated PMNLs in initiating and/or maintaining the inflammatory process during the early phase of atherosclerotic lesion development. Alternatively, PMNLs may also play a protective role by phagocytosing oxidized LDL and, thus, preventing further detrimental atherogenic effects of oxidized LDL.

Cell Adhesion↗
PubMed1997

[Selenium administration in patients with sepsis syndrome. A prospective randomized study].

PATIENTS AND METHOD: In this study the effect of antioxidative therapy with sodium selenite was investigated in patients with systemic inflammatory response syndrome (S. I. R. S.) and multiple organ failure. 40 patients were included in this prospective randomized study. The patients were observed over a period of 28 days. The letality rate within 28 days was excepted as main criteria. The Apache-II and the MOF-Score of Goris were used as clinical parameters. 20 patients were treated with sodium selenite over a period of 28 days. RESULT: This antioxidative therapy reduced the letality rate from 40 to 15%.

Antioxidants↗
PubMed1996

The risk of pancreaticointestinal anastomosis can be predicted preoperatively.

The risk of developing postoperative complications following pancreatic resection depends mainly on how difficult it is to perform a proper pancreaticointestinal anastomosis. We have evaluated the serum pancreolauryl test, a rapid tubeless pancreatic function test, as a simple preoperative predictor of the degree of pancreatic fibrosis. Degree of fibrosis in turn provides an indirect parameter for the difficulties of performing a proper and safe pancreaticointestinal anastomosis. In 35 patients (21 chronic pancreatitis, 14 pancreatic tumors) undergoing major pancreatic resection, we found a negative correlation (r = -0.75, p < 0.001) between the degree of fibrosis at the resection margin and the serum pancreolauryl test results. Patients with chronic pancreatitis had a significantly higher degree of fibrosis at the resection margin (59 +/- 22 vs. 34 +/- 25%; X +/- SD; p < 0.01) and lower fluorescein serum concentrations (2.6 +/- 1.9 vs. 4.3 +/- 2.1 micrograms/ml; X +/- SD; p < 0.01) in comparison with patients with pancreatic tumors. These findings indicate that the degree of pancreatic fibrosis, the difficulties of performing a proper pancreaticointestinal anastomosis, and subsequently the potential risk of postoperative complications can easily be predicted preoperatively.

Adult↗
PubMed1990

[The effect of vitamin E on the survival rate and biochemical parameters such as isocitrate dehydrogenase, lactate and selected peptidases and proteases during endotoxic shock in the rat].

Protective effect of the investigated alpha-tocopherol solution regarding survival and changes of several biochemical parameters in rat endotoxin shock could already be demonstrated after application of the solvent (special oil HCO-60) alone. An additional effect of Vitamin E was observed only in DP IV activity and leukocyte counts.

Animals↗
PubMed1990

[The effect of LPH on the behavior of parameters of the kallikrein-kinin system (KKS) in the early phase of experimental endotoxic shock in the rat].

The effect of a new shock-protective agent LPH on parameters of the kallikrein-kinin-system was studied in a standardized endotoxin shock model. Activation of KKS in endotoxin shock was not significantly influenced by LPH. On the other hand, LPH by itself caused activation of KKS. Decrease of kininogen level by endotoxin, however, was prevented by the pretreatment with LPH.

Animals↗
PubMed1990

Effect of kallikrein-kinin system activation by factor XII f pretreatment on experimental hemorrhagic shock.

Effects of Hageman factor fragment (factor XIIf) administration on shock induction were studied in anesthetized male Wistar rats with hemorrhagic shock. Administration of factor XIIf in non-hemorrhaged rats resulted in an immediate decrease of mean arterial pressure (MAP) for 5 min and in significant increases of blood glucose, lactate and hematocrit (Hct) as well as in a strong tendency for plasma kallikreinogen (KKN) to decrease. At the beginning of bleeding (15 min after factor XIIf administration) MAP has been normalized again. During subsequent hemorrhage pretreated rats showed a sharper decrease in MAP which remained significantly lower up to 25% of estimated blood volume (EBV) and recovered more slowly to normal level after hemorrhage. Blood glucose, lactate and Hct were significantly higher in pretreated animals after hemorrhage of 30% EBV. KKN depicted significant lower values during hemorrhage and in the posthemorrhagic period. Mortality within the observation time increased from 20% (control group) to 60% (pretreated animals). The results demonstrate that prehemorrhagic kallikrein-kinin system (KKS) activation induced an increased severity of shock state with higher mortality.

Animals↗
PubMed1990

[Effect of enkephalins and naloxone on the activity of the kallikrein-kinin system in experimental hemorrhagic shock].

The effect of enkephalin derivates with different receptor subtype specificity and opioid antagonist naloxone on kallikrein-kinin system was studied in anaesthetized rats exposed to 30% hemorrhage. Hemorrhage by itself caused only a slight activation of KKS. Pretreatment with naloxone induced a significant activation of KKS, which was potentiated by subsequent hemorrhage.

Animals↗
PubMed1990

[Incidence of autonomy and immune hyperthyroidism before and following preventive use of iodized salt in the Berlin-Brandenburg area].

The incidence of hyperthyroidism was observed in the area of Berlin (1.2 million inhabitants) and in a rural district in the geographical region of the "Mark Brandenburg" (48.115 inhabitants) during the period from 1975 und 1989. This area is characterized with a iodine deficiency grade II (WHO). In 1985 an iodine salt supplementation was introduced by law. The period before iodine salt supplementation 1975-1985 was compared to the period after iodine prophylaxis: there was an increase in hyperthyroidism in the Berlin-area by the ratio 1:3.1 and 1:2.8 (1975-83 compared to 1988 and 1989), in the rural district by 1:1.7 (1980-1985 compared to 1986/87). The ratio autonomy (non immunogenic form) to immunogenic etiology was 1:12 (1977-83), and changed to 1:1.45 in 1988 and 1:16.3 in 1989 after iodine supplementation. The sex ratio male:female was 1:10 before, and 1:6.8 after prophylaxis for hyperthyroidism in total, in autonomy the ratio was observed as 1:12 before and 1:7.7 (1988), 1:4.7 (1989) after supplementation, in immunogenic hyperthyroidism 1:10 unchanged in the early and late period of observation. The increase of hyperthyroidism after iodine prophylaxis correlated well with the consumption of thyrostatic drug Thiamazol (Methimazol) for the whole country. The defined daily dose (DDD)/1000 inhabitants/day increased during the observation time from 0.5 (1984), 0.55 (1985), 0.66 (1986), to 1.47 (1987), 1.26 (1988) and 0.81 (1989). The results are compared and discussed with reports from USA, Iceland, Great Britain, Denmark, Italy and Tasmania. During the period of seven years (1980-87) in the rural district a seasonal dependence of onset in hyperthyroidism was observed in spring time between May and June only in immunogenic hyperthyroidism, despite in thyroidal autonomy the disease began throughout the year without a seasonal peak.

Berlin↗