Papers by Hans-Joachim Freisleben
Medical Journal of Indonesia, Sep 5, 2023
Pharmaceutical sciences and research, Apr 1, 2012
FEBS Letters, Apr 18, 1994
Fatty acid binding site on isolated mitochondrial uncoupling protein (UcP) is demonstrated using ... more Fatty acid binding site on isolated mitochondrial uncoupling protein (UcP) is demonstrated using EPR spectroscopy of S-DOXYL-stearic acid (5SASL), which also activated H+ transport in proteoliposomes containing UcP. In the presence of UcP the EPR spectrum showed reproducible broadening of the low field peak as well as an increase in h+lI/h+,M ratio, rotational correlation time and in order parameter. The half-height width of the low field peak was even doubled in the presence of another UcP ligand, GDP. Palmitic acid reversed the effect of 5-SASL and non-ionizable 5-DOXYL-decane did not exhibit it.
Medical Journal of Indonesia, Dec 13, 2013
Medical Journal of Indonesia, Nov 1, 2012
PubMed, 2017
Introduction: Ureter obstruction caused by a retro-peritoneal tumor is treated by inserting an in... more Introduction: Ureter obstruction caused by a retro-peritoneal tumor is treated by inserting an indwelling ureter splint (DJ-stent). Indwelling duration is limited by cumulative crystalline deposits into the splint, eventually causing the repeated impairment of urine flow. Deciding when a DJ-stent must be replaced is important since belated removal can be accompanied by severe complications. X-ray or conventional sonography do not allow satisfactory evaluation of early incrustation, therefore, the use of sonographic twinkling artifacts (TA) to provide accurate stent surveillance was investigated. Material and methods: 26 patients with indwelling ureter splints carrying a high risk of developing tumor lysis syndrome (TLS), which is often accompanied by early splint incrustation, were investigated utilizing TA the day after DJ-stent implantation and weekly thereafter. Serum creatinine, uric acid, and urine pH were measured at all TA exams. Results: Early incrustation of the ureter splint was detected by TA in all patients 1-4 weeks after implantation. Incrustation occurred sooner with increased uric acid levels, and high creatinine or acidic urine accelerated early implant incrustation. Conclusions: TA can be used to monitor early crystalline deposits in implanted ureter splints, before they can be detected by conventional sonography or X-ray imaging and before complications occur.
International Journal of Molecular Sciences, Oct 21, 2019
The main phospholipid (MPL) of Thermoplasma acidophilum DSM 1728 was isolated, purified and physi... more The main phospholipid (MPL) of Thermoplasma acidophilum DSM 1728 was isolated, purified and physico-chemically characterized by differential scanning calorimetry (DSC)/differential thermal analysis (DTA) for its thermotropic behavior, alone and in mixtures with other lipids, cholesterol, hydrophobic peptides and pore-forming ionophores. Model membranes from MPL were investigated; black lipid membrane, Langmuir-Blodgett monolayer, and liposomes. Laboratory results were compared to computer simulation. MPL forms stable and resistant liposomes with highly proton-impermeable membrane and mixes at certain degree with common bilayer-forming lipids. Monomeric bacteriorhodopsin and ATP synthase from Micrococcus luteus were co-reconstituted and light-driven ATP synthesis measured. This review reports about almost four decades of research on Thermoplasma membrane and its MPL as well as transfer of this research to Thermoplasma species recently isolated from Indonesian volcanoes.
PubMed, Sep 1, 1999
A malaria intervention study was carried out using permethrin impregnated bed nets in the south-c... more A malaria intervention study was carried out using permethrin impregnated bed nets in the south-central part of Irian Jaya with perennial transmission, from April 1993 to April 1995. Malariometric surveys were carried out periodically for parasite prevalence by species and for spleen rates. Prior to intervention, the percentage of Plasmodium falciparum infected inhabitants was significantly higher in Hiripau, where permethrin-impregnated bed nets were used during the study, than in the placebo-treated control village, Kaugapu. After two years of intervention the situation was reversed and figures higher in the control village (RR 0.19, 95% CI 0.10-0.36, p < 0.0001). Similarly, P. vivax infection rates, 12.4% in Hiripau vs 5.7% in Kaugapu in April 1993. were reversed in April 1995 (3.6% in Hiripau and 11.3% in Kaugapu, p < 0.001). In the treated village, pre-control hyperendemicity was reduced to a low mesoendemic level (spleen rate 12.5%) during two years of intervention, whereas the level was mesoendemic (spleen rate 35.2%) in the control village. Impregnated bed nets were found an effective intervention both in moderate (April 1993 through April 1994, 1,626 mm rainfall) and high (April 1994 through April 1995/1995, 3,321 mm) transmission seasons.
PubMed, 2000
Ischemia and reperfusion were studied in isolated working rat hearts and in exarticulated rat hin... more Ischemia and reperfusion were studied in isolated working rat hearts and in exarticulated rat hind limbs. Free radicals are known to be generated in ischemia/reperfusion and to propagate complications. To reduce reperfusion injury, conditions were ameliorated including the treatment with antioxidants, lipoate or dihydrolipoate. In isolated working rat hearts, cardiac and mitochondrial parameters are impaired during hypoxia and partially recover in reperfusion. Dihydrolipoate, if added into the perfusion buffer at 0.3 microM concentration, keeps the pH higher (7.15) during hypoxia, as compared to controls (6.98). This compound accelerates and stabilizes the recovery of the aortic flow. With dihydrolipoate, ATP synthesis is increased, ATPase activity (ATP hydrolysis) reduced, intracellular creatine kinase activity maintained and thus phosphocreatine contents are higher than in controls. For exarticulated rat hind limbs, the dihydrolipoate group contained 8.3 microM in the modified reperfusate. Recovery of the contractile function was 49% vs. 34% in controls and muscle flexibility was maintained whereas it decreased by 15% in the controls. Release of creatine kinase from cells was significantly lower with dihydrolipoate. Lipoate/dihydrolipoate effectively reduced reperfusion injury in isolated working rat hearts and in exarticulated rat hind limbs after extended ischemia. Finally, the compound was successfully applied in an in vivo pig hind limb model.
Journal of Liposome Research, 1993
INFLUENCE OF THE MAIN PHOSPHOLIPID (MPL) FROM THiFRMOPfASMA AC/DOP/f/f UM AND OF LIPOSOMES FROM M... more INFLUENCE OF THE MAIN PHOSPHOLIPID (MPL) FROM THiFRMOPfASMA AC/DOP/f/f UM AND OF LIPOSOMES FROM MPL ON LIVING CELLS: CYTOTOXICITY AND MUTAGENICITY ... Hans-Joachim Freisleben*, Cornelia Neisser, Michael Hartmann, Petra Rudolph, Peter ...
Methods in Enzymology, 1992
Publisher Summary Free radicals are potentially dangerous for the cell, although in vivo they may... more Publisher Summary Free radicals are potentially dangerous for the cell, although in vivo they may be generated by metabolism. These radicals can be classified into two groups: (1) oxygen-derived radicals and active oxygen species, including superoxide anion radical, hydroxyl radical, hydrogen peroxide, and singlet molecular oxygen and (2) organic radicals that usually originate in the course of lipid peroxidation. According to the location in which they are generated, oxygen-derived radicals react mainly with components in the aqueous phases, such as extra- and intracellular fluids, while organic radicals interact mainly with constituents of the hydrophobic membranous phase. This chapter investigates the antioxidant activity of carotenoids and retinoids compared to α -tocopherol and its homologs. For the assay in the aqueous phase, a modified method of a phycoerythrin fluorescence-based procedure is used, whereas for the assay in the hydrophobic phase, a new cis-parinaric acid fluorescence-based assay is developed.
CRC Press eBooks, May 10, 2000
PubMed, 1991
Hypoxia and reoxygenation in working rat hearts were investigated in this study. Cardiac hemodyna... more Hypoxia and reoxygenation in working rat hearts were investigated in this study. Cardiac hemodynamic parameters which decline immediately under hypoxic conditions, recover during reoxygenation. Biochemical and ultrastructural alterations exhibit a more complicated pattern. There is a primary phase in hypoxic perfusion up to 15 min with a steep increase of ADP contents and ATPase activities, and a severe fall of ATP/ADP ratios in mitochondria, as well as in tissue. High CAT (carboxyatractyloside) sensitivity of the ATPase is observed at 5 min of hypoxia. Furthermore, the number of ATPase particles visible at the inner mitochondrial membrane decreases. During the ensuing second phase of hypoxic perfusion (from 30 min on) the damage of mitochondrial ultrastructure becomes more evident. The amount of ATPase particles visible at the inner mitochondrial membrane further decreases. ATPase activities fluctuate, however, they remain connected with the membrane during hypoxia. ATP/ADP ratios attain values of almost 1. During reoxygenation (after 30 min of hypoxia) the levels of mitochondrial adenine nucleotides, oxidative phosphorylation rate and respiratory control index increase within 20 min and then slightly decline again. The ATP/ADP ratio is diminished in the course of reoxygenation. ATPase activity also decreases within 20 min of reoxygenation and the ADP/O ratio reaches control values. The ATPase activity gains its highest sensitivity towards CAT at 10 min of reoxygenation attaining a value similar to that of 5 min of hypoxic perfusion. It is suggested that hypoxia and reoxygenation under our conditions result in reversible derangement of ATPase and mitochondrial membrane structure.
Archives of Biochemistry and Biophysics, Oct 1, 1988
Thiol reactivity was determined in rat heart mitochondria using chromophores of differing polarit... more Thiol reactivity was determined in rat heart mitochondria using chromophores of differing polarities: monobromobimane (MB), dithionitrobenzoate (Nbs,), and bromobimane-q (MQ). The purpose of this study is to correlate reaction rates of protein thiols in the mitochondrial membrane with the oligomycin-inhibited and uncoupled states: In all cases investigated the reactivity of-SH groups toward MB decreases under the above conditions. In parallel with an increase of their uncoupling activities the uncouplers reduce the reaction rate of thiol groups toward Nbsz and, progressively, toward MQ, indicating differences in sensitivity of thiol groups to uncouplers depending on the polarity of the environment. The pattern of-SH reactivity under inhibition by oligomycin resembles that of carbonylcyanide-p-trifluoromethoxyphenylhydrazone. Functional changes of the mitochondrial membrane probably correlate with reactivity/polarity changes of membrane-SH groups. Masking of membrane thiol groups thus is not specific for uncouplers but is also observed under inhibition with oligomycin.
Biochemical Pharmacology, Mar 1, 1992
Human red blood cell (RBC) membranes (RBC ghosts) were treated with glucose, insulin and metformi... more Human red blood cell (RBC) membranes (RBC ghosts) were treated with glucose, insulin and metformin. The order parameters of RBC membranes were determined by 5- and 16-doxyl-stearic acid spin labels. Metabolic effects were excluded using an isolated system of RBC membranes. The membranes were incubated with glucose in physiological (5 mM), renal threshold (10 mM) and manifested diabetic (20 mM) concentrations for limited times. High concentrations of glucose (10, 20, 100 mM) increase the order parameters of RBC membranes significantly. Insulin by itself has a similar effect which is, however, not strictly concentration-dependent. By contrast, metformin at therapeutic concentrations (0.5 and 5.0 microM) decreases the order parameters. At 50 microM concentration the metformin effect is expressed less and recurs at 100 microM concentration. The effects are significant with 5-doxyl-stearic acid, but are not significant with the 16-doxyl derivative. When RBC membranes are co-incubated with 20 mM glucose and metformin at 0.5 and 5.0 microM concentrations the order parameters as determined by 5-doxyl-stearic acid remain normal (= control values). Higher concentrations of metformin (50 and 100 microM) cause an overshoot to very low order parameters. Insulin at 10, 100 and 200 mU/L does not influence significantly the effects of metformin. Addition of physiological amounts of bovine serum albumin does not abolish the effects of metformin. Metformin, at therapeutic concentrations (0.5 and 5.0 microM), maintains the normal fluidity at the polar interface of isolated RBC membranes by counterbalancing non-enzymatic glycosylation with 20 mM glucose in vitro.
Andrologia, Apr 24, 2009
Semen-chemilurninescencereactive oxygen speciesoxidative stress ~ human Summary. Luminol-dependen... more Semen-chemilurninescencereactive oxygen speciesoxidative stress ~ human Summary. Luminol-dependent chemiluminescence (CL) can be used to determine the production of reactive oxygen species (ROS) by cells. Enhanced formation of ROS in human semen was reported to be of pathological significance for a disturbed sperm function. To investigate incidence of elevated CL-signals in semen samples and their correlation to conventional semen parameters, CL-signals in the semen of both 49 consecutive infertile men and 20 controls were measured. Semen was analysed according to WHO-criteria including bovine mucuspenetration-and water-test. A CL-signal of 1.5 x lo5 counts min-'/2 x lo6 spermatozoa was considered to be the upper normal limit. The CL in infertile men's semen was elevated with statistically significant differences in oligozoospermia patients/controls (P< 0.000 1) and normozoospermia patients/controls (P< 0.05). In the group with elevated CL-signals, a higher percentage of spermatozoa with a pathologic morphology was detected (P=O.O5). In the groups with pathologic results of eosin-and water-tests, the CL-counts were elevated (P< 0.006; P< 0.03). The spermatozoa motility in the group with elevated CL-counts was significantly reduced after 4 h (P<O.O5). The CL-signals correlated inversely with the results of the bovine mucus-penetration-test (r =-0.67, P<O.OOOl). In conclusion, semen samples of 28% of our patients showed elevated CL-signals; these were associated with pathological results of membrane integrity-tests. The negative correlation of CL with the results of Penetrak@-test reflects its importance to depict the functional capacity of spermatozoa.
Human Reproduction, 1995
Peroxidative damage induced by reactive oxygen species (ROS) has been proposed as one of the majo... more Peroxidative damage induced by reactive oxygen species (ROS) has been proposed as one of the major causes of defective sperm function. The ROS detected in semen reflect an imbalance between ROS generation and degradation. The objective of the present study was to investigate the relationship between the oxidative and anti-oxidative potential in semen of infertile patients and healthy donors. Specimens were obtained from 28 patients and 18 healthy donors (controls). A conventional spermiogram, measurement of luminol-chemiluminescence (CL) in washed semen, and high performance liquid chromatography determination of ascorbic acid and urate concentrations in seminal plasma were performed. Oligozoospermic patients exhibited higher CL signals than controls (P &lt; 0.001). Normozoospermic patients showed lower ascorbic acid (mean +/- SE: 491 +/- 46 microM, P &lt; 0.04) and urate concentrations (320 +/- 22 microM, P &lt; 0.009) than controls (612 +/- 35 and 426 +/- 26 microM respectively). Seminal plasma ascorbic acid was negatively correlated with the CL signals (P &lt; 0.0006) and positively correlated with the percentage of spermatozoa with normal morphology (P &lt; 0.006). This is the first report of a correlation between the anti-oxidant ascorbic acid in seminal plasma and ROS generation in human semen. Furthermore, the reduced ascorbic acid/urate concentrations found in semen of normozoospermic patients might be indicative of a reduced anti-oxidative protection.
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Papers by Hans-Joachim Freisleben