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Biomedical subjects

D Kunz

Publications and source records attributed to D Kunz.

At least 55 records · Page 3Linked to original sources
PubMed1999

Selective proteolytic cleavage of IL-2 receptor and IL-6 receptor ligand binding chains by neutrophil-derived serine proteases at foci of inflammation.

Traumatic brain injuries induce a strong, locally restricted inflammatory response. Here we demonstrate that activated neutrophils infiltrate the site of tissue destruction and release large amounts of enzymatically active elastase, cathepsin G, and proteinase 3. High intracerebral protease concentrations were found to be accompanied by a reduced inhibitory potential at foci of inflammation. In 39 neurotrauma patients, a temporal correlation between the protease release from neutrophils and the solubilization of interleukin-2 (IL-2) receptor and IL-6 receptor ectodomains at sites of tissue destruction was observed, suggesting that neutrophil-derived proteases may play a crucial role in the cytokine receptor shedding at foci of inflammation. Under in vitro conditions, the cleavage of membrane-bound IL-2Ralpha was found to be predominantly catalyzed by elastase and, to a lesser extent, by proteinase 3. Cathepsin G was found to be incapable of solubilizing this receptor. In contrast, the cleavage of the IL-6R 80 kDa chain was catalyzed by cathepsin G but not by elastase or proteinase 3. The receptor fragments released by the action of these enzymes were found to retain their ligand-binding capacity. These results strongly suggest a pathophysiologic role of neutrophil-derived serine proteases, particularly in regulation of the expression of functional IL-2 and IL-6 receptors at foci of inflammation.

Adolescent↗
PubMed1999

[Peritonitis models in the rat with special reference to laparoscopic therapy options].

With ongoing development of minimally invasive surgery the laparoscopic techniques are increasingly used also in patients with intra-abdominal inflammatory diseases. The systemic sequelae of laparoscopy are not yet clear. In this study, we investigated three experimental models of peritonitis in rats (cecal ligation and puncture n = 14, cecal stent peritonitis n = 14, implantation of a standardized fecal inoculum n = 18) concerning the therapeutic potential of laparoscopy, reproducibility of the results and clinical relevance (elimination of the inflammatory focus, intraperitoneal modulation of inflammation). The peritonitis model of implantation of a standardized fecal inoculum was shown to be the experimental model with the closest clinical relevance. In this technically simple, reproducible model, the primary inflammatory focus can be eliminated by laparoscopic lavage. A significant difference (p < 0.002) of survival between the groups with and without laparoscopic lavage was found. In addition, the intraperitoneal application of drugs is possible in order to modulate peritoneal and systemic inflammation.

Animals↗
PubMed1998

Energy metabolism in rat pancreatic acinar cells during anoxia and reoxygenation.

Mitochondrial energy metabolism was studied in isolated pancreatic acinar cells during anoxia up to 90 min and reoxygenation for 60 min. To identify critical alterations leading to the known postanoxic impairments in structure and function of acinar cells, adenine nucleotide levels and the rates of phosphorylating and non-phosphorylating respiration were determined. ATP levels and the total amount of adenine nucleotides strongly decreased as early as after 30 min of anoxia. The cells partially restored ATP and the total adenine nucleotides within 60 min of reoxygenation. Long-term anoxia caused an increase in the oligomycin-insensitive part of oxygen consumption. The respiratory capacity measured as uncoupled respiration progressively declined to 40% of controls after 90 min of anoxia. Fluorescence measurements showed that flavoproteins and mitochondrial pyridine nucleotides in reoxygenated cells after short-term anoxia were in a more reduced state than in aerobic controls, and were not fully oxidizable by uncoupling. It is concluded that long-term anoxia produces an irreversible loss of respiratory capacity leading to a limited ATP production. This functional impairment and the progressive damage to acinar cells may be relevant for pancreatic injuries such as acute pancreatitis or post-transplantation pancreatitis.

Adenine Nucleotides↗
PubMed1998

On pineal calcification and its relation to subjective sleep perception: a hypothesis-driven pilot study.

We classified the degree of pineal calcification (DOC) into seven groups using cranial Computer Tomography (cCT) and then correlated pineal DOC to chronic subjective sleep-related disturbances as measured by a sleep questionnaire in 36 patients. Analysed by logistic regression models, age and sex were not, but higher pineal DOC was significantly associated with the presence of daytime tiredness (OR = 4.15, 95% CI: 1.63, 10.54) and sleep disturbance (OR = 1.74, 95% CI: 1.10, 2.74). This study provides initial confirmation of the hypothesis that the increasing degree of pineal calcification (DOC) might indicate a decrease of melatonin production, which consecutively might lead to a disturbed circadian rhythmicity in the sleep-wake cycle, with the principal symptom being daytime tiredness.

Adult↗
PubMed1998

Platelet-derived growth factor and fibroblast growth factor differentially regulate interleukin 1beta- and cAMP-induced group II phospholipase A2 expression in rat renal mesangial cells.

Expression of group II phospholipase A2 (PLA2; EC 3.1.1.4) in rat renal mesangial cells is triggered in response to two principal classes of activating signals. These two groups of activators comprise inflammatory cytokines such as interleukin 1beta (IL-1beta) or tumor necrosis factor alpha and agents that elevate cellular levels of cyclic AMP (cAMP) such as forskolin, an activator of adenylate cyclase. Treatment of mesangial cells with IL-1beta or forskolin for 24 h induces group II PLA2 activity secreted into cell culture supernatants by about 15-fold and 11-fold, respectively. Platelet-derived growth factor (PDGF)-BB potently inhibits secretion of IL-1beta- and forskolin-induced group II PLA2 activity. By Western and Northern blot analyses, we demonstrate that this is due to a reduction of PLA2 protein levels and the corresponding PLA2 mRNA steady-state levels. Basic fibroblast growth factor (bFGF) virtually does not inhibit IL-1beta-stimulated group II PLA2 activity, but markedly inhibits forskolin-induced expression of group II PLA2 activity. These effects are caused by changes in the corresponding PLA2 protein and PLA2 mRNA steady-state levels. Inhibition of protein kinase C (PKC) by the potent and selective PKC inhibitor calphostin C converted the inhibitory action of PDGF into a bFGF-type of response thus suggesting that PKC is a major effector in PDGF-induced inhibition of IL-1beta-stimulated group II sPLA2 expression. In summary, our data suggest that PDGF and bFGF differentially modulate in a stimulus-specific manner the expression of group II PLA2 in mesangial cells.

Animals↗
PubMed1998

Functional imaging of mitochondria in saponin-permeabilized mice muscle fibers.

Confocal laser-scanning and digital fluorescence imaging microscopy were used to quantify the mitochondrial autofluorescence changes of NAD(P)H and flavoproteins in unfixed saponin-permeabilized myofibers from mice quadriceps muscle tissue. Addition of mitochondrial substrates, ADP, or cyanide led to redox state changes of the mitochondrial NAD system. These changes were detected by ratio imaging of the autofluorescence intensities of fluorescent flavoproteins and NAD(P)H, showing inverse fluorescence behavior. The flavoprotein signal was colocalized with the potentiometric mitochondria-specific dye dimethylaminostyryl pyridyl methyl iodide (DASPMI), or with MitoTrackerTM Green FM, a constitutive marker for mitochondria. Within individual myofibers we detected topological mitochondrial subsets with distinct flavoprotein autofluorescence levels, equally responding to induced rate changes of the oxidative phosphorylation. The flavoprotein autofluorescence levels of these subsets differed by a factor of four. This heterogeneity was substantiated by flow-cytometric analysis of flavoprotein and DASPMI fluorescence changes of individual mitochondria isolated from mice skeletal muscle. Our data provide direct evidence that mitochondria in single myofibers are distinct subsets at the level of an intrinsic fluorescent marker of the mitochondrial NAD-redox system. Under the present experimental conditions these subsets show similar functional responses.

Animals↗
PubMed1998

Diagnostic relevance of interleukin pattern, acute-phase proteins, and procalcitonin in early phase of post-ERCP pancreatitis.

Post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis has been suggested as a model for acute pancreatitis (AP), which allows evaluation of early alterations in the time course of the disease. The influence of the clinical course on procalcitonin (PCT), serum amyloid A (SAA), and several proinflammatory and inhibitory cytokines was evaluated in patients with AP following ERCP. Blood samples were prospectively collected from patients undergoing ERCP. The incidence of ERCP-induced pancreatic damage, defined as abdominal complaints, a threefold increase of serum lipase, and elevation of CRP from <10 to >20 mg/liter was 12.8% (12/94). Only mild clinical courses of acute pancreatitis were observed. PCT significantly increased in subjects with post-ERCP pancreatitis after 24 hr. However, PCT levels did not exceed 0.5 ng/ml in any patient. Interleukin-1 receptor antagonist (IL-1RA) began to differ from baseline 2 hr after ERCP, followed by interleukin-6 (IL-6, 6 hr), solubilized tumor necrosis factor-alpha receptor II (sTNF-alphaRII, 24 hr) and SAA (24 hr). Interleukin 10 (IL-10) showed marked interindividual variations with no obvious peak. Among all parameters evaluated, only peak values of IL-6 and IL-10 showed significant correlations with the reported pain score (r2 = 0.62/0.78), degree of ampullar irritation (r2 = NS/0.87), and the duration of ERCP (r2 = 0.58/0.76). No correlation was found with the volume of the injected contrast agent. We conclude that IL-10 and IL-6 appear to be useful to monitor patients after ERCP. The absence of any PCT elevation in the present study is in accordance with the clinical course of the patients who suffered from mild pancreatic damage without systemic or infectious complications.

Acute Disease↗
PubMed1998

Transforming growth factor beta is increased in plasma of patients with hematologic malignancies after transfusion of platelet concentrates.

BACKGROUND: Transforming growth factor beta 1 (TGF-beta 1) acts as a potent inhibitor of bone marrow proliferation. High concentrations were found in human platelets, which release this cytokine during storage. STUDY DESIGN AND METHODS: TGF-beta 1 levels during a storage period of 5 days were compared in the plasma of platelet concentrates prepared by apheresis or by the buffy coat method. In addition, TGF-beta 1 plasma levels were monitored in patients with hematologic malignancies before and after transfusion. RESULTS: TGF-beta 1 levels in the supernatant of platelet concentrates were found to be 55 times higher than those in the plasma of healthy volunteer donors. During storage, an additional increase was observed. Accordingly, the transfusion of platelet concentrates resulted in a significant increase of plasma TGF-beta 1 levels in patients with hematologic malignancies (before transfusion: 2.2 +/- 0.5 ng/mL; after transfusion: 2.9 +/- 0.6 ng/mL), and these higher levels persisted for at least 4 hours. CONCLUSION: Because TGF-beta 1 reduces the clonogenic capacity of hematopoetic progenitor cells, a myelosuppressive effect of platelet transfusions is suggested.

Adult↗
PubMed1997

Platelet-derived growth factor and fibroblast growth factor differentially regulate interleukin 1beta- and cAMP-induced nitric oxide synthase expression in rat renal mesangial cells.

Platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) regulate mesangial cell proliferation and matrix production in vitro and in vivo and crucially participate in the pathogenesis of glomerulonephritis. We investigated whether PDGF-BB and bFGF influence nitric oxide (NO) production, another important effector molecule in inflammatory glomerular injury. Inducible NO synthase (iNOS) induction in rat glomerular mesangial cells has been described in response to two principal classes of activating signals comprising inflammatory cytokines such as interleukin 1beta (IL-1beta) or elevation of cyclic AMP (cAMP). Treatment of mesangial cells with IL-1beta induces iNOS activity measured as nitrite levels in cell culture supernatants. Coincubation of mesangial cells with PDGF-BB inhibits production of nitrite by approximately 95%. This effect can be reversed by the simultaneous incubation of PDGF-BB in the presence of calphostin C, a potent and selective inhibitor of protein kinase C. In contrast, incubation of cells in the presence of bFGF potentiates IL-1beta-induced production of NO and is functionally associated with an increased rate of apoptosis of mesangial cells. Western blot analyses reveal that PDGF-BB causes a decrease in the formation of iNOS protein which is preceded by decreases in iNOS mRNA steady state levels. bFGF drastically increases iNOS protein levels as well as the corresponding iNOS mRNA steady state levels. Nuclear run-on experiments reveal that PDGF-BB decreases the IL-1beta-induced transcription rate of the iNOS gene, whereas bFGF potentiates the transcriptional activity of the iNOS gene. Northern blot analyses demonstrate that bFGF strongly potentiates the formation of IL-1beta-induced IL-1 type I receptor mRNA levels, whereas PDGF-BB has no effect. Treatment of mesangial cells with the membrane-permeable cAMP analogue N6, O-2'-dibutyryladenosine 3',5'-phosphate (Bt2cAMP) markedly increases the production of nitrite. Whereas PDGF-BB does not affect cAMP-induced nitrite levels, bFGF strongly potentiates them. PDGF-BB alters neither cAMP-induced iNOS protein levels nor the corresponding iNOS mRNA steady state levels. By contrast, bFGF superinduces cAMP-stimulated iNOS protein and iNOS mRNA levels. These changes by bFGF are due to an increase in cAMP-induced transcriptional activity of the iNOS gene which is not affected by PDGF-BB. In summary, the results show that PDGF and bFGF differentially regulate iNOS expression in mesangial cells in a stimulus-specific way. The timely sequence of expression of PDGF and bFGF and of cytokines like IL-1 will crucially determine the amounts of NO produced and the functional consequences thereof in the course of progressive glomerular diseases.

Animals↗
PubMed1997

Mechanisms of suppression of inducible nitric-oxide synthase (iNOS) expression in interferon (IFN)-gamma-stimulated RAW 264.7 cells by dexamethasone. Evidence for glucocorticoid-induced degradation of iNOS protein by calpain as a key step in post-transcriptional regulation.

The murine macrophage cell line RAW 264.7 expresses inducible nitric-oxide synthase (iNOS) activity upon stimulation with interferon (IFN)-gamma and/or bacterial lipopolysaccharide. We have studied the mechanisms by which the synthetic glucocorticoid dexamethasone suppresses IFN-gamma-stimulated iNOS expression in RAW 264.7 cells. Treatment of cells with dexamethasone reduces the formation of nitrite, one of the stable end products of NO production measured in culture supernatants with an IC50 of 9 nM. The reduction of iNOS activity is caused by decreased iNOS protein levels as assessed by immunoblotting using a specific anti-iNOS antibody. Dexamethasone treatment also reduces the formation of iNOS mRNA steady state levels to about 50% in IFN-gamma-stimulated cells. This is due to decreased iNOS gene transcription and iNOS mRNA stability. More importantly, dexamethasone reduces the amount of iNOS protein by two additional mechanisms: reduction of the translation of iNOS mRNA and increased degradation of the iNOS protein. Using a specific protease inhibitor for the cysteine protease calpain I, N-acetyl-Leu-Leu-norleucinal (calpain inhibitor I), the enhanced proteolysis of the iNOS protein can efficiently be blocked, whereas other protease inhibitors such as tosyl-L-lysine chloromethyl ketone have no effect. Dexamethasone does not significantly alter calpain gene expression. Northern blot analyses reveal that calpain mRNA steady state levels are virtually not affected upon incubation of the cells with IFN-gamma and dexamethasone. Immunoprecipitation using a polyclonal anti-calpain antibody reveals that calpain protein levels are also not affected by the glucocorticoid. This is the first evidence that the iNOS protein is a molecular target for the cysteine protease calpain.

Animals↗
PubMed1997

Flow cytometric detection of mitochondrial dysfunction in subpopulations of human mononuclear cells.

At 488 nm argon-ion laser excitation human mononuclear cells emit flavoprotein-related autofluorescence signals. Approximately 60% of these are caused by the mitochondrial flavoproteins alpha-lipoamide dehydrogenase and electron transfer flavoprotein, having differences in their fluorescence emission spectra. At the emission wavelength of 530 nm the redox changes of alpha-lipoamide dehydrogenase fluorescence in human mononuclear cells can be monitored by flow cytometry. This allows the estimation of the steady-state reduction level of this flavoprotein being in redox equilibrium with the mitochondrial NAD-system. We applied this method to elucidate the possible impairment of mitochondrial function in subpopulations of mononuclear cells of patients harboring deletions of the mitochondrial DNA in skeletal muscle. In the monocyte fraction of three patients and in the lymphocyte fraction of one patient we observed in the presence of the mitochondrial substrate octanoate elevated steady-state reduction levels of alpha-lipoamide dehydrogenase. This is an indication for the presence of respiratory chain-inhibited mitochondria in mononuclear cell subpopulations of the described patients. These data were confirmed by conventional determinations of maximal oxygen consumption rates of digitonin-permeabilized cells. Therefore, the flow cytometric determination of flavoprotein-caused autofluorescence changes is a useful and sensitive method for the detection of an impairment of mitochondrial respiratory chain in subpopulations of heterogeneous cell suspensions.

Caprylates↗
PubMed1997

Transforming growth factor-beta 2 inhibits interleukin 1 beta-induced expression of inducible nitric oxide synthase in rat renal mesangial cells.

OBJECTIVE AND DESIGN: We have investigated whether transforming growth factor beta 2 (TGF-beta 2) influences the expression of inducible nitric oxide synthase (iNOS). MATERIAL: Rat renal mesangial cells exposed to the inflammatory cytokine interleukin 1 beta (IL-1 beta). RESULTS: Addition of TGF-beta 2 dose-dependently suppresses IL-1 beta-induced nitrite formation. Western and Northern blot analyses of mesangial cell extracts reveal that the inhibition of IL-1 beta-induced nitrite formation by TGF-beta 2 is due to decreased iNOS protein and iNOS mRNA steady state levels. Reduction of iNOS mRNA levels is due to decreased transcriptional activity of the iNOS gene under the action of TGF-beta 2 as shown by nuclear run on experiments. CONCLUSIONS: TGF-beta 2 is a potent inhibitor of iNOS expression acting by reducing the transcriptional activity of the iNOS gene.

Animals↗
PubMed1997

Suppression by cyclosporin A of interleukin 1 beta-induced expression of group II phospholipase A2 in rat renal mesangial cells.

1. We investigated whether cyclosporin A, a potent immunosuppressive drug, affects group II phospholipase A2. (PLA2; EC 3.1.1.4) induction in rat renal mesangial cells. 2. Previously we showed that the expression of group II PLA2 in rat renal mesangial cells is triggered by exposure of the cells to inflammatory cytokines such as interleukin 1 beta (IL-1 beta) or tumour necrosis factor alpha and agents that elevate cellular levels of cyclic AMP. Treatment of mesangial cells with IL-1 beta for 24 h induced PLA2 activity secreted into cell culture supernatants by about 16 fold. Incubation of mesangial cells with cyclosporin A inhibited IL-1 beta-induced PLA2 section in a dose-dependent fashion, with an IC50 value of 4.3 microM. Cyclosporin A did not directly inhibit enzymatic activity of PLA2. 3. Immunoprecipitation of radioactively labelled PLA2 protein from mesangial cell supernatants revealed that the inhibition of PLA2 activity is due to a suppression of PLA2 protein levels. This effect was preceded by a reduction of PLA2 mRNA steady state levels, as demonstrated by Northern blot analyses of total cellular RNA isolated from stimulated mesangial cells. 4. In order to evaluate whether cyclosporin A would affect the transcriptional activity of the PLA2 gene, we performed nuclear run on transcription experiments and provided evidence that the transcription rate of the PLA2 gene is reduced by cyclosporin A. 5. Previously we found that the nuclear transcription factor kappa B (NF kappa B) is an essential component of the IL-1 beta-dependent upregulation of PLA2 gene transcription. By electrophoretic mobility shift analysis, we demonstrated that cyclosporin A diminishes the formation of NF kappa B DNA-binding complexes, thus suggesting that this transcription factor is a target for cyclosporin A-mediated repression of PLA2 gene transcription. 6. The data presented in this study strongly suggest that the cellular mechanism involved in the IL1 beta-dependent transcriptional upregulation of the PLA2 gene in mesangial cells is a target for the action of cyclosporin A.

Animals↗
PubMed1997

Melatonin effects in a patient with severe REM sleep behavior disorder: case report and theoretical considerations.

REM sleep behavior disorder (RBD) is so far a possibly underestimated yet well-described sleep disorder. Its major impact is the vigorous sleep behavior that often results in injuries to the patient himself or to people sleeping nearby. We treated a 64-year-old male with a clinically and polysomnographically confirmed diagnosis of RBD with 3 mg melatonin, which led to a significant reduction of motor activity during sleep, as measured by actigraphy (p < 0.0001 in all analyzed movement parameters), and a full clinical recovery over a 5-month treatment period. RBD phenomena gradually returned after melatonin administration was stopped. After 2 months' treatment, polysomnography showed no major changes except an increase of REM sleep (13 vs. 17% of sleep period time) and a better preservation of REM-sleep-associated muscle atonia. Our results suggest that melatonin might be able to reinforce REM sleep in RBD patients by enhancing its active inhibition of motor activity.

Humans↗
PubMed1997

[Cellular and humoral functions in acute pancreatitis].

Infectious complications are the leading cause of death in acute pancreatitis. Individual factors of immune defence could be of significance, whether or not a patient develops a severe course with infectious complications. In a prospective 5-year trial including 72 patients, we investigated 29 cellular and humoral markers of the body's defence system for their potential to indicate the severity and course of acute pancreatitis. Complement factors C3 and C4 as well as immunoglobulins IgG, IgM and IgA were normal, in general. Measurable levels of IL-1 alpha, IL-1 beta, IL-2 and sIL-2R could be detected only occasionally. Values of alpha 1-AT, TNF-alpha, TNF alpha-Rp75, neopterin, sICAM-1, IL-8, IL-1RA and sIL-6R did not correlate with a severe course. Due to the high magnitude of increase, CRP, IL-6 and granulocyte elastase were the best indicators of the inflammatory process. Delayed-type hypersensitivity response was the only early predictor of a severe course. It was superior over other cellular markers such as monocyte count or CD4+/CD8+ ratio. In vitro function of polymorphonuclear granulocytes (PMN) was not adequate to the severity of the disease already during the first week of illness. During further course, PMN motility and capacities to produce reactive oxygen species even worsened. The compromized PMN function could explain the frequent development of infectious complications in patients suffering from severe pancreatitis. These results should encourage new concepts of infection prophylaxis using stimulants of cellular defence.

Acute Disease↗