Biomedical subjects

F Weitzel

Publications and source records attributed to F Weitzel.

4 recordsLinked to original sources

PubMed1994

Granulocyte colony-stimulating factor prophylaxis before operation protects against lethal consequences of postoperative peritonitis.

BACKGROUND: Postoperative peritonitis has a high mortality in human beings. It is accepted that cytokines are important mediators in pathophysiology of sepsis. The recent failure of clinical trials increased the necessity to proof new drugs in more clinically relevant animal models. The aim of this study was to examine the effect of granulocyte colony-stimulating factor (G-CSF) in addition to an antibiotic in postoperative peritonitis. METHODS: Dose-response curves and experimental conditions were developed in a total of 295 rats. The main experiment included three groups: control animals receiving a fecal inoculum, a group treated with antibiotic, and a third group receiving G-CSF in addition to the antibiotic. The main outcome was death, but in addition, serum tumor necrosis factor (TNF) level was determined. RESULTS: The mortality rate of 60% in antibiotic treated animals was considerably reduced by G-CSF to 20%. All animals of the control group died during the observation period of 120 hours. A correlation between TNF levels and mortality rate was observed. In G-CSF treated animals total suppression of TNF serum levels was accessible in contrast to the others. CONCLUSIONS: In a clinically relevant animal model G-CSF was effective as an additional concept of prophylaxis. These data are promising toward clinical trials.

Animals↗

PubMed1993

Selenoenzymes regulate the activity of leukocyte 5-lipoxygenase via the peroxide tone.

The variation of the selenium status of leukocytes was used as a tool to investigate the influence of selenium-containing glutathione peroxidases on the formation of 5-lipoxygenase metabolites in vitro and ex vivo. Selenium-deficient rat basophilic leukemia cells had < 1% of control glutathione peroxidase activity and 35% of control phospholipid hydroperoxide-glutathione peroxidase activity. Upon stimulation, these cells released an 8-fold amount of lipoxygenase metabolites compared to controls. No (5S)-hydroperoxyeicosatetraenoic acid was detectable in whole cells; however, it was found in homogenates of selenium-deficient cells. Addition of 0.25 microgram/ml selenium to selenium-deficient cells restored control phospholipid hydroperoxide-glutathione peroxidase activity within 8 h, whereas glutathione peroxidase activity needed 7 days. 12 h after resupplementation, selenium-deficient cells had 3% glutathione peroxidase and 100% phospholipid hydroperoxide-glutathione peroxidase activity compared to controls. Resupplemented cells released control amounts of 5-lipoxygenase metabolites, indicating that restoration of phospholipid hydroperoxide-glutathione peroxidase activity is associated with a selenium-adequate leukotriene metabolism. Leukocytes that were isolated from selenium-deficient rats released a 7-fold amount of total lipoxygenase metabolites compared to cells from control animals. By injecting normally fed rats with 500 micrograms/kg selenium as Na2SeO3, leukocyte phospholipid hydroperoxide-glutathione peroxidase activity was raised 8-fold within 114 h compared to controls. Leukocytes from these animals produced significantly less lipoxygenase metabolites than controls. These findings indicate that phospholipid hydroperoxide-glutathione peroxidase activity is primarily responsible for the reduction of 5-hydroperoxyeicosate-traenoic acid and therefore governs the actual activity of leukocyte 5-lipoxygenase via regulating the tone of endogenous hydroperoxides.

Animals↗

PubMed1992

Granulocyte colony-stimulating factor treatment protects rodents against lipopolysaccharide-induced toxicity via suppression of systemic tumor necrosis factor-alpha.

Pretreatment with recombinant human granulocyte CSF (G-CSF) protected mice in two different models of septic shock. Intravenous injection of 250 micrograms/kg G-CSF to mice prevented lethality induced by 5 mg/kg LPS. Injection of 50 micrograms/kg G-CSF protected galactosamine-sensitized mice against LPS-induced hepatitis. In either case, this protection was accompanied by a suppression of LPS-induced serum TNF activity. In contrast, when galactosamine-sensitized mice were pretreated with 50 micrograms/kg murine recombinant granulocyte/macrophage CSF instead of G-CSF and subsequently challenged with LPS, serum TNF activity was significantly enhanced and mortality was increased. The suppressive effect of G-CSF on LPS-induced TNF production was also demonstrated in rats. In vivo, no TNF was detectable in the blood of LPS-treated rats, which had been pretreated with G-CSF. Ex vivo, alveolar macrophages, bone marrow macrophages, Kupffer cells, or peritoneal macrophages prepared from G-CSF-treated rats produced significantly less TNF upon stimulation with LPS than corresponding populations from control rats. However, when these macrophage populations were incubated with G-CSF in vitro, LPS-induced TNF production was unaffected. These data suggest that the G-CSF-mediated suppression of TNF production is not a direct effect of G-CSF on macrophages. To examine whether, independent of the protection against LPS, G-CSF treatment still activated neutrophils, it was demonstrated that granulocytes from G-CSF-treated rats were primed for PMA-induced oxidative burst and for ionophore/arachidonic acid-stimulated lipoxygenase product formation. The experiments of this study support the notion that G-CSF is a negative feedback signal for macrophage-derived TNF-alpha production during Gram-negative sepsis.

Animals↗

PubMed1990

Phospholipid hydroperoxide glutathione peroxidase in various mouse organs during selenium deficiency and repletion.

An assay for the determination of the newly discovered selenoenzyme, phospholipid hydroperoxide glutathione peroxidase (PH-GPx) in biological material is described. Dietary selenium deficiency and repletion was used as a tool in order to modify this enzyme activity in various mouse organs and to compare it to the activity of the 'classical' selenium-dependent glutathione peroxidase (GPx) (EC 1.11.1.9). A semipurified diet containing less than 12 ppb Se was used for depletion. Controls received this diet supplemented with 500 ppb Se in the form of Na2SeO3. The results showed that a rapid loss of GPx activity occurred in liver, kidney and lungs of selenium-deficient mice which reached undetectable levels within 130 days. In the heart, about 24% of control GPx activity was still present. In contrast, PH-GPx activity was more slowly depleted by Se deficiency and resulted in residual activities ranging from 30 to 70% in the different organs even after 250 days of depletion. In repletion experiments with a single application of 10 or 500 micrograms/kg Se, only the high dose restored either enzyme activity. The data demonstrate that the need for selenium of the two glutathione peroxidases is different. A markedly distinct organ distribution of both enzymes suggests that the heart may be the organ more sensitive to oxidative stress.

Animals↗