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Biomedical subjects

A Schiesser

Publications and source records attributed to A Schiesser.

At least 19 recordsLinked to original sources
PubMed2003

Primary structure and transcription analysis of a laccase-encoding gene from the basidiomycete Trametes trogii.

A cDNA coding for laccase was isolated from the white-rot fungus Trametes trogii 201. This cDNA corresponded to the lcc1 gene, which coded for a precursor protein of 517 amino acids with a 21 amino acid signal peptide. Comparison of the deduced sequence with known laccases showed that this enzyme was most closely related to Lac1 from basidiomycete PM1 and Trametes C30 (98% similarity). The expression of lcc1 was analysed under different growth conditions; transcription of this gene was enhanced by the addition of organic nitrogen to the medium. The level of lcc1 transcription was higher when T. trogii was grown on synthetic medium supplemented with yeast extract rather than mycological peptone or tryptone. The transcription data were in agreement with total laccase activity measured in the supernatant and suggested that laccase production and lcc1 transcription are coordinately regulated in this organism. The lcc1 cDNA was expressed in the methylotrophic yeast Pichia pastoris and the detection of laccase activity indicated that this cDNA encodes a laccase.

Basidiomycota↗
PubMed2001

Possible role of TNF on procalcitonin release in a baboon model of sepsis.

Procalcitonin (PCT) has been described as an early and discriminating marker of bacteria-associated sepsis in patients. However, little is known of its source and actions, especially with regard to its relation to tumor necrosis factor (TNF). TNF is responsible for the release of several other mediators of sepsis e.g., chemokines. We tested the hypothesis that plasma PCT levels during sepsis differ with regard to the degree of TNF availability. Severe hyperdynamic sepsis was induced in baboons (n = 14) by i.v. infusion of live E. coli (approximately 2 x 10(9) colony-forming units/kg) over 2 h. Animals were pretreated 2 h before E. coli either with 1 mg/kg humanized anti-TNF antibody (CDP571) or placebo (Ringer solution). Plasma PCT levels at baseline was barely detectable, but increased to about 4000 pg/mL at 4 h after E. coli infusion. Levels were maximal between 8 and 24 h and had returned nearly to baseline at 72 h. Although no TNF could be measured in the treated group, PCT levels were not different between the placebo and the TNF antibody treatment group. We conclude that PCT levels are not dependent on the systemic presence of TNF in an E. coli sepsis model in baboons. Such sepsis induced PCT release is clearly different from the previously reported PCT release during infusion of rhTNF in volunteers or chimpanzees.

Animals↗
PubMed2000

Bioconversion of ferulic acid into vanillic acid by means of a vanillate-negative mutant of Pseudomonas fluorescens strain BF13.

From a ferulic-acid-degrading Pseudomonas fluorescens strain (BF13), we have isolated a transposon mutant, which retained the ability to bioconvert ferulic acid into vanillic acid but lost the ability to further degrade the latter acid. The mutant, BF13-97, was very stable, and therefore it was suitable to be used as a biocatalyst for the preparative synthesis of vanillic acid from ferulic acid. By use of resting cells we determined the effect on the bioconversion rate of several parameters, such as the addition of nutritional factors, the concentration of the biomass, and the carbon source on which the biomass was grown. The optimal yield of vanillic acid was obtained with cells pregrown on M9 medium containing p-coumaric acid (0.1% [wt/vol]) as a sole carbon source and yeast extract (0.001% [wt/vol]) as a source of nutritional factors. Under these conditions, 1 mg (wet weight) of biomass produced 0.23 mg of vanillic acid per h. The genomic region of BF13-97 flanking the transposon's site of insertion was cloned and sequenced revealing two open reading frames of 1,062 (vanA) and 954 (vanB) bp, respectively. The van genes are organized in a cluster and encode the subunits of the vanillate-O-demethylase, which catalyzes the first step of the vanillate catabolism. Amino acid sequences deduced from vanA and vanB genes were shown to have high identity with known VanAs and VanBs from Pseudomonas and Acinetobacter spp. Highly conserved regions known to exist in class IA oxygenases were also found in the vanillate-O-demethylase components from P. fluorescens BF13. The terminal oxygenase VanA is characterized by a conserved Rieske-type [2Fe-2S](R) ligand center. The reductase VanB contains a plant-type ferredoxin [2Fe-2S](Fd), flavin mononucleotide, and NAD-ribose binding domains which are located in its C-terminal and N-terminal halves, respectively. Transfer of wild-type vanAB genes to BF13-97 complemented this mutant, which recovered its ability to grow on either vanillic or ferulic acid.

Base Sequence↗
PubMed1995

Thrombomodulin release in baboon sepsis: its dependence on the dose of Escherichia coli and the presence of tumor necrosis factor.

This study was designed to test whether thrombomodulin is shed in septic baboons and whether shedding is blocked by antibody to tumor necrosis factor (anti-TNF). Live Escherichia coli were injected intravenously into 24 baboons according to one of the following regimens: 5 x 10(8) or 2 x 10(9) cfu/kg (n = 6/8), 2 x 10(9) cfu/kg with placebo (n = 5), or pretreatment with 1 mg/kg anti-TNF 2 h before E. coli injection (n = 5). E. coli administration resulted in a significant release of thrombomodulin in a dose-dependent manner; however, thrombomodulin release was significantly attenuated (180 to 40 ng/mL) by anti-TNF pretreatment. This is parallel to the reduction of neutrophil activation (elastase). These results provide evidence for an E. coli dose-related and TNF-dependent thrombomodulin release into the plasma of septic baboons and suggest a possible role of anti-TNF in protection of the endothelium.

Alanine Transaminase↗
PubMed1993

Tumor necrosis factor is a mediator of phospholipase release during bacteremia in baboons.

Phospholipase A (PLA) activity is elevated in plasma after polytrauma and in sepsis. During both situations, tumor necrosis factor (TNF) and free fatty acids (FFAs) are also increased. To determine whether there is a relationship between the changes in PLA and in TNF that occur during sepsis, we used a primate model of bacteremia. Live Escherichia coli (5 x 10(8) colony-forming units/kg) was injected into anesthetized baboons (n = 10). Four of these animals were pretreated with an anti-TNF antibody (anti-TNF Ab, 15 mg/kg). After the administration of bacteria (2 h), the plasma TNF was 10.2 +/- 3.2 ng/ml. PLA and FFA reached their maximum values of 191 +/- 14 U/l and 1.5 +/- 0.3 mM at 10 and 24 h after the injection of bacteria, respectively. In the animals treated with anti-TNF Ab, plasma TNF was undetectable; the highest values recorded for PLA and FFA were 71 +/- 23 U/l and 0.7 +/- 0.3 mM, respectively. Thus TNF appears to be an important mediator of PLA release during sepsis.

Animals↗
PubMed1990

Effect of the PAF antagonist BN 52021 in ovine endotoxin shock.

It has been reported that a platelet-activating factor (PAF) antagonist ONO-6240 had little effect on pulmonary hypertension and lung lymph in sheep injected with endotoxin lipopolysaccharide (LPS); consequently we evaluated a new PAF antagonist, BN 52021. Twelve adult sheep were surgically prepared for chronic study including lung lymph drainage. LPS (S. abortus equii, 36 ng/kg/h over 7 h) was then administered with (BN group) or without (control group) infusion (1 h before LPS) of the PAF antagonist BN 52021 (4 mg/kg/30 min). Comparison of the hemodynamic data between the control group and the BN group reveals an almost identical pattern. In contrast, we find differences in the pulmonary response of the two experimental groups. The early elevation of pulmonary artery pressure after LPS administration is less in the treatment group, as is the duration of pulmonary hypertension. Similarly, thromboxane levels are lower in the treated animals. The increases in lymph flow (LQ) and transvascular protein clearance (L/P X LQ) as well as the protein flux were less prominent in the treatment group. The mean lymph flow per hour was significantly higher in the control group. The mean lymph flow per hour was significantly higher in the control group, as were the corresponding parameters for clearance and protein flux. Thus the pulmonary vasculature and lung fluid balance disruption produced by LPS was markedly reduced by treatment with the PAF blocker.

Animals↗
PubMed1989

Manganese accumulation in yeast cells. Electron-spin-resonance characterization and superoxide dismutase activity.

Manganese accumulation was studied by room-temperature electron spin resonance (ESR) spectroscopy in Saccharomyces cerevisiae grown in the presence of increasing amounts of MnSO4. Mn2+ retention was nearly linear in intact cells for fractions related to both low-molecular-mass and macromolecular complexes ('free' and 'bound' Mn2+, respectively). A deviation from linearity was observed in cell extracts between the control value and 0.1 mM Mn2+, indicating more efficient accumulation at low Mn2+ concentrations. The difference in slopes between the two straight lines describing Mn2+ retention at concentrations lower and higher than 0.1 mM, respectively, was quite large for the free Mn2+ fraction. Furthermore it was unaffected by subsequent dialyses of the extracts, showing stable retention in the form of low-molecular-mass complexes. In contrast, the slope of the line describing retention of 'bound' Mn2+ at concentrations higher than 0.1 mM became less steep after subsequent dialyses of the cell extracts. This result indicates that the macromolecule-bound Mn2+ was essentially associated with particulate structures. In contrast to Cu2+, Mn2+ had no effect on the major enzyme activities involved in oxygen metabolism except for a slight increase of cyanide-resistant Mn-superoxide dismutase activity, due to dialyzable Mn2+ complexes.

Electron Spin Resonance Spectroscopy↗
PubMed1989

Dog bone less osteogenetic than rat bone. Bone-matrix transplants in nude rats.

Demineralized bone matrix and bone-matrix gelatin prepared from cortical rat bone, and from cortical and cancellous canine bone were implanted into muscle pouches of nude rats for 6 weeks. Evaluation was done by histology, histomorphometry, and determination of alkaline phosphatase. Rat matrix consistently induced new bone and high phosphatase levels. Canine matrix induced but small amounts of bone and lower phosphatase levels, with cortical matrix somewhat more inductive than cancellous matrix; demineralized cancellous bone matrix from the dog was the only material tested not showing any inductivity. Irrespective of bone type or species, gelatin had clearly higher induction capacity than demineralized bone matrix.

Alkaline Phosphatase↗
PubMed1989

The influence of fibrin sealant on demineralized bone matrix-dependent osteoinduction. A quantitative and qualitative study in rats.

Allogeneic demineralized bone matrix (DBM) and bone matrix gelatin (BMG) were implanted with or without fibrin sealant (FS) ectopically (abdominal wall) and orthotopically (7-mm trepanation defect) in 38 male Sprague-Dawley rats. Evaluation was done by descriptive histology, histomorphometry of orthotopic implants, and determination of alkaline phosphatase in ectopic implants. The observation period was 21 days with ectopic implantation and 26 days with orthotopic implantation. In all ectopic specimens, new bone developed without any qualitative difference between specimens with and without FS. The alkaline phosphatase activity did not change significantly upon addition of FS. Morphometry revealed slight differences between the groups with and without FS. The peripheral bone deposits in the BMG + FS group, was significantly larger than in the BMG group. These investigations demonstrated neither a clearly positive nor negative effect of FS on ectopic osteoinduction or BMG-dependent osteoregeneration.

Alkaline Phosphatase↗
PubMed1988

Oxygen-independent induction of enzyme activities related to oxygen metabolism in yeast by copper.

Aerobic growth of Saccharomyces cerevisiae in the presence of CuSO4 (between 0.1 and 1 mM) caused a generalized induction of major enzyme activities involved in 'housekeeping' routes of oxygen metabolism (cytochrome oxidase, glutathione peroxidases and catalase) which were comparable to or higher than that observed with Cu,Zn-superoxide dismutase. Fumarase and glutathione transferase, tested as controls for oxygen-unrelated activities, were found to decrease under the same conditions. In the absence of oxygen, copper addition to yeast resulted in significant increases of Cu,Zn-superoxide dismutase and glutathione peroxidases and a slight increase of cytochrome oxidase, with catalase remaining undetectable irrespective of whether or not copper was present. Other metal ions tested (Mn2+, Co2+) were unable to produce such effects. It is concluded that copper has a general inducing effect on enzymes related to metabolism of oxygen and oxygen derivatives, which is mediated neither by formation of O2-. and H2O2 nor by interaction with copper-specific apoproteins. These results point to a general role of copper as regulator of the expression of major enzyme activities involved in biological oxygen activation.

Aerobiosis↗
PubMed1988

Microbiological quality of fresh pasta dumplings sold in Bologna and the surrounding district.

The microbiological quality of fresh pasta dumplings sold in Bologna and the surrounding district was evaluated. A total of 60 lots (300 subsamples) of fresh pasta dumplings, both 'home-made' and manufactured, were analysed for aerobic plate count (APC), coliforms (total and fecal), Staphylococcus aureus, Clostridium perfringens and Salmonella spp. Thirty one of the 39 lots of 'home-made' pasta were found to exceed APC standards and six lots exceeded S. aureus standards. Five (24%) and six (29%) lots of the manufactured pasta were found to be unsatisfactory as regards APC standards and S. aureus standards respectively. The results obtained indicated that a high percentage of samples had a contamination of fecal origin. No Cl. perfringens or Salmonella spp. were found.

Bacteria↗
PubMed1988

The elastase-inhibitor eglin has no effect in an ovine model of endotoxemia.

Small doses of endotoxin have been shown to induce pulmonary microvascular injury in sheep, possibly by the action of granulocytes. Eglin, a potent inhibitor of neutrophil elastase, was tested in an ovine model of endotoxemia. The experiment was performed in 12 unanesthetized chronically instrumented sheep with a lung lymph preparation. Endotoxin (S. abort. equii) was infused at 24 ng/(kg x h) with application of 20 mg/kg eglin 1 h before endotoxin in the treatment group and followed by 5 mg/(kg x h). No significant improvement due to the treatment was seen for either cardiovascular status (pulmonary and systemic vascular resistance) or permeability changes in the lung (lymph flow and lymph/plasma protein ratio), although sufficient eglin concentrations were achieved in plasma and lymph. The lack of an effect of eglin might be because higher concentrations are needed to block elastase-like activity of ovine granulocytes or because of a minor role for neutrophil elastase in this shock model.

Animals↗
PubMed1988

Irradiation-sterilization of rat bone matrix gelatin.

Bone matrix gelatin induces bone formation in muscle, and when implanted orthotopically it improves bone repair. Co-60 sterilization of bone gelatin impairs the protein-bound induction mechanisms. Gelatin samples nonirradiated or irradiated by 25 or 50 kGy were implanted into a pouch in the abdominal wall of Sprague-Dawley rats, as well as into a 7-mm calvarial defect. Evaluation was done by histologic studies, histomorphometry of orthotopic implants, and determination of alkaline phosphatase in ectopic implants. Gelatin irradiated with 50 kGy was absorbed in the muscle bed without evidence of any specific host reaction. Irradiation of 25 kGy led to histologically confirmed ectopic bone formation, but the wet weight of the explants was only half that of the nonirradiated control samples. Alkaline phosphatase activity was equal in both of these groups. With orthotopic implantation, neither a histologic nor a morphometric effect was seen with 25 kGy. Loss of osteoinduction with 25-kGy irradiation is apparently masked by osteoconductive mechanisms with orthotopic implantation.

Alkaline Phosphatase↗
PubMed1987

Glutathione peroxidase in yeast. Presence of the enzyme and induction by oxidative conditions.

The presence of glutathione peroxidase activity is reported for the first time for a wild type strain of Saccharomyces cerevisiae. Both forms of enzyme, i.e. that specifically active toward H2O2 alone and that decomposing also organic peroxides, were found to be present. The H2O2 specific form disappeared when cells were grown in the absence of oxygen, while the other form was much increased under the same conditions. Addition of copper to the culture greatly increased both forms. The results show that glutathione peroxidase is to be included, as an important component that is also highly responsive to oxidative environments, in the enzyme defense system of yeast against oxidative damage.

Aerobiosis↗