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M Hartmann

Publications and source records attributed to M Hartmann.

At least 145 records · Page 8Linked to original sources
PubMed1999

A method for the preparation of Tetrahymena thermophila phospholipase A1 suitable for large-scale production.

A rapid and economical method for the purification of phospholipase A1 (PLA1) from the extracellular medium of the ciliate Tetrahymena thermophila is presented. Essentially, the procedure, here designated as purification by selective interaction (PSI), entails the incubation of media containing PLA1 with liposomes made of soy bean phospholipids. The PLA1-lipid complexes are precipitated by the addition of CaCl2 and collected by centrifugation. Elution of the PLA1 is effected by treating the complexes with 40% dimethylformamide, a reversible inhibitor of this enzyme, which is easily removed by dialysis. In combination with DEAE cellulose ion exchange chromatography, PSI yielded homogeneous PLA1 preparations with a 14% recovery and a 416-fold increase in specific activity. This procedure, which can be completed within 1 day, may prove useful for the isolation of phospholipases from other sources. This practical method for the purification of a microbial PLA1 opens the way to large-scale production of these types of enzyme, which are not as yet commercially available.

Animals↗
PubMed1999

Zinc protoporphyrin and percentage of hypochromic erythrocytes as markers of functional iron deficiency during therapy with erythropoietin in patients with advanced acquired immunodeficiency syndrome.

BACKGROUND: We assessed zinc protoporphyrin (ZPP) and the percentage of hypochromic erythrocytes in patients with advanced acquired immunodeficiency syndrome (AIDS) treated with recombinant erythropoietin (rhEPO). METHODS: Patients received 150 IU rhEPO subcutaneously every second day for 10 days, and 150 IU rhEPO plus 62.5 mg of intravenous iron every second day for an additional 10 days. RESULTS: Before rhEPO therapy, ZPP was at 64.3 +/- 27.3 micromol/mol heme and the percentage of hypochromic erythrocytes was elevated at 9.7%, indicating mild functional iron deficiency. Ferritin was 1,002 +/- 956 microg/L, with transferrin saturation of 19.1 +/- 9.7%. Under rhEPO alone, ZPP rose to 80.1 +/- 21.6 micromol/mol heme and the percentage of hypochromic red cells rose to 22.9 +/- 4.7%; ferritin fell to 705 +/- 601 microg/L and transferrin saturation fell to 12 +/- 6.3%. When rhEPO was supplemented with iron, ZPP fell to 70.4 +/- 20.5 micromol/mol heme, the percentage of hypochromic red cells fell to 14.7 +/- 3.4%; ferritin was unchanged at 771 +/- 62 microg/L and transferrin saturation rose to 20.5 +/- 5.5%. CONCLUSIONS: In contrast to ferritin and transferrin saturation, ZPP and the percentage of hypochromic erythrocytes effectively detect the functional iron deficiency under rhEPO therapy in advanced AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Crystallization and preliminary X-ray analysis of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (tyrosine inhibitable) from Saccharomyces cerevisiae.

3-Deoxy-D-arabino-heptulosonate-7-phosphate synthase (E.C. 4.1.2.15) catalyses the first step in the biosynthesis of aromatic amino acids: the condensation of phophoenolpyruvate and erythrose 4-phosphate to 3-deoxy-D-arabino-heptulosonate-7-phosphate. Diffraction-quality crystals of the tyrosine-inhibitable form of the enzyme from Saccharomyces cerevisiae have been obtained by the hanging-drop vapour-diffusion method in the presence of polyethylene glycol. The crystals belong to the triclinic space group P1, with unit-cell parameters a = 81.5, b = 94.0, c = 104.6 A, alpha = 65.5, beta = 85.2, gamma = 75.0 degrees, and can be flash-cooled using glycerol as a cryoprotectant. A data set to 2.3 A has been collected at 120 K.

3-Deoxy-7-Phosphoheptulonate Synthase↗
PubMed1999

Contaminations occurring in fungal PCR assays.

Successful in vitro amplification of fungal DNA in clinical specimens has been reported recently. In a collaboration among five European centers, the frequency and risk of contamination due to airborne spore inoculation or carryover contamination in fungal PCR were analyzed. The identities of all contaminants were specified by cycle sequencing and GenBank analysis. Twelve of 150 PCR assays that together included over 2,800 samples were found to be contaminated (3.3% of the negative controls were contaminated during the DNA extraction, and 4.7% of the PCR mixtures were contaminated during the amplification process). Contaminants were specified as Aspergillus fumigatus, Saccharomyces cerevisiae, and Acremonium spp. Further analysis showed that commercially available products like zymolyase powder or 10x PCR buffer may contain fungal DNA. In conclusion, the risk of contamination is not higher in fungal PCR assays than in other diagnostic PCR-based assays if general precautions are taken.

Acremonium↗
PubMed1999

Effect of hyperoxia and hypoxia on subcutaneous tissue gases and pH. An experimental study in pigs.

The effect of different fractions of inspired oxygen on subcutaneous oxygen tension, carbon dioxide tension and pH in relation to arterial and mixed venous blood gases and pH and hemodynamic variables was evaluated in 13 domestic pigs. Subcutaneous, arterial and mixed venous oxygen tensions were closely correlated (r = 0.94). A minor significant increase in subcutaneous carbon dioxide tension was noted during hyperoxia (p < 0.05). A major increase (33%) was noted during the last step of hypoxia, when arterial and mixed venous carbon dioxide tensions increased only 12 and 17%, respectively. A minor decrease in subcutaneous pH was noted during hyperoxia (p < 0.05) and a major decrease during hypoxia (p < 0.05). Measurements of subcutaneous tissue gases and pH are indicators of oxygen utilization during hyper- and hypoxia.

Animals↗
PubMed1999

Prognostic factors in seminomas with special respect to HCG: results of a prospective multicenter study. Seminoma Study Group.

OBJECTIVE: In a prospective multicenter trial, it was our intention to elucidate clinical prognostic factors of seminomas with special reference to the importance of human chorionic gonadotropin (HCG) elevations in histologically pure seminomas. METHODS: Together with 96 participating urological departments in Germany, Austria, and Switzerland, we recruited 803 seminoma patients between 1986 and 1991. Out of 726 evaluable cases, 378 had elevated, while 348 had normal HCG values in the cubital vein. Histology was reviewed by two reference pathologists. HCG levels were determined in local laboratories and in a study laboratory. Standard therapy was defined as radiotherapy in stages I (30 Gy) and IIA/B (36 Gy) to the paraaortal and the ispilateral (stage I) and bilateral (stage IIA/B) iliac lymph nodes; higher stages received polychemotherapy and surgery in case of residual tumor masses. Statistics included chi-square tests, linear Cox regression, and log-rank test. RESULTS: The HCG elevation is associated with a larger tumor mass (primary tumor and/or metastases). HCG-positive and HCG-negative seminomas had no different prognostic outcome after standard therapy. The overall relapse rate of 6% and the survival rate of 98% after 36 months (median) indicate an excellent prognosis. The calculation of the relative risk of developing a relapse discovered only stage of the disease and elevation of the lactate dehydrogenase concentration and its prolonged marker decay as independent prognostic factors for seminomas. A more detailed analysis of the prognostic significance of the stage revealed that the high relapse rate in stage IIB seminomas after radiotherapy (24%) is responsible for this result. CONCLUSIONS: We conclude that HCG-positive seminomas do not represent a special entity. Provided standard therapy is applied, HCG has no influence on the prognosis. Patients with stage IIB disease should be treated with chemotherapy because of the demonstrated higher relapse rate outside the retroperitoneum.

Biomarkers, Tumor↗
PubMed1999

Viral infections in free-living populations of the European wildcat.

While the importance of viral infections is well studied in domestic cats, only limited information is available on their occurence and prevalence in the European wildcat (Felis silvestris silvestris). The aim of this study was to determine the prevalence of antibodies to feline coronavirus (FCoV), calicivirus (FCV), herpesvirus (FHV), parvovirus (FPV), immunodeficiency virus (FIV), leukemia virus (FeLV), and FeLV antigenemia in 51 European wildcat sera. Samples were collected between 1996 and 1997 from wildcat populations in France, Switzerland, and Germany. Antibodies to FCoV were detected in two cats (4%) and FCoV RNA was detected in feces of one of these two cats. Antibodies to FCV, FHV and FPV were found at relatively low frequencies of 16%, 4%, and 2%, respectively. Antibodies to FIV were not detected. Although antigen and antibodies to FeLV were detected in 49%, and 75%, respectively, no evidence of FeLV-associated pathology was found. From the low prevalence of FCoV, FCV, FHV and FPV infections and from the fact that the European wildcats live solitarily, it was concluded that these viral infections do not spread readily within a population. Therefore, it may be assumed that release into the wild of European wildcats bred in captivity would not bring about a high risk of introducing of these viral infections to the free-ranging wildcats. As an exception, wildcats should be tested for absence of FIV infection before release if they were at risk to acquire this infection from domestic cats.

Animals↗
PubMed1999

Pantoprazole lacks induction of CYP1A2 activity in man.

OBJECTIVE: This drug-drug interaction study investigated the potential influence of the proton pump inhibitor pantoprazole on the CYP1A2 activity as assessed by urinary excretion of caffeine metabolites. SUBJECTS, MATERIALS AND METHODS: 12 healthy, non-smoking volunteers underwent two treatment periods of 7 days each in randomized order with once-daily oral intake of 40 mg pantoprazole (test) or placebo (reference). On days 6 and 7 of both periods, 200 mg caffeine was administered two hours after pantoprazole intake, i.e. at the expected t(max) of pantoprazole serum concentrations. Urinary excretion of the caffeine metabolites 1X, 1U, AFMU, 17U was measured up to 8 hours after caffeine intake. In accordance with recent guidelines on drug-drug interactions, lack of interaction was handled as an equivalence problem. RESULTS: Point estimate and 90% confidence intervals (CI) of the respective ratios test/reference were 0.91 (0.81, 1.03) for (1X + 1U + AFMU)/17U, indicative for CYP1A2 activity, 1.03 (0.94, 1.13) for AFMU/1X (N-acetyl transferase activity) and 1.01 (0.94, 1.09) for 1U/1X (xanthine oxidase activity). CONCLUSION: Pantoprazole does not induce CYP1A2 activity, consistent with previous findings following theophylline administration, nor does it have any influence on N-acetyl-transferase or xanthine oxidase activity.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1999

Extradural spinal hemangioblastomas: report of two cases.

Two cases of predominantly extraspinally extra- and intradural spinal cord hemangioblastomas in two patients each with and without von Hippel-Lindau-disease are reported. Preoperative MRI and angiographic findings are presented and the differential diagnosis is discussed. The surgical procedure is described and the literature of hemangioblastomas in this rare localization is reviewed. Improvements in both radiologic diagnosis and microsurgical techniques, and consequent screening programs will enhance life expectancy in patients afflicted with von Hippel-Lindau disease.

Adult↗
PubMed1999

Reduction of the bacterial load by the silver-coated endotracheal tube (SCET), a laboratory investigation.

Microaspiration enabled by high-volume-low-pressure cuffed endotracheal tubes is the most likely explanation for ventilator-associated pneumonia. To decontaminate the secretion at the proximal end of the cuff we developed a silver-coated endotracheal tube (SCET). In an in vitro model we investigated the efficacy of SCET to lower the bacterial load of secretion and aspirate. We developed a continuously contaminated and mechanically ventilated oropharynx-larynx-lung model to investigate the reduction of the bacterial count by SCET compared to controls. The model was continuously contaminated via the oropharynx-larynx with Pseudomonas aeruginosa ATCC 27853. During the investigation period of 50 hours the bacterial count of oropharynx-larynx and lung was measured as colony-forming-units/ml. In addition, the characteristic curve of silver ion release of SCET was determined. SCET significantly reduced the bacterial count in oropharynx-larynx at all timepoints (p < 0.05). In lung the bacterial count was significantly lower beginning with the 36th hour of recording (p < 0.05). A reduction of greater than 2 log was found from 28 hours on in oropharynx-larynx and from 50 hours on in lung. The release of silver ions was very rapid and was described by a mono-exponential function with a time-constant tau of about 60 minutes and a saturation concentration of 200 +/- 80 microg/l. SCET showed a significant inhibition of growth of P. aeruginosa in the continuously contaminated and mechanically ventilated oropharynx-larynx-lung model. SCET by thus might be helpful in reducing ventilator-associated pneumonia.

Bacterial Infections↗
PubMed1999

Disseminated Penicillium marneffei infection in an HIV-positive female from Thailand in Germany.

We report the case of a 33 year old Thai female, who was married in Germany for eight years and used to travel to Thailand every year for several weeks. She presented with abdominal and back pain, prolonged fever, generalized lymphadenopathy, and a recent history of oral thrush. She was diagnosed HIV positive with initial CD4 counts of 18/microliter and an HI virus load of 59,000 copies/ml. Antiviral therapy was installed with zidovudin, lamivudin, and efavirenz. Abdominal CT scans revealed greatly enlarged abdominal lymph nodes. Fine needle aspirates of cervical and retroperitoneal lymph nodes, sputum samples, blood samples, and a bone marrow biopsy were microscopically positive for Penicillium marneffei and grew P. marneffei. The isolates were sensitive to amphotericin B, flucytosine, itraconazole, and fluconazole. Both universal and specific fungal polymerase chain reaction assays were positive in various samples. Serum Aspergillus galactomannan antigen, which is known to crossreact with P. marneffei, was elevated and subsequently used for monitoring of therapy. With antifungal treatment (intravenous amphotericin B 0.6 mg/kg/d for two weeks, oral itraconazole 400 mg/d for 10 weeks and 200 mg/d as maintenance therapy), the fever declined in 6 days, the size of the enlarged lymph nodes gradually decreased in the CT scans, and the initial abdominal and back pain vanished.

Adult↗
PubMed1998

NH2-terminal structural motifs in staphylokinase required for plasminogen activation.

Staphylokinase (Sak) forms an inactive 1:1 stoichiometric complex with plasminogen which requires both conversion of plasminogen to plasmin and hydrolysis of the Lys10-Lys11 peptide bond of Sak to become a potent plasminogen activator (Schlott, B., Guhrs, K.-H., Hartmann, M., Rocker, A., and Collen, D. (1997) J. Biol. Chem. 272, 6067-6072). Exposure of a positively charged NH2-terminal amino acid after hydrolysis of Sak is a major determinant of the plasminogen-activating potential, but in itself is neither necessary nor sufficient. Here, the structural motifs of the NH2-terminal region Lys11-Gly-Asp-Asp-Ala-Ser16-Tyr-Phe-Glu of processed Sak, required for plasminogen activating potential, were studied by deletion and substitution mutagenesis. Expression in Escherichia coli of variants with deletion of 11, 14, 15, or 16 NH2-terminal amino acids yielded correctly processed but inactive molecules. Expression of their homologues with the NH2-terminal amino acid substituted with Lys-generated derivatives from which the NH2-terminal initiation Met was no longer removed, yielding inactive (</= 10%) Sak42DDeltaN11(M),G12K, active (>50%) Sak42DDeltaN14(M), A15K and Sak42DDeltaN15(M),S16K, and inactive Sak42DDeltaN16(M),Y17K. Lys variants without NH2-terminal Met, generated from fusion proteins in which a His6 tag and a factor Xa recognition sequence were linked to the NH2 terminus of the Sak variants, were indistinguishable from their NH2-terminal Met-containing counterparts. All variants studied had intact affinities for plasminogen as measured by biospecific interaction analysis. The activity of Sak42DDeltaN11(M),G12K could be restored by additional substitution of both Asp13 and Asp14 with Asn, yielding active Sak42DDeltaN11(M),G12K, D13N, D14N, whereas substitution in Sak42DDeltaN16(M),Y17K of Phe18 and Glu19 with Asn yielded inactive Sak42DDeltaN16(M),Y17K,F18N,E19N. These data, in combination with the recent finding that the 20 NH2-terminal amino acids of Sak lack secondary structure, suggest that the NH2-terminal region of Sak is not required for binding to plasmin/plasminogen, but that a positively charged amino acid in the ultimate or penultimate NH2-terminal position corresponding to amino acids 11-16 of this flexible region participates in the reconfiguration of the active site of the plasmin molecule to endow it with plasminogen-activating potential.

Amino Acid Sequence↗
PubMed1998

Phase-variable expression of lipopolysaccharide contributes to the virulence of legionella pneumophila.

With the aid of monoclonal antibody (mAb) 2625, raised against the lipopolysaccharide (LPS) of Legionella pneumophila serogroup 1, subgroup OLDA, we isolated mutant 811 from the virulent wild-type strain RC1. This mutant was not reactive with mAb 2625 and exhibited an unstable phenotype, since we observed an in vitro and in vivo switch of mutant 811 to the mAb 2625-positive phenotype, thus restoring the wild-type LPS. Bactericidal assays revealed that mutant 811 was lysed by serum complement components, whereas the parental strain RC1 was almost serum resistant. Moreover, mutant 811 was not able to replicate intracellularly in macrophage-like cell line HL-60. In the guinea pig animal model, mutant 811 exhibited significantly reduced ability to replicate. Among recovered bacteria, mAb 2625-positive revertants were increased by fourfold. The relevance of LPS phase switch for pathogenesis of Legionella infection was further corroborated by the observation that 5% of the bacteria recovered from the lungs of guinea pigs infected with the wild-type strain RC1 were negative for mAb 2625 binding. These findings strongly indicate that under in vivo conditions switching between two LPS phenotypes occurs and may promote adaptation and replication of L. pneumophila. This is the first description of phase-variable expression of Legionella LPS.

Animals↗
PubMed1998

Searching for substitution rate heterogeneity.

A permutation method for detecting regional substitution rate heterogeneity in DNA sequences is described. An estimated phylogeny for the sequences is required. The method is likelihood based and searches through all regions of a DNA sequence to find any regions that have an unusually large (or small) number of substitutions in comparison to an optimal substitution rate for the entire sequence. Likelihood ratio tests do not achieve proper statistical significance levels due to the large number of tests performed. Empirical corrections based on permutations are suggested and shown to give correct statistical accuracy. The ability of the method to detect rate heterogeneity is good even when the region is small and with less than twice the rate of evolution in the remainder of the sequence.

Algorithms↗
PubMed1998

Cardioprotective actions of KC 12291. I. Inhibition of voltage-gated Na+ channels in ischemia delays myocardial Na+ overload.

To characterize KC 12291 (1-(5-phenyl-1,2, 4-thiadiazol-3-yl-oxypropyl)-3-[N-methyl-N-[2-(3,4-dimethoxy phenyl) ethyl] amino] propane hydrochloride), a newly synthezised inhibitor of voltage-gated Na+ channels, the effects of the agent on Na+ current and ischemia-induced Na+ overload were investigated in isolated cardiomyocytes, atria and saline-perfused hearts. As measured by the patch clamp technique, KC 12291 (1 microM) significantly reduced peak Na+ current after activation of voltage-gated Na+ channels in rat cardiomyocytes. Partial depolarization enhanced the inhibitory effects during steady state conditions of the channel. In isolated guinea pig atria, 1 microM KC 12291 had no effect on contractility under basal conditions but effectively delayed the onset and reduced the extent of anoxic contracture. The concentration-response curve was clearly shifted to the left when atria were partially depolarized by increased extracellular K+. As measured by 23Na NMR spectroscopy in isolated perfused guinea pig hearts, intracellular Na+ rose more than four-fold in a linear fashion during 60 min of low-flow ischemia. KC 12291 (1 microM) prevented Na+ overload within the initial 12 min of ischemia; thereafter the slope of Na+ accumulation was identical to controls. Electrical excitability of hearts, evaluated by intracardial ECG, completely ceased within 15 min after the onset of ischemia. KC 12291 (1 microM) accelerated this process by more than 6 min. The data provide first evidence that KC 12291 reduces Na+ influx through voltage-gated Na+ channels during ischemia and thus delays Na+ overload by enhancing the inexcitability of the heart.

Animals↗
PubMed1998

Cardioprotective actions of KC 12291. II. Delaying Na+ overload in ischemia improves cardiac function and energy status in reperfusion.

The novel blocker of voltage-gated Na+ channels KC 12291 (1-(5-phenyl-1,2,4-thiadiazol-3-yl-oxypropyl)-3-[N-methyl-N- [2-(3,4-dimethoxyphenyl)ethyl] amino] propane hydrochloride) delays myocardial Na+ overload in ischemia. To test whether KC 12291 displays cardioprotective properties in the intact heart, cardiac function, energy status and intracellular pH (31P NMR) as well as ion homeostasis (23Na NMR) were investigated during low-flow ischemia (100 microl/min for 36 min) followed by reperfusion. In the well-oxygenated, isolated perfused guinea pig heart, KC 12291 (1 microM) had no effect on left ventricular developed pressure (LVDP; 54+/-19 mmHg). KC 12291 delayed the onset and decreased the extent of ischemic contracture and markedly improved the recovery of LVDP in reperfusion [39+/-14 mmHg (n=4) vs 2+/-2 mmHg in controls (n=5)]. KC 12291 did not influence the rapid drop in phosphocreatine (PCr) following onset of ischemia but attenuated the decline in ATP. It also diminished the ischemia-induced fall in intracellular pH [6.39+/-0.2 (n=6) vs 6.18+/-0.20 in controls (n=6)]. In reperfusion, KC 12291 remarkably enhanced the recovery of PCr (84.8+/-9.6% vs 51.1+/-8.8% of baseline) and ATP (38.2+/-12.9% vs 23.7+/-9.3% of baseline). It also accelerated the recovery of intracellular pH. KC 12291 not only reduced the extent of ischemia-induced Na+ overload, but also enhanced Na+ recovery. It is concluded that KC 12291 delays contracture and reduces ATP depletion and acidosis in ischemia, and markedly improves the functional, energetic and ionic recovery in reperfusion. Blocking voltage-gated Na+ channels in ischemia to delay Na+ overload may thus constitute a promising therapeutic approach for cardioprotection.

Adenosine Triphosphate↗