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M Freitag

Publications and source records attributed to M Freitag.

At least 73 records · Page 4Linked to original sources
PubMed1996

A UV-induced mutation in neurospora that affects translational regulation in response to arginine.

The Neurospora crassa arg-2 gene encodes the small subunit of arginine-specific carbamoyl phosphate synthetase. The levels of arg-2 mRNA and mRNA translation are negatively regulated by arginine. An upstream open reading frame (uORF) in the transcript's 5' region has been implicated in arginine-specific control. An arg-2-hph fusion gene encoding hygromycin phosphotransferase conferred arginine-regulated resistance to hygromycin when introduced into N. crassa. We used an arg-2-hph strain to select for UV-induced mutants that grew in the presence of hygromycin and arginine, and we isolated 46 mutants that had either of two phenotypes. One phenotype indicated altered expression of both arg-2-hph and arg-2 genes; the other, altered expression of arg-2-hph but not arg-2. One of the latter mutations, which was genetically closely linked to arg-2-hph, was recovered from the 5' region of the arg-2-hph gene using PCR. Sequence analyses and transformation experiments revealed a mutation at uORF codon 12 (Asp to Asn) that abrogated negative regulation. Examination of the distribution of ribosomes on arg-2-hph transcripts showed that loss of regulation had a translational component, indicating the uORF sequence was important for Arg-specific translational control. Comparisons with other uORF5 suggest common elements in translational control mechanisms.

Amino Acid Sequence↗
PubMed1996

Radiological videoconferencing in Sweden.

For the last four years there has been a videoconferencing link between the Karlskrona hospital and the university hospital of Lund. Because of a need to transmit angiographic films, its use has been gradually expanded to become an everyday routine, used for both elective and emergency examinations. During 1994 and 1995, 1121 cases were examined over the video link. Apart from 156 normal cases all were discussed with surgeons, most at 96 weekly conferences but approximately 50 at conferences taking place as soon as possible after the examination. Assuming that an average of three doctors attended the conferences before the video link was available, this amounts to a saving of 3 x 8 h in travelling time per videoconference. The average salary was 300 SKr/h and train tickets cost a further 400 SKr per person. The cost of the ISDN connection was approximately 1800 SKr/conference. The net gain was thus about 6500 SKr per videoconference, without taking into account the work that could be done with the doctors still in Karlskrona after the conference.

Angiography↗
PubMed1995

Translational regulation in response to changes in amino acid availability in Neurospora crassa.

We examined the regulation of Neurospora crassa arg-2 and cpc-1 in response to amino acid availability.arg-2 encodes the small subunit of arginine-specific carbamoyl phosphate synthetase; it is subject to unique negative regulation by Arg and is positively regulated in response to limitation for many different amino acids through a mechanism known as cross-pathway control. cpc-1 specifies a transcriptional activator important for crosspathway control. Expression of these genes was compared with that of the cytochrome oxidase subunit V gene, cox-5. Analyses of mRNA levels, polypeptide pulse-labeling results, and the distribution of mRNA in polysomes indicated that Arg-specific negative regulation of arg-2 affected the levels of both arg-2 mRNA and arg-2 mRNA translation. Negative translational effects on arg-2 and positive translational effects on cpc-1 were apparent soon after cells were provided with exogenous Arg. In cells limited for His, increased expression of arg-2 and cpc-1, and decreased expression of cox-5, also had translational and transcriptional components. The arg-2 and cpc-1 transcripts contain upstream open reading frames (uORFs), as do their Saccharomyces cerevisiae homologs CPA1 and GCN4. We examined the regulation of arg-2-lacZ reporter genes containing or lacking the uORF start codon; the capacity for arg-2 uORF translation appeared critical for controlling gene expression.

Amitrole↗
PubMed1995

[Esophagus carcinoid--a rare differential diagnosis in malignant esophageal neoplasia].

Two of patients with a carcinoid tumor of the esophagus are reported, an extremely rare localisation. Eight months after esophagectomy the 50-year-old male is entirely well and without any sign of recurrence; the 56-year-old female has died in this time. Our two cases are discussed in comparison with seven cases found in the literature.

Carcinoid Tumor↗
PubMed1994

[The modified 13C-urea breath test in the diagnosis of Helicobacter pylori colonization of the gastric mucosa].

The value of a modified 13C-urea breath test for the detection of Helicobacter pylori was analysed in a prospective study of 50 consecutive patients (28 women, 22 men, aged 20-90 years) with unknown Helicobacter pylori status about to undergo upper intestinal endoscopy. Four biopsies each were obtained in each patient from the antrum and the body of the stomach and examined for Helicobacter pylori infection of the gastric mucosa histologically (haematoxylin-eosin and Giemsa stain), with the rapid urease test and by culture. The patients then underwent a modified 13C-urea breath test. Results were positive histologically and(or) by culture in 29 patients, while the breath test was positive in 28 (sensitivity 96.3%). The breath test was falsely positive in two (specificity 91.3%). The biopsy urease test had a sensitivity of 96.3% with a 100% specificity. These results demonstrate that the modified 13C-urea breath test is a simple and accurate way of demonstrating Helicobacter pylori infection, equal in diagnostic value to the biopsy urease test.

Adult↗
PubMed1994

Effects of lipoprotein(a) on thrombolysis.

Lipoprotein(a) (Lp(a)) and plasminogen share a high degree of structural homology. Therefore it has been suggested that elevated levels of Lp(a) may inhibit the profibrinolytic activity at the cell surface and increase the risk of thrombosis by competitive inhibition of plasminogen. In the present study we evaluated whether high levels of Lp(a) affect thrombolytic therapy in patients with acute myocardial infarction. Forty-one patients with acute myocardial infarction were treated with a combination of recombinant tissue-type plasminogen activator and human single-chain urokinase-type plasminogen activator. Coronary patency was assessed angiographically 90 min after initiation of treatment. Thrombolysis was successful in 30 and unsuccessful in 11 patients. Patients with high Lp(a) levels (> 25 mg/dl) (n = 9) responded equally well to thrombolytic therapy (8 of 9, patency 89%) as did patients with normal or low levels of Lp(a) (22 of 32, patency 70%, difference P > 0.1). The results demonstrate that high levels of Lp(a) do not influence thrombolysis in patients with acute myocardial infarction when low-dose pharmacologic concentrations of recombinant tissue-type plasminogen activator and human single chain urokinase-type plasminogen activator are applied in combination.

Drug Therapy, Combination↗
PubMed1994

Fibrin-targeted recombinant hirudin inhibits fibrin deposition on experimental clots more efficiently than recombinant hirudin.

BACKGROUND: Although the indirect thrombin inhibitor heparin and the more potent direct inhibitor hirudin are useful in preventing thrombosis, a substantial opportunity remains for improving the thrombus selectivity of thrombin inhibitors. METHODS AND RESULTS: To explore the effect of targeting an antithrombin to the surface of a clot, we covalently linked recombinant hirudin to the Fab' (or IgG) of a monoclonal antibody (59D8) that selectively binds to an epitope on fibrin that becomes exposed only after thrombin cleaves fibrinopeptide B. Antibody-coupled hirudin bound to an immobilized peptide of the fibrin beta-chain amino-terminal sequence and inhibited the peptidolytic activity of thrombin more efficiently than free hirudin. Thrombin inhibition dependent on binding to immobilized fibrin monomer was enhanced 1100-fold (P < .0001). Hirudin-59D8 Fab' was 10 times more effective than hirudin in inhibiting fibrin deposition on experimental clot surfaces in fibrinogen solution (P < .0001) and human plasma (P < .0001). The more effective inhibition of thrombin by the conjugate was supported by significantly diminished concentrations of fibrinopeptide A in the plasma supernatant of the clot (P = .0001). Inhibition of clotting by an uncoupled mixture of hirudin and 59D8 Fab' was indistinguishable from that by hirudin alone, indicating that the conjugate's greater inhibitory activity was due to the covalent linkage between antibody and hirudin. CONCLUSIONS: Fibrin-targeted hirudin (in comparison with unmodified hirudin) significantly reduces fibrin deposition on the surface of experimental clots.

Antibodies, Monoclonal↗
PubMed1994

Intravenous omeprazole/amoxicillin and omeprazole pretreatment in Helicobacter pylori-positive acute peptide ulcer bleeding. A pilot study.

BACKGROUND: The aims of this study were to evaluate a Helicobacter pylori eradication schedule for H. pylori-positive gastroduodenal ulcer bleeding, which could be commenced intravenously after endoscopic diagnosis, and to assess the effect of omeprazole pretreatment on bacterial eradication. METHODS: In a prospective study 20 consecutive patients with H. pylori-positive acute peptide ulcer bleeding, who were managed conservatively including endoscopic injection therapy, were treated with a 2-week regimen consisting of either 40 mg omeprazole three times daily (with the exception of the loading dose of 80 mg) and 2 g amoxicillin three times daily intravenously for 3 days and 20 mg omeprazole twice daily and 1 g amoxicillin twice daily orally for 11 days (n = 10) or only with 40 mg omeprazole three times daily (with the exception of the loading dose of 80 mg) intravenously for 3 days and 20 mg omeprazole twice daily and 1 g amoxicillin twice daily orally for 11 days (n = 10). Subsequently, both groups received 20 mg omeprazole twice daily orally for 4 weeks. RESULTS: H. pylori eradication, defined as negative bacterial findings in urease test, culture and histology, or 13C-urea breath test at least 4 weeks after cessation of omeprazole medication, was achieved in 100% (10/10) of patients in the first group but only in 30% (3/10) of patients in the second group (p < 0.01). Ulcer healing was endoscopically confirmed in all but one patient in the second group. CONCLUSIONS: For the first time a promising concept for H. pylori eradication in H. pylori-positive ulcer bleeding is available by using a combined intravenous and oral omeprazole/amoxicillin therapy, which can be started intravenously immediately after an emergency upper GI endoscopy. In addition, these data imply that omeprazole pretreatment may not be wise when H. pylori eradication is attempted.

Acute Disease↗
PubMed1994

Medium-term results of oral and intravenous omeprazole/amoxicillin Helicobacter pylori eradication therapy.

OBJECTIVES: The aim of the present study was to examine the effect of the application route of the antibiotic amoxicillin in Helicobacter pylori eradication, using omeprazole/amoxicillin. METHODS: In a prospective medium-term study, 31 patients with H. pylori-positive gastroduodenal ulcer disease were treated with a 14-day course of 20 mg omeprazole bid orally, combined with either 1 g amoxicillin tid intravenously (n = 15) or 500 mg amoxicillin six times daily orally (n = 16). RESULTS: H. pylori eradication, defined as negative bacterial findings in urease test, culture, and histology at least 4 wk after cessation of study medication, was achieved in 93% (14/15) of the patients in the first group and in 91% (11/12) of the patients in the second group. To obtain medium-term results, patients in whom H. pylori had been successfully eradicated were investigated with a 13C-urea breath test at least 6 months later. Medium-term eradication rates of 91% (10/11 patients) in the first and 100% (10/10 patients) in the second group were observed. CONCLUSIONS: In view of the equally high eradication rates obtained by a 14-day course of intravenously administered amoxicillin and an oral therapy of the same length and dosage, during the necessary induction of luminal hypoacidity by the proton pump inhibitor omeprazole, we conclude that the route of administration of amoxicillin does not play a decisive role in bacterial eradication.

Administration, Oral↗
PubMed1993

Combinations of thrombolytic agents in acute myocardial infarction.

Combination thrombolytic therapy aims to achieve higher efficacy, higher specificity, better maintained patency of initially successfully reperfused vessels, less bleeding complications and cost containment by exploiting synergistic mechanisms of action and by using much lower doses of two drugs as in monotherapy. However, so far, no combination has been reported to yield significantly higher patency rates than rt-PA monotherapy. The combination of rt-PA and scuPA achieved high patency rates, and that with exquisite specificity. A combination of rt-PA and UK appears to prevent early reocclusion effectively, resulting in an overall improved clinical outcome versus monotherapy with either UK or rt-PA. The use of nonspecific plasminogen activators for the prevention of reocclusion may become obsolete, however, with the advent of more potent antithrombin and antiplatelet agents. Besides improved dosing regimens for monotherapy (front-loading), combination therapy has emerged as another possible means of enhancing thrombolytic efficacy by achieving effects that no single agent can produce. However, to date, no combination regimen has been documented to be clearly superior to monotherapy in a mortality trial.

Drug Therapy, Combination↗
PubMed1992

Myocardial reperfusion in thrombolysis A 99Tcm-Sestamibi SPECT study in patients with acute myocardial infarction.

This study presents the outcome of myocardial scintigraphy performed before and after thrombolytic treatment in 16 patients with acute myocardial infarction using 99Tcm-Sestamibi (Cardiolite, Du Pont Scandinavia AB, Kista, Sweden). The patients were given 99Tcm-Sestamibi intravenously as soon as possible after the decision to give thrombolytic treatment. When the patients were in a clinically stable state after the thrombolytic treatment, myocardial perfusion was analysed with the gamma camera using single photon emission computerized tomography (SPECT). A second 99Tcm-Sestamibi tomography was carried out on the second to fourth day after the myocardial infarction. Data reconstruction was done with the 'Bull's eye technique'. Nine patients received thrombolysis < 3 h from the onset of pain. In this group six patients (66%) improved their myocardial perfusion by > 10% after treatment, while all seven patients who received treatment > or = 3 h after the onset of pain improved their myocardial perfusion by < 10%. This study emphasises the importance of early diagnosis and treatment of patients with acute myocardial infarction in order to salvage myocardium.

Aged↗
PubMed1992

Syncope--brain or heart? A case report.

A 44-year-old man suffered from recurrent episodes of unconsciousness, without any other concomitant manifestations. After routine workup, EEG and CT had proven nondiagnostic, prolonged Holter monitoring revealed a single episode of asystole, lasting 7.6 seconds. A pacemaker was inserted but did not abolish his episodic syncope. Subsequently, long-term EEG recording revealed epileptiform activity with independent foci in both temporal lobes. Antiepileptic treatment relieved the patient of his symptoms. This case illustrates the intimate relationship between the heart and the brain that sometimes lies behind syncope.

Adult↗
PubMed1992

Changes in selected enzyme activities during growth of pure and mixed cultures of the white-rot decay fungus Trametes versicolor and the potential biocontrol fungus Trichoderma harzianum.

Two filamentous fungi, the white-rot fungus Trametes versicolor and the soil fungus and potential biocontrol organism Trichoderma harzianum, have been grown in pure and mixed cultures on low-N (0.4 mM) and high-N (4 mM) defined synthetic media to determine the activities of selected wood-degrading enzymes such as cellobiase, cellulase, laccase, and peroxidases. Growth characteristics and enzyme activities were examined for potential correlations. Such correlations would allow the use of simple enzyme assays for measuring biomass development and would facilitate predictions about competitiveness of species in mixed fungal cultures. Our results show that while laccase and Poly Red-478 peroxidase activities indicate survival of the decay fungus, none of the monitored extracellular enzymes can serve as a quantitative indicator for biomass accumulation. As expected, the level of available nitrogen affected the production of the enzymes monitored: in low-N media, specific cellobiase, specific cellulase, and peroxidase activities were enhanced, while laccase activities were reduced. Most importantly, laccase activities of Trametes versicolor, and to a smaller extent, cellobiase activities of both fungi, were significantly induced in mixed cultures of Trametes versicolor and Trichoderma harzianum.

Cellulase↗
PubMed1991

A recombinant chimeric plasminogen activator with high affinity for fibrin has increased thrombolytic potency in vitro and in vivo.

A recombinant plasminogen activator with high fibrin affinity and specificity was expressed by transfecting hybridoma cells with a plasmid that combines sequence coding for low molecular mass (32 kDa) single-chain urokinase-type plasminogen activator [scuPA(32kDa)] and anti-fibrin monoclonal antibody 59D8. The expression of the recombinant molecule [r-scuPA(32kDa)-59D8] was optimized by replacing the 3' untranslated region (initially that of high molecular mass scuPA) in the plasmid with the 3' untranslated region of either beta-globin or mouse immunoglobulin. This modification resulted in a greater than 100-fold improvement in the level of protein expression. The 103-kDa r-scuPA(32kDa)-59D8 protein displayed catalytic activity indistinguishable from that of high molecular mass scuPA and fibrin binding comparable to that of native antibody 59D8. r-scuPA(32kDa)-59D8 was 6 times more potent than high molecular mass scuPA in lysing a human plasma clot in vitro and was 20 times more potent than high molecular mass scuPA in the rabbit jugular vein model of thrombolysis. Molecules of this type may serve as prototypes for highly specific, antibody-targeted enzymes suitable for human use.

Animals↗
PubMed1991

3H-uridine incorporation in early porcine embryos.

The present study investigated the ontogeny of 3H-uridine incorporation into RNA as a measure for RNA synthesis in preimplantation porcine embryos from the two-cell stage up to the stage of the newly hatched blastocyst. A total of 568 embryos were cultured in vitro for 3 hr in medium (KRB plus lamb serum) containing 9 microM 3H-uridine. After disruption of cell membranes, RNA was isolated on DEAE cellulose filters, and the radioactivity was taken as a measure for the rate of RNA synthesis. No RNA synthesis was detected at the two-cell stage. From the four-cell to the morula stage, 3H-uridine incorporation per embryo increased about ninefold (P less than 0.001); in blastocyst stages, the increase between developmental stages was not statistically significant. Hatched blastocysts had the highest genomic activity. On a per cell basis, 3H-uridine incorporation was not different from the four-cell stage up to the zona pellucida-intact blastocyst and amounted to 0.29-0.37 fmol 3H-uridine incorporation/cell/3 hr. In hatched blastocysts, 3H-uridine incorporation per blastomere was increased (P less than 0.01 compared with younger stages) and amounted to 0.86 fmol 3H-uridine incorporation/cell/3 hr. It is concluded that 1) the rate of uridine incorporation depends on the cell stage in zona pellucida-intact porcine embryos and 2) uridine incorporation per blastomere is significantly increased in hatched blastocysts compared with earlier stages.

Animals↗
PubMed1991

Platelet-targeted fibrinolysis enhances clot lysis and inhibits platelet aggregation.

BACKGROUND: Although plasminogen activator therapy has been shown to reduce mortality in patients with severe myocardial infarction, several problems fuel the search for more potent and specific thrombolytic agents. METHODS AND RESULTS: To explore the effect of plasminogen activator targeting to platelets, we covalently linked urokinase that had been modified with N-succinimidyl-3-(2-pyridyldithio)propionate to the Fab' of a monoclonal antibody (7E3) that selectively binds to platelet membrane glycoprotein (GP) IIb/IIIa. In an assay measuring (as reflected by plasmin generation) a plasminogen activator's ability to bind GP IIb/IIIa immobilized on plastic, urokinase-7E3 Fab' produced 31-fold more plasmin than did urokinase (p = 0.0001). The addition of solubilized GP IIb/IIIa blocked this enhancement of plasmin generation, indicating that binding was impaired. Plasmin generation reflecting binding to immobilized intact platelets was 2.4-fold greater for urokinase-7E3 Fab' than for unconjugated urokinase (p = 0.002). In a plasma clot lysis assay, urokinase-7E3 Fab' was at least 25-fold more potent than either urokinase alone or a mixture of urokinase and 7E3 (Fab')2 (p less than 0.009), and potency could be related to platelet concentration in the clot. Ex vivo, ADP-induced platelet aggregation was inhibited by a urokinase-7E3 IgG conjugate at a concentration of 8 nM, whereas a mixture of urokinase and 7E3 (Fab')2 in equimolar amounts required 60 nM and urokinase alone required 1 microM to achieve the same effect. CONCLUSIONS: Therefore, the targeting of urokinase to the GP IIb/IIIa platelet receptor both accelerates clot lysis (when platelets are associated with a fibrin clot) and inhibits platelet aggregation.

Antigens↗