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Biomedical subjects

J Meyer

Publications and source records attributed to J Meyer.

At least 523 records · Page 29Linked to original sources
PubMed1994

Genetic characterization of the mouse strains of the Institute for Animal Breeding of the Veterinary Faculty of the University of Munich, Germany.

A total of 15 strains of mice (11 inbred lines, 4 outbred stocks) of the institute for animal breeding of the veterinary faculty of the university of Munich (FRG) were scored for 23 biochemical loci each. The allelic distribution and frequencies were recorded as a basis for a so far not established genetic monitoring system. The inbred strains revealed the expected homozygosity with one exception (strain UMDH/+; locus Es1). The outbred stocks showed a remarkable degree of variable loci (17.4-36.3%) with a mean heterozygosity between 0.05 and 0.12. The markers in use allow differentiation between all strains (except for one pair of sublines) and stocks. 14 of the loci show allelic differences among the strains and thus can be used for a genetic monitoring system.

Alleles↗
PubMed1994

[Transthoracic and transesophageal follow-up in patients with left atrial thrombosis].

The embolic risk and changes of thrombus location and size were investigated in 29 consecutive patients with echocardiographically proven thrombi in the left atrium. Inclusion criteria were the visualization of a left atrial thrombus using transesophageal echocardiography. Transesophageal follow-up echocardiograms were performed at a mean period of 18 months. In this period 6 cases of embolism were observed at an interval of 20 days to 26 months after the detection of thrombus. Thus, the embolic rate was 14% per patient year. All patients received phenprocoumon (n = 4) or aspirin at the time of embolism. Furthermore, in two patients after cardiac thrombectomy left atrial thrombi were seen again although patients were treated with anticoagulants. On the other hand, in 12 patients (5 received oral anticoagulation, 2 received aspirin) thrombi completely resolved. It can be concluded from these data, that the majority of patients receiving anticoagulation profit from this therapy, however, a complete protection against arterial embolism or reoccurrence of thrombi cannot be reached. Left atrial spontaneous echo contrast was the only risk factor significantly associated with thromboembolism in patients with left atrial thrombi.

Aged↗
PubMed1994

[Transesophageal echocardiography in cardiogenic shock in acute posterior wall infarct with rupture of the papillary muscles].

A 63-year-old male patient suffered an acute myocardial infarction entirely confined to the posterior wall. As symptoms persisted and cardiogenic shock developed immediate heart catheterization was performed, which demonstrated an occlusion of the left circumflex branch. Right-heart catheterization demonstrated an enlarged v-wave. Thus, acute infarct associated mitral regurgitation was suspected. In the catheterization laboratory transesophageal echocardiography including Doppler- and contrast echocardiography was then performed, which revealed the diagnosis of posterior papillary muscle rupture. The patient proceeded immediately to emergency surgery during which mitral valve replacement with a St. Jude prothesis was performed in addition to venous bypass revascularization of the occluded and a further stenosed coronary artery. The postoperative follow-up was without any complications and the patient recovered satisfactorily from the acute event. This case demonstrates the excellent diagnostic utility of emergency transesophageal echocardiography in the situation of infarct related myocardial rupture, which has to precede the life-saving operation.

Cardiac Catheterization↗
PubMed1994

[DNA ploidy of stem cells and prognosis of ductal adenocarcinoma of the pancreas].

The findings on DNA stem line ploidy of ductal adenocarcinomas of the pancreas, which have hitherto been published in the literature, are rather contradictory last but not least due to methodological problems. Thus, the DNA stem line ploidy and its prognostic significance were examined by Feulgen image cytometry on 10 microns sections of 100 paraffin-embedded radically resected ductal carcinomas of the pancreas from the records. In that process the parts of the tumour with the highest grade of malignancy were preferentially investigated. The aneuploidy rate (42%) was conspicuously low if compared with other adenocarcinomas. A highly significant positive correlation between DNA ploidy and histological grading according to Klöppel et al. could be observed, while there was only a tendency towards a positive correlation of DNA ploidy and post-surgical tumour stage. Regarding the 1-year survival rate, the DNA aneuploid tumour cases were significantly more unfavourable than the DNA peridiploid ones (p < 0.05). The prognostically decisive parameter, however, was the histological grading (p < 0.00005), which also showed the best stratification of the patient population. However, contrary to expectations the postsurgical stage of the primary tumour and the nodular state were only of low prognostic significance. The reason for that is on the one hand that the distribution over the pT-stages (in 81% pT2 tumours) is unbalanced, and on the other hand that the actual tumour cell dissemination is only insufficiently represented in the post-surgical staging.

Adenocarcinoma↗
PubMed1994

[The VO2 performance index for evaluation of cardiopulmonary capacity in respiratory minute volume controlled VVI-R stimulation].

This study was designed to assess the effect of acute minute ventilation sensing, rate-responsive pacing on cardiopulmonary exercise capacity in 27 patients (mean age 60 years) with chronotropic incompetence. The exercise protocol consisted of bicycle exercise in semisupine position with breath-to-breath analysis of gas exchange. At the anaerobic threshold heart rate increased from 75 +/- 9 in the VVI-mode to 113 +/- 21 beats/min in the VVI-R-mode (p < 0.001), oxygen uptake from 9.3 +/- 3.4 to 10.9 +/- 4.3 ml/kg/min (p < 0.001) and work rate from 52 +/- 20 to 65 +/- 24 watts (p < 0.001). Compared to 41 normal subjects, VVI-R pacing increased oxygen uptake up to 75% and work rate up to 79% of normal values, while heart rate increased similarly in both groups. The VO2 to work rate ratio (dVO2/dWR), calculated as the slope of the relation of oxygen uptake to work rate below the anaerobic threshold, improved from 7.9 +/- 2.3 to 10.2 +/- 2.4 ml/min/watts (p < 0.001) in the VVI-R-mode; so it did not differ from normal values. Thus, acute respiratory dependent rate-responsive pacing results in substantial improvement in cardiopulmonary exercise capacity in patients with chronotropic incompetence. The VO2 to work rate ratio demonstrated to be a reliable parameter for assessing this improvement.

Adolescent↗
PubMed1994

[Semi-supine cardiopulmonary stress test in middle-aged probands with healthy hearts].

Normal values for cardiopulmonary bicycle exercise testing in semisupine position using a ramping protocol in a middle-aged group of untrained men and women are presented. We exercised 23 men and 16 women aged from 33 to 66 years without evidence of cardiopulmonary or cardiovascular disease and normal findings during complete heart catheterization. Clinical findings, x-ray, resting and exercise ECG, and laboratory findings were normal. Exercise testing was performed using a ramping protocol with a work rate increase of 20 watts/min. Respiratory gas analysis (breath-to-breath method) was performed and oxygen uptake (VO2), carbon-dioxide production (VCO2), and minute ventilation (VE) were determined at maximal work load and at the ventilatory anaerobic threshold. Work rate increase and heart rate were continuously monitored. From these data oxygen pulse, the respiratory quotient (RQ), and the ventilatory equivalents VE/VO2 and VE/VCO2 were derived. Furthermore, the VO2 to work rate ratio, and the VO2 to heart rate ratio were analyzed. Maximal VO2 was within the 95% confidence interval of predicted VO2max. The anaerobic threshold (V-slope method) was 60% of VO2 max at the RQ of 0.81 for men and 66% of VO2max at the RQ of 0.84 for women. The O2 pulse was 100% of the age predicted value. The VO2 to work rate ratio was 10.7 +/- 1.4 for men and 9.7 +/- 1.2 ml/watts/min for women (p < 0.05). The slope of heart rate to VO2 from rest to peak exercise as a measure of chronotropic competence was nonlinear in 59% of the subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Epidemiology of hepatocellular carcinoma. Evaluation of viral and other risk factors in a low-endemic area for hepatitis B and C.

To assess whether hepatocellular carcinoma (HCC) in patients with cirrhosis of the liver is associated with particular risk factors, a retrospective, case-control study was performed. Eighty-six patients with HCC (90% had underlying cirrhosis of the liver) were compared with 86 controls who had cirrhosis but not hepatocellular carcinoma. Hepatitis B surface antigen (HBsAg), antibodies to hepatitis B core antigen (anti-HBc), and to hepatitis C virus (anti-HCV) were evaluated; and alcohol and nicotine abuse were assessed by history. The prevalence of HBsAg and anti-HBc was similar in both, case and control patients. Antibodies to hepatitis C virus were detected more frequently among patients with HCC and cirrhosis (37%) compared to cirrhosis alone (22%). Alcohol abuse was found more frequently in patients with cirrhosis alone. Smoking habits were comparable between the two groups. None of the tested variables were related to an increased risk for HCC. Using an ordinary logistic regression approach, none of the variables could be identified as an independent risk factor for HCC. However, the combination of hepatitis B virus infection and hepatitis C virus infection was more prevalent in the patients with hepatocellular carcinoma and cirrhosis (48%) when compared to patients with cirrhosis alone (13%) (odds ratio 6.364; CI 1.149-35.229). In conclusion, we failed to identify independent risk factors for the development of HCC in Germany. However, the combination of hepatitis B and C virus infection increases the risk for liver cancer. Molecular analyses have to be performed to elucidate viral hepatocarcinogenesis.

Aged↗
PubMed1993

Analysis, by electrospray ionization mass spectrometry, of several forms of Clostridium pasteurianum rubredoxin.

Clostridium pasteurianum rubredoxin and its recombinant counterpart purified from Escherichia coli have been analysed by electrospray ionization m.s. (e.s.i.m.s.). Whereas the N-terminal methionine of the native protein is formylated, the recombinant one has a free N-terminal methionine. E. coli cells also produce a colourless protein from the cloned gene. This protein is absent from C. pasteurianum and was shown to be zinc-substituted rubredoxin. The molecular forms of rubredoxin detected by e.s.i.m.s. depended on the experimental conditions used. Significant conversion into apo-rubredoxin occurred when the proteins were ionized at acidic pH and detected in the positive-ion mode. This conversion was quantitative in the case of Zn-rubredoxin. In contrast, when the proteins were analysed at neutral pH in the negative-ion mode, only the holoproteins, i.e. the species initially present in the solutions, were detected in the spectra. The e.s.i.m.s. experimental conditions set up here may prove useful for the analysis of other acidic metalloproteins with weakly bound metals.

Clostridium↗
PubMed1993

[Restenosis after the implantation of Palmaz-Schatz vascular stents in the coronary arteries].

Restenosis rate after successful intracoronary implantation of Palmaz-Schatz stents in 100 patients (92 men, 8 women; mean age 57 +/- 11 years) was quantitatively assessed by angiography performed on average 5.3 +/- 0.3 months after the procedure. Restenosis was defined as a more than 50% decrease in lumen. Data from patients with acute or subacute thrombotic complications were excluded from the analysis. The restenosis rate of the total group was 22%. After placement of only one stent (n = 87) it was 17%, of multiple stents per lesion (n = 13) 54%. Restenosis rate after emergency implantation of a single stent (n = 23) was 17.4%, after elective single stent implantation (n = 64) 17.2%. There was no significant difference regarding treatment of new stenoses (n = 16), and recurrent stenosis (n = 48), namely 12.5% vs 18.8%. The following were risk factors for chronic restenosis after stent implantation: multiple stents (odds ratio [OR] 5.6; 95% confidence interval [CI]: 1.6-19.1); implantation in a small vessel, reference diameter < or = 3.0 mm (OR 6.7, CI 2.4-18.7); and residual stenosis after stent implantation of > 8% (OR 3.1, CI 1.2-8.1).

Aged↗
PubMed1993

Transcript mapping of the rubredoxin gene from Clostridium pasteurianum.

The transcripts of the rubredoxin gene from C. pasteurianum have been shown to have a size of approx. 230 bases by Northern blotting techniques. The transcription start has been located within 41 bases upstream of the initiator codon. The data demonstrate that the rubredoxin gene is monocistronic. Two of the three open reading frames occurring upstream of the rubredoxin gene are adjacent and appear to encode a thioredoxin (or glutaredoxin) reductase and a thioredoxin (or glutaredoxin).

Amino Acid Sequence↗
PubMed1993

Inhibition of HIV-1 replication by a high-copy-number vector expressing antisense RNA for reverse transcriptase.

We report the construction of a high-copy-number (hcn) expression vector for human cells. Amplification of this vector occurs due to the presence of an element derived from the murine DNA encoding ribosomal RNA (rDNA). HIV-1 replication in Jurkat T lymphocytes is nearly abolished when antisense RNA directed against the gene encoding reverse transcriptase is expressed from this hcn vector. The replication of the virus is only slightly reduced by the plasmid control version lacking the murine amplification-promoting element. This kind of hcn vector may represent an important improvement for the genetic engineering of eukaryotic cells and may also provide some ideas for the future gene therapy of some human diseases.

Culture Media, Conditioned↗
PubMed1993

Cloning and sequencing of the gene encoding the [2Fe-2S] ferredoxin from Clostridium pasteurianum.

A 1348 basepair EcoRI fragment of genomic DNA containing the [2Fe-2S] ferredoxin gene from Clostridium pasteurianum has been cloned and sequenced. The translated protein sequence is identical to the sequence of the protein as previously determined by Edman chemistry. Two potential open reading frames occur upstream and downstream of the ferredoxin gene. However, the features surrounding the latter gene strongly suggest that it constitutes a separate transcriptional unit. The sequence data provide no evidence that this ferredoxin is involved in nitrogen fixation.

Amino Acid Sequence↗
PubMed1993

Mutated forms of a [2Fe-2S] ferredoxin with serine ligands to the iron-sulfur cluster.

The [2Fe-2S] ferredoxin from Clostridium pasteurianum contains five cysteine residues in positions 11, 14, 24, 56 and 60. Residues 24, 56 and 60 have been separately mutated into serine. The modified ferredoxins have been purified and were all found to contain a [2Fe-2S]-type cluster. The electronic absorption and EPR spectra of the C24S protein were only slightly different from those of the native one. In contrast, the C56S and C60S ferredoxins displayed spectroscopic features witnessing the presence of an oxygen ligand to the iron-sulfur cluster: the UV-visible absorption bands were shifted to higher energy by ca. 20 nm, and the high field components of the EPR spectra were shifted from gx = 1.92 and gy = 1.95 to gx = 1.88 and gy = 1.92, respectively.

Amino Acid Sequence↗
PubMed1993

Synergistic platelet antiaggregatory effects of the adenylate cyclase activator iloprost and the guanylate cyclase activating agent SIN-1 in vivo.

The aim of our study was to evaluate the platelet antiaggregatory and hemodynamic effects of the stable prostacyclin analog iloprost and the NO-donor SIN-1, an active metabolite of molsidomine. The number of circulating platelets was determined in anesthetized male Wistar rats as a measure of in vivo platelet aggregation. Platelet count decreased from 648 +/- 25 to 476 +/- 15 x 10(3) platelets/microliter and from 578 +/- 36 to 411 +/- 40 (mean +/- SEM) in response to two repetitive injections of collagen (70 micrograms/kg body weight). Treatment with SIN-1 bolus injections (0.3 or 1 mg/kg bw) and/or continuous i.v. infusion of iloprost (0.2 or 0.4 micrograms/kg bw/min) was initiated 15 min before the second collagen bolus. As a single agent, SIN-1 did not influence platelet count. Iloprost at 0.2 micrograms/kg/min reduced platelet aggregation (PA) by 15.5%, and at 0.4 micrograms/kg/min by 27.1% (p = n.s.). When iloprost (0.2 micrograms/kg) and SIN-1 (0.3 mg/kg) were administered simultaneously, PA was suppressed by 56.2%, iloprost at 0.4 micrograms/kg/min and SIN-1 at 0.3 mg/kg were even more effective and inhibited PA synergistically by 64.9% (p < 0.05). A statistically significant decrease in mean arterial blood pressure (MABP) was seen in response to all SIN-1 and iloprost groups. However, the vasorelaxant effect of both agents given simultaneously was not synergistic but less than additive. In conclusion, iloprost and SIN 1 exert synergistic platelet inhibitory effects in vivo. In contrast, the decrease in MABP is less then additive. These results are of major interest for the therapeutic regimen with NO-donors (nitrovasodilators).

Adenylyl Cyclase Inhibitors↗
PubMed1993

Cloning and expression in Escherichia coli of the gene encoding the [2Fe-2S] ferredoxin from Clostridium pasteurianum.

The gene encoding the [2Fe-2S] ferredoxin from Clostridium pasteurianum has been amplified from genomic DNA by the polymerase chain reaction and cloned under the control of a promoter specifically recognized by T7 RNA polymerase. The protein has been overproduced in E. coli and found to be identical to its native counterpart purified from C. pasteurianum, including the molecular weight, the N-terminal sequence and the spectroscopic properties of the [2Fe-2S] chromophore.

Amino Acid Sequence↗