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Biomedical subjects

P Seidel

Publications and source records attributed to P Seidel.

At least 19 recordsLinked to original sources
PubMed2006

Modified nucleosides: an accurate tumour marker for clinical diagnosis of cancer, early detection and therapy control.

Modified nucleosides, regarded as indicators for the whole-body turnover of RNAs, are excreted in abnormal amounts in the urine of patients with malignancies. To test their usefulness as tumour markers and to compare them with the conventional tumour markers, fractionated urine samples were analysed using chromatography. The excretion patterns of nucleosides of 68 cancer patients with malignant and benign tumours and 41 healthy controls have been studied. Significant elevations in the total sum and the concentrations of at least three (or four) of indicator nucleosides cytidine, pseudouridine, 2-pyridone-5-carboxamide-N1-ribofuranoside, N2,N2-dimethylguanine, 1-methylguanosine, 2-methylguanosine and 1-methyladenosine indicate a tumour with a sensitivity of 54% (77%) and a specificity of 86% (98%). Using an artificial neural network analysis, a sensitivity of 97% and a specificity of 85% were achieved in differentiating between tumour and control volunteers. The comparison with carcinoembryonic antigen, cancer antigen 15-3 und tissue polypeptide antigen indicates that urinary nucleosides may be useful tumour markers. This study suggests that the simultaneous determination of modified nucleosides and creatinine in urine samples of patients with cancer leads to an advantage to current methods and is a useful method to detect cancer early and to control the success of therapy.

Adult↗
PubMed2004

[Nanoparticulate silver. A new antimicrobial substance for bone cement].

BACKGROUND: Multiresistant bacteria have become an important problem in prosthetic joint infections. Their frequent resistance against gentamicin, which is commonly used in antibiotic-loaded bone cements, makes a new prophylaxis necessary. METHODS: PMMA-cement was loaded with 1% nanoparticulate silver and its antibacterial activity tested in vitro against gentamicin-resistant MRSE and MRSA strains as well as being compared to the activity of plain and gentamicin-loaded bone cements. A quantitative elution testing was also done to study the potentially cytotoxic effects of NanoSilver cement. RESULTS: Unloaded and PMMA-cement loaded with 2% gentamicin did not exhibit any antibacterial activity against MRSE and MRSA. At 1%, NanoSilver cement completely inhibited the proliferation of MRSA and MRSE. NanoSilver bone cement did not show any significant differences compared to the non-toxic control group. CONCLUSIONS: If these promising in vitro results can be confirmed in vivo, NanoSilver bone cement may be of considerable value in total joint arthroplasty.

Animals↗
PubMed2001

Reproducibility of HTS-SQUID magnetocardiography in an unshielded clinical environment.

A new technology has been developed which measures the magnetic field of the human heart (magnetocardiogram, MCG) by using high temperature superconducting (HTS) sensors. These sensors can be operated at the temperature of liquid nitrogen without electromagnetic shielding. We tested the reproducibility of HTS-MCG measurements in healthy volunteers. Unshielded HTS-MCG measurements were performed in 18 healthy volunteers in left precordial position in two separate sessions in a clinical environment. The heart cycles of 10 min were averaged, smoothed, the baselines were adjusted, and the data were standardized to the respective areas under the curves (AUC) of the absolute values of the QRST amplitudes. The QRS complexes and the ST-T intervals were used to assess the reproducibility of the two measurements. Ratios (R(QRS), R(STT)) were calculated by dividing the AUC of the first measurement by the ones of the second measurement. The linear correlation coefficients (CORR(QRS), CORR(STT)) of the time intervals of the two measurements were calculated, too. The HTS-MCG signal was completely concealed by the high noise level in the raw data. The averaging and smoothing algorithms unmasked the QRS complex and the ST segment. A high reproducibility was found for the QRS complex (R(QRS)=1.2+/-0.3, CORR(QRS)=0.96+/-0.06). Similarly to the shape of the ECG it was characterized by three bends, the Q, R, and S waves. In the ST-T interval, the reproducibility was considerably lower (R(STT)=0.9+/-0.2, CORR(STT)=0.66+/-0.28). In contrast to the shape of the ECG, a baseline deflection after the T wave which may belong to U wave activity was found in a number of volunteers. HTS-MCG devices can be operated in a clinical environment without shielding. Whereas the reproducibility was found to be high for the depolarization interval, it was considerably lower for the ST segment and for the T wave. Therefore, before clinically applying HTS-MCG systems to the detection of repolarization abnormalities in acute coronary syndromes, further technical development of the systems is necessary to improve the signal-to-noise ratio.

Adult↗
PubMed1995

Cyclosporins from Tolypocladium terricola.

New natural cyclosporins were isolated from the mycelium of surface cultivated fungus Tolypocladium terricola. The chemical structures of [Leu4] CS and [MeLeu1] CS = cyclosporin-J, were deduced from the NMR and mass spectral data. Biological activity of new cyclosporins is reported based on the proliferative mitogen stimulation test.

Amino Acid Sequence↗
PubMed1994

Cloning and analysis of the Saccharomyces cerevisiae MNN9 and MNN1 genes required for complex glycosylation of secreted proteins.

Proteins secreted by the yeast Saccharomyces cerevisiae are usually modified by the addition at asparagine-linked glycosylation sites of large heterogeneous mannan units that are highly immunogenic. Secreted proteins from mnn1 mnn9 mutant strains, in contrast, have homogeneous Man10GlcNAc2 oligosaccharides that lack the immunogenic alpha 1,3-mannose linkages. We have cloned and sequenced the MNN9 and MNN1 genes, both of which encode proteins with the characteristics of type II membrane proteins. Mnn9p is a membrane-associated protein with unknown function that is required for the addition of the long alpha 1,6-mannose backbone of the complex mannan, whereas Mnn1p is most likely the alpha 1,3-mannosyltransferase located in the Golgi apparatus.

Amino Acid Sequence↗
PubMed1990

Non-invasive assessment of right and left ventricular volumes 11 to 24 years after corrective surgery on patients with tetralogy of Fallot.

Patients who had corrective surgery for tetralogy of Fallot using a transannular right ventricular outflow tract (TRVOT) patch showed a higher risk of post-operative mortality and reoperation in the long-term follow-up. A total of 642 patients were operated upon for tetralogy of Fallot between 1952 and 1982. Twenty-six patients who survived for more than 10 years were selected for this study. Fifteen randomly selected patients (group 1) without outflow tract patch were compared with 11 patients (group 2) where a transannular right ventricular outflow patch had been used. Right and left ventricular volumes were assessed using combined first-pass and equilibrium radionuclide ventriculography. After administration of 25 mCi of 99mTc-pertechnetate, data were acquired with a gamma camera with a large viewing field and the patient at rest and during exercise. The patients in group 1 were able to manage a workload of 65 +/- 24 W on the bicycle ergometer while the patients in group 2 could only reach a mean maximum of 34 +/- 12 W. Right ventricular end-diastolic volume (RV-EDV) at rest was 198 +/- 67 ml in group 1 and 224 +/- 69 ml in group 2. During exercise, RV-EDV was increased to 218 +/- 75 ml in group 1 (P less than 0.01) and to 246 +/- 79 ml in group 2. Right ventricular end-systolic volumes did not change significantly during exercise. In group 1, the left ventricular (LV) volumes were comparable to the normal; in group 2, LV-EDV was diminished at rest and during the stress test.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

[Prophylactic irradiation of blood components with conventional radiotherapy devices].

The irradiation of blood components is supposed to be the safest way of the graft versus host reaction prophylaxis. The radiotherapy facilities and compact irradiators for blood preparations and biological materials are used for prophylactic irradiations, practically. The radiotherapy machines allow a homogeneous dose application, but need a high organizing effort. The use of compact irradiators is less complicated but the large dose differences can be found in the target volume. There is no agreement about the extent of the prophylactic dose. For radiation biology reasons the application of prophylactic doses between 15 and 50 Gy seems to be justified. A restriction of this range in favor of higher doses can be expected, when newer experimental findings are proven by clinical observations.

Blood↗