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Biomedical subjects

F Schubert

Publications and source records attributed to F Schubert.

12 recordsLinked to original sources
PubMed1992

Fluorescent labelling of sequencing primers for automated oligonucleotide synthesis.

A fluorescein derivative is described which can be used as a normal phosphoramidite in oligonucleotide synthesis, giving high yields of fluorescein labelled sequencing primers. The labelled primers were used in automated DNA-sequence analysis without modification of existing protocols, the computer-processed sequences being reproducibly readable up to 400 bases. The procedure described makes the fluorescent labelling of oligonucleotides much easier, and the time of labelling can be significantly reduced. It speeds up the "primer walking" approach of automated DNA sequencing.

Base Sequence↗
PubMed1991

Enzyme sensor-FIA-system for on-line monitoring of glucose, lactate and glutamine in animal cell cultures.

Enzyme sensors for glucose, lactate and glutamine were connected via flow-injection analysis (FIA) devices to two different bioprocesses. They were used for on-line process control of perfused bioreactor systems containing mammalian cell lines producing a monoclonal antibody and recombinant interleukin-2. The biosensor system gives direct access to important process data which can be used as control parameters for long term cell cultivation systems.

Animals↗
PubMed1991

Second generation biosensors.

Enzyme-membrane electrodes using glucose oxidase in combination with peroxide detection dominate in the field of laboratory analyzers for diluted samples. Using the same indication principle, extremely fast responding glucose sensors have been fabricated by covering thin metal electrodes with a porous enzyme layer. In the second generation auxiliary enzymes and/or co-reactants are coimmobilized with the analyte converting enzyme in order to improve the analytical quality and to simplify the performance. Following this line oxidizable interferences are suppressed by using a glucose oxidase/peroxidase complex which communicates with the electrode at a low working potential. Furthermore, fluctuations of pH or buffer capacity are ineffective when using a glucose oxidase/peroxidase layer covered fluoride FET in the potentiometric glucose determination. Enzymatic recycling of the analyte and/or accumulation of intermediates increase the sensitivity by several orders of magnitude. Inclusion of NAD bound to PEG in the glucose dehydrogenase layer allows a reagentless glucose measurement.

Biosensing Techniques↗
PubMed1990

Perioperative assessment of cardiac energy metabolism by means of arterio-coronary venous difference in lactate concentration (acDL). A parameter for optimizing ventricular function of the postcardioplegic myocardium.

Fourty-three patients undergoing open heart surgery were subjected to extended hemodynamic and metabolic monitoring (arterial and coronary sinus (CS) lactate concentration). In 95% of patients investigated, a significant increase in CS lactate concentration above the arterial lactate concentration was established at the beginning of reperfusion (RPT). In these cases, a decrease in the CS lactate below the arterial concentration occurs within the RPT creating a cross-over point (COP) from negative to positive lactate extraction values. Whereas the initial rise in CS lactate is an expression of the expected ischemia-induced acceleration of anaerobic glycolysis, the onset of a positive lactate extraction can be related to reconsolidation of mitrochondrial oxidative phosphorylation. We found two groups with an early and late COP at 7.2 +/- 0.8 min (ECOP) and 42.5 +/- 5.2 min (LCOP) (P less than 0.005). Whereas a short cross-over time was associated with a normal postoperative outcome, cardiac recovery was delayed in the LCOP group. With the aid of metabolic monitoring it is possible to identify the COP and cardiac overload situations and so to optimize the perioperative outcome, especially in selected patients (NYHA stage III/IV, re-operation, high-risk operation).

Adenosine Triphosphate↗
PubMed1990

[Heart surgery interventions in risk patients. New possibilities for improving therapeutic results].

Perioperative therapy in conjunction with cardiac surgery had so far been guided by functional, paraclinical, and clinical parameters which only conditionally enabled objective appraisal of the present condition of the myocardium. Perioperative recording of the arterio-coronary-venous concentration difference of lactate (acDL) has now enabled the use of an objectivated parameter for accurate description of the metabolic-energetic situation of the myocardium. This will be helpful in metabolic-energetic condition monitoring (MESM) to optimise perioperative cardiotonic therapy. Stabilisation of the metabolic-energetic situation of the myocardium, objectivated by MESM, has proved to be superior to premature cardiac support, using catecholamines. It has been associated with improved restitution with high significance (p less than 0.005).

Adult↗
PubMed1989

Angiotensin II stimulates human gastric smooth muscle in vitro.

1. For a precise analysis of angiotensin II (ANG) effects on human gastric muscle, we dissected longitudinal (lo) and circular (ci) strips from fundus (Fu), corpus (Co) and antrum (An), and circular muscle from the inner and outer part of the pyloric sphincter (Py-inn and Py-out) and from duodenum. The mechanical activity of these muscle strips was recorded simultaneously under auxotonic conditions. Preparations were taken from a total of 10 stomachs (from organ donors or gastrectomy preparations). 2. Excitatory effect after application of ANG (10(-9) to 10(-6) mol l-1) were regularly observed in all types of preparation (threshold: 10(-9) mol/l). 3. The quality of the responses depended on the general characteristics of the type of preparation. Tonic types of muscle showed predominantly tonic responses to ANG (Fu-lo, Fu-ci, Co-lo). Purely phasic muscles (An-ci) showed increases of the phasic activity (amplitude up to 33% delta 1). Intermediate types of muscle exhibited combined phasic/tonic responses (Co-ci, An-lo). Phasic responses were also seen in Py-out. Inner pyloric muscle (Py-inn) responded only to a small extent to ANG. Phasic/tonic activations were observed in the duodenal preparations, accompanied by slight increases in frequency. 4. The intensity of the ANG-induced responses often exceeded the maximum acetylcholine-induced activation. The qualitative pattern of ANG responses was similar to that of bombesin-induced activation.

Acetylcholine↗