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Biomedical subjects

H Ludt

Publications and source records attributed to H Ludt.

13 recordsLinked to original sources
PubMed1994

Application of minimal spanning trees in glioma grading--a CLIPPER program for the calculation and construction of minimal spanning trees.

We present a CLIPPER program for the calculation and graphical representation of minimal spanning trees (MST) which is available on request on diskette from the authors. The MST are a useful parameter for structural cluster detection. They can be applied to grading problems in tumour biology. We present and discuss the applicability of MST by an example from the field of astrocytoma grading.

Algorithms↗
PubMed1986

Stainless steel skin staples--a useful electrode system for long-term electrophysiological measurements in neurosurgery. Technical note.

Stainless steel staples commonly used for skin suture were tested for their suitability as electrodes for recording electrophysiological data. Investigations were performed in vivo and as well as in vitro, and showed the typical behaviour of electrodes made from a polarizable metal, i.e., an increase of electrode impedance with low frequencies. In spite of this fact most electrophysiological data can be recorded if the input impedance of the amplifier is in the common range of 100 MOhms. Advantage of these electrodes is their quick and easy application, their resistance to mechanical stress and the possibility of leaving them in place for a long time.

Brain↗
PubMed1979

Sodium nitroprusside (NPS) stimulates the lactate formation and causes intracellular electrolyte shifts in brain slices.

Nitroprusside sodium (NPS) was added to slices from grey and white rabbit brain matter. The respiration, consumption of glucose, formation of lactate and pyruvate, water content, size of the extracellular space, and total and intracellular sodium and potassium concentrations were determined and calculated. 0.5 and 1 mM NPS stimulated the glycolytic glucose breakdown, and inhibited the respiration of grey and white slices. The respiration of white matter slices was stimulated by 0.05 and 0.01 mM NPS. The total and intracellular potassium concentrations in slices from grey and white matter were lowered markedly by 1 mM NPS. The total and the intracellular sodium concentrations in grey brain matter slices became higher in the presence of 1 mM NPS. A warning is given against uncritical clinical use of higher concentrations of NPS.

Animals↗
PubMed1979

Examination of the metabolism of oedematous brain tissue. V. The metabolism of oedematous white matter from rabbit brain.

Glucose and gas metabolism as well as water, sodium, and potassium content of normal and oedematous white matter slices of rabbit brain have been determined. A cutting technique for the preparation of the slices is described. Although the increase of the relative water content in oedematous white matter is much more pronounced than in oedema of the grey matter, we observed only one significant change: the pyruvate production in vitro is about 20% higher in slices prepared from oedematous brain.

Animals↗
PubMed1976

A simple bubble-flowmeter with quasicontinuous registration.

The construction of a simple bubble-flow-meter is described. The instrument has the following features: 1. automatic bubble injection, 2. precise measurement of the bubble passage time by a digital counter, 3. quasicontinuous registration of the flow rate, 4. alternative run with clear fluid (water) and coloured fluid (blood), 5. low volume, 6. closed measuring system for measurements in low and high pressure systems.

Regional Blood Flow↗
PubMed1975

Advantage of defined tissue slices against minced samples in biochemical in vitro investigations of brain cortex.

A cutting device for the preparation of brain cortex slices with a regular cylindric shape and a defined thickness is described. Determinations of the glucose and the electrolyte metabolism and the reactions of both to substances' additions were made with minced brain and with brain slices of different thichknes. The comparison of the methods and of the results makes evident that experimentation with slices has several advantages.

Animals↗