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Biomedical subjects

M H Muheim

Publications and source records attributed to M H Muheim.

5 recordsLinked to original sources
PubMed1979

Blood pressure fluctuations in human nailfold capillaries.

Dynamic blood pressure was measured in 33 human finger nailfold capillaries after direct cannulation with glass micropipettes by means of a resistance servo-nulling pressure measuring method. ECG, finger pulsations, and respiratory thorax excursions were monitored simultaneously. All recordings exhibited pulsatile oscillations related to the cardiac rhythm. These oscillations resembled the wave forms of arterial pulsations with steep upstroke and dicrotic notch when the pressure amplitudes were above 10 mmHg. There was no apparent dependence on respiration. In 12 instances, pressure fluctuations with frequencies ranging from 0.2 down to 0.07 Hz were observed in both the arteriolar and venular limb. Blood pressure in human skin capillaries is pulsatile and subject to remarkable fluctuations in the arteriolar as well as in the venular limb, systolic pressure values ranging from 14 to 71 mmHg and from 11 to 52 mmHg, respectively.

Adult↗
PubMed1977

Fabrication of well defined micropipette tips by hydrofluoric acid etching.

Glass tubes were drawn on a two stage pipette puller such that tips with 0.5-2.0 micron inner diameters were obtained as confirmed by scanning electron imaging. The pipettes were attached to an air reservoir with a pressure set at 0.5 bar to prevent fluid from entering the tip. They were lowered into 2% hydrofluoric acid by means of a micromanipulator. When air bubbles began to escape from the tips, they were withdrawn and immersed into 0.5 molar phosphate buffer, pH 7.4, and then rinsed with tap water and ethanol. Etching during 100 s (mean) yielded inner tip diameters of 5 micron (+/- 5% S.D.). The tips were beveled at the same angle at which they had been dipped into the etching fluid. No continuation of the etching process was noticed even after several days.

Glass↗