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Biomedical subjects

A Rothen

Publications and source records attributed to A Rothen.

18 recordsLinked to original sources
PubMed1979

Tryptic action across a membrane.

Tryptic action occurs when a layer of bovine serum albumin adsorbed on a nickel-plated slide and protected by a Formvar membrane 120 A thick is treated with dilute trypsin solution. But experimental evidence indicates that the trypsin molecules to not cross the membrane. Thus the proposal that trypsin can exert its enzymatic action without intimate contact with the substrate, first set forth in 1948 but later abandoned in favor of a "forced diffusion" hypothesis, now appears the correct interpretation. Analogously, antibodies can be specifically immobilized on one side of a membrane separating them from adsorbed antigens located on the other side.

Diffusion↗
PubMed1975

Daily periodicity in the activity of a slide used to perform immunologic reactions at a liquid-solid interface.

Nickel-plated slides were prepared by evaporating a nickel layer (congruent to 4000 A thick) on glass slides in the presence of a magnetic field whose lines of force were perpendicular to the surface of the slides. Such slides are called active. After being coated with a layer of bovine albumin, they could absorb a layer of antibodies 70-80 A thick. However, if the active slides before they were coated with bovine serum albumin, were submitted to a magnetic field with lines of force parallel to the surface, the layer of antibodies absorbed was only 40 A thick. They had become inactive. It has been found that slides remain active at night but that shortly after sunrise they become slowly inactivated and reach a minimum in their activity at exactly the midday period. They regain full activity at sunset. It is shown that the inactivation results from a solar radiation that can be stopped by 3.5 cm of lead. On December 13th, 1974 there was an eclipse of the sun with 65% occultation at noon (Daylight Saving Time). The activity of the slide at noon was 65% of the maximum activity (83 A) observed before sunrise. The thickness of the adsorbed layer of antibodies were 75 A instead of 63 A observed in the absence of the eclipse. The activation of the slides originates in a radiation of non-solar origin that is adsorbed by 1 can of lead.

Animals↗
PubMed1975

A 24-hour periodicity in the activity of a nickel-coated glass slide used for carrying out immunologic reactions at a liquid-solid interface.

Active nickel-plated slides are prepared by evaporating the metal in the presence of a magnetic field oriented perpendicularly to the slide, the surface being metallized facing the south pole of the field. Active slides coated with an antigen layer (bovine albumin or ovalbumin) can specifically adsorb a layer of antibodies nearly twice as thick (70 to 80 A) as that adsorbed on inactive slides (40 A). The activity of a slide varies within a 24-hour period. Fully active at night, a slide gradually loses its activity from sunrise on but regains it at sunset. The experimental evidence favors the view that inactivation is brought about by soft cosmic rays emanating from the sun. The inactivation can be prevented by keeping the slide under 3.5 cm of lead.

Animals↗