Biomedical subjects

F J Schmitt

Publications and source records attributed to F J Schmitt.

4 recordsLinked to original sources

PubMed1992

Long-range attraction and molecular rearrangements in receptor-ligand interactions.

A surface force apparatus was used to measure a long-range attractive protein-ligand force at separations D less than 85 angstroms. This force may effectively "steer" ligand trajectories, resulting in a greater than 27-fold enhancement of the association rate. A much stronger specific attraction is measured at contact (D less than 4 angstroms). A sevenfold increase in intermembrane adhesion resulted from increased lateral mobility of the receptors and molecular rearrangements in membranes above the solid-fluid transition temperature.

Bacterial Proteins↗

PubMed1992

Streptavidin binding observed with an atomic force microscope.

An atomic force microscope (AFM) was used to investigate a specific recognition reaction: the binding of streptavidin to a biotinylated lipid bilayer. Prior to the recognition reaction, the phase coexistence of the lipid bilayer was clearly observed: fluid domains were lower than the crystalline domains. After introducing to the bilayer a very dilute solution of streptavidin to give a final concentration of approximately 0.5 microM, the recognition reaction was imaged in real time. Several hours later, we observed a contrast reversal, i.e., the previously lower fluid domains grew so much in height that they became higher than the crystalline domains. We found that the streptavidin molecules bound almost exclusively to the biotin in the fluid domain (less than 0.25% coverage of the crystalline domains). The apparent structure of the few streptavidin molecules bound to the crystalline domain of the bilayer is shown to depend on the applied force. Finally, in a 2-dimensional quasi-crystal in which the streptavidin molecules were compressed at the air-water interface molecular resolution was achieved.

Bacterial Proteins↗

PubMed1986

[Amyloidosis of the A-kappa type].

A 73-year-old patient complained of increasing macroglossia and symmetrical enlargement of the submandibular region. A tongue biopsy showed typical deposits of amyloid by Congo red staining and polarization microscopy. Similar deposits were found in biopsy specimens of the submaxillary gland and the rectum. Electron microscopy revealed typical amyloid fibrils. With the indirect immunoperoxidase technique the amyloid was classified as being of immunoglobulin kappa-light-chain origin (A-kappa), because only anti-A kappa, but not anti-A lambda (several antisera of non-overlapping specificity), anti-ASc1 or anti-AF antisera were found to be reactive. Correspondingly, Bence Jones protein of the kappa type was found in the urine. In the bone marrow there was an increase in plasma cells of up to 10%. Cytostatic therapy with melphalan and methylprednisolone seemed to stop the progression of amyloid deposition.

Aged↗

PubMed1976

A method for the treatment of metamerism in colorimetry.

All of the spectrally different colors that match according to an observer form a metamer ensemble. We present a new method to generate the metamer ensembles for both direct light and reflecting-surface-color problems. The method is based on the properties of particular metameric functions (the simple elements) and is particularly appropriate for treating problems of theoretical limits of metamerism. The method is illustrated with several practical examples and is compared with previously known methods.

Color Perception↗