PubMed Health⌕ Search

Biomedical subjects

M De Vries

Publications and source records attributed to M De Vries.

5 recordsLinked to original sources
PubMed1977

Comparison between the size of granular vesicles in intact cells and vesicles obtained by fragmentation of biomembranes.

Preparations of biomembranes, consisting of membrane vesicles, were analyzed with the analytical ultracentrifuge. Under certain conditions depending on the speed of rotation and the temperature, a sedimentation profile was observed that was highly characteristic for membranous material. From the sedimentation coefficients obtained, we calculated particle weights for the various well-defined membrane components. In certain types of preparations the particle weights of two adjacent components differed on average by a factor of 2. When vesicles obtained by fragmentation of biomembranes were compared with the granular vesicles present in intact cells, the accordance in diameters was striking. This may indicate that the size of vesicles is determined by purely physical factors.

Animals↗
PubMed1976

Sedimentation studies on membrane vesicles.

Analytical centrifugation was used in order to investigate the size distribution of vesicles in various membrane preparations. Under certain conditions depending among others on the speed of rotation and the temperature, a sedimentation profile was observed that was characteristic for membraneous material. Since the membrane vesicles exhibited a discontinuous distribution of sedimentation coefficients it was concluded that membrane vesicles only occur in a few size classes.

Cell Fractionation↗
PubMed1975

Run-off ribosomes in liver, spleen and pancreas of the rat.

Free polyribosomes, isolated from liver, spleen and pancreas of the rat, were suspended in a medium at 0.5 mM Mg2+ and analyzed in the analytical ultracentrifuge. The percentage of run-off ribosomes, distinguised by a sedimentation coefficient below 77S was calculated from centrifugal experiments. The amount of run-off ribosomes differed in the various tissues of the rat but was not influenced by fasting overnight.

Animals↗
PubMedDate not supplied

Motion onset-offset VEPs in children.

We analysed motion onset-offset visually evoked potentials (VEPs), pattern appearance-disappearance VEPs and pattern reversal VEPs recorded in 23 adults and 37 children, ranging in age from 5 to 12 years. Motion-specific responses (i.e., responses that could not be attributed to the changes in contrast that are associated with the onset and offset of motion) were found in 25 children (67.6%) and in 19 (83%) adults. These percentages do not differ significantly. Also the age distributions of children with and without motion-specific VEPs do not differ significantly. For these reasons no development of motion VEPs with age could be established, in contrast with the well-known maturation of the pattern appearance VEPs.

Child↗