Catalase depression in malignant liver from chickens with myeloblastosis and Marek's disease.

In rapidly frozen livers from chickens affected with myeloblastosis and Marek's disease and from unaffected control birds there exists a strong correlation between catalase activity and catalase Electron Paramagnetic Resonance (EPR) signal intensities. The diseased chickens had activities and signals reduced to as little as 10% of control values. There were no changes in the EPR parameters in diseased liver and the data support the hypothesis that the lowering in activity is due to lowered catalase levels rather than to catalase inhibition.

Electron spin resonance spin label studies of the erythrocyte membrane in Duchenne muscular dystrophy.

The membrane organisation of erythrocytes from patients with Duchenne muscular dystrophy (DMD) and from asymptomatic carriers was studied by the electron spin resonance (ESR) spin label technique. Following the work of Sato et al [1978], we used 2-(14-carboxytetradecyl)-2-ethyl-4, 4-dimethyl-3-oxazolidinyloxyl as probe. We found no significant difference in lipid fluidity at 30 degrees C, measured by the ratio of the line height at central field to that at high field ho/h-1, in DMD patients or carriers compared to appropriate control persons.

Measurement of erythrocyte membrane elasticity as a diagnostic aid in Duchenne muscular dystrophy.

Using a micropipette aspiration technique, erythrocyte membrane shear elastic modulus was determined for 23 patients with Duchenne muscular dystrophy, for 14 female carriers, and for three control groups (age matched boys and adult males and females). On average the elastic modulus was slightly greater than normal for both affected males and female carriers. However, there was overlap in the values from all groups.

Erythrocyte membrane elasticity during in vivo ageing.

Changes in the ability of senescent erythrocytes to pass through the microcirculation may cause them to be trapped in the spleen and removed from the blood. To help understand this process we have measured erythrocyte membrane elasticity, to see whether it changes during in vivo ageing. Human and rabbit red cells were fractionated by isopycnic sedimentation to obtain samples of aged and young cells.

Physics.

It is tempting for a lecturer in physics to present medical students with a course which, though sound and vigorous, is more suited to a physicist or engineer. At Guy's Hospital Medical School, physics is taught at a level which the student can follow and the relevance of the subject to the practice of medicine is made clear.

Bacteriorhodopsin, boundary lipid and protein conformers: a spin label study.

A spin label study, as a function of temperature, has been made with the bacteriorhodopsin membrane using a stearic acid spin label. The ESR spectra show a strong variation with temperature and the presence of isosbestic points. The spectra are interpreted as indicating the presence of a two-component system with an activation energy (approx.

Electron spin resonance spin-label studies of mouse olfactory epithelium.

Three classes of interaction of spin-labeled odors with olfactory membrane of mouse were identified by electron spin resonance spectroscopy and correlated with the olfactory potencies of those odors. Also, variation of fluidity in this membrane was probed using spin-labeled lipids in which the nitroxide group was at increasing distances from the lipid headgroup. A cooperative model of olfactory transduction in agreement with the results is introduced, and typical dose response curves are computed that can predict molecular features necessary for a strong odor.