Apolipoproteins of the orotic acid fatty liver: implications for the biogenesis of plasma lipoproteins

Rats fed orotic acid develop fatty livers characterized by triglyceride-laden, membrane-bounded vesicles designated "liposomes." We have measured the levels of apolipoproteins in isolated liposomes and other subcellular fractions by SDS-polyacrylamide gel electrophoresis, electrotransfer, and immunodecoration. Apolipoproteins Bh, Bl, E, and C appear to cofractionate; for these proteins, the liposomal pool represents a large portion of their total intracellular mass. However, liposomes are deficient in both variants of apoB relative to apoE and apoC when compared with rat plasma very low density lipoprotein (VLDL). Albumin and apolipoproteins A-I and A-IV are also found in liposomes, but this organelle represents a minor fraction of their total intracellular mass. The liposomal apolipoproteins show varying degrees of association with cisternal lipid and with organelle membranes. Orotic acid may selectively block VLDL production at the level of particle assembly or transorganellar movement. We conclude that liposomal contents probably represent exaggerated accumulations of VLDL assembly intermediates, and that the intracellular partitioning of high density lipoprotein-destined from VLDL-destined components occurs at an early stage in particle biogenesis. Moreover, some unique structural feature of apoB may effect movement of VLDL assembly intermediates through secretory organelles.

Complex cytogenetic changes in Ph-negative chronic myelogenous leukemia

A Ph-negative chronic myelogenous leukemia (CML) with t(3;7)(q21;q32), t(4;9)(q21;q34), and del(8)(q22) is reported. This case is rather unusual for Ph-negative CML in being associated with complex chromosome changes. The patient was diagnosed as in the accelerated phase of CML. It will be important to study this malignant disorder in detail cytogenetically and molecularly in order to ascertain its nature and place among the myeloproliferative disorders.

UHV-manipulator attachment for azimuthal sample rotation with electrical readout

A nonmagnetic UHV-compatible sample manipulator is described, which allows direct electrical readout of the azimuthal rotation angle by a wire-wound potentiometer inside the vacuum. The rotation about an axis in the sample surface is completely decoupled from the azimuthal rotation about the surface normal. The sample temperature can be varied between +2000 degrees and -70 degrees C by resistive heating or by cooling the current leads. The sample manipulator is designed such that it can easily be attached to commercial manipulators with a flip actuator.

On the Field Emission from Ni, Gd, and EuS Evaporated on to Tungsten

Tungsten tips coated with Ni, Gd and EuS are studied in a field electron microscope. Reproducible patterns are observed. The Gd-patterns show epitaxy with the W-substrate. With tempered tips the work functions are: Ni 5.1 ± 0.3 eV, Gd 3.2 ± 0.3 e V and EuS 3.1 ± 0.3eV.

For the production of polarized electrons by field emission from materials with spin polarized bandstructure 1 - 4 the field emission from Gd, Ni and EuS is of interest.