Abnormal Kinetics of Red Cell Membrane Cholesterol in Acanthocytes: Studies in Genetic and Experimental Abetalipoproteinaemia and in Spur Cell Anaemia

S ummary . Abnormalities in the content and kinetics of red cell membrane cholesterol are described in several syndromes associated with spurring of red cells ('acanthocytosis'). In all (hereditary abetalipoproteinaemia, 'spur cell anaemia' of severe hepatic failure, and in a lipid-deprived infant with acquired hypobeta-lipoproteinaemia) red cell membrane cholesterol was 15–50% increased. Free cholesterol normally flows bidirectionally between red cell membranes and plasma betalipoproteins, but plasmas from affected patients with acanthocytosis were uniformly inefficient in accepting cholesterol from red cells. Stagnation of the sterol on red cells resulted. Plasma from rats in which abetalipoproteinaemia was experimentally produced by prolonged feeding of orotic acid, demonstrated similar abnormalities. Thus, red cells from treated animals became acanthocytic within I mth; with the shape change an increase in membrane cholesterol of about 20% and a significant decrease in osmotic fragility occurred. ¹⁴C-cholesterol flux from rat red cell membranes was 30–40% decreased into the experimentally-abetalipoproteinaemic, relative to betalipoprotein-replete, rat plasmas.
We conclude that stagnation and, less importantly, accumulation of red cell cholesterol may be associated with conformational changes in the structural lipoproteins of the red cell membrane leading to spurring. Regardless of mechanism, this shape change causes acanthocytes to become abnormally rigid and resistant to flow, documented in the present studies by their increased viscosity in cone-plate viscosimeters and by their diminished filterability through micropore filters. Both features are probably involved in the diminished survival of these cells in the circulation.     

Diagnostic laparoscopy.

Six hundred fifty-eight laparoscopies were performed at St. Luke's Hospital, Kansas City, Missouri, USA, between March 1, 1976 and February 28, 1977. One hundred sixty-eight (25.5%) were performed for diagnostic purposes. A review of the preoperative diagnoses and the laparoscopic findings demonstrates the value of laparoscopy as a diagnostic procedure.     

Stannous-ion quantitation in pyrophosphate and polyphosphate radiopharmaceutical kits using differential pulse polarography.

Stannous salts are used as reducing agents in many radiopharmaceutical kits. Differential pulse polarography, with 1 M sulfuric acid as the supporting electrolyte, is a relatively simple and effective technique for stannous quantitation and can be used in the quality assurance testing of pyrophosphate and polyphosphate radiopharmaceutical kits.