Membrane flow within the myelin sheath in IDPN neuropathy

This report describes some aspects of beta,beta'-iminodipropionitrile (IDPN) neuropathy in rats as observed by ultrastructural methods and X-ray diffraction. Light microscopy shows gross swelling of the axons in proximal lumbar spinal roots 8 days after intraperitoneal injection of IDPN. Mean axon cross-sectional area and mean axon perimeter increased to 280% and 160% of their control values, respectively. At the same time, myelin membrane packing was not visibly disturbed. In addition, X-ray diffraction patterns, recorded under physiological conditions, demonstrate that the myelin lipid bilayer thickness and widths of the aqueous spaces between bilayers did not change. Related observations are made on posterior tibial nerve (PNS myelin) and ventral spinal cord (CNS myelin). The various observations together are interpreted in terms of a fluid myelin membrane. It is proposed that the myelin membrane flows during axon swelling even though normal membrane-membrane contacts are maintained within the sheath. Membrane flow and slippage between membranes are explained in terms of a molecular model of the myelin multilayer.     

Lack of Peroxisome Proliferation in Marmoset Liver Following Treatment with Ciprofibrate for 3 Years

The effect of treatment of marmosets with ciprofibrate for 3years on activities of hepatic enzymes, hepatic histomorphology,and ultrastructure were investigated. Male and female mar mosetswere dosed with ciprofibrate (2, 10, and 20 mg/kg) by oral gavageonce daily for 3 years. No effect on liver weight (adjustedfor body weight) or liver morphology was observed. The activitiesof catalase, glutathione peroxidase, -glycero phosphate dehydrogenase,benzphetamine N-dernethylase, and ethoxyresorufln O-deethylasewere unaffected by treatment with ciprofibrate. Activity ofglutathione transferase was in creased in the low dosage groupbut unaffected in the mid and high dosage groups. Modest increasesin activities of peroxiso mal ß-oxidation (2.5-fold,maximal), carnitine acetyl transfer ase (1.7-fold, maximal),and carnitine palmitoyl transferase (2- fold, maximal) wereobserved. Cytochemical staining and quan titative image analysisfailed to indicate any effect on peroxisomal number, size, orvolume density. Similarly, there was no increase in lipofuscindeposition. This study provides data on the effects of a potentperoxisome proliferator on pri mate liver following a dosingperiod much greater than that used in previously published studiesand is further evidence that the marmoset is relatively insensitiveto the well-documented effects that ciprofibrate and other peroxisomeproliferators have on rat liver.     

TAKAYASU'S DISEASE ASSOCIATED WITH GENERALISED AMYLOIDOSIS

A case of Takayasu's disease in a young Caucasian female is described. The major complications which developed over the ten year course of the disease include nephrotic syndrome, severe refractory hypertension, aortic valve regurgitation associated with aneurysmal dilatation of the ascending aorta, and recurrent congestive heart failure. Amyloid deposits have been demonstrated in the aorta, atrial appendage, aortic valve, and renal cortex.
The association of amyloidosis and Takayasu's disease is discussed. (Aust NZ J Med 1985; 15: 343–345.)