The Lipid Composition of Urodele Myelin Which Lacks Hydroxycerebroside and Hydroxysulfatide

The concentrations of cerebrosides and sulfatides were measured in the nervous systems of urodeles and related orders with a high performance liquid chromatographic technique. The peripheral and central nervous systems of all three urodele species, Necturus maculosis (mud puppy, a salamander), Notophthalmus viridescens (eastern red spot newt), and Desmognathus ochropheus (mountain salamander), were found to be completely devoid of alpha-hydroxy fatty acid-containing cerebrosides and sulfatides. All species of reptiles and fish classes close to urodeles contain these galactolipids. The levels of nonhydroxy fatty acid-containing cerebrosides and sulfatides are essentially similar in both urodeles and reptiles. Myelin isolated from Necturus spinal cord had a specific density of 1.07, lighter than mammalian myelin. Except for the absence of hydroxycerebrosides and hydroxysulfatides, the lipid composition of Necturus spinal cord myelin is essentially similar to that of frog and rat myelin. The fatty acids of nonhydroxycerebrosides are rich in monounsaturated homologs of C22-C25, and the sphingoid base consists of both sphinganine and sphingosine. Electron microscopic examination of the sciatic nerve showed that the general structure and interlamellar distances of salamander and newt myelin are identical to those of frog, chameleon, and rat. Necturus myelin, therefore, can be used as a model for the study of the functional and structural role of hydroxygalactolipids.     

Hydroxyl-radical production and ethanol oxidation by liver microsomes isolated from ethanol-treated rats.

In order to distinguish between the mechanism of microsomal ethanol oxidation and hydroxyl-radical formation, the rate of cytochrome P-450 (P-450)-dependent oxidation of dimethyl sulphoxide (Me2SO) was determined in the presence and in the absence of iron-chelating compounds, in liver microsomes from control, ethanol- and phenobarbital-treated rats. Ethanol treatment resulted in a specific increase (3-fold) of the microsomal ethanol oxidation and NADPH consumption per nmol of P-450. A form of P-450 was purified to apparent homogeneity from the ethanol-treated rats and characterized with respect of amino acid composition and N-terminal amino acid sequence. Specific ethanol induction of a cytochrome P-450 species having a catalytic-centre activity of 20/min for ethanol and consuming 30 nmol of NADPH/min could account for the results observed with microsomes. Phenobarbital treatment caused 50% decrease in the rate of ethanol oxidation and NADPH oxidation per nmol of P-450. The rate of oxidation of the hydroxyl-radical scavenger Me2SO was increased 3-fold by ethanol or phenobarbital treatment when expressed on a per-mg-of-microsomal-protein basis, but the rate of Me2SO oxidation expressed on a per-nmol-of-P-450 basis was unchanged. Addition of iron-chelating agents to the three different types of microsomal preparations caused an 'uncoupling' of the electron-transport chain accompanied by a 4-fold increase of the rate of Me2SO oxidation. It is concluded that ethanol treatment results in the induction of P-450 forms specifically effective in ethanol oxidation and NADPH oxidation, but not in hydroxyl-radical production, as detected by the oxidation of Me2SO.     

Suppressive effect of elcatonin, an eel calcitonin analogue, on excessive urinary hydroxyproline excretion in polyostotic fibrous dysplasia (McCune-Albright's syndrome)

A 12-year-old Japanese girl with polyostotic fibrous dysplasia and endocrine concomitants, was treated with elcatonin, a synthetic eel calcitonin analogue, 10 MRC unit/twice a week given by intramuscular injection. Significant decreases in 24 hr urinary content of hydroxyproline and other amino acids from bone collagen were observed during the course of treatment over 5 months. This biochemical result suggests that the synthetic eel calcitonin analogue exhibits the therapeutic effect in patients with polyostotic fibrous dysplasia by inhibiting bone resorption.     

COMPARISON OF THE FATTY ACIDS OF LIPIDS OF SUBCELLULAR BRAIN FRACTIONS

Abstract— Rat brain grey and white matter were fractionated to yield myelin, nerve terminal, synaptic vesicle, nerve terminal 'ghost', and microsomal fractions of white and grey matter. Ester-type glycolipids were found in all fractions except myelin, while cerebrosides occurred in significant concentrations only in myelin and white microsomes. Comparison of the fatty acid profile of the ethanolamine- and serine-containing phospholipids showed marked differences between myelin and the particles from grey matter, while the microsomes of white matter were of intermediate composition. Docosahexaenoic acid, a minor acid in myelin, was a major fatty acid in microsomes of grey and white matter. The fatty acid composition of sphingomyelin was distinctly different in the fractions derived from grey and white matter, clustering about stearate and nervonate in the latter, but only about stearate in the grey. Marked differences in the positional distribution of fatty acids were seen within phosphatidyl choline from myelin and nerve terminals. Ribonucleic acid was found in nerve terminal and synaptic vesicle fractions. The sphingosine found in the ganglioside from microsomes of both grey and white matter was similar with respect to distribution of the C₁₈ and C₂₀ homologues.
The possibility is discussed that microsomes furnish characteristic lipids for the synthesis or renewal of specific membranes, and that these lipids are accumulated somewhat before being released.     

A new species and a new subspecies of the stargazer genusGnathagnus from Northwestern Australia

Heretofore the genusGnathagnus (Uranoscopidae) has been composed of three species:G. elongatus (Temminck et Schlegel) from northern Australia to Japan,G. innotabilis (Waite) from Australasia, andG. egregius (Jordan et Thompson) from the western Atlantic Ocean. In this paper, a new species and a new subspecies from northwestern Australia are described and a key to the known species and subspecies of the genus is presented.