Dural arteriovenous malformation in the anterior fossa

A case of dural arteriovenous malformation in the anterior fossa is reported. It first caused a subarachnoid hemorrhage and subsequently an intracerebral hematoma. Pertinent literature is briefly reviewed. Such malformations may be divided into three groups; those involving primarily the basal dura mater of the anterior fossa, the anterior portion of the falx, or the dura mater of the frontal convexity. Principal blood supply comes from the ophthalmic artery with an additional supply from the external carotid system. The treatment of choice is surgical excision with or without artificial embolization of the feeding arteries from the external carotid artery.

Turnover of myelin proteins in mouse brain in vivo

The incorporation of tyrosine into proteins was measured after the subcutaneous implantation of a pellet of [14C]tyrosine in mice. This method keeps the specific radioactivity of free tyrosine fairly constant and makes it possible to follow incorporation up to a 10-day period. At the end of 10 days most of the protein-bound tyrosine was replaced (i.e. most protein turned over) in lung, liver, heart, kidney and spleen; about half was replaced in brain, one-quarter in muscle. The rate of protein turnover in myelin was approx. 40% of that of whole brain proteins; at 10 days one-fifth of the myelin proteins were replaced. All protein components of myelin measured were in a dynamic state; incorporation decreased in the following order, Wolfgram greater than DM-20 greater than basic greater than proteolipid proteins. The incorporation of tyrosine into each protein fraction was greater in the 0-5-day than in the 5-10-day period, indicating heterogeneity of metabolic rates. The results show that after myelination at least a portion of each protein component of myelin is undergoing significant metabolic turnover. In the adult, myelin components are not stable, but turnover is heterogeneous, and each protein may be compartmentalized. Turnover can be influenced by a variety of factors.

A novel synthesis of 2-deoxy-alpha-glycosides

The key step of the synthesis involves the reaction of glycals [3,4,6-tri-O-acetyl-D-glucal (1), the new glycal derivative 4-O-acetyl-1,5-anhydro-2,6-dideoxy-3-C-methyl-3-O-methyl-L-ribo-hex-1-enitol (2), and 3-acetamido-4,6-di-O-acetyl-1,5-anhydro-2,3-dideoxy-D-arabino-hex-1-enitol (3)] with 1.5 molar equivalents of several alcohols in the presence of N-bromosuccinimide in acetonitrile to give mainly the corresponding 2-bromo-2-deoxy-alpha-glycopyranosides (4--21). The glycopyranosides (4-8 and 16-21) from 1 and 3 have the alpha-D-manno configuration and those (10--15) from 2 have the alpha-L-altro configuration. The yields are high from 1, virtually quantitative from 2, and moderate from 3. Debromination of the 2-bromo-2-deoxy compounds with tributylstannane and a radical initiator gives the corresponding 2-deoxy-alpha-glycopyranosides (22-38) in quantitative yields. In particular, the branched-chain glycal 2 reacts with alcohols to give exclusively the corresponding alpha-glycopyranosides (27--32) of cladinose in strikingly high overall yields. The stereoselectivity and regiospecificity of the bromination reaction are described. 1,3-Dibromo-5,5-dimethylhydantoin and N-bromoacetamide are also found to be useful for the reaction.

Morphological and biochemical characterization of light and heavy myelin isolated from developing rat brain

Myelin from developing rat brains was separated on a discontinuous sucrose gradient into subfractions of two different densities, i.e. light and heavy myelin. Electron photomicrographs showed that heavy myelin consisted primarily of large compacted multilamellar structures with a distinct intraperiod line characteristic of myelin in situ. Light myelin, on the other hand, was composed of small vesicles having a unilamellar structure. Similar to whole myelin, both membrane subfractions were highly enriched in 2',3'-cyclic nucleotide-3'-phosphohydrolase. The specific activity of the enzyme, however, showed no developmental trend. Both subfractions contained all the four major proteins characteristic of the whole myelin membrane. There were, however, quantitative differences in the relative distribution of these proteins between light and heavy myelin. Basic protein accounted for 55% and proteolipid protein for 46% of the total myelin proteins of light and heavy myelin, respectively. DM-20 (Agrawal, H.C., Burton, R. M., Fishman, M.A., Mitchell, R.F. and Prensky, A.L. (1972) J. Neurochem. 19, 2083-2089) exhibited a developmental "switch" between light and heavy myelin. Light myelin appeared to contain more DM-20 in 15- to 20-day-old rat brain, whereas the concentration of this protein was higher in heavy myelin at subsequent ages studied.

Accumulation and turnover of the classical Folch-Lees proteolipid proteins in developing and adult rat brain

The turnover of classical Folch-Lees proteolipid proteins was studied after administration of [2,3-3H]tryptophan to both developing and adult rat brain. The animals were killed from 2h to 250 days after subcutaneous injections of [3H]tryptophan. The measured specific radioactivity in developing brain attained maximum value 24h after the administration of label, whereas the total radioactivity per brain reached a maximum 21 days after injection. The half-life of proteolipid protein from the measured specific radioactivity was 7-20 days, depending on the time-points used for the calculation, whereas calculation from total radioactivity between 28-77 and 91-257 days gave half-lives of 35-40 and 188 days respectively. In contrast, in animals injected at 40 days of age, the half-life from the whole-brain-radioactivity data was 188 days. The problem of the recycling of radioactivity for the synthesis of myelin proteins from either a general or a discrete amino acid pool is discussed.

Relation of C-6 glial cells in culture to myelin

C-6 glial cells were shown to contain enriched in their plasma membranes an enzyme, 2':3'-cyclic nucleotide 3'-phosphohydrolase, characteristic of myelin, and, in addition, proteolipid protein and two basic proteins that are identical in their electrophoretic mobilities with the respective proteins found in myelin. The data indicate that C-6 cells exhibit features of myelin-producing glia as well as astrocytes.