Halogenated monoterpenes of the red alga Microcladia

The red marine algae Microcladia borealis, M. californica and M. coulteri produce several unusual halogenated monoterpenes including violacene, plocamene-B, plocamene-C, and plocamane-D. The isolation of these terpenes along with a study of their variation in each Microcladia at different locations are described.     

Biogenesis of mitochondria

Summary The action of ethidium bromide and berenil on the mitochondrial genome of Saccharomyces cerevisiae has been compared in three types of study: (i) early kinetics (up to 4 h) of petite induction by the drugs in the presence or absence of sodium dodecyl sulphate; (ii) genetic consequences of long-term (8 cell generations) exposure to the drugs; (iii) inhibition of mitochondrial DNA replication, both in whole cells and in isolated mitochondria.The results have been interpreted as follows. Firstly, the early events in petite induction differ markedly for the two drugs, as indicated by differences in the short-term kinetics. After some stage a common pathway is apparently followed because the composition of the population of petite cells induced after long-term exposure are very similar for both ethidium bromide and berenil. Secondly, both drugs probably act at the same site to inhibit mitochondrial DNA replication, in view of the fact that a petite strain known to be resistant to ethidium bromide inhibition of mitochondrial DNA replication was found to have simultaneously acquired resistance to berenil. From consideration of the drug concentrations needed to inhibit mitochondrial DNA replication in vivo and in vitro it is suggested that in vivo permeability barriers impede the access of ethidium bromide to the site of inhibition of mitochondrial DNA replication, whilst access of berenil to this site is facilitated. The site at which the drugs act to inhibit mitochondrial DNA replication may be different from the site(s) involved in early petite induction. Binding of the drugs at the latter site(s) is considered to initiate a series of events leading to the fragmentation of yeast mitochondrial DNA and petite induction.     

Purification of rat brain succinate-semialdehyde dehydrogenase and study of its inhibition by branched chain fatty acids]

Rat brain succinic semialdehyde deshydrogenase has been purified 1300 fold. This enzyme is inhibited non competitively by the same branched chain fatty acids which inhibit GABA-transaminase competitively with respect to GABA. The respective activities of GABA-T and SSADH found in rat brain indicate that at anticonvulsant doses, the acids dipropylacetic and 2-methyl 2-ethyl caproic preferentially inhibit GABA-transaminase thus inducing a rise in cerebral GABA level. This increase is therefore not due to metabolism of the succinic semialdehyde by GABA-T.     

Bovine Heterografts for Hemodialysis

Long-term results with 52 bovine, 53 saphenous vein and 78 radial-cephalic arteriovenous fistulas (AVF) were analyzed. Side-to-end radial-cephalic AVF provided the best patency data, and remain the preferred access system for hemodialysis. Bovine AVF were next in ranking with better patency rates than for the saphenous vein AVF studied. Corrected one-year patency rates were 71 percent for bovine, 45 percent for saphenous and 91 percent for radial-cephalic AVF. The incidence of nonthrombotic complications with bovine AVF was higher than with saphenous vein AVF. Distal ischemia due to “steal” and certain bleeding and wound complications were unique to bovine AVF. Excellent dialysis blood flow rates and easy accessibility were provided by bovine grafts. When a satisfactory radial-cephalic AVF cannot be created, bovine graft AVF is an acceptable alternative for hemodialysis access.     

911. COELOGYNE KALIANA

Coelogyne kaliana from Malaysia is illustrated and the history of its collection and habitat are described. Distinctions from related species are discussed, and suggestions for its cultivation are given.