The effect of the enantiomers of ibuprofen and flurbiprofen on the beta-oxidation of palmitate in the rat.

The effects of the enantiomers of ibuprofen (0.25 and 0.50 mmol/kg b.w.) and flurbiprofen (0.01, 0.03, and 0.06 mmol/kg b.w.) on the beta-oxidation of palmitate were investigated in the rat. The mean cumulative exhalation of 14CO2 after ip administration of [U-14C]palmitic acid was significantly reduced over 6 h by ibuprofen at the higher dose but not at the lower dose for either enantiomer. There was no difference between the enantiomers, the reduction over 6 h being 31.3 and 33.0% for (R)- and (S)-ibuprofen, respectively. There was also a significant inhibition of beta-oxidation by flurbiprofen at all 3 doses. Again, there was no stereoselectivity evident in this inhibition. Flurbiprofen was much more potent than ibuprofen in eliciting this effect, the 0.01mmol/kg dose giving a similar reduction in beta-oxidation as observed for the 0.50 mmol/kg dose of ibuprofen. The data support the hypothesis that inhibition of the in vivo beta-oxidation of palmitate by ibuprofen and flurbiprofen is primarily via a nonstereoselective noncoenzyme A-dependent mechanism.     

Reconstitution of the tonoplast amino-acid carrier into liposomes

The tonoplast amino-acid transporter of barley (Hordeum vulgare L.) mesophyll cells was functionally reconstituted by incorporating solubilized tonoplast membranes, vacuoplast membranes or tonoplast-enriched microsomal vesicles into phosphatidylcholine liposomes. (i) Time-, concentration- and ATP-dependence of amino-acid uptake were similar to results with isolated vacuoles. Although the orientation of incorporation could not be controlled, the results indicate that the transporter functions as a uniport system which allows regulated equilibration by diffusion between the cytosolic and vacuolar amino-acid pools. (ii) The ATP-modulated amino-acid carrier was also successfully reconstituted from barley epidermal protoplasts and Valerianella or Tulipa vacuoplasts, indicating its general occurrence. (iii) Fractionation of solubilized tonoplasts by size-exclusion chromatography followed by reconstitution of the fractions for glutamine transport gave two activity peaks: the first eluted in the region of high-molecular-mass vesicles and the second at a size of 300 kDa for the Triton-protein micelle.Abbreviation SDS-PAGE sodium dodecyl sulfate-polyacryl-amide gel electrophoresis This work was part of our research efforts within the Sonderforschungsbereich 176 of the University. We gratefully acknowledge experimental support by Marion Betz and valuable discussions with Professors U. Heber and U.-I. Flügge and Dr. Armin Gross (University of Würzburg) and Dr. E. Martinoia (ETH, Zürich, Switzerland).     

Microalgae aquaculture feeds

Microalgae feeds are currently used in relatively small amounts in aquaculture, mainly for the production of larvae and juvenile shell- and finfish, as well as for raising the zooplankton required for feeding of juvenile animals. The blue-green algaSpirulina is used in substantial amounts (over 100 t y^–1) as a fish and shrimp feed, and even larger markets can be projected if production costs could be reduced. Another potential large-scale application of microalgae is the cultivation ofHaematococcus for the production of the carotenoid astaxanthin, which gives salmon flesh its reddish color. In the long-term microalgae biomass high in lipids (omega-3 fatty acids) may be developed as substitutes for fish oil-based aquaculture feeds. In shrimp ponds the indigenous algal blooms supply a part of the dietary requirements of the animals, but it is difficult to maximize algal productivities. A separate algal production system could feed the shrimps and minimize the need for added feed. Bivalves feed essentially exclusively on marine microalgae throughout their life cycle. The development of cultivation technologies for such microalgae would allow the onshore production of these animals, with greatly improved product quality and safety.This paper was presented at the Symposium on Applied Phycology at the Fourth International Phycological Congress, Duke University.     

Interactions between central glutamatergic,catecholaminergic and cholinergic systems with regard to locomotor activity in monoamine-depleted mice

Summary Following injection of 5µg of the competitive NMDA receptor antagonist AP-5 into the nucleus accumbens, but not following injection of the same dose into the dorsal striatum, a pronounced locomotor stimulation in monoamine-depleted mice was produced; the-adrenoceptor agonist clonidine (1 mg/kg) administered ip caused a marked potentiation of an intraaccumbens AP-5 (2.5µg) injection.On the other hand, 10µg of AP-5 combined with an ip injection of clonidine (1 mg/kg) caused a marked locomotor stimulation following local application into the dorsal striatum but not following application into the prefrontal cortex. Likewise, in combination with systemically administered clonidine, a substantial locomotor stimulation was observed after application of the muscarine receptor antagonist methscopolamine (62µg) into the dorsal striatum but not into the prefrontal cortex.This study suggests that NMDA receptors in the nucleus accumbens exert an inhibitory influence on locomotor activity. The dorsal striatum may also be involved in such control via NMDA and muscarinic receptors.     

The amnesic shellfish poison domoic acid enhances neurotoxicity by excitatory amino acids in cultured neurons

Summary A recent episode of human intoxication by cultured mussels containing a rare excitatory amino acid named domoic acid, received particular attention for its neurological implications. The intoxication produced neurological problems, such as headache, confusion, and loss of memory, particularly severe at times. Neuronal damage was found in the hippocampus and amygdala of four patients. We now report that in neuronal cultures the neurotoxicity of a domoic acid-containing mussel extract is the result of domoic acid potentiation of the excitotoxic effect of glutamic acid and aspartic acid present in high amounts in mussel tissue. Moreover, we show that subtoxic concentrations of domoic acid are sufficient to potentiate glutamic acid and aspartic acid neurotoxicity. We present evidence suggesting that the neurotoxic synergism may be due to a reduction of Mg^{+ +} block at the NMDA receptor-associated channel, following activation of NON-NMDA receptors by domoic acid.     

Quinolinate-like neurotoxicity produced by aminooxyacetic acid in rat striatum

Summary The endogenous tryptophan metabolite quinolinic acid elicits in rodent brain a pattern of neuronal degeneration which resembles that caused by L-glutamate. Its qualities as a neurotoxic agent raised the hypothesis that quinolinic acid might be involved in the pathogenesis of human neurodegenerative disorders. Kynurenic acid, another endogenous tryptophan metabolite and preferential N-methyl-D-aspartate (NMDA) antagonist, has been shown to block quinolinic acid neurotoxicity. Here we report that microinjections of aminooxyacetic acid (AOAA), an inhibitor of kynurenine transaminase and of other pyridoxal phosphate-dependent enzymes, into the rat striatum produce neuronal damage resembling that caused by quinolinic acid. AOAA-induced striatal lesions can be prevented by kynurenic acid and the selective NMDA antagonist 2-amino-7-phosphonoheptanoic acid. These results suggest that AOAA produces excitotoxic lesions by depleting brain concentrations of kynurenic acid (inhibition of synthetic enzyme) or due to impairment of intracellular energy metabolism (depletion of cell energy resources). The concept of deficient neuroprotection due to metabolic defects might help to clarify the pathogenesis of human neurodegenerative disorders and to develop strategies that may be useful in their treatment.This work was supported by research grant from the Polish Academy of Sciences.These data have been communicated to the International Congress on Amino Acid Research held in Vienna in August 7–12, 1989.     

Binding of kynurenine to catecholamine

Summary Papiliochrome II is a pale yellow pigment of butterflies and consists of one molecule each ofL-kynurenine and N--alanyldopamine (NBAD). The aromatic amino nitrogen of kynurenine is bonded to the-carbon of NBAD. There are isomers IIa and IIb which show opposite circular dichroism. The-alanine contents of IIa and IIb were determined and the molar ratio of IIa to IIb has proved to be 1.17. The IIa and IIb were decomposed toL-kynurenine and N--alanylnorepinephrine (NBANE) by being heated in water at 80°C for 30 min. In both IIa and IIb, circular dichroism of the NBANE showed the same positive peak at 280 nm. The NBANE were further decomposed to-alanine and norepinephrine (NE) by being heated in 1 N HC1 at 100°C for 2 hr. The NE was submitted to enantioseparation and has proved to be a racemic mixture in both cases of IIa and IIb. These results are discussed in the light of the enzymic synthesis of IIa and IIb.     

Are prealbumin plasma levels linked to amino acid supply from peripheral tissues in liver cirrhosis?

Summary Prealbumin plasma level is considered a good index of liver function in liver cirrhosis. However, plasma protein levels depend not only on liver function, but also on amino acid supply which is consequent to nutritional status.In 12 cirrhotics we measured prealbumin plasma levels and the lower limb venous-artero difference of amino acid plasma levels in blood samples taken from femoral vein and femoral artery in post-absorptive conditions considered as a direct index of protein release from peripheral tissues and an indirect index of protein nutritional status.In arterial and in venous plasma amino acid sum was 1.86±0.40 (mean + sd) and 2.00 ± 0.04 mMol/l respectively.Prealbumin plasma levels were found directly correlated with the venousartero difference of amino acid plasma levels (r = 0.57p < 0.05) and of glutamate + glutamine levels (r = 0.73p < 0.007).In conclusions, these data suggest that prealbumin plasma levels are linked to amino acid supply from peripheral tissues in cirrhotics.     

Lipid accumulation inRhodotorula glutinis on sugar cane molasses in single-stage continuous culture

Microbial lipids produced byRhodotorula glutinis grown in continuous culture with molasses under nitrogen-limiting conditions were evaluated and the effects of growth rate on fatty acid composition were studied. As the growth rate decreased, cell biomass, lipid content and lipid yield gradually increased. The maximum lipid content recorded was 39% (w/w) of dry cell biomass at a dilution rate of 0.04 h^–1. The growth rate also affected fatty acid composition: oleic acid decreased with decreasing growth rate while stearic acid increased.     

Nectar sugar and amino acid preferences of Battus philenor (Lepidoptera, Papilionidae)

Abstract.

• 1 Butterflies of Battus philenor were tested for their preferences for nectar sugars and amino acids in an outdoor cage experiment.
• 2 The butterflies clearly preferred both sucrose and fructose over glucose. They also preferred sucrose over fructose.
• 3 No other preferences were found to be statistically significant, although male butterflies tended to prefer a plain sugar solution over a sugar solution containing a mixture of amino acids: females consumed both of these solutions in almost equal proportions.
• 4 The results are discussed with respect to nectar composition of butterfly pollinated flowers, flower preferences, physiological and reproductive aspects of butterflies.