Local Differences in GABA Release Induced by Excitatory Amino Acids During Retina Development: Selective Activation of NMDA Receptors by Aspartate in the Inner Retina

Glutamate and GABA are the major excitatory and inhibitory neurotransmitters in the CNS. In the retina, it has been shown that glutamate and aspartate and their agonists kainate and NMDA promote the release of GABA. In the chick retina, at embryonic day 14 (E14), glutamate and kainate were able to induce the release of GABA from amacrine and horizontal cells as detected by GABA-immunoreactivity. NMDA also induced GABA release restricted to amacrine cell population and its projections to the inner plexiform layer (E14 and E18). Although aspartate reduced GABA immunoreactivity, specifically in amacrine cells of E18 retinas, it was not efficient to promote GABA release from retinas at E14. As observed in differentiated retinas, dopamine inhibited the GABA release promoted by NMDA and aspartate but not by kainate. Our data show that different retinal sites respond to distinct EAAs via different receptor systems.     

The antinociceptive effect of iontophoretic direct application of diclofenac to arthritic knee-joints of rats

This study compared the antinociceptive effect produced by cathodic iontophoresis of sodium diclofenac close to an arthritic knee-joint in rats with that of systemic application. Arthritic nocifensive incapacitation was induced by LPS (1 microg) injection into a knee-joint previously (72 h) primed with carrageenan (300 microg). Diclofenac (0.1, 0.25 and 0.5 mg/kg) given intraperitoneally 1 h after LPS injection caused dose-dependent inhibition of incapacitation. Diclofenac iontophoresis was performed by varying either the current density (0.1, 0.2, and 0.3 mA/cm2) or the duration of application (4, 10, 20 and 30 min) of a polyvinylpirrolydone-hydroxymethylcellulose gel containing 1% sodium diclofenac. A clear, current density-dependent effect was observed for 0.1, 0.2 and 0.3 mA/cm2 (10 min period), which was similar to the effect observed for the intraperitoneal application of 0.1, 0.25 and 0.5 mg/kg doses. Combining different application periods with different current densities, in a manner that resulted in the same total current (1.6 mA*min) application, did not produce similar therapeutic effects, but the antinociceptive effect was directly proportional to the current density. The ipsilateral iontophoresis (0.25 mA/cm2 x 10 min or 0.5 mA/cm2 x 4 min) of diclofenac produced an effect significantly greater than the same contralateral application (p<0.05). In conclusion, our results suggest that the therapeutic effect depends on the current density but not on the application time, and also that the iontophoretic, direct application to the inflamed knee-joint enhances the therapeutic effect probably as a result of the direct delivery of the drug.     

Norditerpene dilactones from Podocarpus saligna

Rimuene and nubigenol have been identified in Podocarpus saligna for the first time, and the structures of three new norditerpene dilactones, salignones K, L and M, isolated from this species have been elucidated.     

Diterpenoids from Micrandropsis scleroxylon

The structure of micrandrol-C from Micrandropsis scleroxylon (Euphorbiaceae) is revised to 2,6-dihydroxy-7-methyl-1-methylthiophenanthrene. This and other micrandrols are probably diterpenes in view of their co-occurrence with micrandrol-D, the hemiketal of 1,2,3,4,9,10-hexahydro-6-hydroxy-4a-hydroxymethyl-1,1,7-trimethy-2-oxophenanthrene.     

Affinity purification of cytosolic epoxide hydrolase from human, rhesus monkey, baboon, rabbit, rat and mouse liver

An affinity purification system based on elution of cytosolic epoxide hydrolase from a methoxycitronellyl thiol ligand with 4-azidochalcone oxide was applied to a variety of samples including liver from human, monkey, baboon, rabbit, rat and mouse as well as mammary gland from mouse. Hepatic tissues yielded a major 58 kDa band on SDS-PAGE, but the system had to be modified slightly to remove a 33 kDa band for rat. All of the affinity purified hydrolases showed similar properties with regard to substrate selectivity, pH dependence and mobilities on SDS-PAGE.     

Genetic instability of sporulation-associated characters in a Bacillus subtilis mutant: relationship between sporulation, segregation and the synthesis of extracellular enzymes (kinetic studies).

In the genetically unstable, protease-overproducing 'medusa (M) strains of Bacillus subtilis, segregation of stable, wild-type-like B cells occurred mainly during sporulation. After the end of the exponential growth phase, a small fraction of M cells sporulated quickly and formed M spores, while the majority of the cells, after a 'critical period', gave rise to B segregants which sporulated after a delay. Segregation occurred without cell division. Delayed sporulation, segregation and protease overproduction are related. Similar but more complex results were obtained with the highly unstable TD strains. Sporulation and the kinetics of protease overproduction were also followed in several stable segregants. Depending on the strain, either the rate of protease production or both the rate and time course were affected. The results are interpreted in terms of sequential activation and de-activation of sporulation genes. The production of the alkaline and the neutral proteases was, in general, under common genetic control. In some strains alpha-amylase was also overproduced.     

On the degradation of heparin by human blood platelets.

Human blood platelets are able to degrade heparin from different tissues and species. The main degradation product is an oligosaccharide. Low molecular weight components such as inorganic sulfate or monosaccharides, i.e. products released by exoenzymes are not detected. The in vitro degradation of heparin by the crude enzyme is observed at pHs below 6.5 with an optimum temperature around 37 degrees C. The presence of sulfate in the substrate structure is shown to be essential for the enzyme activity. Since the oligosaccharides formed have only 10 per cent of the anticoagulant activity of the heparins tested, it is conceivable that the platelet enzyme may play an important role in the inactivation of some of the biological properties of heparin.     

Symmetry and asymmetry in fingerprints of three genera of South American monkeys in relation to morphological evolutionary problems

Fingerprints of South American monkeys of the genera Alouatta, Ateles and Cebus were studied. Dermatoglyphics were analysed in relation to pattern intensities; the distribution of symmetric and asymmetric designs was also determined. Results have been related to some aspects of the contribution of dermatoglyphics to the study of Primate morphological evolution.