Vasoactive intestinal polypeptide in rat heart atria: the effect of hyperthyroidism

The effects of transient and sustained hyperthyroidism on vasoactive intestinal polypeptide-like immunoreactivity (VIP-LI) levels were studied in the heart atria of developing and adult rats. Newborn rats were divided into 5 groups. Neo-T animals were treated with thyroxine (T4) during postnatal days 1-8 and sacrificed at the age of 60 days. Neo-S rats were treated with T4 during postnatal days 1-60 and sacrificed one day later. Adult-1 and Adult-2 animals received T4 during days 52-60 and were sacrificed 5-6 days and 1 day later, respectively. Control animals were injected with saline. VIP-LI concentrations were determined in extracts from the left and right atria separately. In Neo-S and Adult-2 rats, spontaneous heart rate, the weight of both atria and total T4 serum levels were significantly enhanced, while their body weight was decreased. The ratio atria weight to body weight was significantly increased in all groups except for Adult-1 animals. Hyperthyroidism led to a significant decrease in VIP-LI levels in both atria of Neo-S and Neo-T rats. Hyperthyroidism induced in adult rats also decreased VIP-LI levels in both atria. However, this change was only transient. In conclusion, our data have provided new evidence that hyperthyroidism induced during the early neonatal period interferes with the development of VIP-ergic innervation in rat atria. The period of the first few postnatal days seems to be essential for this effect, since VIP-LI concentrations in 60-day-old animals did not significantly differ between Neo-S and Neo-T atria.     

Passive smoking impairs endothelium-dependent relaxation of isolated rabbit arteries

The aim of the present study was to examine the effect of prolonged passive smoking (lasting 3 weeks) on plasma catecholamine levels and reactivity of isolated rabbit arteries. Plasma noradrenaline, adrenaline and dopamine levels were determined radioenzymatically. Isolated rings of the thoracic aorta and carotid artery were suspended in organ chambers and connected to a force transducer for the recording of isometric tension. Plasma noradrenaline levels were found to be significantly elevated in rabbits subjected to passive smoking for 3 weeks. Plasma adrenaline and dopamine levels were not changed. Transmural nerve stimulation of arterial rings evoked frequency-dependent contractions. Prolonged passive smoking did not affect neurogenic contractions of the arteries tested. On the other hand, endothelium-dependent relaxations of phenylephrine-precontracted arteries were significantly impaired. Furthermore, hypertrophy of the left ventricle was observed. In conclusion, passive smoking impairs endothelium-dependent relaxations but not neurogenic contractions of systemic arteries. The impaired relaxations of arteries may be, at least in part, mediated through the degradation of released nitric oxide by superoxide anions derived from cigarette smoke.     

Preparation and structure determination of two sugar amino acids via corresponding hydantoin derivatives

(4R)-2,3-O-Isopropylidene-methylspiro[4,6-dideoxy-alpha-L-lyxo+ ++-hexopyranosid-4,5'-imidazolidin]-2',4'-dione and (4R)-2,3-O-isopropylidene-methylspiro[4,6-dideoxy-beta-D-ribo-h exopyranosid-4,5'-imidazolidin]-2',4'-dione were prepared under various reaction conditions starting from methyl 6-deoxy-2,3-O-isopropylidene-alpha-L-lyxo-hexopyranosid-4-++ +ulose. Corresponding alpha-amino acids methyl (4R)-4-amino-4-C-carboxy-4,6-dideoxy-alpha-L-lyxo-hexopyranosid e and methyl (4R)-4-amino-4-C-carboxy-4,6-dideoxy-beta-D-ribo-hexopyranoside were obtained from the above hydantoins by selective acid hydrolysis of the isopropylidene group, followed by basic hydrolysis of the hydantoin ring. The crystal structures of both hydantoin derivatives are also presented.     

Inhibition of plant telomerase by telomere-binding proteins from nuclei of telomerase-negative tissues

The activity of telomerase in plant cells is precisely regulated in response to changes in cell division rate. To explore this regulatory mechanism, the effect on telomerase activity of protein extracts from nuclei of telomerase-negative tissues was examined. An inhibition of telomerase activity was found which was species-non-specific. This inhibition was due to proteins which form salt-stable, sequence-specific complexes with the G-rich telomeric strand and reduce its accessibility, as shown by gel retardation and by terminal transferase (TdT) extension of G-rich telomeric and non-telomeric (substrate) primers. A 40 kDa polypeptide was detected by SDS-PAGE after cross-linking the complex formed by extracts from tobacco leaf nuclei. Such proteins may be involved in regulation of telomerase activity in plants.     

Anti-phospholipase A2 and anti-inflammatory activity of Santolina chamaecyparissus

The activity of the Santolina chamaecyparissus methanol extract was tested against the phospholipase A2 (PLA2)-induced mouse paw edema and in vitro inhibition of PLA2 activity. After fractionation, only the dichloromethane extract was active against the PLA2 in vitro test. In addition, it reduced the edema induced by arachidonic acid, and by 12-O-tetradecanoylphorbol-13-acetate in a multidose test. After chromatography on silicagel and gel filtration on Sephadex, and using an in vitro anti-PLA2 assay-guided process, we have isolated and identified from the dichloromethane extract the flavone nepetin and four sesquiterpenes.     

Glucuronidation of apomorphine

Apomorphine, a dopaminergic receptor agonist, is largely used in the therapy of Parkinson's disease. In this study, we characterized the glucuronidation of apomorphine and other catechols in rat liver and brain microsomes, using UDP-[U-14C]glucuronic acid and separation of the glucuronides formed by a thin layer chromatographic method. rat liver microsomes glucuronidate apomorphine at a significant rate, that was increased in the presence of dithiothreitol. Two apomorphine glucuronides were separated by high pressure liquid chromatography. We showed by electrospray mass spectrometry that both products were monoglucuronides. Other catechols were also glucuronidated in liver microsomes at various rates, and among them, 4-nitrocatechol was the most efficiently conjugated. in rat brain microsomes, only 4-nitrocatechol was significantly glucuronidated, suggesting that in the liver, several uridine-diphosphate glucuronosyltransferase (UGT) isoforms participate to the conjugation of catechols. To determine which isoforms catalyze apomorphine glucuronidation, two recombinant enzymes expressed in V79 cells were used. The isoform UGT1A6 was unable to glucuronidate apomorphine, but we observed a significant activity catalyzed by the isoform UGT2B1. These results provide, to our knowledge, the first demonstration of apomorphine conjugation by recombinant UGT2B1, and the first evidence of the lack of apomorphine glucuronidation in the rat brain.     

Effect of RQ and pre-seed conditions on biomass and galactosyl transferase production during fed-batch culture of S. cerevisiae BT150

A feedback RQ controlled fed-batch process for the recombinant production of a soluble human N-deglycosylated recombinant beta-1, 4-galactosyltransferase (NdrGal-T) with Saccharomyces cerevisiae BT150 was investigated. Several RQ values were tested for optimal production of NdrGal-T. Four times higher volumetric activity was reached at RQ=1.0 (32 U l(-1)) than at all higher RQ values (about 8 U l(-1)). RQ, 1.0 was the best choice for both, biomass and enzyme production. Optimal concentration of glucose in preculture was 25 g l(-1). At higher values slightly more ethanol was produced than at lower values of preculture glucose concentrations, moreover no positive effect on biomass and enzyme production was found. Lower values caused not only decrease of ethanol but also decrease of biomass formation (from 1.69 g h(-1) to 0.81 g h(-1)) and enzyme overall productivity (from 2.2 U h(-1) to 0.63 U h(-1)). Successfully performed cultivation with three precultures predicted scale-up possibility of feedback RQ-controlled NdrGal-T production with S. cerevisiae BT150 from lab to pilot-scale fermentor.     

Variations in competitive mechanisms of captive male hamadryas-like baboons in two feeding situations

Experiments were carried out to determine the influence of food distribution (clumped vs dispersed) on processes of competition among seven captive male hamadryas-like baboons. Spatial cohesion, cohesive behaviours that males performed and received from their females, and aggressive and feeding behaviours of the males were collected during 35 min after food supply. Median values and variability of these variables were compared in both the feeding situations. Food distribution influenced both asymmetries in access and the form of competition. When food was clumped, those with less access fed by means of compensatory or alternative strategies (away from the main source and/or by feeding supplants), and they were more aggressive towards other males. When food was dispersed, all individuals could feed simultaneously, males that were more aggressive were those with less cohesive OMUs, despite the fact that cohesive behaviours remained constant. Females appeared to contribute to variation in the OMU's cohesion through their responses to both food distribution and males' competitive ability.     

Nitrogen availability influences the biochemical composition and photosynthesis of tank-cultivated Ulva rigida (Chlorophyta)

Physiological and biochemical changes in relation to inorganic nitrogen availability were studied for tank-cultivated Ulva rigida grown under nitrogen- enriched and nitrogen-depleted seawater. U. rigida was initially cultivated in nitrogen-enriched seawater (daily concentrations of NH4+ and NO3- + NO2- ranged between 0.5–1.7 and 0.06–0.15 mg L-1, respectively), then transferred to nitrogen-depleted seawater where photosynthetic capacity decreased to zero after 23 d. At the time (14 d) when photosynthetic rates were lower than 2.0 μmol O2 g-1 FW min-1 and strong bleaching had occurred, some algae were returned to the initial nitrogen-enriched seawater to study recovery from N-limited growth. Data on biochemical composition (chlorophylls, ash, caloric content, fatty acids and dietary fibres) and colouration varied significantly depending on the nitrogen conditions. C:N ratios correlated significantly with biochemical parameters. Fatty acid (FA) synthesis continued during the N-starvation period; saturated and mono-unsaturated FA increased to a maximun of 72.2%, while poly-unsaturated fatty acids (PUFA) decreased to 27.7%. During the N-enriched recovery period, the reverse was found. C:N ratios above 10 correlated with carbohydrate synthesis as shown by the dietary fibre level. Under nitrogen enriched conditions, C:N ratios decreased along with a decrease in fibre level. Under controlled conditions, nitrogen represents a major influence on the development of intensive tank cultivation of Ulva rigida, not only by affecting parameters closely related to nitrogen metabolism but also some clearly influenced by carbon uptake. This revised version was published online in June 2006 with corrections to the Cover Date.     

In vitro and in vivo assessment of the antioxidant activity of melatonin and related indole derivatives

Effects of melatonin and some structurally related indole compounds were studied by in vitro methods such as (i) an inhibition of the hyaluronic acid degradation and (ii) a standard lipid peroxidation assay. In vivo approach was based on the alloxan model of hyperglycaemia. Reduction of the viscosity of a hyaluronic acid solution in the reaction mixture was inhibited by tryptamine (91% inhibition), as well as by indole-3-carboxylic acid and indomethacin (80% and 77% inhibition, respectively). Lipid peroxidation with tert-butyl hydroperoxide as a source of radicals was followed by the formation of thiobarbituric acid reactive substances. Tested drugs inhibited lipid peroxidation in the order: tryptamine (59%) > indole-2-carboxylic acid (38%) > indomethacin (26%) > melatonin and indole-3-carboxylic acid (13%). In vivo, alloxan-induced hyperglycaemia was reduced in mice pretreated with drugs tested. The highest protective effect was observed with indomethacin (52% inhibition), followed by tryptamine and melatonin (18% and 16% inhibition, respectively).