Synthesis and biological activities of some pseudo-peptide analogues of tetragastrin: the importance of the peptide backbone

Pseudo-peptide analogues of the C-terminal tetrapeptide of gastrin, in which a peptide bond has been replaced by a CH2-NH bond, i.e. (tert-butyloxycarbonyl)-L-tryptophyl-psi (CH2-NH)-L-leucyl-L-aspartyl-L-phenylalanine amide (8), (tert-butyloxycarbonyl)-L-tryptophyl-L-leucyl-psi (CH2-NH)-L-aspartyl-L-phenylalanine amide (13), (tert-butyloxycarbonyl)-L-tryptophyl-L-leucyl-L-aspartyl-psi (CH2NH)-L-phenylalanine amide (20), were synthesized. The pseudo-peptides 8 and 13 were shown to have the same affinity as (tert-butyloxycarbonyl)-L-tryptophyl-L-leucyl-L-aspartyl-L-phenylalanine amide (21) for the gastrin receptor on isolated mucosal cells. The pseudo-peptide 20 exhibited lower affinity (IC50 congruent to 10(-5) M). The biological activity of these pseudo-peptides was studied on acid secretion in the anesthetized rat. Compound 8 stimulated acid secretion, identically with that of 21. Compound 13 did not exhibit any agonist activity but was able to antagonize the action of gastrin (ED50 = 0.3 mg/kg). Compound 20 did not show any agonist activity but was able to inhibit gastrin-induced acid secretion, with lower potency (ED50 = 15 mg/kg). The importance of the peptide bonds in the mode of action of gastrin is discussed, and a hypothetical approach of the mechanism of action is presented.

Toxicity evaluation of three pesticides on non-target aquatic and soil organisms: commercial formulation versus active ingredient

The Ecological Risk Assessment of pesticides requires data regarding their toxicity to aquatic and terrestrial non-target species. Such requirements concern active ingredient(s), generally not considering the noxious potential of commercial formulations. This work intends to contribute with novel information on the effects of short-term exposures to two herbicides, with different modes of action (Spasor, Stam Novel Flo 480), and an insecticide (Lannate), as well as to corresponding active ingredients (Glyphosate, Propanil and Methomyl, respectively). The microalga Pseudokirchneriella subcapitata (growth inhibition), the cladoceran Daphnia magna (immobilisation), and the earthworm Eisenia andrei (avoidance behaviour) were used as test species. Both herbicides were innocuous to all test organisms at environmentally realistic concentrations, except for Stam and Propanil (highly toxic for Pseudokirchneriella; moderately toxic to Daphnia). Lannate and Methomyl were highly toxic to Daphnia and caused Eisenia to significantly avoid the spiked soil at realistic application rates. The toxicity of formulations either overestimated (e.g. Stam/Propanil for P. subcapitata) or underestimated (e.g. Stam/Propanil for D. magna) that of the active ingredient.

Crystal structure of the protein drug urate oxidase-inhibitor complex at 2.05 A resolution

The gene coding for urate oxidase, an enzyme that catalyzes the oxidation of uric acid to allantoin, is inactivated in humans. Consequently, urate oxidase is used as a protein drug to overcome severe disorders induced by uric acid accumulation. The structure of the active homotetrameric enzyme reveals the existence of a small architectural domain that we call T-fold (for tunnelling-fold) domain. It assembles to form a perfect unusual dimeric alpha 8 beta 16 barrel. Urate oxidase may be the archetype of an expanding new family of tunnel-shaped proteins that now has three members; tetrahydropterin synthase, GTP cyclohydrolase I and urate oxidase. The structure of the active site of urate oxidase around the 8-azaxanthine inhibitor reveals an original mechanism of oxidation that does not require any ions or prosthetic groups.

Concentration and timing of application reveal strong fungistatic effect of tebuconazole in a Daphnia-microparasitic yeast model

Given the importance of pollutant effects on host-parasite relationships and disease spread, the main goal of this study was to assess the influence of different exposure scenarios for the fungicide tebuconazole (concentration×timing of application) on a Daphnia-microparasitic yeast experimental system. Previous results had demonstrated that tebuconazole is able to suppress Metschnikowia bicuspidata infection at ecologically-relevant concentrations; here, we aimed to obtain an understanding of the mechanism underlying the anti-parasitic (fungicidal or fungistatic) action of tebuconazole. We exposed the Daphnia-yeast system to four nominal tebuconazole concentrations at four timings of application (according to the predicted stage of parasite development), replicated on two Daphnia genotypes, in a fully crossed experiment. An "all-or-nothing" effect was observed, with tebuconazole completely suppressing infection from 13.5μgl^-1 upwards, independent of the timing of tebuconazole application. A follow-up experiment confirmed that the suppression of infection occurred within a narrow range of tebuconazole concentrations (3.65-13.5μgl^-1), although a later application of the fungicide had to be compensated for by a slight increase in concentration to elicit the same anti-parasitic effect. The mechanism behind this anti-parasitic effect seems to be the inhibition of M. bicuspidata sporulation, since tebuconazole was effective in preventing ascospore production even when applied at a later time. However, this fungicide also seemed to affect the vegetative growth of the yeast, as demonstrated by the enhanced negative effect of the parasite (increasing mortality in one of the host genotypes) at a later time of application of tebuconazole, when no signs of infection were observed. Fungicide contamination can thus affect the severity and spread of disease in natural populations, as well as the inherent co-evolutionary dynamics in host-parasite systems.

Short-term effects of neuroactive pharmaceutical drugs on a fish species: biochemical and behavioural effects

The presence of pharmaceutical residues in the aquatic environment is receiving great attention since significant levels of contamination have been found, not only in sewage treatment plant effluents, but also in open waters. In our study, the toxicity of three anticonvulsant drugs commonly found in the environment (diazepam, carbamazepine, and phenytoin) was evaluated in Lepomis gibbosus (pumpkinseed sunfish). This study focused on oxidative stress parameters, namely: glutathione reductase (GRed), glutathione S-transferases (GSTs), catalase (CAT), and lipid peroxidation (thiobarbituric acid reactive substances, TBARS) in the hepatic, digestive, and gill tissues of exposed animals. Simultaneously, we assessed the effects of these drugs in terms of behavioural parameters, such as scototaxis and activity. Exposure to diazepam caused an increase in GST activities in the gills and an inhibition of GRed in the digestive tract, relative to control, suggesting an antioxidant response. It also caused fish to spend more time swimming and less time in a refuge area (black compartment of an aquarium). Exposure to carbamazepine caused an increase in GSTs and GRed activity in the digestive tract, which is not always consistent with the literature. A significant positive correlation was found between carbamazepine concentration and time spent in motion and a negative correlation with time spent in black compartment. Exposure to phenytoin was responsible for adaptive responses in the activities of CAT and GSTs (in the liver), but it did not elicit any behavioural alterations. Although all three drugs seemed to induce oxidative stress in some organs, peroxidative damage (measured as TBARS concentrations) was not found at the selected range of concentrations. Our results enlighten the need for more research on the ecological consequences of pharmaceuticals in the aquatic environment, especially drugs that interfere with the CNS and behaviour, because the net outcome of these effects may be difficult to predict.

Molecular recognition between serine proteases and new bioactive microproteins with a knotted structure

Microproteins with proteinase inhibitory activity, 28 to 30 amino acids long, with 3 disulfide bridges have been isolated from Ecballium elaterium seeds. A peptide (EETI II) was isolated and behaved as a powerful trypsin inhibitor (Kd = 10(-11) to 10(-12) M). It was sequenced, chemically synthesized and the 3-D structure determined by 2-D 1H NMR. The information gained in the process enabled us to synthesize modified derivatives with inhibitory activity towards pancreatic elastase, chymotrypsin and human leucocyte elastase (Kd = 10(-7) to 10(-9) respectively). The most striking characteristic that appeared during the synthetic approach was the unfailing ability of the 28 amino acid peptides to refold and correctly close the 3 disulfide bridges, giving in each case an active compound. These disulfide bridges are assembled in a particular knotted structure, shared by few other bioactive peptides and called the 'knottin' structure. Molecular modeling of the peptide and a comparison with the other active molecules with similar topology allowed the synthesis of a chimaeric peptide, bearing 1 active site against a seryl-protease (trypsin), and 1 against a metallo-protease (carboxypeptidase A). The bis-headed peptide was able to inhibit both enzymes separately and concomitantly.

Toxic potential of paracetamol to freshwater organisms: a headache to environmental regulators?

Paracetamol is one of the most prescribed drugs globally, due to its antipyretic and analgesic properties. However, it is highly toxic at elevated doses, with involvement of an already described oxidative stress pathway. Despite this, the number of ecotoxicological studies on potential effects of paracetamol in wild organisms is still scarce. The present article presents a comprehensive series of standardized assays for the assessment of paracetamol effects in freshwater organisms. The results show that paracetamol toxicity is widely variable among species, even when these species are phylogenetically related. Furthermore, comparisons between data from the literature and our results reinforce this conclusion, providing evidence of the inadequacy of standardized toxicity testing guidelines for pharmaceutical compounds in wild organisms. Paracetamol toxicity can be modulated by unpredictable physiological conditions that might compromise extrapolations and comparisons of responsiveness among species. The ecological relevance of data obtained from classical tests for this compound is further discussed.

Protease inhibitors from Ecballium elaterium seeds

Several protease inhibitors were found in the seeds of a Cucurbitacea, Ecballium elaterium, and were separated from one another by affinity and molecular sieve chromatography. Three main trypsin isoinhibitors were purified by ion-exchange chromatography and the sequence of the major one, EETI II, was elucidated and compared with other inhibitors of the squash family. It is a peptide of M.W. 3020 of strong inhibitory activity (Ka = 8 x 10(11) M-1) against trypsin, showing high Gly content, six half-cystine residues, but devoid of histidine, threonine, tryptophan, and tyrosine residues.

1H 2D NMR and distance geometry study of the folding of Ecballium elaterium trypsin inhibitor, a member of the squash inhibitors family

The solution conformation of synthetic Ecballium elaterium trypsin inhibitor II, a 28-residue peptide with 3 disulfide bridges, has been studied by 1H 2D NMR measurements. Secondary structure elements were determined: a miniantiparallel beta-sheet Met 7-Cys 9 and Gly 25-Cys 27, a beta-hairpin 20-28 with beta-turn 22-25, and two tight turns Asp 12-Cys 15 and Leu 16-Cys 19. A set of interproton distance restraints deduced from two-dimensional nuclear Overhauser enhancement spectra and 13 phi backbone torsion angles restraints were used as the basis of three-dimensional structure computations including disulfide bridges arrangement by using distance geometry calculations. Computations for the 15 possible S-S linkage combinations lead to the proposal of the array 2-19, 9-21, 15-27 as the most probable structure for EETI II.

The influence of impeller type in pilot scale xanthan fermentations

The rheological complexity of Xanthan fermentations presents an interesting problem from a mixing viewpoint, because the phenomena of poor bulk blending and low oxygen mass transfer rates inherent in highly viscous fermentations (and their consequences) can be systematically investigated, even at the pilot plant scale. This study in a 150 L fermentor compares the physical and biological performance of four pairs of impellers: a standard Rushton turbine, a large diameter Rushton turbine, a Prochem Maxflo T, and a Scaba 6SRGT. Accurate in-fermentor power measurements, essential for the comparison of impellers in relation to operating costs are also reported. It is demonstrated that the agitator performance in Xanthan fermentations is very specific and the choice of which impeller to use in bioreactors to obtain enhanced performance is dependant on the applied criterion. None of the criterion favored the use of the standard Rushton turbine, therefore suggesting that there are strong grounds for retrofitting these impellers with either large diameter impellers of similar design or with novel agitators. In addition, fluid dynamic modeling of cavern formation has clearly highlighted the importance of a well mixed and oxygenated region for providing the capacity for high microbial oxygen uptake rates which govern Xanthan productivity and quality. Copyright 1998 John Wiley & Sons, Inc.

Immunologic identification of both plasma and human renal inactive renin as prorenin

Antibodies were raised against a synthetic tetradecapeptide which is a component of the non-renin portion (prosegment) of human renin precursor. Inactive renin from human kidney and plasma strongly adsorbed to a gel coupled to immunoglobulins purified from such an antiserum. These results suggest that renal and circulating inactive human renins contain in their structure the prosegment of prorenin.

Prevalence and Factors Associated With Fatigue in Patients With Inflammatory Bowel Disease: A Multicentre Study

BACKGROUND AND AIMS

The aims of this study were to determine the prevalence of fatigue in patients with inflammatory bowel disease [IBD], to identify the factors associated with fatigue and its severity, to assess the impact of fatigue on quality of life [QoL], and to evaluate the relationship between fatigue and sleep disorders.

METHODS

This was a prospective multicentre study conducted at 22 Spanish centres. Consecutive patients followed at IBD Units were included. Fatigue was evaluated with the Fatigue Severity Scale [FSS] and the Fatigue Impact Scale [FIS]. Quality of life and sleep quality were assessed using the IBD Questionnaire-Short Form [IBDQ-9] and the Pittsburgh Sleep Quality Index [PSQI], respectively.

RESULTS

A total of 544 consecutive adult IBD patients were included [50% women, mean age 44 years, 61% Crohn's disease]. The prevalence of fatigue was 41% (95% confidence interval [CI] = 37-45%). The variables associated with an increased risk of fatigue were: anxiety [OR = 2.5, 95% CI = 1.6-3.7], depression [OR = 2.4, 95% CI = 1.4-3.8], presence of extraintestinal manifestations [EIMs] [OR = 1.7, 95% CI = 1.1-2.6], and treatment with systemic steroids [OR = 2.8, 95% CI = 1.4-5.7]. The presence of EIMs [regression coefficient, RC = 8.2, 95% CI = 2.3-14.2], anxiety [RC = 25.8, 95% CI = 20.0-31.5], depression [RC = 30.6, 95% CI = 24.3-37.0], and sleep disturbances [RC = 15.0, 95% CI = 9.3-20.8] were associated with severity of fatigue. Patients with fatigue had a significantly decreased IBDQ-9 score [p < 0.001].

CONCLUSIONS

The prevalence of fatigue in IBD patients is remarkably high and has a negative impact on QoL. Therapy with systemic steroids is associated with an increased risk of fatigue. The severity of fatigue is associated with anxiety, depression, sleep disorders, and the presence of EIMs. Fatigue was not associated with anaemia, disease activity or anti-TNF therapy.

Drought-induced Amazonian wildfires instigate a decadal-scale disruption of forest carbon dynamics

Drought-induced wildfires have increased in frequency and extent over the tropics. Yet, the long-term (greater than 10 years) responses of Amazonian lowland forests to fire disturbance are poorly known. To understand post-fire forest biomass dynamics, and to assess the time required for fire-affected forests to recover to pre-disturbance levels, we combined 16 single with 182 multiple forest census into a unique large-scale and long-term dataset across the Brazilian Amazonia. We quantified biomass, mortality and wood productivity of burned plots along a chronosequence of up to 31 years post-fire and compared to surrounding unburned plots measured simultaneously. Stem mortality and growth were assessed among functional groups. At the plot level, we found that fire-affected forests have biomass levels 24.8 ± 6.9% below the biomass value of unburned control plots after 31 years. This lower biomass state results from the elevated levels of biomass loss through mortality, which is not sufficiently compensated for by wood productivity (incremental growth + recruitment). At the stem level, we found major changes in mortality and growth rates up to 11 years post-fire. The post-fire stem mortality rates exceeded unburned control plots by 680% (i.e. greater than 40 cm diameter at breast height (DBH); 5-8 years since last fire) and 315% (i.e. greater than 0.7 g cm^-3 wood density; 0.75-4 years since last fire). Our findings indicate that wildfires in humid tropical forests can significantly reduce forest biomass for decades by enhancing mortality rates of all trees, including large and high wood density trees, which store the largest amount of biomass in old-growth forests. This assessment of stem dynamics, therefore, demonstrates that wildfires slow down or stall the post-fire recovery of Amazonian forests.This article is part of a discussion meeting issue 'The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications'.

Use of restrained molecular dynamics in water to determine three-dimensional protein structure: prediction of the three-dimensional structure of Ecballium elaterium trypsin inhibitor II

Refinement of distance geometry (DG) structures of EETI-II (Heitz et al.: Biochemistry 28:2392-2398, 1989), a member of the squash family trypsin inhibitor, have been carried out by restrained molecular dynamics (RMD) in water. The resulting models show better side chain apolar/polar surface ratio and estimated solvation free energy than structures refined "in vacuo." The consistent lower values of residual NMR constraint violations, apolar/polar surface ratio, and solvation free energy for one of these refined structures allowed prediction of the 3D folding and disulfide connectivity of EETI-II. Except for the few first residues for which no NMR constraints were available, this computer model fully agreed with X-ray structures of CMTI-I (Bode et al.: FEBS Lett. 242:285-292, 1989) and EETI-II complexed with trypsin that appeared after the RMD simulation was completed. Restrained molecular dynamics in water is thus proved to be highly valuable for refinement of DG structures. Also, the successful use of apolar/polar surface ratio and of solvation free energy reinforce the analysis of Novotny et al. (Proteins 4:19-30, 1988) and shows that these criteria are useful indicators of correct versus misfolded models.

Comparative enzymatic studies of human renin acting on pure natural or synthetic substrates

Some of the essential structural requirements for the enzymatic reaction of pure human renin acting on pure human and rat angiotensinogen and on their synthetic tetradecapeptide substrates were investigated. The five carboxy terminal amino acids of synthetic tetradecapeptides played a significant role in substrate recognition and/or hydrolysis by human renin. Kinetic constants Km, Kcat and kcat/Km of the various human renin assays were different according to the substrate used. The presence of either an asparagine or a threonine residue in the S'4 renin subsite did not affect significantly the kinetic constant values. A tyrosine residue, rather than a histidine residue, in the S'3 renin subsite gave the best synthetic substrate studied. When tyrosine residue was present in the S'2 renin subsite an important decrease in kcat was observed. Human angiotensinogen was hydrolysed by human renin with lower Km and kcat values than those measured with human and porcine synthetic substrates, suggesting that the 3-dimensional structure of human angiotensinogen plays a key role in the hydrolysis. This finding was supported by assays performed with rat angiotensinogen, which was cleared by human renin with the same kcat value as rat tetradecapeptide, but with a 49-fold lower Km. Between human and rat angiotensinogen a kcat/Km value of only 2-fold higher has been found in the renin assay using human substrate.

Characterization and 2D NMR study of the stable [9-21, 15-27] 2 disulfide intermediate in the folding of the 3 disulfide trypsin inhibitor EETI II

The three disulfide Ecballium elaterium trypsin inhibitor II (EETI II) reduction with dithiothreitol (DTT) and reoxidation of the fully reduced derivative have been examined. A common stable intermediate has been observed for both processes. Isolation and sequencing of carboxymethylated material showed that the intermediate lacks the [2-19] bridge. The NMR study showed a very strong structural conservation as compared to the native EETI II, suggesting that the bridges are the [9-21] and [15-27] native ones. The differences occurred in sections 2-7 (containing the free cysteine 2 and the Arg 4-Ile 5 active site) and 19-21 (containing the second free cysteine). Distance geometry calculations and restrained molecular dynamics refinements were also in favor of a [9-21, 15-27] arrangement and resulted in a well-conserved (7-28) segment.

Seawater is a reservoir of multi-resistant Escherichia coli, including strains hosting plasmid-mediated quinolones resistance and extended-spectrum beta-lactamases genes

The aim of this study was to examine antibiotic resistance (AR) dissemination in coastal water, considering the contribution of different sources of fecal contamination. Samples were collected in Berlenga, an uninhabited island classified as Natural Reserve and visited by tourists for aquatic recreational activities. To achieve our aim, AR in Escherichia coli isolates from coastal water was compared to AR in isolates from two sources of fecal contamination: human-derived sewage and seagull feces. Isolation of E. coli was done on Chromocult agar. Based on genetic typing 414 strains were established. Distribution of E. coli phylogenetic groups was similar among isolates of all sources. Resistances to streptomycin, tetracycline, cephalothin, and amoxicillin were the most frequent. Higher rates of AR were found among seawater and feces isolates, except for last-line antibiotics used in human medicine. Multi-resistance rates in isolates from sewage and seagull feces (29 and 32%) were lower than in isolates from seawater (39%). Seawater AR profiles were similar to those from seagull feces and differed significantly from sewage AR profiles. Nucleotide sequences matching resistance genes bla_TEM, sul1, sul2, tet(A), and tet(B), were present in isolates of all sources. Genes conferring resistance to 3rd generation cephalosporins were detected in seawater (bla_CTX-M-1 and bla_SHV-12) and seagull feces (bla_CMY-2). Plasmid-mediated determinants of resistance to quinolones were found: qnrS1 in all sources and qnrB19 in seawater and seagull feces. Our results show that seawater is a relevant reservoir of AR and that seagulls are an efficient vehicle to spread human-associated bacteria and resistance genes. The E. coli resistome recaptured from Berlenga coastal water was mainly modulated by seagulls-derived fecal pollution. The repertoire of resistance genes covers antibiotics critically important for humans, a potential risk for human health.

Partial Discharge Monitoring in Power Transformers Using Low-Cost Piezoelectric Sensors

Power transformers are crucial in an electric power system. Failures in transformers can affect the quality and cause interruptions in the power supply. Partial discharges are a phenomenon that can cause failures in the transformers if not properly monitored. Typically, the monitoring requires high-cost corrective maintenance or even interruptions of the power system. Therefore, the development of online non-invasive monitoring systems to detect partial discharges in power transformers has great relevance since it can reduce significant maintenance costs. Although commercial acoustic emission sensors have been used to monitor partial discharges in power transformers, they still represent a significant cost. In order to overcome this drawback, this paper presents a study of the feasibility of low-cost piezoelectric sensors to identify partial discharges in mineral insulating oil of power transformers. The analysis of the feasibility of the proposed low-cost sensor is performed by its comparison with a commercial acoustic emission sensor commonly used to detect partial discharges. The comparison between the responses in the time and frequency domain of both sensors was carried out and the experimental results indicate that the proposed piezoelectric sensors have great potential in the detection of acoustic waves generated by partial discharges in insulation oil, contributing for the popularization of this noninvasive technique.

Safety and efficacy of non-steroidal anti-inflammatory drugs to reduce ileus after colorectal surgery

BACKGROUND

Ileus is common after elective colorectal surgery, and is associated with increased adverse events and prolonged hospital stay. The aim was to assess the role of non-steroidal anti-inflammatory drugs (NSAIDs) for reducing ileus after surgery.

METHODS

A prospective multicentre cohort study was delivered by an international, student- and trainee-led collaborative group. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The primary outcome was time to gastrointestinal recovery, measured using a composite measure of bowel function and tolerance to oral intake. The impact of NSAIDs was explored using Cox regression analyses, including the results of a centre-specific survey of compliance to enhanced recovery principles. Secondary safety outcomes included anastomotic leak rate and acute kidney injury.

RESULTS

A total of 4164 patients were included, with a median age of 68 (i.q.r. 57-75) years (54·9 per cent men). Some 1153 (27·7 per cent) received NSAIDs on postoperative days 1-3, of whom 1061 (92·0 per cent) received non-selective cyclo-oxygenase inhibitors. After adjustment for baseline differences, the mean time to gastrointestinal recovery did not differ significantly between patients who received NSAIDs and those who did not (4·6 versus 4·8 days; hazard ratio 1·04, 95 per cent c.i. 0·96 to 1·12; P = 0·360). There were no significant differences in anastomotic leak rate (5·4 versus 4·6 per cent; P = 0·349) or acute kidney injury (14·3 versus 13·8 per cent; P = 0·666) between the groups. Significantly fewer patients receiving NSAIDs required strong opioid analgesia (35·3 versus 56·7 per cent; P < 0·001).

CONCLUSION

NSAIDs did not reduce the time for gastrointestinal recovery after colorectal surgery, but they were safe and associated with reduced postoperative opioid requirement.

Aldehydic peptides inhibiting renin

Aldehydic peptides in which the C terminal residue is leucinal or phenylalaninal were synthesized. These compounds exhibited potent inhibition of renin activity and appeared to be precursors of transition state analogues for renin-catalysed amide bond hydrolysis.

Evidence for dopaminomimetic effect of intrastriatally injected cholecystokinin octapeptide in mice

The behavioural effect of intrastriatally injected cholecystokinin sulphated octapeptide (CCK-8S), and its interactions with the antagonists Z-CCK-(27-32)NH2 and proglumide, were investigated in mice. When injected into the right striatum, CCK-8S (0.05-1 ng) induced contralateral rotations, as did the dopamine agonist apomorphine. Non-sulphated CCK-8 was inactive and sulphated desamino-CCK-7 was only weakly active in this respect. CCK-8S-induced turning was antagonized by co-injected Z-CCK-(27-32)NH2 (0.01-10 ng) or proglumide (0.1-1 micrograms), as well as by intraperitoneal injection of the neuroleptic drug haloperidol. These data suggest that CCK-8S may, in these conditions, stimulate dopamine-mediated neurotransmission, and that Z-CCK-(27-32)NH2, in addition to its peripheral effect, is also a very potent CCK antagonist at the striatal level.

Evaluation of water column and sediment toxicity from an abandoned uranium mine using a battery of bioassays

Uranium mining activities in Cunha Baixa, Mangualde (Portugal), were extensive between 1967 and 1993, with high production of poor ore. Ore exploitation left millions of tons of tailings in the surrounding area, close to human houses. Contamination of the area (water and soil compartment) presently represents a serious hazard to humans and wildlife. The aim of this work was to evaluate the acute toxicity of water and sediments from a pond that floods a uranium mine pit, in two periods (spring and autumn). High contents of metals were found in water samples (chiefly Mn, Fe, Al, U, Sr). A battery of assays was applied to screen the acute toxicity of the different compartments using algae, crustaceans and dipterans. Results showed that the sediments were non-toxic, unlike the superficial water. Water toxicity was higher in the autumn, when the effluent was more acidic, compared to spring. In the water toxicity assays, the relative sensitivity of the test species used was Daphnia longispina>Pseudokirchneriella subcapitata>Daphnia magna. The present study is part of the chemical and ecotoxicological characterisation of the aquatic compartment performed in the Tier 1 of the Ecological Risk Assessment of the Cunha Baixa mining area.

Solid phase synthesis of a trypsin inhibitor isolated from the Cucurbitaceae Ecballium elaterium

The synthesis of a 28-residue peptide isolated from Ecballium elaterium of the Cucurbitaceae family which strongly inhibits trypsin activities (Ka = 8.10(-11)M), using BOP as the coupling reagent in a solid phase procedure is presented. This micro protein contains three disulfide bridges in its sequence and was obtained after oxidation of the six half-cystine residues either by air or with the use of carboethoxysulfenyl chloride. After purification by semi-preparative HPLC, the synthetic product was shown by trypsin inhibition tests to be identical with the trypsin inhibitor EETI II isolated from Ecballium elaterium.