Plasmodium falciparum SERA protein peptide analogues having short helical regions induce protection against malaria

Three Plasmodium falciparum serine repeat antigen (SERA) protein peptides were studied by NMR and structure calculations being done in 70:30 water:trifluoroethanol solution. Peptide 22834 was shown to be immunogenic and protective against malaria in Aotus monkeys, whilst native peptide 6737 and its analogue 14096 did not present protection against the disease in these monkeys. Results showed a relationship between these peptides' secondary structure and their function as immunogen against malaria.     

Study of the peptide length and amino acid specific substitution in the antigenic activity of the chimeric synthetic peptides, containing the p19 core and gp46 envelope proteins of the HTLV-I virus

Four chimeric synthetic peptides (Q5, Q6, Q7(multiply sign in circle), and Q8(multiply sign in circle)), incorporating immunodominant epitopes of the core p19 (105-124 a.a.) and envelope gp46 proteins (175-205 a.a.), of HTLV-I were obtained. Also, two gp46 monomeric peptides M4 and M5(multiply sign in circle) (Ser at position 192) were synthesized. The analysis of the influence of the peptide lengths and the proline to serine substitution on the chimeric and monomeric peptides' antigenicity, with regard to the chimeric peptides Q1, Q2, Q3(multiply sign in circle), and Q4(multiply sign in circle), reported previously, for HTLV-I was carried out. The peptides' antigenicity was evaluated in an ultramicroenzyme-linked immunosorbent assay (UMELISA) using sera of HTLV-I/II. The peptides' antigenicity was affected appreciably by the change of the peptide length and amino acid substitutions into the immunodominant sequence of gp46 peptide.     

Central administration of thyrotropin-releasing hormone and histidyl-proline-diketopiperazine disrupts the acquisition of a food rewarded task by a non-aversive action

The effects of thyrotropin-releasing hormone (TRH) and its metabolites on operant behaviour have rarely been explored. In this study, the effects of intracerebroventricular (icv) administration of TRH and histidyl-proline-diketopiperazine (DKP), a metabolite of TRH, on the acquisition of a food-rewarded lever-press task were compared with saline-treated controls. TRH and DKP severely retarded the acquisition of lever pressing. The effects of systemically administered D-amphetamine were also examined in order to test whether this result was due to any stimulant properties of these peptides. These results suggest that stimulatory effects do not adequately account for impaired acquisition. The possibility that the disruption of learning was due to an aversive effect of icv administration of these peptides was tested by means of a conditioned place paradigm. Neither peptide induced an avoidance of the environment with which it had previously been paired. Several possible reasons for the peptides' adverse effect on learning are discussed, including the possibility that TRH and DKP act on attentional mechanisms.     

High performance liquid chromatography of peptide bioregulators, their fragments and derivatives. III. Regularities of sorption, prediction of retention and analysis of peptides by a reversed phase HPLC method

Parameters of statistical models of fully or partially protected peptides' retention on Zorbax ODS and Silasorb C18 have been compared. The proposed model can be used for non-protected linear and cyclic peptides. Special increments have to be introduced in calculation of hydrophobicity of these peptides.     

Steric-electronic effects in malarial peptides inducing sterile immunity

Conserved Plasmodium falciparum high activity binding peptides' (HABPs) most relevant proteins involved in malaria parasite invasion are immunologically silent; critical binding residues must therefore be specifically replaced to render them highly immunogenic and protection-inducing. Such changes have a tremendous impact on these peptides' steric-electronic effects, such as modifications to peptide length peptide bonds and electronic orbitals' disposition, to allow a better fit into immune system MHCII molecules and better interaction with the TCR which might account for the final immunological outcome.     

Effect of enkephalins on training the white rat in a T-maze

It is shown that met-enkephalin and morphine injected intraperitoneally to rats in a dose of 0.15 mg/kg do not significantly affect the elaboration of conditioned reaction to place in a T-maze with food reinforcement. D-Ala-met-enkephalin amid in the same dose increases the number of unaccomplished reactions on the 2-nd day of learning without eliciting significant changes of other parameters. Leu-enkephalin and D-Ala-D-Leu-enkephalin (intraperitoneally, 0.15 mg/kg) increase the number of unaccomplished reactions and the time of maze-run when injected before the learning seances. D-Ala-D-enkephalin increases the time of run at its injection "immediately after" the learning seances as well. In this case the Leu-enkephalin is not effective. The obtained data show that enkephalin effects in this experimental test to a certain extent correlate with peptides' ability of binding tightly with delta-opiate brain receptors. Different effects of met- and leu-enkephalins confirm the hypothesis on diversity of peptides' functions in the central nervous system.     

Ionic liquids as novel solvent additives to separate peptides

A novel analytical approach involving the addition of an ionic liquid into the mobile phase of the thin-layer chromatography (TLC) system during the optimization of chromatographic separation of peptides was demonstrated. Different behavior of peptides in the TLC sytem was observed after the addition of 1,3-dimethylimidazolium methyl sulfate to the eluent in comparison to the system without the ionic liquid. The objective of the work was to study the effect of the addition of different contents of ionic liquid to the mobile phase comprising mostly water and to observe the behavior of peptides' retention. The potential usefulness of environmentally friendly ionic liquids for the optimization of separation of peptides was demonstrated. An increase of R(f) values was observed with increasing the ionic liquid content in the mobile phase. The benefits of the used approach were related to the separation achieved. Finally, quantitative structure-retention relationships (QSRR) were used for the studies on the predictions of peptides' retention in the TLC systems with the addition of ionic liquid in terms of the predictions performed recently in HPLC systems.     

Selectivity of opioid peptide effects on excitability and various sensory inputs in LPl1 and PPl1 command neurons participating in defensive behavior of the snail Helix lucorum

Opioid peptides effects on neural membrane as well as neural responses evoked by sensory stimuli with different modality and site of application, were investigated in L-RPII command neurones of defensive behaviour of semi-intact preparation in the land snail Helix lucorum. Met-enkephalin (10 uM) application onto the snail CNS increases membrane excitability and produces facilitation of neural responses evoked by quinine solution (0.5%) application onto snail head and depression of reactions evoked by tactile stimulation of the head. Met-enkephalin in dose of 0.1 uM initiates only a depression of neural responses evoked by tactile stimulation of the head. Leu-enkephalin (10 uM) application suppresses neural reactions evoked by tactile stimulation of the head. Membrane excitability and neural responses evoked by quinine application onto the snail head do not change after leu-enkephalin administration. Effects appear 10-20 min after initiation of the peptide application. Initial neural responses were observed 15-30 min after CNS washing with Ringer solution. In addition, facilitation of neural responses evoked by chemical stimulation of the snail head was found 30-50 min after leu-enkephalin washing. Peptides do not change neural responses evoked by tactile stimulation of the snail foot. Neural effects of peptides were prevented by simultaneous naloxon administration (50 uM). Experimental results show selective opioid peptides' effects on excitability and plasticity of L-RPII neural inputs with site- and modality-specifics.     

Development of a pharmacologically improved peptide agonist of the leptin receptor

Leptin, a hormone produced by adipose tissue, regulates energy balance in the hypothalamus and is involved in fertility, immune response and carcinogenesis. The existence of disorders related to leptin deficit and leptin overabundance calls for the development of drugs activating or inhibiting the leptin receptor (ObR). We synthesized four proposed receptor-binding leptin fragments (sites I, IIa and IIb, III), their reportedly antagonist analogs, and a peptide chimera composed of the two discontinuous site II arms. To assess the pharmacological utility of leptin fragments, we studied the peptides' ability to stimulate the growth of ObR-positive and ObR-negative cells. The combined site II construct and site III derivatives selectively reversed leptin-induced growth of ObR-positive cells at mid-nanomolar concentrations. However, these peptides appeared to be partial agonists/antagonists as they activated cell growth in the absence of exogenous leptin. A designer site III analog, featuring non-natural amino acids at terminal positions to decrease proteolysis and a blood-brain barrier (BBB) penetration-enhancing carbohydrate moiety, proved to be full agonist to ObR, i.e., stimulated proliferation of different ObR-positive but not ObR-negative cells in the presence or absence of leptin. This glycopeptide bound to isolated ObR on solid-phase assays and activated ERK-1/2 signaling in ObR-positive MCF-7 cells at 100-500 nM concentrations. The glycopeptide was stable in mouse serum, readily crossed endothelial/astrocyte cell layers in a cellular BBB model, and was distributed into the brain of Balb/c mice after intraperitoneal administration. These characteristics suggest a potential pharmaceutical utility of the designer site III glycopeptide in leptin-deficient diseases.     

Elongating modified conserved peptides eliminates their immunogenicity and protective efficacy against P. falciparum malaria

Plasmodium falciparum malaria protein peptides were synthesised in the search for more effective routes for inducing a protective immune response against this deadly parasite and this information has been associated with such molecules' three-dimensional structure. These peptides had high red blood cell binding activity and their carboxy- and amino-terminal extremes were elongated for determining their immunogenic and protection-inducing activity against this disease in the Aotus monkey experimental model. 1H-NMR was used for analysing their three-dimensional structure; FAST ELISA, immunofluorescence antibody test, and Western blot were used for identifying their antibody inducing capacity and these previously immunised Aotus were inoculated with a highly infective P. falciparum strain to determine whether these elongated peptides were able to induce protection. This was aimed at establishing an association or correlation between long peptides' three-dimensional structure and their immunogenic and protection-inducing response in these monkeys. Peptides 20026 (25 residue), 20028 (30 residue), and 20030 (35 residues) were synthesised based on elongating the amino-terminal region of the 10022 highly immunogenic and protection-inducing modified peptide. 1H-NMR studies revealed that the first three had Classical type III beta-turn structures, different from the 20-amino acid long modified peptide 10022 which had a distorted type III beta-turn. Humoral immune response analysis showed that even when some antibodies could be generated against the parasite, none of the immunised Aotus could be protected with elongated peptides suggesting that elongating them eliminated modified peptide 10022 immunogenic and protection-inducing capacity.     

Synthesis of a 17-member peptide (143-159)--the VP(1) protein fragment of A(12) foot-and-mouth disease virus. II. Condensation of fragments

A 17-membered peptide corresponding to the amino acid sequence of (143-159) site of protein VP1 of A12 foot-and-mouth disease virus has been obtained by mixed anhydride method condensations of the earlier synthesized fragments. A norleucine residue has been attached, as a label, to the ends of peptides obtained. The complete deprotection was performed by hydrogenation peptides' hydrochlorides and the products were purified by HPLC. The antigenic properties of the synthesized peptides are discussed.     

Comprehensive peptidome analysis of mouse livers by size exclusion chromatography prefractionation and nanoLC-MS/MS identification

Peptidome analysis has received increasing attention in recent years. Cancer diagnosis by serum peptidome has also been reported by peptides' profiling for discovery of peptide biomarkers. Tissue, which may have a higher biomarker concentration than blood, has not been investigated extensively by means of peptidome analysis. Here, a method for the peptidome analysis of mouse liver was developed by the combination of size exclusion chromatography (SEC) prefractionation with nano-liquid chromatography-tamdem mass spectrometry (nanoLC-MS/MS) analysis. The extracted peptides from mouse liver were separated according to their molecular weight using a size exclusion column. MALDI-TOF MS was used to characterize the molecular weight distribution of the peptides in fractions eluted from the SEC column. The low molecular weight (LMW) (MW < 3000 Da) peptides in the collected fractions were directly analyzed by LC-MS/MS which resulted in the identification of 1181 unique peptides (from 371 proteins). The high molecular weight (HMW) (MW > 3000 Da) peptides in the early two fractions from the SEC column were first digested with trypsin, and the resulted digests were then analyzed by LC-MS/MS, which led to the identification of 123 and 127 progenitor proteins of the HMW peptides in fractions 1 and 2, respectively. Analysis of the peptides' cleavage sites showed that the peptides are cleaved in regulation, which may reflect the protease activity and distribution in body, and also represent the biological state of the tissue and provide a fresh source for biomarker discovery.     

儿茶酚胺激素剂和阻断剂对大鼠胃粘膜适应性细胞保护作用…

本文观察了儿茶酚胺激素剂和阻断剂对大鼠慢性应激诱发的胃粘膜适应性细胞保护作用的影响,并分析内源性生长抑素与保护作用的关系。结果表明,慢性应激诱导的大有粘膜性保护作用在交感神经切除后完全消失,多巴胺或异丙肾上腺素使保护作用部分恢复,去甲明上腺素无作用,在交感神经完整大鼠,心得安或氟哌啶醇可抑制慢性应激诱发的保护作用,酚妥拉明无作用。血浆生长抑素在应激及交感神经切除后均无显著变化,提示惯性应激时交感冒     

Functional state of the endogenous opioid peptide system in traumatic shock in rats]

The experiments have been performed on 120 Wistar rats and 546 CBWH mice. Met-enkephalin (ME) and beta-endorphin (BE) levels were determined to increase in blood and mid-brain 3 hours later after soft tissue compression of pelvic extremities. 48 hours later after six-hour compression BE and ME level in blood was increased, BE concentration in blood was also increased, and enkephalins' content in brain and blood was decreased as against the control. Opioid peptides influence on the host compression period has been studied. D-agonists were established to decrease, but mu-agonists were established to increase mice survival in shock. Opioid peptides' significance in traumatic shock pathogenesis is being discussed.     

A cumulative experience examining the effect of natural and synthetic antimicrobial peptides vs. Chlamydia trachomatis.

We tested the activity of 48 structurally diverse antimicrobial peptides against Chlamydia trachomatis, serovar L2. The peptides' activity against C. trachomatis, serovar L2 was measured in 48-h McCoy cell shell vial assays. Peptides of 16-20 amino acids were more active than larger peptides, such as defensins. Beta-sheet protegrins, as well as alpha-helical peptides such as novispirin (G-10) were equally active. Enantiomers were as active as native structures. Moderate-sized circular mini-defensins were less effective against C. trachomatis. Moderate-sized cationic peptides may be useful in microbicide preparations designed to prevent chlamydial infection.     

Protective effect of melatonin on myocardial infarction

The dose- and time dependence of melatonin and the effective window of melatonin administration were determined in a mouse model of myocardial infarction. When mouse hearts were subjected to 60 min of occlusion of the left anterior descending artery (LAD) followed by 4 h of reperfusion, melatonin pretreatment for 30 min significantly reduced the infarct size/risk area. The most effective dose was found to be 150 microg/kg intraperitoneally, and the effective period of protection lasted up to 2 h after melatonin administration. Melatonin administration 45 min after LAD ligation or right before reperfusion was as effective as administration 30 min before ligation; however, melatonin administered after the release of occlusion was not protective. Melatonin's effect was still present in mice deficient for the Mel1a melatonin receptor. 8-Methoxy-2-propionamidotetralin, a melatonin receptor agonist with no antioxidant activity, offered no protection, suggesting a lack of involvement of melatonin receptors. Finally, the effects of melatonin were similar in rats and mice. Our results demonstrate that melatonin is an effective cardioprotective agent when administered either before or during coronary occlusion at a very low dose.     

Synthesis of glycocluster peptides

A new type of glycoconjugate mimetic is introduced that combines a glycocluster head group with a peptide part. These 'glycocluster peptides' are designed to serve as mimetics of glycocalyx constituents. A convergent synthetic scheme was followed, consisting of (i) the synthesis of a clustered carbohydrate head group carrying an amino acid at the focal point, and (ii) the solid phase synthesis of the peptide moiety. Finally, peptide coupling on resin furnished two prototype glycocluster peptides, which each exposes three alpha-mannosyl residues in the form of a dendritic wedge, with different conformational features. Extensive purification and NMR studies were necessary to characterize the target compounds and the results of these investigations are reported here together with the synthesis.     

A molecular mechanism for lipopolysaccharide protection of Gram-negative bacteria from antimicrobial peptides

Cationic antimicrobial peptides serve as the first chemical barrier between all organisms and microbes. One of their main targets is the cytoplasmic membrane of the microorganisms. However, it is not yet clear why some peptides are active against one particular bacterial strain but not against others. Recent studies have suggested that the lipopolysaccharide (LPS) outer membrane is the first protective layer that actually controls peptide binding and insertion into Gram-negative bacteria. In order to shed light on these interactions, we synthesized and investigated a 12-mer amphipathic alpha-helical antimicrobial peptide (K(5)L(7)) and its diastereomer (4D-K(5)L(7)) (containing four d-amino acids). Interestingly, although both peptides strongly bind LPS bilayers and depolarize bacterial cytoplasmic membranes, only the diastereomer kills Gram-negative bacteria. Attenuated total reflectance Fourier transform infrared, CD, and surface plasmon resonance spectroscopies revealed that only the diastereomer penetrates the LPS layer. In contrast, K(5)L(7) binds cooperatively to the polysaccharide chain and the outer phosphate groups. As a result, the self-associated K(5)L(7) is unable to traverse through the tightly packed LPS molecules, revealed by epifluorescence studies with LPS giant unilamellar vesicles. The difference in the peptides' modes of binding is further demonstrated by the ability of the diastereomer to induce LPS miscellization, as shown by transmission electron microscopy. In addition to increasing our understanding of the molecular basis of the protection of bacteria by LPS, this study presents a potential strategy to overcome resistance by LPS, and it should help in the design of antimicrobial peptides for future therapeutic purposes.     

Teratogenicity study of some pesticides in chicken embryos

The use of pesticides involves the risk of poisoning on wild animals. Teratological tests carried out on avian embryos provide useful data for environmental protection and facilitate the development of environment-friendly chemical plant protection techniques. A 30% dimethoate containing insecticide formulation (BI 58 EC) and a 20% benfluralin containing herbicide formulation (Flubalex) and a 960 g/l S-metolachlor containing herbicide formulation (Dual Gold 960 EC) were studied in chicken embryos after single administration by immersion and injection technique. Treatment was done on day 0 of incubation. Applied concentration of pesticides were 0.1% (dimethoate) and 2.05% (S-metolachlor) and 0.375% (benfluralin) corresponding to that used in plant protection practice. Test materials were injected into the air chamber in a volume of 0.1 ml/egg, or eggs were treated by the immersion technique for 30 min. at 37 degrees C. Evaluation was done on day 19 of incubation. Injection treatment: the administration of S-metolachlor and benfluralin did not result a significant decrease in the average body weight of embryos. At the same time the body weight of embryos significantly decreased because of single administration of dimethoate. The embryomortality increased markedly after the administration of test materials (S-metolachlor, benfluralin, dimethoate). Immersion treatment: the administration of S-metolachlor and benfluralin and dimethoate did not result a significant decrease in the average body weight of embryos. The rate of embryomortality was low after the administration of S-metolachlor, benfluralin and dimethoate. After the immersion and the injection treatment the incidences of developmental anomalies were sporadic. In summary it can be established that the injection treatment was more toxic than immersion technique of the test materials in our study.