Luliberin analogues containing the nuclear localization sequence of the SV-40 virus T-antigen

With the goal of improving the efficacy of anticancer drugs due to the directed delivery to intracellular targets, a set of luliberin analogues containing the nuclear localization signal (NLS) of the SV-40 virus large T-antigen has been synthesized. The NLS was attached to the parent molecule via the D-lysine ɛ-amino group introduced into position 1 or 6 of the peptide sequence using the orthogonal protection strategy. Biological tests demonstrated that this modification supported in vitro a significant increase in the cytotoxic activity of luliberin analogues containing palmitoyl residues. The influence of the studied peptides on tumor cells was not associated with the distortion of the membrane integrity, which was confirmed by experiments with normal fibroblasts used as a control.     

Cortexolone as a modulator of diazepam activity

The influence of ACTH (200 micrograms/kg), corticosterone (20 mg/kg) and cortexolone (20 mg/kg) on the anxiolytic activity of diazepam was studied. ACTH partly and corticosterone completely blocked the action of diazepam. Cortexolone injection 30 min before the administration of diazepam induced a 100% anxiolytic effect of diazepam in the range of doses from 0.1 to 0.3 mg/kg (ED50 of anxiolytic diazepam effect is 0.2 mg/kg). The role of stress hormones in the regulation of psychotropic drug activity is discussed.     

Effects of combined action of heavy metal salts and phenol on energetics of isolated rat liver mitochondria]

Experiments were carried out to investigate effects of heavy metal salts and phenol both alone and in different combinations on respiration rate and coupling of respiration and oxidative phosphorylation by rat liver mitochondria. Oxygen consumption measurements were obtained using a Clark electrode and lactate plus glutamate as substrates. It is shown that a 50% decrease of the respiratory rate was achieved in less concentrations of substances in the mixture compared with the effects of the individual substances. For respiratory control recovery by EDTA titration more amounts of complexion for model mixtures was necessary. The results evidence synergism of the substances responsible for a considerable increase in toxicity. Mitochondrial test-systems are suggested for rapid prognosis of toxicity of multicomponent mixtures of substances.     

Derivatives of N-amidinoproline and their use in conventional and solid phase peptide synthesis

N-Amidinoproline, a hybrid structure modeling key features of the Arg-Pro sequence, was synthesized. The activation of carboxyl group of free N-amidinoproline was found to result in the formation of a cyclic side product, whose structure was confirmed by ESI MS, 1H NMR, and 13C NMR spectra. The preparation of N-(mesitylenesulfonylamidino)-L-proline using the mesitylenesulfonyl derivative of 2-methylisourea was demonstrated to be accompanied by partial racemization. The target product was synthesized by modification of N-amidinoproline by mesitylenesulfonyl chloride. The possibility of using N-amidinoproline in the N-terminal modification of a peptide chain was shown by the example of synthesis of an analogue of the 95-98 fragment of fibrinogen alpha chain.     

Protective Effects of Some Creatine Derivatives in Brain Tissue Anoxia

Some derivatives more lipophylic than creatine, thus theoretically being capable to better cross the blood–brain barrier, were studied for their protective effect in mouse hippocampal slices. We found that N-amidino-piperidine is harmful to brain tissue, and that phosphocreatine is ineffective. Creatine, creatine–Mg-complex (acetate) and phosphocreatine–Mg-complex (acetate) increased the latency to population spike disappearance during anoxia. Creatine and creatine–Mg-complex (acetate) also increased the latency of anoxic depolarization, while the delay induced by phosphocreatine–Mg-complex (acetate) was of borderline significance (P = 0.056). Phosphocreatine–Mg-complex (acetate) significantly reduced neuronal hyperexcitability during anoxia, an effect that no other compound (including creatine itself) showed. For all parameters except reduced hyperexcitability the effects statistically correlated with tissue levels of creatine or phosphocreatine. Summing up, exogenous phosphocreatine and N-amidino piperidine are not useful for brain protection, while chelates of both creatine and phosphocreatine do replicate some of the known protective effects of creatine. In addition, phosphocreatine–Mg-complex (acetate) also reduced neuronal hyperexcitability during anoxia.     

Effect of morphine on the sensitivity of cerebral cortical neurons to acetylcholine

Sensitivity of sensorimotor cortical neurons to microiontophoretically applied morphine and acetylcholine has been studied in the experiments on unanesthetized rabbits. The predominant reaction to morphine and acetylcholine was decrease and increase in the rate of neuronal impulse activity, respectively. There was no correlation in the responses to morphine and acetylcholine. Atropine failed to influence the morphine effect. When both drugs are simultaneously applied to neurons, morphine decreases both excitatory and inhibitory responses to acetylcholine. This effect of morphine may occur in the case when the drug is applied in doses which do not change spontaneous neuronal activity. On the contrary, excitatory effect of glutamic acid decreased only when morphine was applied in doses causing local anesthetic effect and decreasing background neuronal activity. It is suggested that morphine can exercise a modulating influence on choline receptors of cortical neurons.     

Effect of ethanol on the concentration of enkephalins in the brain of rats with different levels of alcoholic motivation

Radioimmunoassay was used to measure the content of leu- and met-enkephalins in white random-bred rats divided into groups according to the duration of ethanol anesthesia and the levels of 15% ethanol consumption under the conditions of free choice. The concentration of neuropeptides was determined in the cortex of the large hemispheres, striatum, thalamus, and medulla oblongata. The short-sleeping animals manifested elevated concentration of leu-enkephalin in the cortex and that of met-enkephalin in the striatum, medulla oblongata, and thalamus. Prolonged alcoholization under the conditions of free choice led, in the much-drinking animals, to decreased concentration of leu- and met-enkephalins in the striatum, thalamus and medulla oblongata and to increased concentration of leu-enkephalin in the cortex. The importance of leu- and met-enkephalins in the pathogenesis of chronic experimental alcoholism in rats with different alcoholic motivation is considered.     

Serological relationships of azospirilla revealed by their motility patterns in the presence of antibodies to lipopolysaccharides

Motility of the serologically different Azospirillum brasilense strains Sp245 (serogroup I) and Sp7 (serogroup II) was studied in the presence of antibodies to their lipopolysaccharides (LPS). A procedure was proposed in order to determine the motility patterns indicating the specificity of the interaction between the anti-LPS antibodies and bacteria. Analysis of the effect of such antibodies on motility of 25 strains (A. brasilense, A. lipoferum, A. irakense, and Azospirillum sp.) revealed bacteria exhibiting antigenic cross reactions with A. brasilense Sp7 or Sp245. The effect of anti-LPS antibodies on motility of azospirilla was in agreement with the results of immune agglutination analysis of bacterial cells and of immunodiffusion analysis of the LPS preparations. According to our results, strains Azospirillum sp. SR81 and A. brasilense SR14 should be included into serogroups I and II, respectively.     

Level of delta sleep-inducing peptide (DSIP) in the brain of rats with different alcoholic motivation

Radioimmunoassay was used to measure the content of delta-sleep-inducing peptide (DSIP) in random-bred albino rats divided into groups according to the duration of ethanol anesthesia and the levels of 15% ethanol consumption under free-choice conditions. The concentration of the neuropeptide was assayed in intact brain, in the cortex of large hemispheres, medulla oblongata, thalamus and striatum. The short-sleeping rats manifested a statistically significant lowering of the DSIP content in intact brain homogenates, in the cortex of large hemispheres and striatum. On the contrary, thirty minutes after a single intraperitoneal injection of ethanol in a dose of 1 g/kg the DSIP content in the medulla oblongata, thalamus and striatum was found to be increased. The raising of the ethanol dose up to 2.5 and 4.5 g/kg was followed by a less significant increase in the neuropeptide content. Prolonged chronic alcoholization under free-choice conditions led after 12 months to the reduced DSIP content in the medulla oblongata, thalamus and striatum. The importance of DSIP for the pathogenesis of experimental alcoholism using rats with different levels of alcoholic motivation is discussed.