Role of endothelium, oxygen and ionic milieu in the prostacyclin and thromboxane production of rat aortic tissue slices.

The present study was executed in order to get further data on the role of vessel wall constituents in prostanoid synthesis and on the effect of anorganic constituents on it. Prostacyclin and tromboxane production of rat aortic tissue slices with intact endothelium and after mechanical as well as chemical endothelium removal were studied. The effects of hypoxia and changes in the ionic milieu on the release of these prostanoids were also examined. The tissue slices were incubated in normal or in modified Krebs-Ringer solution, bubbled with 95% O2 and 5% CO2 (with the exception of the studies in hypoxic conditions). Prostacyclin and thromboxane release was determined by specific radioimmunoassay of the stable metabolites, 6-keto-PGF1 alpha and TxB2, from the incubation medium. 174 tissue samples obtained from 164 rats were studied. Mechanical removal of the endothelium increased prostacyclin production of the aortic segments about fivefolds from a basal rate of 52.9 +/- 19.4 ng/gr/min, while it had no significant effect on thromboxane release (basal rate 0.83 +/- 0.13 ng/gr/min). Treating the endothelium with 1.0 M HCl almost totally suppressed prostacyclin release. Lowering the partial oxygen tension of the incubation medium significantly decreased the production of prostacyclin, while release of TxB2 somewhat increased. Increasing the Ca2+ concentration of the medium between 0-5 mM the release of prostacyclin was augmented and the release of thromboxane was diminished. Potassium free medium caused a very large increase in prostacyclin release of the tissue slices. The results show that release of vasoactive prostanoids from isolated rat aortic wall is dependent not exclusively on the endothelium and that various methods of endothelium removal may have distinct influences on prostacyclin and thromboxane productions. The changes in anorganic constituents of the surrounding medium could massively affect prostacyclin and thromboxane production of rat aortic tissue. The alternative effects of the above listed treatments on the release of prostacyclin and thromboxane from the rat aortic wall suggest the existence of different mechanisms in the control of the production of the two major prostanoids possessing opposite physiological effects.     

Demonstration of two forms of calcium pumps by thapsigargin inhibition and radioimmunoblotting in platelet membrane vesicles

In mixed membrane vesicles prepared from human platelets, the presence of two distinct calcium pump enzymes (molecular mass 100 and 97 kDa) was demonstrated by 32P autoradiography, immunoblotting, and thapsigargin inhibition. Both the 100- and 97-kDa membrane proteins showed calcium-dependent phosphoenzyme formation and reacted with a polyclonal anti-sarcoplasmic reticulum calcium pump antiserum, while only the 100-kDa protein reacted with the antiserum specific for the sarco-endoplasmic reticulum-type calcium transport ATPase 2b isoform. Thapsigargin, inhibiting active calcium transport in platelet membrane vesicles, predominantly blocked the phosphoenzyme formation of the 100-kDa isoform and of the tryptic calcium pump fragments of 55 and 35 kDa, while lanthanum specifically increased the phosphoenzyme formation of the 97-kDa enzyme and of the tryptic fragment of 80 kDa. These results indicate the presence of the sarco-endoplasmic reticulum-type calcium transport ATPase 2b isoform and of a yet unidentified, 97-kDa calcium pump protein in human platelet membranes.     

Homologies between a brain-specific identifier (ID) sequence and regions of Harvey murine sarcoma virus and Rous sarcoma virus genomes. Putative role of identifier sequences in the tissue specificity of malignant transformation by RNA tumor viruses

As a step toward understanding of the tissue specificity of cellular transformation by RNA tumor viruses were looked for the presence of a putative brain specific regulatory (identifier) sequence (C82B) in the genome of various oncornaviruses. The genomes of Harvey murine sarcoma virus and Rous sarcoma virus contain sequences flanking the viral oncogenes with greater than 80% and greater than 60% homology to C82B, respectively. We suggest that identifier sequences acquired by oncoviruses may determine the potential target cells of malignant transformation after virus penetration.     

A two-component sex attractant for males of the geometrid moth Alsophila quadripunctata

The binary mixture of the hydrocarbons (3Z,6Z,9Z)-3,6,9-nonadecatriene and (6Z,9Z)-6,9-nonadecadiene is a sex attractant for males of Alsophila quadripunctata Esp. (Lepidoptera, Geometridae). Triene/diene ratios from 1:1 to 1:0.01 attracted males in the field, the ratios 1:1 and 1:0.7 were most effective. The triene on its own also attracted males, but in significantly lower numbers than the 1:1 mixture. In a dosage test the highest dose, 1800 g of 1:0.8 [triene:diene] mixture applied to rubber caps was most effective. This is the first report of a geometrid sex attractant with field activity containing more than one component.

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Zusammenfassung Die binäre Mischung der Kohlenwasserstoffe (3Z,6Z,9Z)-3,6,9-Nonadecatrien [ZZZ3,6,9-19:H] und (6Z,9Z)-6,9-Nonadecadien [ZZ6,9-19:H] in den Verhältnissen 1:1 bis 1:0.01 erwies sich im Freiland als Sexuallockstoff für Männchen von Alsophila quadripunctata (Geometridae, Lepidoptera). Dabei besaß die 1:1-Mischung die beste Fängigkeit, das Nonadecatrien allein lockte schlechter, während das C₁₉-Alkadien unwirksam war. Ein Dosiswirksamkeitstest ergab bei Köderbeladungen von 1.8 mg (Trien:Dien + 1:0.8) die besten Fangergebnisse. Im Verlauf der Untersuchungen wurden weitere zwölf geometrische-oder positionsisomere C₁₉-Polyenkohlenwasserstoffe getestet, wobei keine der geprüften Verbindungen Attraktant-oder Inhibitorwirkung zeigte.

     

A comparison of the conformations adopted by some 5-bromovinyl-2''-deoxyuridines and a correlation with their antiviral properties: an X-ray study.

Crystal structures of (Z)-5-(2-bromovinyl)-2'-deoxyuridine, 3',5'-di-O-acetyl-(E)-5-(2-bromovinyl)-2'-deoxyuridine and 3',5'-di-O-p-chlorobenzoyl-5-(2-dibromovinyl)-2'-deoxyuridine are compared with each other and with that of the most potent antiviral agent (E)-5-(2-bromovinyl)-2'-deoxyuridine (E-BVDU) reported earlier. A comparison of the conformation of 3',5'-di-O-acetyl-pyrimidine nucleoside structures in which intermolecular hydrogen bond network formation is minimized, with those of their parent compounds has shown that the greatest change in rotation about the glycosyl bond and in the sugar ring pucker is exhibited by E-BVDU. Upon acylation this molecule changes from C2'-endo/C3'-exo conformation to C3'-endo/C4'-exo conformation. The relevance of these structures upon the biological activity of the nucleosides and in particular to their ability to be a substrate for thymidine kinase is discussed.     

Substitution analysis of callus induction and plant regeneration from anther culture in wheat (Triticum aestivum L.)

The genetic determination of callus induction, total plant regeneration and green plant regeneration from anther culture were studied using a Chinese Spring/Cheyenne substitution series. All the three characteristics were found to be polygenically determined, but their inheritance was independent from one another. The 7A and 18 chromosomes had a considerable effect on callus induction. In the case of total plant regeneration the most influential chromosome as the 3A while the 2D chromosome showed a definite influence on green plant regeneration. The interaction between the genetic background of the recipient plant and the substituted chromosome plays an important role in the manifestation of the studied features.     

Effect of oxytocin and its antagonist microinjected into the hippocampus on the intravenous self-administration of heroin in rats

The paper deals with the effect of oxytocin (OXT) and its antagonist--oxytocin antiserum (ANT) microinjected in the ventral hippocampus--on learning of heroin intravenous self-administration in rats. OXT weakened the processes of heroin self-administration, while ANT in contrast improved the learning. The results of the study and data analysis suggest that endogenous OXT in the ventral hippocampus is involved in the mechanisms of behavioural reactions.     

Potent GnRH agonists containing L-amino acid derivatives in the six position

New agonists related to gonadotropin-releasing hormone (GnRH) have been synthesized that are comparable in potency to the GnRH and its superagonists for release of LH and estrus suppression without substitutions with D- or unnatural amino acids in position 6. We now report a series of L-beta-aspartyl-6 GnRH analogs containing only naturally occurring L-amino acids in the whole sequence, exhibiting considerable in vivo biological activity. Dose and time dependent LH release capability of the different analogs in adult male mice, estrus suppression comparisons and blockade of ovulation in female rats are given. The incorporation of L-Asp-OMe and L-Asp-OBzl in position 6 of GnRH resulted in the most potent GnRH agonists (to 12-20xGnRH potency) in this series inducing a biphasic biological response similar to the D-amino acid-6 substituted superactive GnRH analogs. A correlation between the LH releasing potencies of the analogs and their HPLC retention times was also investigated. Peptide synthesis were achieved using either solid phase or solution phase methodology.     

The effect of indol-3-yllactic acid on maize seedling growth

D,L-indol-3-yllactie acid was applied at concentrations 0.2 – 20 mg 1^-1 (10^-6–10^-4M) to the roots of 3-d-old intact maize seedlings grown in the dark and in the light. By day 3 after application, ILA at lower concentrations (0.2–1 mg l^-1) caused slight increase in the mass of etiolated plants, mainly roots. Shoot and root length was not increased. ILA at concentrations equal to, or greater than, 2 mg 1^-1 reduced the length of the main roots and from 10 mg 1^-1 on also the length of the shoots. In contrast, root mass was decreased by higher ILA concentrations to a lesser extent than shoot mass. The response to ILA application of etiolated seedlings differed from that of the seedlings grown in the light only at 20 mg 1^-1. The inhibitory effect was more pronounced in the case of quickly growing etiolated plants.     

Comparative study of growth and carbon uptake inFagus sylvatica L. trees growing under different light conditions

Growth, carbon uptake and carbon utilization in leaves of various growing phase shoots (GPS) on beech trees(Fagus sylvatica L.) growing under different light conditions were compared. The values of photosynthetic capacity (maximum daily net photosynthetic rate, Pn max) were used as comparable parameters. Daily time and irradiance (I, PhAR), when PN max was attained, were investigated similarly. Statistically significant differences were found in growth, Pn max and SLM (specific leaf mass) between different GPS and within the same stand, as well as within the same GPS and different stands. Pn max and SLM increased in the leaves of GPS I (spring - plagiotropic shoots) on trees from a sun stand from May till September. At the end of the growing season, the spring leaves exhibited, in comparison with the summer ones, intensive senescence, but leaves of the GPS II and III (summer -orthotropic shoots) evidently attained higher values of Px max and SLM at higher I (PhAR). The correlation of growth, PN max and SLM in relation to environmental conditions, as well as the importance of transport, distribution and utilization of assimilates for annual carbon gain and biomass production are discussed in detail.