Diabetes-induced changes of nitric oxide influence on the cardiovascular action of secretin

The modulation by condition of the lack or the excess of nitric oxide (NO) on cardiovascular action of secretin in diabetic rats was investigated. In vitro the isolated heart function and in vivo, the systolic (SBP), diastolic (DSP) blood pressure and heart rate (HR) were measured. Secretin evoked inotropic positive effect and increased coronary outflow (CO), in vivo did not increase systemic pressure and the highest dose of the peptide increased the heart rate. NO synthase inhibitor, N(G) nitro-L-arginine methyl ester (L-NAME) deeply increased the systemic pressure and in vitro decreased coronary outflow. L-arginine and sodium nitroprusside (SNP) did not influence the isolated heart function and in vivo decreased the systemic pressure. L-NAME preserved the inotropic positive effect of secretin and the increase of the coronary outflow. In vivo co-administration of L-NAME+secretin evoked hypotensive effect and abolished the increase of the heart rate after the highest dose of the peptide. L-arginine abolished inotropic positive effect of the peptide and the increase of coronary outflow. In vivo co-administration of these substances caused hypotension and attenuated the increase of the heart rate after the highest dose of secretin. Co-injection of SNP and secretin preserved the inotropic effect of secretin and abolished the increase of the coronary outflow. In vivo infusion of SNP+secretin evoked hypotension and similarly to L-arginine, SNP abolished tachycardia induced by the highest dose of secretin. Both the lack and the excess of nitric oxide changed the cardiovascular action of secretin in diabetic rats.     

Photothermal Spectra of Thylakoids Isolated from Cucumber Cotyledons at Various Stages of Greening

The character of interaction between carotenoids (Cars) and chlorophylls (Chls) in thylakoids isolated from cucumber cotyledons at three stages of greening (3, 6, and 24 h of irradiation with 120 µmol m^–2 s^–1) was studied. The shapes of the steady state photoacoustic spectra were changed with the change in time of greening and with the frequency of radiation modulation. The shapes show that changes not only in the contents of various pigments but also in pigment interactions with surrounding occur and that processes of thermal deactivation characterised by different kinetics take place. Slow processes of thermal deactivation are in most cases due to deactivation of triplet states. Long living triplet states are very often engaged in photochemical reactions that can destroy the tissue. Analysis of the time-resolved photothermal spectra shows that at later stage of greening, the chlorophyll (Chl) molecules are better shielded against photo-destruction because Cars more efficiently quench their triplet states. The yield of formation of the pigment triplet states measured by the time resolved photothermal method, always at the same energy absorbed by pigment mixture, declined during sample greening. The decay time of the slow component of pigment thermal deactivation, due predominantly to deactivation of the triplet state of Chl, decreases with the increase of time of greening from 6.2 µs for the 3-h sample to 1.5 µs for the 24 h sample. The energy taken by Cars from Chls is dissipated into heat, therefore the steady state and quick thermal deactivation values increased during the greening process. The Cars/Chls ratio in the thylakoids decreased during greening approximately 2 fold. Hence at a later phase of greening the Cars can quench the triplet states of Chls more efficiently than at an earlier phase of greening.     

Assessment of RAPD markers for barley doubled haploid lines resistant and susceptible to Fusarium culmorum at seedling and adult plant growth stages

Thirty doubled haploid (DH) lines of barley derived from F(1) of a cross between the six-rowed cultivar Pomo and two-rowed cultivar Maresi were examined for susceptibility to Fusarium seedling blight (SB) and head blight (FHB), measured by mycotoxin (nivalenol) content of kernels. RAPD (random amplified polymorphic DNA) polymorphism was analysed by using 53 decamer primers. Amplification products (APs) were 200 bp up to 2000 bp in size on average 5.7 per primer and the total number of APs was 284, 51.06% of which were polymorphic. Only 32 APs differentiated the examined DH lines - 19 APs for nivalenol content of kernels and 13 for seedling resistance. DH lines segregated with continuous distribution of resistance to FHB and SB. At the seedling stage all DH lines exhibited lower susceptibility than parental cultivars, but in the adult stage only two lines (MP 2 and MP 7) appeared to be more resistant to FHB, i.e. accumulated in kernels a lower amount of mycotoxin than cultivars Maresi and Pomo.     

Cellular aspects of folate and antifolate membrane transport

Folates--one carbon carriers--take part in the metabolism of purine, thymidylate and some amino acids. Internalization of these compounds employs several mechanisms of transport systems. Reduced folate carriers and folate receptors play the most important role in this process. The physiological role of these molecules in normal and neoplastic cells is described regarding changes in transport activity and connection of transport systems with resistance to antifolates and cancer development.     

X-Ray diffraction and high resolution NMR analysis of methyl D-glucopyranuronate derivatives

X-Ray diffraction and high resolution 1H and 13C NMR spectral data for methyl 2,3,4,-tri-O-acetyl-alpha-D-glucopyranuronate and methyl (allyl 2,3,4-tri-O-acetyl- beta-D-glucopyranosid)uronate are presented. Both compounds adopt the 4C1 conformation.     

Preparation, chemical and crystal structures of N-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glucopyranosyl)pyridinium chloride

Preparation and isolation of N-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glucopyranosyl)pyridinium chloride are described. Its structure was determined by 1H NMR spectroscopy and X-ray analysis. X-ray crystallography revealed that the salt crystallizes with one molecule of water. Ab initio calculations were used to determine charges on atoms in the cation of the title compound.     

Transgenic Complementation of MARCKS Deficiency with a Nonmyristoylatable, Pseudo-Phosphorylated Form of MARCKS: Evidence for Simultaneous Positive and Dominant-Negative Effects on Central Nervous System Development

MARCKS is a widely expressed protein kinase C substrate that is essential for normal prenatal development of the central nervous system in mice. MARCKS-deficient mice exhibit universal perinatal mortality and numerous developmental abnormalities of the brain and retina. To determine which domains of the protein were important in complementing these neurodevelopmental anomalies, we have interbred MARCKS knockout mice with transgenic mice expressing an epitope-tagged human MARCKS transgene that can completely correct the MARCKS-deficient phenotype. Previous structure–function studies showed that a nonmyristoylatable form of MARCKS could correct all of the neuroanatomical abnormalities, and resulted in approximately 25% viable pups that grew to adulthood and were fertile. The present experiment attempted a similar complementation strategy in which a nonmyristoylatable, “pseudo-phosphorylated” form of the protein was used, which has been shown to be almost completely cytosolic in cell expression studies. Surprisingly, this transgene was able to complement almost all of the cerebral anatomical abnormalities characteristic of the knockout mice. However, these mice also exhibited a universal, novel phenotype: profound retinal ectopia, in which retinal tissue was often found in the vitreous humor as well as extraocularly. Retrospective evaluation of the original MARCKS knockout phenotype revealed that this anomaly was present in about 43% of the knockout mice, and was clearly detectable as early as embryonic day 12.5, before retinal cell differentiation begins. These data suggest that a nonmyristoylatable, pseudo-phosphorylated form of MARCKS can complement most if not all cerebral aspects of the MARCKS-deficient phenotype, but that it appears to worsen a retinal phenotype, perhaps by exerting a dominant-negative effect on a coexpressed MARCKS homologue.     

The effect of some physical and serological treatments on haemofusing activity of bovine parainfluenza virus type 3.

Bovine parainfluenza virus type 3 irrespective of the time of its harvesting from Madin-Darby bovine kidney cells, expressed little or no haemofusing activity. Treatment of the virus by freezing and thawing, sonication or antibody and complement enhanced this activity. Moreover haemofusing activity did not correlate with the viral capacity for fusion of susceptible cells in monolayer cultures.