Inhibition of pig kidney diamine oxidase by nazlinin and nazlinin derivatives

Nazlinin (1-(4-butylamino)-1,2,3,4-tetrahydro-beta-carboline) (1), an alkaloid recently isolated from Nitraria schoberi, and its two derivatives, 1-(4-butylamino)-3,4-dihydro-beta-carboline (2) and 1-(4-butylamino)-beta-carboline (3), were synthesized and their interaction with pig kidney diamine oxidase (PKDO) was studied. Nazlinin appeared to be a very poor substrate while 3 was a good substrate with an apparent Km of 9.3-10(-5) M. The enzyme was inhibited by 1 and 2. With both compounds the mode of inhibition found was non-competitive and inhibition constants calculated from the slopes and intercepts of double-reciprocal plots show that 2 is a much more potent inhibitor than the natural product. The relationship between the structure of these compounds and the results found is discussed.     

Recognition of shiny dielectric objects by analysing the polarization of reflected light

The degree of polarization of light reflected from a transparent or translucent object depends only upon the angle of incidence, refractive index and absorption coefficient of the material. It is therefore possible to determine the orientation of the surface normal from the direction of the plane of polarization. The feasibility of this is demonstrated both theoretically and practically by calculating and measuring the reflectance map of a sphere when viewed through a plane polarizing filter. Ambiguities in the mapping from radiance to orientation are removed by orienting the filter at three angles. The orientation of our objects is determined to within an uncertainty of less than seven degrees.     

Effect of in utero radiation dose fractionation on rat postnatal development, behavior and brain structure: 3-hour interval

Effect of In Utero Radiation Dose Fractionation on Rat Postnatal Development, Behavior and Brain Structure: 3-Hour Interval. Neurotoxicology 15(1): 183-190, 1994. We have previously shown that exposure of the rat fetus to ionizing radiation produces dose-dependent (0.25-1.25 Gy) changes in postnatal growth and behavior, and decreases in cerebral cortex thickness. Pregnant rats were exposed to single doses of 0.5 or 1.0 Gy, or to two doses of 0.5 Gy (separated by a 3 h interval) on gestational day 15. Pups were weighed and subjected to behavioral tests (righting reflex; reflex suspension; negative geotaxis; continuous corridor; and length, width, and sine of gait) over postnatal days 7-28. The rats were then sacrificed and brains removed for histology. The fractionated doses produced responses that were generally intermediate between those produced by the single doses and which, by interpolation, could be expressed as equivalent to a single dose between 0.5 and 1.0 Gy. Overall, exposure of the fetal rat to two doses of 0.5 Gy separated by 3 h produced effects equivalent to a single dose of 0.85 Gy. We conclude that fractionation of radiation dose results in less damage to the developing rat cerebral cortex, as measured by postnatal growth, behavioral tests, and morphological assessment.     

Long range-inverse PCR (LR-IPCR): extending the useful range of inverse PCR

The inverse PCR technique (IPCR) has proven to be very useful for the amplification of uncharacterized stretches of DNA upstream or downstream of regions that have already been cloned and sequenced. In practice, however, chromosome walking using standard IPCR is often a slow, repetitive process because only small DNA fragments are effectively amplified. The development of long and accurate PCR methodology has greatly expanded the range of DNA fragment sizes that is amenable to amplification by conventional PCR. We reasoned that combining long range PCR with IPCR would also extend the useful range of the IPCR technique. In this paper we demonstrate the utility of the hybrid, long range-inverse PCR (LR-IPCR) technique by generating clones containing long stretches of DNA flanking endogenous chicken proviral elements.     

Analysis of genes encoding highly conserved lysine-rich proteins in Aplysia californica and Saccharomyces cerevisiae

To isolate a gene that can be used as an internal control in studies on gene expression in Aplysia californica neurons, we have characterized a cDNA clone (pKRP-A) isolated on the basis of its high expression in A. californica neurons. This cDNA is of 850 nucleotides and codes for a putative 29-kDa lysine-rich protein. Blotting experiments revealed that the gene is expressed in all tested A. californica tissues, and in individually identified neurons of the abdominal ganglion, suggesting that this gene can be efficiently used as internal control in studies of gene expression. We have also isolated one cDNA and two different genomic clones from yeast libraries that show 59% identity with pKRP-A. Sequence comparison of genomic clones, as well as PCR and Southern blotting experiments, revealed that at least two homologous genes are present in yeast. Northern blotting experiments revealed that the expression of the gene is strongly repressed at 39 degrees C.     

Pathology of mitral valve stenosis and pure mitral regurgitation--Part I

This two-part article examines the histologic and morphologic basis for stenotic and purely regurgitant mitral valves. In Part I, conditions producing mitral valve stenosis are reviewed. In over 99% of stenotic mitral valves, the etiology is rheumatic disease. Other rare causes of mitral stenosis include congenital malformed valves, active infective endocarditis, massive annular calcium, and metabolic or enzymatic abnormalities. In Part II, conditions producing pure mitral regurgitation will be discussed. In contrast to the few causes of mitral stenosis, the causes of pure (no element of stenosis) mitral regurgitation are multiple. Some of the conditions producing pure regurgitation include floppy mitral valves, infective endocarditis, papillary muscle dysfunction, rheumatic disease, and ruptured chordae tendinae.     

A 5 S rRNA gene is present in the mitochondrial genome of the protist Reclinomonas americana but is absent from red algal mitochondrial DNA

Except in the case of land plants, mitochondrial ribosomes apparently lack a 5 S rRNA species, even though this small RNA is a component of all prokaryotic, chloroplast and eukaryotic cytosol ribosomes. In plants, the mitochondrial 5 S rRNA is encoded by mtDNA and differs in sequence from the 5 S rRNA specified by plant nuclear and chloroplast genomes. A distinctive 5 S rRNA component has not been found in the mitochondrial ribosomes of non-plant eukaryotes and, with the notable exception of the chlorophycean alga, Prototheca wickerhamii, a 5 S rRNA gene has not been identified in those non-plant mtDNAs characterized to date. Here, we report the presence of a 5 S rRNA gene in the mtDNA of the heterotrophic flagellate Reclinomonas americana. This unicellular eukaryote is a member of the jakobid flagellates, an early-diverging group of protists that share ultrastructural characteristics with the retortamonads, primitive protists that lack mitochondria. We report sequence data from the mtDNAs of the red algae Porphyra purpurea and Gracilariopsis lemaneiformis, which we use to evaluate a recent claim that a 5 S rRNA gene exists in the mtDNA of a third rhodophyte alga, Chondrus crispus. Our results lead us to the opposite conclusion: that a 5 S rRNA gene is not encoded by red algal mtDNA. In view of the accumulating evidence favoring a monophyletic origin of the mitochondrial genome, it is likely that a 5 S rRNA gene was present in an ancestral proto-mitochondrial genome, and that contemporary mtDNA-encoded 5 S rRNA genes have all descended from this ancestral gene. Considering the highly restricted phylogenetic distribution of identified mtDNA-encoded 5 S rRNA genes, it follows that the mitochondrial 5 S rRNA gene must have been lost multiple times during evolutionary diversification of the eukaryotic lineage.