(1) The results presented refute arguments that these enzymes proceed by a concerted mechansim and support the intermediacy of aminoacyladenylates.
(2) This inactivation was very rapid but reversible, with regeneration of enzyme activity being spontaneous and hydrazine-accelerated, suggestive of the intermediacy of a stable acyl enzyme.
(3) A series of different related diethoxy-phosphorous-acid derivatives were also synthesized; their (31P)-NMR signals between 123.9 and 130.8 ppm are additional evidence for the intermediacy of a tetrazolide species.
(4) Using [14C]cholesterol-labeled membranes and HPLC with radiodetection, we identified 3 beta-hydroxy-5 alpha-cholest-6-ene-5-hydroperoxide as the major cholesterol photoproduct, thereby confirming 1O2 intermediacy.
(5) A microsomal preparation from seedlings of Zea mays catalyzed the NADPH dependent reduction of the delta 7-bond of delta 5,7-cholestadienol (1) giving the first in vitro evidence for the intermediacy of delta 5,7-sterols in plant sterol biosynthesis.
(6) A number of other related products generated by reaction of cyclase with the analog were also identified, the structures and proportions of which were consistent with the intermediacy in catalysis of a cyclopropylcarbinyl cation X pyrophosphate anion pair.
(7) 262, 962], implied the intermediacy of a substrate imine complex in the catalytic redox mechanism.
(8) The epimerization of ecdysone to 3-epiecdysone has been investigated in a dialysed cytosolic enzyme preparation from midgut of sixth instar Spodoptera littoralis larvae, with particular emphasis on establishing the intermediacy of 3-dehydroecdysone.
(9) These studies are consistent with 1O2 intermediacy in the mechanism of MC540-mediated photosensitization.
(10) If the biological conversion of cholest-7-en-3beta-ol (I) into cholesterol (IV) occurred thorugh the intermediacy of cholest-7-ene-3beta,5alpha-diol (II) then the factor(s) adversely affecting the convwesion of the 5alpha-hydroxy sterol (II) into cholesterol must at least equally adversely affect the formation of cholesterol from cholest-7-en-3beta-ol.
(11) Kinetics for the base-catalyzed hydrolysis of compounds 9--13 were investigated by UV and NMR methods and are considered in connection with service of these compounds as pro(phosphorodiamidic acid mustards) [MP(O)(NHR)OAr leads to MP(O)(NHR)OH] via an E1cB mechanism involving the intermediacy of a mustard-bearing metaphosphorodiimide [MP(O)=NR].
(12) GTP gamma S alone stimulated both the release of free arachidonic acid and production of diacylglycerol (DAG), while EGF itself neither stimulated DAG nor augmented the DAG response to GTP gamma S. These findings suggest the intermediacy of a G-protein in PLC-independent stimulation of PLA2 by a growth factor, and provide a model system for determining the relationship between G-protein intermediacy and the intrinsic tyrosine kinase activity of the growth factor receptor.
(13) However, O2-, H2O2, and iron are all required for lipid peroxidation and nondisulfide crosslinking, suggesting the intermediacy of OH generated via the iron-catalyzed Haber-Weiss reaction.
(14) This interaction suggests that the site of nucleoside attachment is in close proximity to the 12-methyl group and that binding occurs, therefore, through the intermediacy of a 3,4-diol-1,2-oxide, i.e.
(15) Comparison of the yields of CO2 from this series of compounds suggests the intermediacy of malonic semialdehyde in the metabolism of MDA.
(16) The results tend to indicate that progesterone is as good a precursor of cardenolides as pregnenolone It is suggested that the biosynthesis of cardenolides might proceed through the intermediacy of progesterone.
(17) The formation of the 5-bromo derivatives under the reported conditions probably occurred through the intermediacy of the 3,5-acyloxonium ions.
(18) A mechanism for the removal of the 14alpha-methyl group in ergosterol biosynthesis that involves the intermediacy of an 8,14-diene system is outlined.
(19) The results are compatible with the intermediacy of certain of these arene oxides in the metabolic pathway from hydrocarbons to phenols.
(20) Heterozygotes displayed strict intermediacy for all kinetic and structural properties examined.
Penumbra
Definition:
(n.) An incomplete or partial shadow.
(n.) The shadow cast, in an eclipse, where the light is partly, but not wholly, cut off by the intervening body; the space of partial illumination between the umbra, or perfect shadow, on all sides, and the full light.
(n.) The part of a picture where the shade imperceptibly blends with the light.
Example Sentences:
(1) Our analysis showed that the interpolation errors are proportional to the curvature of the dose distribution and are relatively high in regions on either side of, but not including, the steepest part of the penumbra.
(2) Analysis of the penumbra width of cross dose distributions, as a function of field sizes, allowed us to postulate that the dmax shift could be due to the phantom scattered photons, which in turn were generated by the collimator scattered photons.
(3) If true, this is the first demonstration of the ischemic penumbra by MR imaging and may reflect our use of Wistar rats, a new image analysis technique, and ultra-high resolution MR imaging.
(4) The combination for this applicator of sharp penumbra and low out-of-field dose leads to reduced lung and opposite breast doses.
(5) An extracellular acidosis that occurs in the penumbra zone was investigated in vitro as to its role in the formation of cytotoxic cell swelling.
(6) The ischemic thresholds for the initial increase in CMRG and the complete depletion of ATP content represent the metabolic equivalent of the penumbra zone and provide a basis for the evaluation of therapeutic procedures for the treatment of stroke.
(7) If the entire cross-section is blocked, the point will be in the umbra of the shadow; if only a portion of the light is blocked, the point will be in the penumbra of the shadow.
(8) The mechanisms involved in this sequence of events and the role of pH changes in the development of the so-called "ischaemic penumbra" are discussed.
(9) In the light of these findings, we suggest that use of a selective antagonist of LTs may be helpful in reducing the ischemic penumbra during acute cerebral ischemia by controlling the vasogenic edema.
(10) Opening the hinge adjustment restores field flatness, without changing penumbra or the inverse square law behavior of the teletherapy unit.
(11) The area of "penumbra" could be estimated in regions with CBF value just above this threshold.
(12) In the penumbra zone, comparable trends were noted in OER and CMRO2 but the difference in the changes between the two groups did not reach statistical significance.
(13) The agreement is within experimental errors both in the penumbra region and along the central ray of the asymmetric field.
(14) These results confirm the concept of a metabolic penumbra.
(15) These wedges were designed to increase the penumbra width at the field junction from about 1.5 to about 3.5 cm, to achieve dose uniformity.
(16) These studies suggest that 1) the expression of 72-kd heat-shock protein in neurons precedes the development of ischemic cellular alterations detectable by conventional hematoxylin and eosin light microscopy methods; 2) there is a hierarchy of cell types and anatomic sites that express 72-kd heat-shock protein, and this hierarchy reflects cellular and anatomic vulnerability to ischemic cell damage; and 3) 72-kd heat-shock protein induction in neurons bordering a necrotic ischemic core may be the morphological equivalent of the ischemic penumbra.
(17) While within the penumbra, some direct sunlight falls on the Moon but little darkening of the disc will be noticed until a few minutes before the Moon begins to enter the umbra at 19:23.
(18) Measurements with the diode interfaced to an X-Y recorder required only a fraction of the time required with the chambers, minimizing error due to change in machine output, and permitted resolution of isodose lines in the penumbra.
(19) A typical spot has a central dark umbra, surrounded by a lighter penumbra.
(20) The rate in the penumbra differed (P = .01) from that in the predicted low-dose region, where scotoma did not increase with time.