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91.
Liver phenylalanine hydroxylase activity in relation to blood concentrations of tyrosine and phenylalanine in the rat 总被引:5,自引:5,他引:0
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The plasma concentration of phenylalanine and tyrosine decreases in normal rats during the first few postnatal days; subsequently, the concentration of phenylalanine remains more or less constant, whereas that of tyrosine exhibits a high peak on day 13. The basal concentrations of the two amino acids were not altered by injections of thyroxine or cortisol, except in 13-day-old rats, when an injection of cortisol decreased the concentration of tyrosine. In young rats (13-15 days old), treatment with cortisol increased the activity of phenylalanine hydroxylase in the liver (measured in vitro) and accelerated the metabolism of administered phenylalanine: the rate constant of the disappearance of phenylalanine from plasma and the initial increase in tyrosine in plasma correlated quantitatively with the activity of phenylalanine hydroxylase in the liver. In adult rats, the inhibition of this enzyme (attested by assay in vitro) by p-chlorophenylalanine resulted in a proportionate decrease in tyrosine formation from an injection of phenylalanine. However, the quantitative relationship between liver phenylalanine hydroxylase activity and phenylalanine metabolism within the group of young rats was different from that observed among adult rats. 相似文献
92.
J O McGee M H Jimenez A M Felix G J Cardinale S Udenfriend 《Archives of biochemistry and biophysics》1973,154(1):483-487
A number of substituted bradykinin analogs were prepared in which the proline in position 3 was replaced by analogs of proline. All of the bradykinin analogs, with the exception of l-azetidine-2-carboxyl3-bradykinin showed significant ability to inhibit prolyl hydroxylase activity. Addition of an l-glutamyl residue to the amino terminus of 3,4-dehydro-l-prolyl3-bradykinin and trans-4-hydroxy-l-prolyl3-bradykinin resulted in competitive inhibitors of increased effectiveness with Ki, values approximately 10?4m. One of the peptides, l-3,4-dehydro-l-prolyl3-bradykinin, appeared to serve as a substrate for prolyl hydroxylase. 相似文献
93.
94.
Study was made of 234 cases of placenta previa occurring in 48,752 deliveries at one hospital during the period 1947-1956. There was no maternal mortality. The uncorrected fetal mortality rate for all weight groups was 21.4 per cent. The rate varied from 88 per cent in babies under 1,500 grams to 5.7 per cent in babies over 2,500 grams. Initial conservative management to permit gestation to continue as close to term as possible is advisable.Ultimate termination of the pregnancy by cesarean section under spinal anesthesia gave the best results. The incidence of transverse and breech presentations in association with placenta previa was inordinately high. A progressive trend toward more conservative treatment of placenta previa was noted in the present series, with a concomitant reduction in fetal mortality rate. 相似文献
95.
96.
F Clinard C Milan M Harb P M Carli C Bonithon-Kopp J P Moutet J Faivre P Hillon 《Bioelectromagnetics》1999,20(5):319-326
Residential magnetic field (MF) measurements were performed for the first time in a representative sample of French dwellings. Exposure levels were assessed by two methods: indoor and outdoor measurements. Linear and logistic regression models were used to determine factors associated with the time-weighted average (TWA) home MF. TWA magnetic field magnitudes were approximately log-normally distributed with geometric means under 0.010 microT for both indoor and outdoor measurements. Only 5% of the dwellings presented indoor MF levels greater than 0.120 microT (1.2 mG). Both indoor and outdoor MF variations were explained by three factors: wiring configuration, the dwelling's location (i.e., urban or rural), and housing characteristics (individual houses or apartment building). The reliability of outdoor spot measurements with 30-min bedroom recordings was assessed by an intraclass correlation coefficient. The measurements were accurate in rural areas and small towns. In urban centers, local MF variations spoil the outdoor measurement's reliability. If indoor measurements are taken as the reference method, the use of outdoor instead of indoor measurement leads to an important decrease in statistical power. Further assessment of MF near high power transmission lines is necessary to evaluate the usefulness of outdoor spot recordings near such lines. The urban MF environment also has to be explored to identify extraneous sources. 相似文献
97.
98.
Katherine M. Partridge Stephen Antonysamy Shobha N. Bhattachar Srinivasan Chandrasekhar Matthew J. Fisher Adrian Fretland Karen Gooding Anita Harvey Norman E. Hughes Steven L. Kuklish John G. Luz Peter R. Manninen James E. McGee Daniel R. Mudra Antonio Navarro Bryan H. Norman Steven J. Quimby Matthew A. Schiffler Xiao-Peng Yu 《Bioorganic & medicinal chemistry letters》2017,27(6):1478-1483
We describe a novel class of acidic mPGES-1 inhibitors with nanomolar enzymatic and human whole blood (HWB) potency. Rational design in conjunction with structure-based design led initially to the identification of anthranilic acid 5, an mPGES-1 inhibitor with micromolar HWB potency. Structural modifications of 5 improved HWB potency by over 1000×, reduced CYP2C9 single point inhibition, and improved rat clearance, which led to the selection of [(cyclopentyl)ethyl]benzoic acid compound 16 for clinical studies. Compound 16 showed an IC80 of 24 nM for inhibition of PGE2 formation in vitro in LPS-stimulated HWB. A single oral dose resulted in plasma concentrations of 16 that exceeded its HWB IC80 in both rat (5 mg/kg) and dog (3 mg/kg) for over twelve hours. 相似文献
99.
Arctic ground squirrel neuronal progenitor cells resist oxygen and glucose deprivation-induced death
Kelly L Drew Matthew Wells Rebecca McGee Austin P Ross Judith Kelleher-Andersson 《World journal of biological chemistry》2016,7(1):168-177
AIM: To investigate the influence of ischemia/reperfusion on arctic ground squirrel(AGS) neuronal progenitor cells(NPCs), we subjected these cultured cells to oxygen and glucose deprivation.METHODS: AGS NPCs were expanded and differentiated into NPCs and as an ischemia vulnerable control, commercially available human NPCs(hNPCs) were seeded from thawed NPCs. NPCs, identified by expression of TUJ1 were seen at 14-21 d in vitro(DIV). Cultures were exposed to control conditions, hypoxia, oxygen and glucose deprivation or glucose deprivation alone or following return to normal conditions to model reperfusion. Cell viability and death were assessed from loss of ATP as well as from measures of alamarB lue~ and lactate dehydrogenase in the media and from counts of TUJ1 positive cells using immunocytochemistry. Dividing cells were identified by expression of Ki67 and phenotyped by double labeling with GFAP, MAP2 ab or TUJ1. RESULTS: We report that when cultured in NeuraLife~(TM), AGS cells remain viable out to 21 DIV, continue to express TUJ1 and begin to express MAP2 ab. Viability of hN PCs assessed by fluorescence alamarB lue(arbitrary units) depends on both glucose and oxygen availability [viability of hNPCs after 24 h oxygen glucose deprivation(OGD) with return of oxygen and glucose decreased from 48151 ± 4551 in control cultures to 43481 ± 2413 after OGD, P 0.05]. By contrast, when AGS NPCs are exposed to the same OGD with reperfusion at 14 DIV, cell viability assessed by alamar Blue increased from 165305 ± 11719 in control cultures to 196054 ± 13977 after OGD. Likewise AGS NPCs recovered ATP(92766 ± 6089 in control and 92907 ± 4290 after modeled reperfusion; arbitrary luminescence units), and doubled in the ratio of TUJ1 expressing neurons to total dividing cells(0.11 ± 0.04 in control cultures vs 0.22 ± 0.2 after modeled reperfusion, P 0.05). Maintaining AGS NPCs for a longer time in culture lowered resistance to injury, however, did not impair proliferation of NPCs relative to other cell lineages after oxygen deprivation followed by re-oxygenation.CONCLUSION: Ischemic-like insults decrease viability and increase cell death in cultures of human NPCs. Similar conditions have less affect on cell death and promote proliferation in AGS NPCs. 相似文献
100.
Gleason FH Letcher PM Evershed N McGee PA 《The Journal of eukaryotic microbiology》2008,55(4):351-354
ABSTRACT. The survival of an isolate of Hyphochytrium catenoides collected from soil in the Blue Mountains in eastern New South Wales, Australia, was tested under extreme conditions in the laboratory. This isolate recovered growth after being subjected to drying on filter paper, to heat while desiccated, to hypersalinity, to strict anaerobic conditions, to freezing temperatures, and to a short period in solutions at pH 2.8–11.2. The capacity to survive under these conditions in the laboratory suggests adaptation to fluctuating conditions in the soil. The partial DNA sequence of the 28S ribosomal RNA gene in the isolate from New South Wales was 98% similar to that in an isolate from Arizona with a similar morphology. 相似文献