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991.
Salsolinol and dopamine in rat medial basal hypothalamus after chronic ethanol exposure 总被引:4,自引:0,他引:4
Endogenous levels of salsolinol and dopamine were measured by a gas chromatography/mass spectrometry (GC/MS) - selected ion monitoring technique using deuterated internal standards in Long Evans rats chronically exposed to ethanol for ten months. Chronic ethanol exposure produced significant increases of dopamine and salsolinol concentrations in the medial basal hypothalamus but not striatum. The data suggest that the occurrence of salsolinol in rat brain tissue is a consequence of an in vivo Pictet-Spengler cyclization. 相似文献
992.
993.
S O Smith A B Myers R A Mathies J A Pardoen C Winkel E M van den Berg J Lugtenburg 《Biophysical journal》1985,47(5):653-664
We have obtained Raman spectra of a series of all-trans retinal protonated Schiff-base isotopic derivatives. 13C-substitutions were made at the 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 positions while deuteration was performed at position 15. Based on the isotopic shifts, the observed C--C stretching vibrations in the 1,100-1,400 cm-1 fingerprint region are assigned. Normal mode calculations using a modified Urey-Bradley force field have been refined to reproduce the observed frequencies and isotopic shifts. Comparison with fingerprint assignments of all-trans retinal and its unprotonated Schiff base shows that the major effect of Schiff-base formation is a shift of the C14--C15 stretch from 1,111 cm-1 in the aldehyde to approximately 1,163 cm-1 in the Shiff base. This shift is attributed to the increased C14--C15 bond order that results from the reduced electronegativity of the Schiff-base nitrogen compared with the aldehyde oxygen. Protonation of the Schiff base increases pi-electron delocalization, causing a 6 to 16 cm-1 frequency increase of the normal modes involving the C8--C9, C10--C11, C12--C13, and C14--C15 stretches. Comparison of the protonated Schiff base Raman spectrum with that of light-adapted bacteriorhodopsin (BR568) shows that incorporation of the all-trans protonated Schiff base into bacterio-opsin produces an additional approximately 10 cm-1 increase of each C--C stretching frequency as a result of protein-induced pi-electron delocalization. Importantly, the frequency ordering and spacing of the C--C stretches in BR568 is the same as that found in the protonated Schiff base. 相似文献
994.
Characterization of the cycle of iron-mediated electron transfer from Adriamycin to molecular oxygen 总被引:4,自引:0,他引:4
The anticancer drug adriamycin binds iron and these complexes cycle to reduce molecular oxygen (Zweier, J. L. (1984) J. Biol. Chem. 259, 6056-6058). Optical absorption, EPR, and M?ssbauer spectroscopic data are correlated with polarographic O2 consumption and chemical Fe2+ extraction measurements in order to characterize each step in this cycle. Fe3+ binds to adriamycin at physiologic pH forming a complex with an optical absorbance maximum at 600 nm. EPR signals at g = 4.2 and g = 2.01, and a doublet M?ssbauer spectrum with isomer shift delta = 0.57 mm/s and quadrupole splitting delta EQ = 0.74 mm/s are observed indicating that the Fe3+ bound to adriamycin is high spin S = 5/2. Under anaerobic conditions the absorbance maximum at 600 nm decreases with an exponential decay constant = 0.77 h-1, and the EPR and M?ssbauer spectra of Fe3+-adriamycin similarly decrease as the Fe3+ is reduced to EPR silent Fe2+. The Fe2+-adriamycin complex which is formed exhibits a M?ssbauer spectrum with delta = 1.18 mm/s and delta EQ = 1.82 mm/s indicative of high spin Fe2+. As the EPR spectra of Fe3+-adriamycin decrease on reduction of the Fe3+ to Fe2+ a signal of the oxidized adriamycin free radical appears at g = 2.004 with line width of 8 G. On exposure to O2 the absorption maximum at 600 nm, the Fe3+ EPR, and the Fe3+ M?ssbauer spectra all return. Polarographic measurements demonstrate that O2 is consumed and that H2O2 is formed. Addition of high affinity Fe2+ chelators block O2 consumption indicating that Fe2+ formation is essential for O2 reduction. This cycle of iron-mediated O2 reduction can explain the formation of the reactive reduced oxygen and adriamycin radicals which are thought to mediate the biological activity of adriamycin. 相似文献
995.
The interactions of the opioid peptide [D-Ala2]methionine-enkephalinamide with dipalmitoylphosphatidylcholine (DPPC) large unilamellar vesicles containing gangliosides GM1, Gd1a, and Gt1b and synaptic plasma membranes selectively enriched with dimyristoylphosphatidylcholine (DMPC) and ganglioside Gd1a have been investigated by using high-sensitivity differential scanning calorimetry. In the absence of gangliosides, the addition of enkephalinamide in concentrations of up to 10(-3) M does not induce any appreciable change in the heat capacity function of DPPC. In the presence of gangliosides, however, changes in the heat capacity function were observed with as little as micromolar concentrations of the enkephalinamide; the same is true for DMPC-Gd1a-enriched synaptic membranes. The magnitude and the nature of the enkephalinamide effect depend on the type of ganglioside studied. For DPPC vesicles containing ganglioside GM1 only a slight broadening in the heat capacity function and a small upward shift in the transition temperature were observed. For DPPC vesicles containing ganglioside Gd1a the effect was more dramatic; enkephalinamide concentrations as low as 10(-5) M caused the appearance of two well-defined peaks in the heat capacity function in contrast to the one peak observed in the absence of enkephalinamide. In the case of DPPC vesicles containing ganglioside Gt1b the enkephalinamide effect was seen at concentrations of 10(-4) M or higher. Synaptic plasma membranes were isolated from bovine brain, selectively enriched with exogenous lipid, and their thermotropic behavior was characterized by steady-state fluorescence spectroscopy and differential scanning calorimetry. This lipid enrichment results in the appearance of a membrane phase transition otherwise absent in the intact membrane preparation.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
996.
Gene expression of type I, III and IV collagens in hepatic fibrosis induced by dimethylnitrosamine in the rat. 总被引:6,自引:0,他引:6 下载免费PDF全文
L Ala-Kokko T Pihlajaniemi J C Myers K I Kivirikko E R Savolainen 《The Biochemical journal》1987,244(1):75-79
Dimethylnitrosamine (DMN)-induced hepatic fibrosis was used as an experimental model to study collagen-gene expression during liver fibrogenesis. Increase in the concentrations of the mRNAs for type I, III, and IV collagens was found to be an early event in the development of hepatic fibrosis, as the mRNAs for all three collagen types showed a definite increasing tendency by day 7 of DMN treatment. Prolyl 4-hydroxylase (EC 1.14.11.2) and galactosylhydroxylysyl glucosyltransferase (EC 2.4.1.66) activities were also distinctly elevated at this stage, whereas no increase could be detected in the liver collagen content. The increase in the mRNAs for type I collagen was the smallest and that for type IV collagen the greatest at all the time points studied. The relative concentrations of the mRNAs for the three collagen types on day 21 of DMN treatment were 350% of the control mean for type I collagen, 490% for type III and 660% for type IV. The data further indicate that the proportions of the mRNAs for the three collagen types are 1.0:0.9:0.2 in normal rat liver, 1.0:1.4:0.8 on day 14 of DMN treatment, and 1.0:1.3:0.5 on day 21. The early marked increase in the mRNA for type IV collagen suggests that enhanced production of basement-membrane collagen may be an early event in the development of hepatic fibrosis. 相似文献
997.
D S Barkley S I Hardiwidjaja J H Menkes G W Ellison L W Myers 《Cellular immunology》1977,32(2):385-390
Lymphocytes from patients with Huntington's disease (H.D.) exhibit a cellular immune response which consists of two components: a minor component directed against antigen common to all human brains, and a major component directed against antigen found thus far only in H.D. and multiple sclerosis (M.S.) gray matter. M.S. lymphocytes exhibit a response to antigen common to all human brains, but fail to show any H.D. or M.S. brain-specific response. 相似文献
998.
Altering the position (elevated or dependent) had no immediate effect on the blood supply of delayed or transplanted delayed tubed flaps. However, after 72 hours the mean survival length in the dependent tubes was less than that in the elevated tubes. (This difference was only significant in the delayed untransplanted flaps, and not so in the delayed transplanted flaps). All of the dependent tubes had a significant increase in water content (compared to the elevated tubes). This increase was greater in the transplanted delayed tubed flaps. The tissue pCO2 levels were significantly increased after 24 hours in the dependent transplanted tubes, reflecting poor circulation and ischemia in them. The rate of clearance of subcutaneously injected technetium-99m was significantly increased in the dependent transplanted tubes after 72 hours, while in the elevated tubes the clearance rate was similar to that in normal skin. The morphological appearance of the vessels in these flaps complemented the results of the functional study. 相似文献
999.
1000.