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31.
The glucocorticoid receptor represses cyclin D1 by targeting the Tcf-beta-catenin complex 总被引:4,自引:0,他引:4
Takayama S Rogatsky I Schwarcz LE Darimont BD 《The Journal of biological chemistry》2006,281(26):17856-17863
32.
An overview of the serpin superfamily 总被引:2,自引:1,他引:1
Law RH Zhang Q McGowan S Buckle AM Silverman GA Wong W Rosado CJ Langendorf CG Pike RN Bird PI Whisstock JC 《Genome biology》2006,7(5):216-11
Serpins are a broadly distributed family of protease inhibitors that use a conformational change to inhibit target enzymes. They are central in controlling many important proteolytic cascades, including the mammalian coagulation pathways. Serpins are conformationally labile and many of the disease-linked mutations of serpins result in misfolding or in pathogenic, inactive polymers. 相似文献
33.
Henry P. Simpson John J. Schwarcz Christopher B. Stringer 《Journal of human evolution》1998,35(6):635-645
The Neanderthal hominid Tabun C1, found in Israel by Garrod & Bate, was attributed to either layer B or C of their stratigraphic sequence. We have used gamma-ray spectrometry to determine the230Th/234U and231Pa/235U ratios of two bones from this skeleton, the mandible and a femur. The ages calculated from these ratios depend on the uranium uptake history of the bones. Assuming a model of early U (EU) uptake the age of the Tabun C1 mandible is 34±5 ka. The EU age of the femur is 19±2 ka. The femur may have experienced continuous (linear) U uptake which would give an age of 33±4 ka, in agreement with the mandible's EU age, but implies marked inhomogeneity in U uptake history at the site. These new age estimates for the skeleton suggest that it was younger than deposits of layer C. This apparent age is less than those of other Neanderthals found in Israel, and distinctly younger than the ages of the Skhul and Qafzeh burials. This suggests that Neanderthals did not necessarily coexist with the earliest modern humans in the region. All of the more complete Neanderthal fossils from Israel are now dated to the cool period of the last glacial cycle, suggesting that Neanderthals may have arrived in this region as a result of the southward expansion of their habitable range. The young age determined for the Tabun skeleton would suggest that Neanderthals survived as late in the Levant as they did in Europe. 相似文献
34.
Abstract: The de novo production and subsequent disposition of the endogenous excitotoxin quinolinic acid (QUIN) was investigated in vitro in tissue slices from rat brain and liver. Incubation of tissue with QUIN's immediate bioprecursor 3-hydroxyanthranilic acid (3-HANA) in oxygenated Krebs-Ringer buffer yielded measurable amounts of QUIN both in the tissue and in the incubation medium. Saturation was reached between 16 and 64 μM 3-HANA (166 pmol of QUIN formed per milligram of protein after a 60-min incubation with 64 μM 3-HANA). In the brain, more QUIN was recovered from the tissue than from the incubation medium at all time points examined (5 min to 4 h). In contrast, the tissue-to-medium ratio for QUIN in parallel experiments with hepatic slices was ? 1. The disposition of newly synthesized QUIN was further elaborated in tissue slices that had been preincubated for 60 min with 64 μM 3-HANA. Subsequent incubation of brain tissue in fresh buffer revealed a steady but relatively slow efflux of QUIN from the cellular compartment, with >30% remaining in the tissue after a 90-min incubation. Analogous experiments with liver slices showed that >93% of newly synthesized QUIN had entered the extracellular compartment within 30 min. Striatal and nigral slices obtained 7 days after an intrastriatal ibotenic acid injection showed severalfold increases in QUIN production compared with control tissues, in all likelihood due to astrogliosis and associated large increases in 3-hydroxyanthranilic acid oxygenase activity. In addition, the apparent tissue-to-medium ratio was markedly reduced in striatal slices from lesioned animals. Taken together, these data indicate that both brain and liver cells have a rather limited capacity to retain QUIN, and that 3-hydroxyanthranilic acid oxygenase activity is a critical determinant controlling extracellular QUIN concentrations in both organs. Changes in the activity of QUIN's biosynthetic enzyme in the brain can therefore be expected to influence the possible function of QUIN as an endogenous agonist at the N-methyl-D-aspartate receptor in health and disease. 相似文献
35.
From Meroitic to Christian times (350 B .C .–A .D . 1400), Sudanese Nubia experienced political, economic, cultural, and environmental upheaval. Change in any one of these aspects of ancient lifeways can affect subsistence. Dietary patterns from this period are reconstructed by measuring stable carbon and nitrogen isotope ratios in tissue samples from 146 mummies excavated from five sites in the Wadi Halfa area. On average, δ13C values of bone collagen, muscle, and skin indicate high consumption levels of C3 plants (presumably wheat or barley staples, mixed vegetables, and fruits) throughout the sequence. However, during the X-Group period (A .D . 350–550), there is a statistically significant increase in consumption of C4 plants (millet or sorghum), which are predominant in both the archeological record and in modern crop production for most of the Northern Sudan. The X-Group period was also associated with a low Nile and political and economic restructuring. Increased use of C4 plants on a seasonal basis is also indicated by shifting δ13C values along hair shafts for both X-Group and Christian periods. δ15N values suggest that the major source of protein for all time periods came from herbivorous animals. A small, but significant increase in 15N over the 1,000-year sequence could be the result of fertilization. © 1994 Wiley-Liss, Inc. 相似文献
36.
Binding of 3H-kainic acid (KA) to brain membranes is saturable (KD = 72 nM) and displays markes specificity for compounds that bear relation to excitatory amino acids. Its regional distribution correlates roughly with the regional neurotoxicity of in situ KA injections. Striatal kainate lesions, but not interruption of striatal afferents, reduce striatal KA binding by 36%. This decrease is due to a loss in the number of neuronal binding sites without affecting the affinity for the ligand. It is suggested that 3HKA binding to neuronal elements may be a valuable instrument for studies of the mechanism of neuronal degeneration caused by KA. 相似文献
37.
The present findings indicate, in agreement with previous work, that there may exist at least two types of dopamine (DA) receptors within the neostriatum, one linked to the adenylate cyclase system and one present on axon terminals belonging to corticostriatal fibres. Spiroperidol may have a somewhat higher affinity for the axonic DA receptors than for the DA receptors linked to the adenylate cyclase system. Finally, Bromocriptine has a high affinity for both axonic DA receptors and some DA receptors associated with adenylate cyclase which are localized on neostriatal interneurons. 相似文献
38.
Unilateral injection of 2 μg kainic acid into the substantia nigra of the rat results in a 45% decrease in tyrosine hydroxylase activity in the injected substantia nigra and in the ipsilateral corpus striatum. In contrast, the GABAergic nerve terminals in the substantia nigra are unaffected by this treatment. Injection of kainic acid into the striatum results in a 60% decrement in the activity of glutamate decarboxylase and of endogenous GABA levels in the ipsilateral substantia nigra whereas tyrosine hydroxylase activity remains unchanged; in addition, dopamine-sensitive adenylate cyclase activity in the ipsilateral substantia nigra decreases by 74%. These findings further support the hypothesis that intracerebral injections of kainic acid cause degeneration of neurons with cell bodies near the injection site while sparing axons passing through or terminating in the region. 相似文献
39.
P A Castelfranco J D Weinstein S Schwarcz A D Pardo B E Wezelman 《Archives of biochemistry and biophysics》1979,192(2):592-598
A developing chloroplast preparation obtained from greening cucumber cotyledons is able to bring about the synthesis of Mg-protoporphyrin-IX and/or Mg-protoporphyrin-IX monomethyl ester. l-glutamate, δ-aminolevulinic acid, and protoporphyrin-IX can serve as precursors for Mg-protoporphyrin synthesis. However, when δ-aminolevulinic acid or protoporpyrin are used, no Mg-protoporphyrin is formed unless l-glutamate is also added. Mg-Protoporphyrin synthesis with δ-aminolevulinic acid plus l-glutamate, or proto-porphyrin plus l-glutamate, is much more active than with l-glutamate alone. Therefore, it is apparent that l-glutamate plays a role in the Mg chelation step in chloroplasts. α-Keto-glutarate can replace l-glutamate in this role; glutamine cannot. ATP is also required for Mg chelation. The role of l-glutamate in the Mg insertion step is not yet understood, except that l-glutamate itself does not need to be converted to porphyrins in this process, because Mg-protoporphyrin can be synthesized from protoporphyrin and l-glutamate even in the presence of the δ-aminolevulinic acid dehydratase inhibitor, levulinate. 相似文献
40.
Summary. In this review, recent studies on the electrophysiological effects of de novo synthesized ("endogenous") kynurenic acid (KYNA)
are discussed. Endogenous KYNA is normally formed as a byproduct of tryptophan metabolism. Evidence for a physiological role
in neuronal excitability has not been strong, in part because brain levels are much lower than the KD of KYNA at the glycine site of the NMDA receptor, where KYNA is thought to exert its most potent effect. The results suggest
that, unexpectedly, even low concentrations of endogenous KYNA have physiological consequences. These levels of KYNA reduced
the number of hippocampal slices with spontaneous epileptiform discharges after exposure to buffer lacking magnesium. However,
effects on evoked responses to single afferent stimuli were not detected. Taken together, the data argue for a potentially
important role of endogenous KYNA in suppression of seizure-like activity, and suggest a novel approach to anticonvulsant
drug development that could have few side effects.
Received August 31, 1999 Accepted September 20, 1999 相似文献