共查询到20条相似文献,搜索用时 0 毫秒
1.
A. Lajtha H. Sershen T. Cooper A. Hashim J. Gaál Ph.D. 《Neurochemical research》1996,21(10):1155-1160
We examined the cerebral metabolism of L-deprenyl and its fluoro-derivative pF-deprenyl, assaying the parent compounds, their
metabolites desmethyl deprenyl, L-amphetamine, and L-methamphetamine, and the fluoro analogs of these metabolites. We compared
the levels of the metabolites after subcutaneous injection with those after intracerebral administration (via microdialysis)
of the parent compounds. The assay of the parent compounds and their metabolites was by GC-MS measurement of the components
of brain microdialysate samples. After their subcutaneous administration, deprenyl and F-deprenyl rapidly entered the brain
and then their concentration decreased, with an approximate half-life of 4.5 h. After the intracerebral administration the
diffusion from the site of administration was minor. A small fraction (a few percent) of the intracerebrally administered
deprenyl was metabolized in situ in the brain possibly by a nonenzymatic process. Metabolism of pF-deprenyl was somewhat more
rapid. The higher cerebral levels of metabolites after the subcutaneous administration indicate their exogenous origin—metabolism
of parent compounds in the periphery and penetration of the brain by the metabolites. 相似文献
2.
A juvenile rhesus macaque presented with atrophy of the musculature of its left leg. Physical examination localized the problem to the coxofemoral joint. Radiography revealed changes consistent with Legg-Calvé-Perthes (LCP) disease. Femoral head ostectomy was performed, and the femoral head was submitted for histologic examination, results of which confirmed a diagnosis of LCP. 相似文献
3.
《Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology》1990,1037(2):240-247
1-2H-Phthalazine hydrazone (hydralazine; HYD), 2-1H-pyridinone hydrazone (2-hydrazinopyridine; HP), 2-quinoline-car☐ylic acid (QCA), 1-isoquinolinecar☐ylic acid (IQCA), 2,2′-bi-1H-imidazole (2,2′-biimidazole; BI), and 1H-imidazole-4-acetic acid (imidazole-4-acetic acid; IAA) directly and reversibly inhibit homogeneous soluble bovine dopamine β-hydroxylase (3,4-dihydroxyphenethylamine, ascorbate:oxygen oxidoreductase (β-hydroxylating), EC 1.14.17.1). HYD, QCA and IAA show competitive allosteric inhibition of dopamine β-hydroxylase with respect to ascorbate (Kis = 5.7(±0.9) μM, 0.14(±0.03) mM, 0.80(±0.20) mM; nH= 1.4(±0.1), 1.8(±0.4), 2.8(±0.6), respectively). HYD and IAA show slope and intercept mixed-type allosteric inhibition of dopamine β-hydroxylase with respect to tyramine. QCA shows allosteric uncompetitive inhibition of dopamine β-hydroxylase with respect to tyramine. HP, BI and IQCA all show linear competitive inhibition (Kis = 1.9(±0.3) μM, 21(±6) μM, and 0.9(±0.3) μM, respectively) with respect to ascorbate. HP and BI show linear mixed-type while IQCA shows linear uncompetitive inhibition of dopamine β-hydroxylase with respect to tyramine. In the presence of HP, HYD or IAA intersecting double-reciprocal plots of the initial velocity as a function of tyramine concentration at differing fixed levels of ascorbate are observed. These findings are consistent with a uni-uni-ping-pong-ter-bi kinetic mechanism for dopamine β-hydroxylase that involves a ternary enzyme-ascorbate-tyramine-oxygen complex. The results for HYD, QCA and IAA are the first examples of allosteric inhibitor interactions with dopamine β-hydroxylase. 相似文献
4.
Barbary apes are known to exhibit male care of babies at various locations, but only in the Middle Atlas mountains of Morocco has it been reported that a baby may be used in male-male interactions, apparently reducing the likelihood of aggression. The present study was made in order to discover if the behavior was characteristic of other groups reproductively isolated from the Atlas population. Male-male interactions involving a baby were observed in two groups and are described in detail; their friendly nature supports the hypothesis that the presence of a baby reduces the likelihood of aggression. We did not, however, see the active use of babies in this context which has been described for the Atlas population. 相似文献
5.
Ahsana Dar Khalid M. Khan Humayun S. Ateeq Shagufta Khan Shagufta Rahat Shahnaz Perveen 《Journal of enzyme inhibition and medicinal chemistry》2013,28(3):269-274
A series of hydrazine derivatives was synthesized in order to evaluate their monoamine oxidase A (MAO-A) inhibitory effects. MAO-A inhibitory activity of 4-tosyl benzoic acid carbohydrazide was quite potent, similarly to that of the corresponding 4-benzyloxy-benzoic acid carbohydrazide and its N-cyanoethylated derivative. Structural variations of these compounds, such as the replacement of the 4-substitutent, of the aromatic ring on which the carbohydrazide moiety is grafted, as well as cyclization of the hydrazide moiety in five- or six-membered rings caused either significant decline or complete loss of MAO inhibitory properties. The most active compound (4-tosyl benzoic acid carbohydrazide) was also subjected to the forced swim test, an animal model of depression, eliciting a marked reduction in immobility time in rats, without affecting the locomotor activity, implying that it possesses anti-depressant properties due to inhibition of MAO type-A. 相似文献
6.
(p-Chlorophenoxy)isobutyric acid (PCIB) inhibited indole-3-acetic acid (IAA)-induced ethylene production in etiolated mung bean hypocotyl sections. The endogenous level of 1-aminocyclopropane-1-carboxylic acid (ACC) was not significantly affected by PCIB, indicating that PCIB exerted its effect primarily by inhibiting the activity of the ethylene-forming enzyme (EFE). This conclusion was supported by the observations that PCIB inhibited the conversion of exogenously applied ACC to ethylene. The inhibitory effect of PCIB was already evident with 0.05 mM PCIB, and it increased with time after application of the inhibitor. PCIB also significantly inhibited ethylene production in apple fruit tissues, but it only slightly reduced the level of endogenous ACC. Similar to mung bean, EFE activity in apple tissue was significantly inhibited by PCIB. The possibility that PCIB also inhibits auxin-induced ACC synthase activity is discussed. 相似文献
7.
Akiko Takagaki 《Bioscience, biotechnology, and biochemistry》2016,80(1):199-202
Isoflavone-metabolizing bacteria, Adlercreutzia equolifaciens, Asaccharobacter celatus, Slackia equolifaciens, and Slackia isoflavoniconvertens catalyzed C-ring cleavage of (–)-epicatechin and (+)-catechin, (+)-epicatechin, and (–)-catechin in varying degrees. The cleaving abilities of (–)-epicatechin and (+)-catechin were enhanced by hydrogen, except (+)-catechin cleavage by S. equolifaciens, which was not accelerated. (?)-Catechin cleavage by Ad. equolifaciens was remarkably accelerated by hydrogen. 相似文献
8.
9.
10.
Exoglycoproteins (X-GPs) are a group of very abundant soluble glycoproteins in the goldfish, brain. Immunostaining with polyclonal antisera to X-GPs revealed consistent perinuclear staining in the cells of the inner and intermediate layers of the leptomeninx, which is homologous to the piaarachnoid. Immunolabelling was also prominent in the outer wall of capillaries, and in a variable population of 10–12 m granular cells that appeared mainly near the ventricles and occasionally within the ventricles or under the meninges. In some cases, small and medium-sized lymphocytes were immunostained. Lymphocytes were sometimes associated with the granular cells, which may be hematogenous cells in transit toward the ventricles. the choroid plexus, saccus dorsalis, the roof of the third ventricle and Reissner's fiber showed strong immunostaining. The localization of the X-GPs suggests that they may contribute to maintenance of the blood-brain barrier or to regulation of immune function within the brain.Special issue dedicated to Dr. Sidney Ochs. 相似文献
11.
The movement rates of sharks are intrinsically linked to foraging ecology, predator–prey dynamics and wider ecosystem functioning in marine systems. During ram ventilation, however, shark movement rates are linked not only to ecological parameters, but also to physiology, as minimum speeds are required to provide sufficient water flow across the gills to maintain metabolism. We develop a geometric model predicting a positive scaling relationship between swim speeds in relation to body size and ultimately shark metabolism, taking into account estimates for the scaling of gill dimensions. Empirical data from 64 studies (26 species) were compiled to test our model while controlling for the influence of phylogenetic similarity between related species. Our model predictions were found to closely resemble the observed relationships from tracked sharks, providing a means to infer mobility in particularly intractable species. 相似文献
12.
Qingqing Wang Lijing Sun Shaoyang Ji Dawei Zhao Jiaxin Liu Zhiguo Su Tao Hu 《Biochimica et Biophysica Acta - Proteins and Proteomics》2014,1844(7):1201-1207
As a potential hemoglobin (Hb)-based oxygen carrier (HBOC), the PEGylated Hb has received much attention for its non-nephrotoxicity. However, PEGylation can adversely alter the structural and functional properties of Hb. The site of PEGylation is an important factor to determine the structure and function of the PEGylated Hb. Thus, protection of some sensitive residues of Hb from PEGylation is of great significance to develop the PEGylated Hb as HBOC. Here, Cys-93(β) of Hb was conjugated with 20 kDa polyethylene glycol (PEG20K) through hydrazone and disulfide bonds. Then, the conjugate was modified with PEG5K succinimidyl carbonate (PEG5K-SC) using acylation chemistry, followed by removal of PEG20K Hb with hydrazone hydrolysis and disulfide reduction. Reversible conjugation of PEG20K at Cys-93(β) can protect Lys-95(β), Val-1(α) and Lys-16(α) of Hb from PEGylation with PEG5K-SC. The autoxidation rate, oxygen affinity, structural perturbation and tetramer instability of the PEGylated Hb were significantly decreased upon protection with PEG20K. The present study is expected to improve the efficacy of the PEGylated Hb as an oxygen therapeutic. 相似文献
13.
《Bioscience, biotechnology, and biochemistry》2013,77(7):1352-1354
When n-alcohols were added to the β-glucosidase-catalyzed hydrolysis of arbutin, the rate was decreased almost linearly with their elevating concentrations. The inhibition was shown in two modes, competitive for higher n-alcohols and noncompetitive for lower n-alcohols than n-butanol. The inhibition constants (Ki) obtained, moreover, clearly demonstrated classifying the modes in two groups according to physicochemical parameters, log P, Hildebrand solubility parameter (δ), and dielectric constant (?), of n-alcohols. n-Butanol being between two modes of inhibition showed a mixed-type inhibition. The data suggested that the inhibition of n-alcohols for p-glucosidase may be related with their chain length. An imaging model in this case of inhibition is presented. 相似文献
14.
The neurotransmitter dopamine has been shown to inhibit fibrillation of α-synuclein by promoting the formation of nonamyloidogenic oligomers. Fibrillation of α-synuclein is accelerated in the presence of pesticides and the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The aim of this study was to determine whether dopamine continues to have an adverse effect on the fibrillation of α-synuclein in the presence of MPTP and its metabolite 1-methyl-4-phenylpyridinum ion (MPP(+) ). We also attempted to answer the ambiguous question of whether conversion of MPTP to MPP(+) is required for the fibrillation of α-synuclein. For this, α-synuclein was incubated in the presence of MPTP and MPP(+) along with dopamine. The fibrillation of α-synuclein was monitored by Thioflavin T fluorescence and immunoblotting. The morphology of the aggregates formed was observed using scanning electron microscopy. The concentrations of the neurotoxin and its metabolite were estimated by reverse phase HPLC. We found definitive evidence that the conversion of MPTP to MPP(+) is not required for aggregation of α-synuclein. MPP(+) was found to accelerate the rate of α-synuclein aggregation even in the absence of components of mitochondrial complex I. In contrast to the effect of dopamine on the aggregation of α-synuclein alone, in the presence of MPTP or MPP(+) , the aggregates formed are Thioflavin T-positive and amyloidogenic. Thus, the effect of dopamine on the nature of aggregates formed in case of α-synuclein alone and in the presence of MPTP/MPP(+) is different. 相似文献
15.
16.
Anin vitro kinetic study on inhibition of the monoamine oxidase-A (MAO-A) of the rat brain by two pyrethroids, namely permethrin (PM) and cypermethrin (CPM), has shown that PM and CPM competitively inhibit MAO-A by altering both the Michaelis-Menten constant (Km) and the maximum velocity (Vmax). Inhibitor constant values (Ki) indicated that CPM was a more effective inhibitor of MAO-A than PM. Both PM and CPM caused maximum inhibition of MAO-A at neutral pH. CPM significantly elevated the activation energy values of MAO-A as compared to those of PM.Abbreviations MAO
Manoamine Oxidase
- PM
Permethrin
- CPM
Cypermethrin
- TTV
Toxicity Test Value
- IC50
Inhibitor Concentration that causes 50 percent inhibition 相似文献
17.
《Biomarkers》2013,18(5):434-444
Damage to DNA by dopamine quinone and/or catechol estrogen quinones may play a significant role in the initiation of Parkinson’s disease (PD). Depurinating estrogen–DNA adducts are shed from cells and excreted in urine. The aim of this study was to discover whether higher levels of estrogen–DNA adducts are associated with PD. Forty estrogen metabolites, conjugates, and DNA adducts were analyzed in urine samples from 20 PD cases and 40 matched controls by using ultra performance liquid chromatography/tandem mass spectrometry. The levels of adducts in cases versus controls (P?<?0.005) suggest that unbalanced estrogen metabolism could play a causal role in the initiation of PD. 相似文献
18.
19.
Phenethyl β-d-galactopyranoside (PEG) was hydrolyzed by the β-galactosidase of Escherichia coli to form the toxic product phenethyl alcohol. Salmonella typhimurium did not hydrolyze PEG. In mixed culture, the ratio of S. typhimurium to E. coli was increased by growing the organisms in lactose broth containing 2.5% PEG. The high concentration of PEG required for inhibition of E. coli can be attributed to inadequate cell permeability rather than to prevention of β-galactosidase induction. 相似文献
20.
Zinc (Zn2+) was shown to invariably inhibit muscimol-stimulated36Cl− uptake by synaptoneurosomes in the cerebral cortex, hippocampus and cerebellum. The Zn2+ sensitivity of the GABAA receptor-gated36Cl− uptake in the cerebral cortex was comparable to that in the hippocampus, whereas the uptake in the cerebellum was less sensitive
to Zn2+. Although diazepam-potentiation of muscimol-stimulated36Cl− uptake was unaltered by 100 μM Zn2+ in the cerebellum. Zn2+ inhibited [3H]diazepam binding significantly at 1 mM in the cerebral cortex and cerebellum, whereas Ni2+ increased the binding in a concentration-dependent manner in both regions. Although lower concentrations of Zn2+ did not affect [3H]Ro 15-4513 binding to diazepam-sensitive sites, higher concentrations of Zn2+ increased the binding in both regions. Unlike the diazepam-sensitive sites the diazepam-insensitive [3H]Ro 15-4513 binding was not affected by Zn2+ or Ni2+ at any of the tested concentrations. These results suggest that the GABAA ligand-gated Cl− flux and its diazepam-potentiation are heterogeneously modulated in various brain regions. It is also suggested that cerebellar
diazepam-insensitive [3H]Ro 15-4513 binding sites are insensitive to Zn2+ and Ni2+. 相似文献