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1.
Arginase (EC 3.5.3.1) localization was studied in soybean (Glycine max L.) seedling cotyledons. Subcellular fractionation in a discontinuous Percoll gradient showed that arginase was localized
in the mitochondrion. Arginine (Arg) uptake by mitochondria was demonstrated by co-sedimentation of [3H]Arg-derived label and the mitochondrial marker enzyme cytochrome c oxidase. Arginine uptake was complete in about 10 min. Since detergent but not NaCl released most label, we conclude that
Arg was taken up and not bound to the organellar surface. Arginine transport was not saturable, at least up to 20 mM. Basic
amino acids were the best inhibitors of Arg uptake. The uncoupler 2,4-dinitrophenol did not inhibit Arg uptake. At least 30%
of l-[guanido-14C]Arg taken up by mitochondria was degraded by arginase in seedling cotyledons, while little or no degradation was detected
in mitochondria from developing embryos, even though the Arg uptake level was similar in both mitochondrial preparations.
These results are consistent with our previously reported pattern of arginase expression and urea accumulation during embryo
development and seed germination (A. Goldraij and J.C. Polacco, 1999, Plant Physiol. 119: 297–303). The lack of Arg degradation
allows developing embryos to conserve Arg, the main N-reserve amino acid utilized by germinating soybean.
Received: 7 July 1999 / Accepted: 21 September 1999 相似文献
2.
Summary. N-alkyl-β-alanine oligomers (β-peptoids) with α-chiral side chains [(R)- or (S)-1-(phenylethyl)amino groups] were synthesized and analyzed by CD spectroscopy. These chiral β-peptoid homomers exhibited
chain-length-dependent and solvent-dependent ellipticity, strongly indicating the presence of a secondary structure in solution.
The CD behaviour was only slightly temperature-dependent upon heating, as also previously observed for stable α-peptoid helices
containing the same type of side chains. Thus, the data presented here comprise the first evidence for a chain length-dependent
secondary folding of compounds with this novel peptidomimetic backbone design. In addition, applicability of a novel hyphenated
technique, HPLC-SPE-NMR/MS, for analysis of crude SPPS reaction products was demonstrated.
Authors’ address: Dr. C. A. Olsen, Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen,
Universitetsparken 2, DK-2100 Copenhagen, Denmark; Present address: The Scripps Research Institute 相似文献
3.
Yurixhi Maldonado–López Edelmira Linares–Mazari Robert Bye Guillermo Delgado Francisco J. Espinosa–García 《Economic botany》2008,62(2):161-170
Mexican Arnica Anti–Inflammatory Action: Plant Age Is Correlated with the Concentration of Anti–inflammatory Sesquiterpenes
in the Medicinal Plant
Heterotheca inuloides
Cass. (Asteraceae). Mexican árnica (Heterotheca inuloides Cass.) is a widely used anti–inflammatory medicinal plant in Mexican folk medicine. Although it has been suggested that plant
age, fertilization, and harvesting regime influence the concentration of secondary compounds affecting the therapeutic activity
of the plant, the effect of these variables on the concentration of the Mexican árnica anti–inflammatory compounds was not
known. We quantified anti–inflammatory sesquiterpenes (caryolan–1, 9β–diol, cadalen–15–oic acid, 7–hydroxycadalene, 4–hydroxy–2–isopropyl–4,
7–dimethyl–1[4H] naftalinone, 7–hydroxy–4αH–3, 4–dihydrocadalene, β–caryophyllene, and β–caryophyllene epoxide) in Mexican
árnica plants subjected to fertilization and successive harvests of flowering stems, conditions that mimic the cultivation
and harvesting for árnica in México. Fertilization and successive harvesting and their interaction had no significant effect
on the concentration of anti–inflammatory compounds. However, the concentrations of these compounds were 60% higher in flowering
stems from 15–month–old plants than in those from 4– or 8–month–old plants and was independent of the number of harvests and
fertilization regime applied. 相似文献
4.
The negative gravitropism of the sporangiophores of Phycomyces blakesleeanus Burgeff is elicited by different sensory inputs, which include flexure of the growing zone, buoyance of lipid globules and
sedimentation of paracrystalline proteins, so-called octahedral crystals (C. Schimek et al., 1999a, Planta 210: 132–142).
Gravity-induced absorbance changes (GIACs), which are associated with primary events of gravity sensing, were detected in
the growing zones of sporangiophores. After placing sporangiophores horizontally, GIACs were detected after a latency of about
5 min, i.e. 15–25 min prior to gravitropic bending. The spectroscopic properties of the GIACs indicate that gravitropic stimulation
could imply the reduction of cytochromes. The GIACs were spectrally distinct from light-induced absorbance changes (LIACs),
showing that the primary responses of the light and gravity transduction chains are different. A dual stimulation with gravity
and light generated GIAC-LIACs which were distinct from the absorbance changes occurring after the single stimuli and which
indicate that light and gravity interact early in the respective transduction chains.
Received: 2 September 1999 / Accepted: 9 November 1999 相似文献
5.
Summary. The influence of the operation conditions (temperature and residence time) of a thermic treatment on the total amount (free
and protein-bound) of amino acid enantiomers of dry fullfat soya was investigated. Total amino acid content was determined
using conventional ion-exchange amino acid analysis of total hydrolysates and chiral amino acid analysis was performed by
HPLC after precolumn derivatization with o-phthaldialdehyde and 1-thio-β-D-glucose tetraacetate. Contrary to corn that was investigated previously, notable racemization
was detected even at lower temperatures. At 140 °C the ratio of the D-enantiomer was 0.87% for glutamic acid, 2.81% for serine,
and 1.92% for phenylalanine; at 220 °C the ratios of the D-enantiomer of the above amino acids were 1.43, 4.61, and 4.68%,
respectively. The concentration of several L-amino acids decreased. At 220 °C there was 10% less L-glutamic acid, 17% less
L-serine, 5% less L-phenylalanine, 6.6% less L-aspartic, acid and 21% less L-lysine than in the control; their loss can be
assigned to different degrees of L – D conversion. While nearly complete transformation of L-phenylalanine can be attributed
to racemization, the main cause of the loss of L-lysine is not racemization. The treatments in the same order of magnitude
resulted in the formation of more D-amino acids and greater extent of racemization of amino acids in fullfat soya than that
of maize.
Authors’ address: J. Csapó, Faculty of Animal Science, Institute of Chemistry, University of Kaposvár, Guba S. u. 40., H-7400
Kaposvár, Hungary 相似文献
6.
Geranylhydroquinone 3′′-hydroxylase, a cytochrome P-450 monooxygenase from Lithospermum erythrorhizon cell suspension cultures 总被引:2,自引:0,他引:2
Geranylhydroquinone 3′′-hydroxylase, which is likely to be involved in shikonin and dihydroechinofuran biosynthesis, was
identified in cell suspension cultures of Lithospermum erythrorhizon Sieb. et Zucc. (Boraginaceae). The enzyme hydroxylates the isoprenoid side chain of geranylhydroquinone (GHQ), a known precursor
of shikonin. Proton/proton correlation spectroscopic and proton/proton long-range correlation spectroscopic studies confirmed
that hydroxylation takes place specifically at position 3′′, i.e. at the methyl group involved in the cyclization reaction.
The enzyme is membrane-bound and was found in the microsomal fraction. It requires NADPH and molecular oxygen as cofactors,
and is inhibited by cytochrome P-450 inhibitors such as cytochrome c and CO. The inhibitory effect of CO is reversed by illumination.
These data suggest that the enzyme is a cytochrome P-450-dependent monooxygenase. The optimum pH of GHQ 3′′-hydroxylase is
7.4, and the apparent K
m value for GHQ is 1.5 μM. The reaction velocity obtained with 3-geranyl-4-hydroxybenzoic acid was more than 100 times lower
than that obtained with geranylhydroquinone.
Received: 20 March 1999 / Accepted: 20 July 1999 相似文献
7.
Summary. We use a modeling and simulation approach to carry out an in silico analysis of the metabolic pathways involving arginine
as a precursor of nitric oxide or polyamines in aorta endothelial cells. Our model predicts conditions of physiological steady
state, as well as the response of the system to changes in the control parameter, external arginine concentration. Metabolic
flux control analysis allowed us to predict the values of flux control coefficients for all the transporters and enzymes included
in the model. This analysis fulfills the flux control coefficient summation theorem and shows that both the low affinity transporter
and arginase share the control of the fluxes through these metabolic pathways.
The first two authors equally contributed to this work.
Current address for the second author: ICREA-Complex Systems Laboratory, Universitat Pompeu Fabra, Barcelona, Spain.
Authors’ address: Dr. Miguel ángel Medina, Departamento de Biología Molecular y Bioquímica, Facultad de Ciencias, Universidad
de Málaga, E-29071 Málaga, Spain 相似文献
8.
Michael Wille Henry Hooghiemstra Hermann Behling Klaas van der Borg Alvora Jose Negret 《Vegetation History and Archaeobotany》2001,10(2):61-77
We present a reconstruction of forest history and climatic change based on 11 pollen records from eight sites, all located
in the lower montane forest belt of the northern Andes in Colombia. We compared records from the Popayán area in southern
Colobia, Timbio (1750 m), Genagra (1750 m) and Pitalito (1300 m) and the new Piagua (1700 m) record with the records from
Lusitania (1500 m), Libano (1820 m), Pedro Palo (2000 m) and Ubaqué (2000 m) from Central Colombia. The changes of the altitudinal
position of the lower/upper montane (= subandean/Andean, S/At) forest belt transition were used to estimate temperature change
for the last 50 kyr. We infer a Last Glacial Maximum (LGM) temperature drop of 6°–7°C at 1700 m, and a steeper LGM lapse rate
of 0.76°C/100 m compared to today (ca. 0.6°C/100 m). Around 50 uncal. kyr B.P. the temperature at 1700 m was ca. 3°C lower
than today. Until 20 uncal. kyr B.P. the temperature oscillated and gradually decreased. During the LGM, temperature was down
to ca. 6°–7°C lower than today. After the LGM, temperature increased and ca. 14 uncal. kyr B.P. it was 2°–3°C lower than today
(S/At at ca. 1800 m, 500 m below present elevation; Susacá interstadial). An unquantified cooling (Ciega stadial) followed.
During ca. 12.3–11.7 uncal. kyr B.P. the S/At shifted upslope to 2100 m indicating a temperature of 1°–2°C cooler than today
(Guantiva interstadial). From 11.7–10.9 uncal. kyr B.P. the S/At was at 1800 m indicating that the temperature was ca. 3°C
lower than today and wet conditions prevailed (partly coinciding with the El Abra stadial). The period 10.9–9 uncal. kyr B.P.
was also cool, but drier. During 9–7.5 uncal. kyr B.P. temperature was ca. 1°C warmer relative to today (mid Holocene hypsithermal).
During the last 5 kyr the presence of cultivated plants demonstates human colonization of the lower montane zone in Colombia.
Received June 14, 2000 / Accepted December 19, 2000 相似文献
9.
Calderón-Cortés E Clemente-Guerrero M Sierra-Campos E Cortés-Rojo C Gaona-Zamudio FJ Villalobos-Molina R Saavedra-Molina A 《Amino acids》2006,31(1):73-80
Summary. Starting from a collection of 1386 druggable compounds obtained from the 3D pharmacophore search, we performed a similarity
search to narrow down the scope of docking studies. The template molecule is KZ7088 (Chou et al., 2003, Biochem Biophys Res Commun 308: 148–151). The MDL MACCS keys were used to fingerprint the molecules. The Tanimoto coefficient is taken as the metric
to compare fingerprints. If the similarity threshold was 0.8, a set of 50 unique hits and 103 conformers were retrieved as
a result of similarity search. The AutoDock 3.011 was used to carry out molecular docking of 50 ligands to their macromolecular
protein receptors. Three compounds, i.e., C28H34O4N7Cl, C21H36O5N6, and C21H36O5N6, were found that may be promising candidates for further investigation. The main feature shared by these three potential
inhibitors as well as the information of the involved side chains of SARS Cov Mpro may provide useful insights for the development
of potent inhibitors against SARS enzyme. 相似文献
10.
Summary. Glutathione (reduced form GSH and oxidized form GSSG) constitutes an important defense against oxidative stress in the brain,
and taurine is an inhibitory neuromodulator particularly in the developing brain. The effects of GSH and GSSG and glycylglycine,
γ-glutamylcysteine, cysteinylglycine, glycine and cysteine on the release of [3H]taurine evoked by K+-depolarization or the ionotropic glutamate receptor agonists glutamate, kainate, 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate
(AMPA) and N-methyl-D-aspartate (NMDA) were now studied in slices from the hippocampi from 7-day-old mouse pups in a perfusion system.
All stimulatory agents (50 mM K+, 1 mM glutamate, 0.1 mM kainate, 0.1 mM AMPA and 0.1 mM NMDA) evoked taurine release in a receptor-mediated manner. Both
GSH and GSSG significantly inhibited the release evoked by 50 mM K+. The release induced by AMPA and glutamate was also inhibited, while the kainate-evoked release was significantly activated
by both GSH and GSSG. The NMDA-evoked release proved the most sensitive to modulation: L-Cysteine and glycine enhanced the
release in a concentration-dependent manner, whereas GSH and GSSG were inhibitory at low (0.1 mM) but not at higher (1 or
10 mM) concentrations. The release evoked by 0.1 mM AMPA was inhibited by γ-glutamylcysteine and cysteinylglycine, whereas
glycylglycine had no effect. The 0.1 mM NMDA-evoked release was inhibited by glycylglycine and γ-glutamylcysteine. In turn,
cysteinylglycine inhibited the NMDA-evoked release at 0.1 mM, but was inactive at 1 mM. Glutathione exhibited both enhancing
and attenuating effects on taurine release, depending on the glutathione concentration and on the agonist used. Both glutathione
and taurine act as endogenous neuroprotective effectors during early postnatal life.
Authors’ address: Prof. Simo S. Oja, Brain Research Center, Medical School, FI-33014 University of Tampere, Finland 相似文献
11.
Summary. Transmembrane (TM) proteins represent about 20–30% of the protein sequences in higher eukaryotes, playing important roles
across a range of cellular functions. Moreover, knowledge about topology of these proteins often provides crucial hints toward
their function. Due to the difficulties in experimental structure determinations of TM protein, theoretical prediction methods
are highly preferred in identifying the topology of newly found ones according to their primary sequences, useful in both
basic research and drug discovery. In this paper, based on the concept of pseudo amino acid composition (PseAA) that can incorporate
sequence-order information of a protein sequence so as to remarkably enhance the power of discrete models (Chou, K. C., Proteins:
Structure, Function, and Genetics, 2001, 43: 246–255), cellular automata and Lempel-Ziv complexity are introduced to predict
the TM regions of integral membrane proteins including both α-helical and β-barrel membrane proteins, validated by jackknife
test. The result thus obtained is quite promising, which indicates that the current approach might be a quite potential high
throughput tool in the post-genomic era. The source code and dataset are available for academic users at liml@scu.edu.cn.
Authors’ address: Menglong Li, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, P.R. China 相似文献
12.
Summary. We previously reported that L-leucine suppresses myofibrillar proteolysis in chick skeletal muscles. In the current study,
we compared the effects of L- and D-enantiomers of leucine on myofibrillar proteolysis in skeletal muscle of chicks. We also
assessed whether leucine itself or its metabolite, α-ketoisocaproate (α-KIC), mediates the effects of leucine. Food-deprived
(24 h) chicks were orally administered 225 mg/100 g body weight L-leucine, D-leucine or α-KIC and were sacrificed after 2 h.
L-Leucine administration had an obvious inhibitory effect on myofibrillar proteolysis (plasma Nτ-methylhistidine concentration) in chicks while D-leucine and α-KIC were much more effective. We also examined the expression
of the proteolytic-related genes (ubiquitin, proteasome, m-calpain and cathepsin B) by real-time PCR of cDNA in chick skeletal
muscles. Ubiquitin mRNA expression was decreased by D-leucine and α-KIC but not L-leucine. Proteasome and m-calpain mRNA expressions
as well as cathepsin B mRNA expression were likewise decreased by L-leucine, D-leucine and α-KIC. These results indicate that
D-leucine and α-KIC suppress proteolytic-related genes, resulting in an decrease in myofibrillar proteolysis while L-leucine
is much less effective in skeletal muscle of chicks, may be explain by conversion of D-leucine to α-KIC. 相似文献
13.
Ermel FF Follet-Gueye ML Cibert C Vian B Morvan C Catesson AM Goldberg R 《Planta》2000,210(5):732-740
The development of pectin structural features during the differentiation of cambial derivatives was investigated in aspen
(Populus tremula L. × P. tremuloides Michx.) using biochemical and immunocytochemical methods. Comparisons were also made between active and resting tissues.
Active tissues, in particular cambial cells and phloem derivatives, were characterized by a high pectin content. Use of antibodies
raised against arabinan side chains of rhamnogalacturonan 1 (LM6), as well as biochemical analysis, revealed an obvious decrease
from the cortex to the differentiating xylem. Galactan side chains, detected with LM5 antibodies, were present mainly in the
cambial zone and enlarging xylem cells. In contrast, they were totally absent from sieve-tube cell walls. Image analysis of
LM5 immunogold labelling in the cambial zone showed a clustered distribution of galactan epitopes in the radial walls, a distribution
which might result from the association of two different periodic processes, namely the exocytosis of galactan and wall expansion.
Cessation of cambial activity was characterized by cell wall thickening accompanied by a sharp decrease in the relative amount
of pectin and a lowering of the degree of methylesterification. The data provide evidence that the walls of phloem and xylem
cells differ in their pectin composition even at a very early stage of commitment. These differences offer useful tools for
identifying the initial cells among their immediate neighbours.
Received: 12 June 1999 / Accepted: 20 October 1999 相似文献
14.
Fujii N Shimmyo Y Sakai M Sadakane Y Nakamura T Morimoto Y Kinouchi T Goto Y Lampi K 《Amino acids》2007,32(1):87-94
Summary. Lens alpha-crystallin, composed of two subunits alpha A- and alpha B-crystallin, forms large aggregates in the lens of the
eye. The present study investigated the aggregate of human lens alpha-crystallin from elderly and young donors. Recombinant
alpha A- and alpha B-crystallins in molar ratios of alpha A to alpha B at 1:1, corresponding to the aged sample, were also
studied in detail. We found by ultra-centrifugation analysis that the alpha-crystallin aggregate from elderly donors was large
and heterogeneous with an average sedimentation coefficient of 30 S and a range of 20–60 S at 37 °C. This was higher compared
to the young samples that had an average sedimentation coefficient of 17 S. The sedimentation coefficients of recombinant
alpha A- and alpha B-crystallins were approximately 12 S and 15 S, respectively. Even when recombinant alpha-crystallins were
mixed in molar ratios equivalent to those found in vivo, similar S values as the native aged alpha-crystallin aggregates were
not obtained.
Changes in the self-association of alpha-crystallin aggregate were correlated to changes in chaperone activity. Alpha-crystallin
from young donors, and recombinant alpha A- and alpha B-crystallin and their mixtures showed chaperone activity, which was
markedly lost in samples from the aged alpha-crystallin aggregates. 相似文献
15.
Batch cultures of photoautotrophic cell suspensions of Chenopodiumrubrum L., growing in an inorganic medium on CO2 under a daily balanced light–dark regime of 16 : 8 h could be maintained for approximately 100 d without subcultivation.
The long-lived cultures showed an initial cell division phase of 4 weeks, followed by a stationary phase of another 4 weeks,
after which ageing and progressive cell death reduced the number of living cells and the cultures usually expired after another
3–4 weeks. These developmental phases of the cell culture were characterised with respect to photosynthetic performance, dark
respiration, content of phytohormones and capacity of cell division. Cell division of the majority of the cells finished in
the G1- or G0-phase of the cell cycle, caused by a pronounced decline in the endogenous levels of auxin and cytokinins. Supply
of these growth factors to resting cells resulted in resumption of cytokinesis, at least by some of the cells. However, responsiveness
to the phytohomones declined during the stationary phase, and subcultivation was no longer possible beyond day 60 when the
phases of ageing and death commenced. Ageing was characterised by a further decline in the photosynthetic capacity of the
cells, by a climacteric enhancement of dark respiration, but also by a slight increase in the level of IAA and cytokinins
concomitant with a decrease in ethylene. Similarities and differences between the development of batch-cultured photoautotrophic
cells of C. rubrum and that of a leaf are discussed with respect to using the cell culture as a model for a leaf.
Received: 30 April 1999 / Accepted: 21 August 1999 相似文献
16.
Arriagada C Dagnino-Subiabre A Caviedes P Armero JM Caviedes R Segura-Aguilar J 《Amino acids》2000,18(4):363-373
Summary. Aminochrome was found to be toxic in a mouse-derived neuronal cell line (CNh). The effect was concentration dependent (10–150
μM). The issue whether aminochrome toxicity involves glutamate transmission was studied with several glutamate receptors antagonists.
Incubation of the cells with aminochrome (150 μM) in the presence of 100 μM of the AMPA an-tagonist, NBQX resulted in an increase of cell survival, from 52 to 73%. However, this protective effect
did not seem to be related to activation of ionotropic glutamate receptors since incubation of CNh cells with 200 μM of glutamate resulted in only 10% decrease of cell survival. However, NBQX was found to inhibit in vitro the autoxidation process. One hundred μM AP-5 did not have any effect on aminochrome toxicity. The toxic effect of aminochrome on CNh cells seems to be dependent
of extracellular activation since addition of dicoumarol, a specific inhibitor of DT-diaphorase, did not affect that toxicity,
which can be explained perhaps by a lack of a transport system for aminochrome into the CNh cells.
Received July 28, 1999, Accepted December 6, 1999 相似文献
17.
Haspel HC Stephenson KN Davies-Hill T El-Barbary A Lobo JF Croxen RL Mougrabi W Koehler-Stec EM Fenstermacher JD Simpson IA 《The Journal of membrane biology》1999,169(1):45-53
Barbiturates inhibit GLUT-1-mediated glucose transport across the blood-brain barrier, in cultured mammalian cells, and in
human erythrocytes. Barbiturates also interact directly with GLUT-1. The hypotheses that this inhibition of glucose transport
is (i) selective, preferring barbiturates over halogenated hydrocarbon inhalation anesthetics, and (ii) specific, favoring
some GLUT-# isoforms over others were tested. Several oxy- and thio-barbiturates inhibited [3H]-2-deoxyglucose uptake by GLUT-1 expressing murine fibroblasts with IC50s of 0.2–2.9 mm. Inhibition of GLUT-1 by barbiturates correlates with their overall lipid solubility and pharmacology, and requires hydrophobic
side chains on the core barbiturate structure. In contrast, several halogenated hydrocarbons and ethanol (all ≤10 mm) do not significantly inhibit glucose transport. The interaction of these three classes of anesthetics with purified GLUT-1
was evaluated by quenching of intrinsic protein fluorescence and displayed similar specificities and characteristics. The
ability of barbiturates to inhibit other facilitative glucose transporters was determined in cell types expressing predominantly
one isoform. Pentobarbital inhibits [3H]-2-deoxyglucose and [14C]-3-O-methyl-glucose uptake in cells expressing GLUT-1, GLUT-2, and GLUT-3 with IC50s of ∼1 mm. In contrast, GLUT-4 expressed in insulin-stimulated rat adipocytes was much less sensitive than the other isoforms to inhibition
by pentobarbital (IC50 of >10 mm). Thus, barbiturates selectively inhibit glucose transport by some, but not all, facilitative glucose transporter isoforms.
Received: 10 November 1998/Revised: 3 February 1999 相似文献
18.
Hypaphorine, the major indolic compound isolated from the ectomycorrhizal fungus Pisolithus tinctorius, controls the elongation rate of root hairs. At inhibitory concentrations (100 μM), hypaphorine induced a transitory swelling
of root hair tips of Eucalyptus globulus Labill. ssp. bicostata. When the polar tip growth resumed, a characteristic deformation was still visible on elongating hairs. At higher hypaphorine
concentrations (500 μM and greater), root hair elongation stopped, only 15 min after application. However, root hair initiation
from trichoblasts was not affected by hypaphorine. Hypaphorine activity could not be mimicked by related molecules such as
indole-3-acetic acid (IAA) or tryptophan. While IAA had no activity on root hair elongation, IAA was able to restore the tip
growth of root hairs following inhibition by hypaphorine. These results suggest that hypaphorine and endogenous IAA counteract
in controlling root hair elongation. During ectomycorrhiza development, the absence of root hairs might be due in part to
fungal release of molecules, such as hypaphorine, that inhibit the elongation of root hairs.
Received: 27 October 1999 / Accepted: 14 March 2000 相似文献
19.
Ossowska K Konieczny J Wardas J Pietraszek M Kuter K Wolfarth S Pilc A 《Amino acids》2007,32(2):179-188
Summary. Several data indicate that inhibition of glutamatergic transmission may be important to alleviate of parkinsonian symptoms.
Therefore, the aim of the present paper is to review recent studies on the search for putative antiparkinsonian-like effects
of mGluR ligands and their brain targets. In order to inhibit glutamatergic transmission, the group I mGluRs (mGluR1 and mGluR5)
were blocked, and group II (mGluR2/3) or III (mGluR4/7/8) mGluRs were activated.
Systemic or intrastriatal administration of group I mGluR antagonists (mGluR5 – MPEP, MTEP; mGluR1 – AIDA) was found to inhibit
parkinsonian-like symptoms (catalepsy, muscle rigidity) in rats. MPEP administered systemically and mGluR1 antagonists (AIDA,
CPCCOEt, LY367385) injected intrastriatally reversed also the haloperidol-increased proenkephalin (PENK) mRNA expression in
the striatopallidal pathway. Similarly, ACPT-1, a group III mGluR agonist, administered into the striatum, globus pallidus
or substantia nigra inhibited the catalepsy. Intrastriatal injection of this compound reduced the striatal PENK expression
induced by haloperidol. In contrast, a group II mGluR agonist (2R,4R-APDC) administered intrastriatally reduced neither PENK
expression nor the above-mentioned parkinsonian-like symptoms. Moreover, a mixed mGluR8 agonist/AMPA antagonist, (R,S)-3,4-DCPG,
administered systemically evoked catalepsy and enhanced both the catalepsy and PENK expression induced by haloperidol.
The results reviewed in this article seem to indicate that group I mGluR antagonists or some agonists of group III may possess
antiparkinsonian properties, and point at the striatopallidal pathway as a potential target of therapeutic intervention. 相似文献
20.
Nikolic J Stojanovic I Pavlovic R Sokolovic D Bjelakovic G Beninati S 《Amino acids》2007,32(1):127-131
Summary. The existing interrelation in metabolic pathways of L-arginine to polyamines, nitric oxide (NO) and urea synthesis could be
affected in sepsis, inflammation, intoxication and other conditions. The role of polyamines and NO in the toxic effect of
mercury chloride on rat liver function was studied. Administration of mercury chloride for 24 h led to significantly elevated
plasma activities of Alanine transaminase (ALT) and Aspartate transaminase (AST). Malondyaldehyde (MDA) levels were unaffected
(p > 0.05) and arginase activity was significantly decreased (p < 0.05) while nitrate/nitrite production was significantly
elevated (p < 0.001) in liver tissue. Polyamine oxidase (PAO) and diamine oxidase (DAO) activities, enzymes involved in catabolism
of polyamines, were decreased. L-arginine supplementation to intoxicated rats potentiated the effect of mercury chloride on
NO production and it was ineffective on arginase activity.
Results obtained in this study show that mercury chloride-induced toxicity leads to abnormally high levels of ALT and AST
that may indicate liver damage with the involvement of polyamine catabolic enzymes and NO. 相似文献