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1.
The present study investigates the correlation between the hypoxia-induced phosphorylation of cyclic AMP response element
binding protein and the expression of apoptotic proteins (proapoptotic proteins Bax and Bad and antiapoptotic proteins Bcl-2
and Bcl-xl) during hypoxia in the cerebral cortex of newborn piglets. Piglets were divided into normoxic (Nx) and hypoxic
(Hx, FiO 2 = 0.06 for 1 h) groups. Cerebral tissue hypoxia was documented by ATP and phosphocreatine (PCr) levels. Ser 133 phosphorylation of cyclic AMP response element binding (CREB) protein was determined by Western blot analysis using a specific
anti-phosphorylated Ser 133-CREB protein antibody. The expression of apoptotic proteins was determined by using specific anti-Bax, anti-Bad, anti-Bcl-2
and anti-Bcl-xl antibodies. ATP and PCr values (μmoles/g brain) in Hx were significantly different from Nx (ATP: 4.40 ± 0.39
in Nx vs. 1.19 ± 0.44 in Hx, P < 0.05 vs. Nx; PCr: 3.60 ± 0.40 in Nx vs. 0.70 ± 0.31 in Hx, P < 0.05 vs. Nx). Ser 133 phosphorylated CREB protein (OD × mm 2) was 74.55 ± 4.75 in Nx and 127.13 ± 19.36 in Hx ( P < 0.05 vs. Nx). The expression of proapoptotic proteins Bax and Bad increased and strongly correlated with the increase in
CREB protein phosphorylation (correlation coefficient r = 0.82 and r = 0.85, respectively). The expression of antiapoptotic proteins Bcl-2 and Bcl-xl did not show correlation with CREB protein
phosphorylation. We conclude that cerebral hypoxia results in differential regulation of CREB protein-mediated expression
of proapoptotic and antiapoptotic proteins in the cerebral cortex of newborn piglets. We propose that the increased expression
of proapoptotic vs antiapoptotic genes will lead to an increased potential for apoptotic programmed cell death in the Hx newborn
brain. 相似文献
2.
In previous studies, we have shown that cerebral hypoxia results in increased activity of caspase-9, the initiator caspase,
and caspase-3, the executioner of programmed cell death. We have also shown that cerebral hypoxia results in high affinity
Ca 2+–ATPase-dependent increase in nuclear Ca 2+-influx in the cerebral cortex of newborn piglets. The present study tests the hypothesis that inhibiting nuclear Ca 2+-influx by pretreatment with clonidine, an inhibitor of high affinity Ca 2+–ATPase, will prevent the hypoxia-induced increase in caspase-9 and caspase-3 activity in the cerebral cortex of newborn piglets.
Thirteen newborn piglets were divided into three groups, normoxic (Nx, n = 4), hypoxic (Hx, n = 4), and hypoxic treated with clonidine (100 mg/kg) (Hx–Cl, n = 5). Anesthetized, ventilated animals were exposed to an FiO 2 of 0.21 (Nx) or 0.07 (Hx) for 60 min. Cerebral tissue hypoxia was documented biochemically by determining levels of ATP and
phosphocreatine (PCr). Caspase-9 and -3 activity were determined spectrofluoro-metrically using specific fluorogenic synthetic
substrates. ATP (μmoles/g brain) was 4.6 ± 0.3 in Nx, 1.7±0.4 in Hx ( P < 0.05 vs. Nx), and 1.5 ± 0.2 in Hx–Cl ( P < 0.05 vs. Nx). PCr (μmoles/g brain) was 3.6 ± 0.4 in Nx, 1.1 ± 0.3 in Hx ( P < 0.05 vs. Nx), and 1.0 ± 0.2 in Hx–Cl ( P < 0.05 vs. Nx). Caspase-9 activity (nmoles/mg protein/h) was 0.548 ± 0.0642 in Nx and increased to 0.808 ± 0.080 ( P < 0.05 vs. Nx and Hx–Cl) in the Hx and 0.562 ± 0.050 in the Hx–Cl group (p = NS vs. Nx). Caspase-3 activity (nmoles/mg protein/h)
was 22.0 ± 1.3 in Nx and 32 ± 6.3 in Hx ( P < 0.05 vs. Nx) and 18.8 ± 3.2 in the Hx–Cl group ( P < 0.05 vs. Hx). The data demonstrate that clonidine administration prior to hypoxia prevents the hypoxia-induced increase
in the activity of caspase-9 and caspase-3. We conclude that the high afinity Ca 2+–ATPase-dependent increased nuclear Ca 2+ during hypoxia results in increased caspase-9 and caspase-3 activity. 相似文献
3.
Previous studies have shown that hyperoxia results in cerebral cortical neuronal apoptosis. Studies have also shown that phosphorylation
of anti-apoptotic proteins Bcl-2 and Bcl-xl results in loss of their anti-apoptotic potential leading to alteration in mitochondrial
membrane permeability and the release of apoptogenic proteins in the neuronal cell of the newborn piglets. The present study
tests the hypothesis that cerebral hyperoxia will result in increased serine phosphorylation of apoptotic proteins Bcl-2,
Bcl-xl, Bax, and Bad in the mitochondrial membranes of the cerebral cortex of newborn piglets. Twelve newborn piglets were
divided into normoxic (Nx, n = 6) exposed to an FiO 2 of 0.21 for 1 h and hyperoxic (Hyx, n = 6) exposed to FiO 2 of 1.0 for 1 h. In the Hyx group, PaO 2 was maintained above 400 mmHg while the Nx group was kept at 80–100 mmHg. Cerebral cortical tissue was harvested and mitochondrial
fractions were isolated. Mitochondrial membrane proteins were separated using 12% SDS-PAGE, and probed with anti-serine phosphorylated
Bcl-2, Bcl-xl, Bax, and Bad antibodies. Protein bands were detected, analyzed by imaging densitometry and density expressed
as absorbance (OD × mm 2). Phosphorylated Bcl-2 (p-Bcl-2) protein density (OD × mm 2) was 81.81 ± 9.24 in Nx and 158.34 ± 10.66 in Hyx ( P < 0.05). Phosphorylated Bcl-xl (p-Bcl-xl) protein density was 52.98 ± 3.59 in Nx and 99.62 ± 18.22 in Hyx ( P < 0.05). Phosphorylated Bax (p-Bax) protein was 161.13 ± 6.27 in Nx and 174.21 ± 15.95 in Hyx ( P = NS). Phosphorylated Bad (p-Bad) protein was 166.24 ± 9.47 in Nx 155.38 ± 12.32 in Hyx ( P = NS). The data show that there is a significant increase in serine phosphorylation of Bcl-2 and Bcl-xl proteins while phosphorylation
of Bad and Bax proteins were not altered during hyperoxia in the mitochondrial fraction of the cerebral cortex of newborn
piglets. We conclude that hyperoxia results in differential post-translational modification of anti-apoptotic proteins Bcl-2
and Bcl-xl as compared to pro-apoptotic proteins Bax and Bad in mitochondria. We speculate that phosphorylation of Bcl-2 and
Bcl-xl will result in loss of their anti-apoptotic potential by preventing their dimerization with Bax leading to activation
of the caspase cascade of neuronal death. 相似文献
4.
The present study aims to investigate the mechanism of calmodulin modification during hypoxia and tests the hypothesis that
hypoxia-induced increase in Tyr 99 phosphorylation of calmodulin in the cerebral cortex of newborn piglets is mediated by NO derived from nNOS. Fifteen piglets
were divided into normoxic (Nx, n = 5), hypoxic (Hx, F iO 2 of 0.07 for 1 h, n = 5) and hypoxic-pretreated with nNOSi (Hx-nNOSi, n = 5) groups. nNOS inhibitor I (selectivity >2,500 vs. eNOS and >500 vs. iNOS) was administered (0.4 mg/kg, I.V.) 30 min prior
to hypoxia. Cortical membranes were isolated and tyrosine phosphorylation (Tyr 99 and total) of calmodulin determined by Western blot using anti-phospho-(pTyr 99)-calmodulin and anti-pTyr antibodies. Protein bands were detected by enhanced chemiluminescence, analyzed by densitometry
and expressed as absorbance. The pTyr 99 calmodulin (ODxmm 2) was 78.55 ± 10.76 in Nx, 165.05 ± 12.26 in Hx ( P < 0.05 vs. Nx) and 96.97 ± 13.18 in Hx-nNOSi ( P < 0.05 vs. Hx, P = NS vs. Nx). Expression of total tyrosine phosphorylated calmodulin was 69.24 ± 13.69 in Nx, 156.17 ± 16.34 in Hx ( P < 0.05 vs. Nx) and 74.18 ± 3.9 in Hx-nNOSi ( P < 0.05 vs. Hx, P = NS vs. Nx). The data show that administration of nNOS inhibitor prevented the hypoxia-induced increased Tyr 99 phosphorylation of calmodulin. Total tyrosine phosphorylation of calmodulin was similar to Tyr 99 phosphorylation. We conclude that the mechanism of hypoxia-induced modification (Tyr 99 phosphorylation) of calmodulin is mediated by NO derived from nNOS. We speculate that Tyr 99 phosphorylated calmodulin, as compared to non-phosphorylated, binds with a higher affinity at the calmodulin binding site
of nNOS leading to increased activation of nNOS and increased generation of NO. 相似文献
5.
The present study tested the hypothesis that magnesium sulfate administration prior to hypoxia prevents hypoxia-induced increase
in Ca 2+/Calmodulin-dependent-kinase (CaM Kinase) IV and Protein Tyrosine Kinase (PTK ) activities. Animals were randomly divided
into normoxic (Nx), hypoxic (Hx) and magnesium-pretreated hypoxic (Mg 2+-Hx) groups. Cerebral hypoxia was confirmed biochemically by measuring ATP and phosphocreatine (PCr) levels. CaM Kinase IV
and PTK activities were determined in Nx, Hx and Mg 2+-Hx newborn piglets. There was a significant difference between CaM kinase IV activity (pmoles/mg protein/min) in Nx (270 ± 49),
Mg 2+-Hx (317 ± 82) and Hx (574 ± 41, P < 0.05 vs. Nx and Mg 2+-Hx) groups. Similarly, there was a significant difference between Protein Tyrosine Kinase activity (pmoles/mg protein/h)
in normoxic (378 ± 68), Mg 2+-Hx (455 ± 67) and Hx (922 ± 66, P < 0.05 vs. Nx and Mg 2+-Hx ) groups. We conclude that magnesium sulfate administration prior to hypoxia prevents hypoxia-induced increase in CaM
Kinase IV and Protein Tyrosine Kinase activities. We propose that by blocking the NMDA receptor ion-channel mediated Ca 2+-flux, magnesium sulfate administration inhibits the Ca 2+/calmodulin-dependent activation of CaMKIV and prevents the generation of nitric oxide free radicals and the subsequent increase
in PTK activity. As a result, phosphorylation of CREB and Bcl-2 family of proteins is prevented leading to prevention of programmed
cell death. 相似文献
6.
The present study aims to investigate the mechanism of EGFR kinase activation during hypoxia and tests the hypothesis that
hypoxia-induced increased activation of EGFR kinase in the cerebral cortical membrane fraction of newborn piglets is mediated
by nitric oxide (NO) derived from neuronal nitric oxide synthase (nNOS). Fifteen newborn piglets were divided into normoxic
(Nx, n = 5), hypoxic (Hx, n = 5) and hypoxic-treated with nNOS inhibitor (Hx-nNOSi, n = 5). Hypoxia was induced by an FiO2 of 0.07 for 60 min. nNOS inhibitor I (selectivity >2,500 vs. endothelial NOS, eNOS,
and >500 vs. inducible NOS, iNOS) was administered (0.4 mg/kg, i. v.) 30 min prior to hypoxia. EGFR kinase tyrosine phosphorylation
at Tyr1173, an index of activation of EGFR kinase, was determined by Western blot analysis using an anti-phospho (pTyr 1173)-EGFR kinase antibody. Protein bands were analyzed by imaging densitometry and expressed as absorbance (OD × mm 2). EGFR kinase activity was determined radiochemically using immunopurified enzyme. EGFR kinase activity was expressed as
pmols/mg protein/hr. Density of phosphor (pTyr 1173)-EGFR kinase (OD × mm 2) was 60.2 ± 9.8 in Nx, 177.0 ± 26.9 in Hx ( P < 0.05 vs. Nx) and 79.9 ± 15.7 in Hx-nNOSi ( P < 0.05 vs. Hx, P = NS vs. Nx). Activity of EGFR kinase (pmoles/mg protein/hr) was 4,603 ± 155 in Nx, 8,493 ± 427 in Hx ( P < 0.05 vs. Nx) and 4,516 ± 104 in Hx-nNOSi ( P < 0.05 vs. Hx, P = NS vs. Nx). Pretreatment with nNOS inhibitor prevented the hypoxia-induced increased phosphorylation and increased activity
of EGFR kinase. We conclude that the mechanism of hypoxia-induced increased activation of EGFR kinase is mediated by nNOS-derived
NO. 相似文献
7.
The present study tests the hypothesis that hyperoxia results in increased tyrosine phosphorylation of apoptotic proteins
Bcl-2, Bcl-xl, Bax & Bad in the mitochondrial fraction of the cerebral cortex of newborn piglets. Twelve newborn piglets were
divided into normoxic [Nx, n = 6], exposed to a FiO 2 of 0.21 for 1 h and hyperoxic [Hyx, n = 6], exposed to FiO 2 of 1.0 for 1 h. PaO 2 in Hyx group was maintained at 400 mmHg while the Nx group was kept at 80 to100 mmHg. The density (O.D.x mm 2) of phosphorylated Bcl2 protein on westernblot was 19.3 ± 3.6 in Nx and 41.5 ± 18.3 in Hyx, ( P < 0.05). The density of phosphorylated Bcl-xl protein density was 26.9 ± 7.0 in Nx and 47.9 ± 2.5 in Hyx, ( P < 0.05). Phosphorylated Bax density was 43.5 ± 5.0 in Nx and 43.3 ± 5.2 in Hyx. Phosphorylated Bad density was 23.6 ± 3.9
in Nx, 24.4 ± 4.7 in Hyx. The data show that during hyperoxia there is a significant increase in tyrosine phosphorylation
of Bcl2 and Bcl-xl, while the phosphorylation of proapototic proteins Bax & Bad was not altered. We conclude that hyperoxia
leads to post translational modification of anti apoptotic proteins Bcl2 and Bcl-xl in cerebral cortical mitochondria. We
propose that phosphorylation of Bcl2 will result in loss of its antiapoptotic potential by preventing its dimerization with
Bax leading to activation of the caspase pathway and subsequent neuronal death in the cerebral cortex of the newborn piglets. 相似文献
9.
Ventricular arrhythmias commonly originate from the right ventricular out‐flow tract (RVOT). However, the electrophysiological characteristics and Ca 2+ homoeostasis of RVOT cardiomyocytes remain unclear. Whole‐cell patch clamp and indo‐1 fluorometric ratio techniques were used to investigate action potentials, Ca 2+ homoeostasis and ionic currents in isolated cardiomyocytes from the rabbit RVOT and right ventricular apex (RVA). Conventional microelectrodes were used to record the electrical activity before and after (KN‐93, a Ca 2+/calmodulin‐dependent kinase II inhibitor, or ranolazine, a late sodium current inhibitor) treatment in RVOT and RVA tissue preparations under electrical pacing and ouabain (Na +/K + ATPase inhibitor) administration. In contrast to RVA cardiomyocytes, RVOT cardiomyocytes were characterized by longer action potential duration measured at 90% and 50% repolarization, larger Ca 2+ transients, higher Ca 2+ stores, higher late Na + and transient outward K + currents, but smaller delayed rectifier K +, L‐type Ca 2+ currents and Na +‐Ca 2+ exchanger currents. RVOT cardiomyocytes showed significantly more pacing‐induced delayed afterdepolarizations (22% versus 0%, P < 0.05) and ouabain‐induced ventricular arrhythmias (94% versus 61%, P < 0.05) than RVA cardiomyocytes. Consistently, it took longer time (9 ± 1 versus 4 ± 1 min., P < 0.05) to eliminate ouabain‐induced ventricular arrhythmias after application of KN‐93 (but not ranolazine) in the RVOT in comparison with the RVA. These results indicate that RVOT cardiomyocytes have distinct electrophysiological characteristics with longer AP duration and greater Ca 2+ content, which could contribute to the high RVOT arrhythmogenic activity. 相似文献
10.
The patch clamp K +-conductance G of the nicotinic acetylcholine receptor (AcChoR) dimer (M r≈ 590 000) of Torpedo californica, reconstituted in lipid vesicles, which decreases with increasing Ca 2+-concentration in the range 0.1≤[Ca 2+]/mM≤2, can be quantitatively rationalized by Ca 2+-binding to negatively charged sites, causing charge reversal reducing the normal K +-accumulation in the channel vestibules. Cleavage of the sialic acid residues (up to 20±2 per dimer) reduces the K +-accumulation factor α = G 0/G ∞ from α = 3±0.8 of the normal AcChoR to α = 2±0.7 for the desialyated AcChoR. Desialysation also decreases the Ca 2+-sensitivity of the conductance from G 0 = 96.6±6 pS at [Ca 2+]→0 of the normal AcChoR to G 0 = 84.2±6 pS. Endogenous hyperphosphorylation (to up to 28±4 phosphates per dimer) enhances the vestibular K +-accumulation to α = 3.6±0.7, without affecting the Ca 2+-dissociation equilibrium constant K Ca = 0.34± 0.05 mM at 295 K (22 °C). Most interestingly, even in the absence of AcCho, the hyperphosphorylated AcChoR dimer
exhibits spontaneously long-lasting open channel events ( τ = 200±50 ms). At [AcCho] = 2 μM there are two open states ( τ
1 = 20±10 ms, τ
2 = 140±60 ms) whereas the normal AcChoR dimer has only one open state ( τ = 6±4 ms). – Physiologically important is that (i) the sialic acid and phosphate residues render the AcChoR conductance sensitive
to control by divalent ions and (ii) the channel behavior of the hyperphosphorylated AcChoR without AcCho appears to indicate
pathophysiologically high phosphorylation activity of the cell leading, among others, to myasthenic syndromes.
Received: 10 November 1997 / Revised version: 12 January 1998 / Accepted: 7 March 1998 相似文献
11.
Chronic obstructive pulmonary disease (COPD) is known to elicit intrinsic abnormalities in male skeletal muscle. However,
it is unclear to what extent these changes occur in women and whether they are fiber-type specific. We investigated fiber-type
specific differences in selected histochemical properties in muscle obtained from women with moderate to severe COPD compared
to healthy control (CON) women. Tissue was obtained from the vastus lateralis in five COPD patients (age 66.9 ± 2.6 years;
FEV 1 = 43 ± 7%) and eight CON (age 68 ± 4.9 years; FEV 1 = 113 ± 4.2%). Compared to CON, the distribution (30.6 ± 5.2 vs. 57.9 ± 4.6%) and cross sectional area of type I (CSA, 5660 ± 329
vs. 3586 ± 257 μm 2) and type IIA (2770 ± 302 vs. 2099 ± 206 μm 2) were lower ( P < 0.05) and higher ( P < 0.05), respectively, in COPD. Disease state did not alter either the distribution or CSA of the IIA, IIAX or type X subtypes.
Although differences were found between fiber types in the number of capillary contacts ( n) (I > IIAX, IIX; IIA > IIX) and the capillaries per CSA (μm 210 −3) (I < IIA, IIAX, IIX), no differences were found between CON and COPD. Succinic dehydrogenase activity and sarcoplasmic reticulum
(SR) Ca 2+-ATPase activity, measured photometrically (OD units), were higher ( P < 0.05), and lower ( P < 0.05), respectively, in type I compared to the type II fiber subtypes. These properties were not altered with COPD. COPD
in females is accompanied by a higher percent of type II fibers, a larger CSA of type I and type IIA fibers, both of which
occur in the absence of differences in oxidative potential and the potential for SR Ca 2+-sequestration. 相似文献
12.
Forest ecosystems are self-fertilizing systems, and development of forest stands depends on nutrient supply via biogeochemical
cycling within the ecosystem. Therefore, it is important to clarify the nutrient cycle mediating growth and development. In
addition, long-term hydrochemical monitoring is needed to understand the influence of environmental changes on biogeochemical
cycling in forest ecosystems. The Oyasan Experimental Forest Watershed (OEFW) is located in the Field Museum Oyasan, the university
forest of Tokyo University of Agriculture and Technology, in Gunma prefecture, Japan. OEFW comprises two small adjacent forested
watersheds—A-watershed and B-watershed—with respective areas of 1.3 and 1.8 ha. A-watershed is a reestablished forest planted
with sugi (Japanese cedar; Cryptomeria japonica) and hinoki (Japanese cypress; Chamaecyparis obtusa) in 1976, and has been managed intensively with fertilizer application. By contrast, B-watershed is an established forest
planted with sugi and hinoki in 1907. No forest practices have been carried out except for thinning of suppressed trees in
1983. However, the sugi plantation on the lowest slope (18% of the watershed area) was cut in 2000, and sugi was replanted
the following year. In this data paper, we present data on the daily precipitation, discharge, pH, and concentrations of major
nutrients (Ca 2+, Mg 2+, K +, Na +, NH 4
+, Cl −, NO 3
−, and SO 4
2−) in rainwater and stream water since November 1978. The arithmetical mean pH of precipitation, stream water in A- and B-watershed
from the beginning of the monitoring to the present were 4.77 ± 0.67, 6.85 ± 0.41 and 6.88 ± 0.36 (average ± SD), respectively.
The arithmetical mean concentrations in precipitation in mmol c L −1 were 0.030 ± 0.030 for Ca 2+, 0.010 ± 0.011 for Mg 2+, 0.009 ± 0.013 for K +, 0.020 ± 0.024 for Na +, 0.035 ± 0.041 for NH 4
+, 0.026 ± 0.029 for Cl −, 0.033 ± 0.038 for NO 3
−, and 0.046 ± 0.043 for SO 4
2−. The mean concentrations in stream water in A-watershed were 0.180 ± 0.032 for Ca 2+, 0.073 ± 0.013 for Mg 2+, 0.018 ± 0.009 for K +, 0.182 ± 0.024 for Na +, 0.010 ± 0.010 for NH 4
+, 0.060 ± 0.008 for Cl −, 0.111 ± 0.038 for NO 3
−, and 0.074 ± 0.012 for SO 4
2−; whereas for B-watershed the mean concentrations were 0.169 ± 0.025 for Ca 2+, 0.079 ± 0.016 for Mg 2+, 0.018 ± 0.005 for K +, 0.192 ± 0.026 for Na +, 0.010 ± 0.010 for NH 4
+, 0.065 ± 0.010 for Cl −, 0.093 ± 0.025 for NO 3
−, and 0.087 ± 0.011 for SO 4
2−. 相似文献
13.
We studied the peculiarities of permeability with respect to the main extracellular cations, Na + and Ca 2+, of cloned low-threshold calcium channels (LTCCs) of three subtypes, Ca v3.1 (α1G), Ca v3.2 (α 1H), and Ca v3.3 (α1I), functionally expressed in Xenopus oocytes. In a calcium-free solution containing 100 mM Na + and 5 mM calcium-chelating EGTA buffer (to eliminate residual concentrations of Ca 2+) we observed considerable integral currents possessing the kinetics of inactivation typical of LTCCs and characterized by
reversion potentials of −10 ± 1, −12 ± 1, and −18 ± 2 mV, respectively, for Ca v3.1, Ca v3.2, and Ca v3.3 channels. The presence of Ca 2+ in the extracellular solution exerted an ambiguous effect on the examined currents. On the one hand, Ca 2+ effectively blocked the current of monovalent cations through cloned LTCCs ( K
d = 2, 10, and 18 μM for currents through channels Ca v3.1, Ca v3.2, and Ca v3.3, respectively). On the other hand, at the concentration of 1 to 100 mM, Ca 2+ itself functioned as a carrier of the inward current. Despite the fact that the calcium current reached the level of saturation
in the presence of 5 mM Ca 2+ in the external solution, extracellular Na + influenced the permeability of these channels even in the presence of 10 mM Ca 2+. The Ca v3.3 channels were more permeable with respect to Na + ( P
Ca/ P
Na ∼ 21) than Ca v3.1 and Ca v3.2 ( P
Ca/ P
Na ∼ 66). As a whole, our data indicate that cloned LTCCs form multi-ion Ca 2+-selective pores, as these ions possess a high affinity for certain binding sites. Monovalent cations present together with
Ca 2+ in the external solution modulate the calcium permeability of these channels. Among the above-mentioned subtypes, Ca v3.3 channels show the minimum selectivity with respect to Ca 2+ and are most permeable for monovalent cations.
Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 183–192, May–June, 2006. 相似文献
14.
The primary aim of our study was to determine the influence of taking chromium plus carnitine on insulin resistance, with a secondary objective of evaluating the influences on lipid profiles and weight loss in overweight subjects with polycystic ovary syndrome (PCOS). In a 12-week randomized, double-blind, placebo-controlled clinical trial, 54 overweight women were randomly assigned to receive either supplements (200 μg/day chromium picolinate plus 1000 mg/day carnitine) or placebo (27/each group). Chromium and carnitine co-supplementation decreased weight (− 3.6 ± 1.8 vs. − 1.0 ± 0.7 kg, P < 0.001), BMI (− 1.3 ± 0.7 vs. − 0.3 ± 0.3 kg/m2, P < 0.001), fasting plasma glucose (FPG) (− 5.1 ± 6.0 vs. − 1.1 ± 4.9 mg/dL, P = 0.01), insulin (− 2.0 ± 1.4 vs. − 0.2 ± 1.2 μIU/mL, P < 0.001), insulin resistance (− 0.5 ± 0.4 vs. − 0.04 ± 0.3, P < 0.001), triglycerides (− 18.0 ± 25.2 vs. + 5.5 ± 14.4 mg/dL, P < 0.001), total (− 17.0 ± 20.3 vs. + 3.6 ± 12.0 mg/dL, P < 0.001), and LDL cholesterol (− 13.3 ± 19.2 vs. + 1.4 ± 13.3 mg/dL, P = 0.002), and elevated insulin sensitivity (+ 0.007 ± 0.005 vs. + 0.002 ± 0.005, P < 0.001). In addition, co-supplementation upregulated peroxisome proliferator-activated receptor gamma (P = 0.02) and low-density lipoprotein receptor expression (P = 0.02). Overall, chromium and carnitine co-supplementation for 12 weeks to overweight women with PCOS had beneficial effects on body weight, glycemic control, lipid profiles except HDL cholesterol levels, and gene expression of PPAR-γ and LDLR. Clinical trial registration number: http://www.irct.ir: IRCT20170513033941N38. 相似文献
15.
In this investigation, morphological and physiological differences between fringe and dwarf Avicennia marina (Forsk.) Vierh. growing in seawater and hypersalinity were compared along a tree height and productivity gradient in Richards
Bay, South Africa. Dwarf trees had thicker leaves and cuticles, lower specific leaf area and salt gland frequency, while the
concentrations of total chlorophyll and chlorophylls a and b were lower by 26, 23 and 39%, respectively, compared to fringe
trees. Soil ψ and soil salinity were −3.04 ± 0.09 MPa and 36 ± 3 psu in the fringe zone, compared to −7.24 ± 0.38 MPa and
58 ± 5 psu, respectively, in the dwarf zone. Midday minimum xylem ψ was −4.3 ± 0.23 MPa in the fringe zone and −6.4 ± 0.28 MPa
in the dwarf zone. In leaves of dwarf trees, the concentration of Na + was 30% higher, while those of K +, Ca 2+ and Mg 2+ were lower by 41, 38 and 55%, respectively, than fringe trees. The Na +/K + ratio of leaves was 2.1 ± 0.03 for fringe and 5.6 ± 0.05 for dwarf trees. Rates of secretion of Na +, Cl −, K +, Ca 2+ and Mg 2+ over 24 h were significantly lower in dwarf trees by 44, 45, 78, 66 and 54%, respectively. In fringe trees, the rate of secretion
of Na + and Cl − was about 28% higher during the night than during the day, while in dwarf trees the corresponding increase was about 174%.
CO 2 exchange, leaf conductance, quantum yield of PS II, ETR through PSII and intrinsic photochemical efficiency of PS II were
significantly lower in dwarf trees by 50, 83, 39, 33 and 12%, respectively. 相似文献
16.
Crustaceans present a very interesting model system to study the process of calcification and calcium (Ca 2+) transport because of molting-related events and the deposition of CaCO 3 in the new exoskeleton. Dilocarcinus pagei, a freshwater crab endemic to Brazil, was studied to understand Ca 2+ transport in whole gill cells using a fluorescent probe. Cells were dissociated, all of the gill cell types were loaded with
fluo-3 and intracellular Ca 2+ change was monitored by adding Ca as CaCl 2 (0, 0.1, 0.25, 0.50, 1.0 and 5 mM), with a series of different inhibitors. For control gill cells, Ca 2+ transport followed Michaelis–Menten kinetics with K
m = 0.42 ± 0.04 mM and V
max = 0.50 ± 0.02 μM (Ca 2+ change × initial intracellular Ca −1 × 180 s −1; N = 14, r
2 = 0.99). Verapamil (a Ca 2+ channel inhibitor) and amiloride (a Na +/Ca 2+ exchanger [NCX] inhibitor) completely reduced intracellular Ca 2+ transport, while nifedipine, another Ca 2+ channel inhibitor, did not. Vanadate, a plasma membrane Ca 2+-ATPase inhibitor (PMCA), increased intracellular Ca 2+ in gill cells through a decrease in the efflux of Ca 2+. Ouabain increased intracellular Ca 2+, similar to the effect of KB-R, a specific NCX inhibitor for Ca 2+ in the influx mode. Alterations in extracellular [Na] in the saline did not affect intracellular Ca 2+ transport. Caffeine, responsible for inducing Ca release from sarcoplasmic reticulum in vertebrate muscle, increased intracellular
Ca 2+ compared to control, suggesting an effect of this inhibitor in gill epithelial cells of Dilocarcinus pagei, probably through release of intracellular stores. We also demonstrate here that intracellular Ca 2+ in gill cells of Dilocarcinus pagei was kept relatively constant in face of an extracellular Ca concentration of 50-fold, suggesting that crustaceans are able
to display Ca 2+ homeostasis through various Ca 2+ intracellular sequestration mechanisms and/or plasma membrane Ca 2+ influx and outflux that are highly regulatory. In summary, studies using whole gill cells are an interesting approach for
working with real regulatory Ca 2+ mechanisms in intact cells under physiological Ca levels (mM range), compared to earlier work using isolated vesicles of
various epithelial cells. 相似文献
17.
The Ca 2+-activated maxi K + channel was found in the apical membrane of everted rabbit connecting tubule (CNT) with a patch-clamp technique. The mean
number of open channels (NP
o
) was markedly increased from 0.007 ± 0.004 to 0.189 ± 0.039 ( n= 7) by stretching the patch membrane in a cell-attached configuration. This activation was suggested to be coupled with the
stretch-activation of Ca 2+-permeable cation channels, because the maxi K + channel was not stretch-activated in both the cell-attached configuration using Ca 2+-free pipette and in the inside-out one in the presence of 10 m m EGTA in the cytoplasmic side. The maxi K + channel was completely blocked by extracellular 1 μ m charybdotoxin (CTX), but was not by cytoplasmic 33 μ m arachidonic acid (AA). On the other hand, the low-conductance K + channel, which was also found in the same membrane, was completely inhibited by 11 μ m AA, but not by 1 μ m CTX. The apical K + conductance in the CNT was estimated by the deflection of transepithelial voltage (Δ V
t
) when luminal K + concentration was increased from 5 to 15 mEq. When the tubule was perfused with hydraulic pressure of 0.5 KPa, the Δ V
t
was only −0.7 ± 0.4 mV. However, an increase in luminal fluid flow by increasing perfusion pressure to 1.5 KPa markedly enhanced
Δ V
t
to −9.4 ± 0.9 mV. Luminal application of 1 μ m CTX reduced the Δ V
t
to −1.3 ± 0.6 mV significantly in 6 tubules, whereas no significant change of Δ V
t
was recorded by applying 33 μ m AA into the lumen of 5 tubules (Δ V
t
=−7.2 ± 0.5 mV in control vs.Δ V
t
=−6.7 ± 0.6 mV in AA). These results suggest that the Ca 2+-activated maxi K + channel is responsible for flow-dependent K + secretion by coupling with the stretch-activated Ca 2+-permeable cation channel in the rabbit CNT.
Received: 21 August 1997/Revised: 20 March 1998 相似文献
18.
In this study, we employed bio-derived bone scaffold and composited with the marrow mesenchymal stem cell induced into osteoblast
to replicate a “biomimetic niche.” The CD34 + cells or mononuclear cells (MNC) from umbilical cord blood were cultured for 2–5 weeks in the biomimetic niche (3D system)
was compared with conventional two dimensional cultures (2D system) without adding cytokine supplement. After 2 weeks in culture,
the CD34 + cells from umbilical cord blood in the 3D system increased 3.3–4.8 folds when compared with the initial CD34 + cells. CD34 +/CD38 − cells accounted for 82–90% of CD34 + cells. After 5 weeks, CD34 +/CD38 − cells in the 3D system increased when compared with initial (1.3 ± 0.3 × 10 3 vs. 1.0 ± 0.5 × 10 4, p < 0.05), but were decreased in the 2D system (1.3 ± 0.3 × 10 3 vs. 2.5 ± 0.7 × 10 2, p < 0.05). The CFU progenitors were produced more in the 3D system than in the 2D system (4.6–9.3 folds vs. 1.0–1.5 folds)
after 2 weeks in culture, and the colony distribution in the 3D system manifested higher percentage of BFU-E and CFU-GEMM,
but in the 2D system was mainly CFU-GM. The LTC-ICs in the 3D system showed 5.2–7.2 folds increase over input at 2 weeks in
culture, and maintain the immaturation of hematopoietic progenitor cells (HPCs) over 5 weeks. In conclusion, this new 3D hematopoietic
progenitor cell culture system is the first to utilize natural cancellous bone as scaffold with osteoblasts as supporting
cells; it is mimicry of natural bone marrow HSC niche. Our primary work has demonstrated it could maintain and expand HSC/HPC
in vitro. 相似文献
19.
Characteristics for the up-regulated response in the concentration of intracellular calcium ion ([Ca 2+]
i
) and in the sodium ion (Na +) current by serotonin (5-HT) were investigated in differentiated neuroblastoma × glioma hybrid NG108-15 (NG) cells. The results
for the changes in [Ca 2+]
i
by 5-HT were as follows, (1) The 5-HT-induced Ca 2+ response was inhibited by 3 × 10 −9 M tropisetron (a 5-HT 3 receptor blocker), but not by other types of 5-HT receptor blockers; (2) The 5-HT-induced Ca 2+ response was mainly inhibited by calciseptine (a L-type Ca 2+ blocker), but not by other types of Ca 2+ channel blockers or 10 −7 M TTX (a voltage-sensitive Na + channel blocker); (3) When the extracellular Na + was removed by exchange with choline chloride or N-methyl- d-glucamine, the 5-HT-induced Ca 2+ response was extremely inhibited. The results for the 5-HT-induced Na + current by the whole cell patch-clamp technique were as follows, (1) The 5-HT-induced Na + current in differentiated cells was significantly larger than that in undifferentiated cells; (2) The ED 50 value for 5-HT-induced Na + current in undifferentiated and differentiated cells was almost the same, about 4 × 10 −6 M each other; (3) The 5-HT-induced Na + current was completely blocked by 3 × 10 −9 M tropisetron, but not by other 5-HT receptor antagonists and 10 −7 M TTX. These results suggested that 5-HT-induced Ca 2+ response in differentiated NG cells was mainly due to L-type voltage-gated Ca 2+ channels allowing extracellular Na + to enter via 5-HT 3 receptors, but not through voltage-gated Na + channels. 相似文献
20.
There is growing concern over detrimental neurologic effects to human newborns caused by increased inspired oxygen concentrations.
We hypothesize that hyperoxia (FiO 2 > 0.95) results in increased high-affinity Ca 2+-ATPase activity, Ca 2+-influx, and proapoptotic protein expression in cortical neuronal nuclei of newborn piglets. Neuronal cerebral energy metabolism
was documented by determining ATP and phosphocreatine levels. Neuronal nuclear conjugated dienes and fluorescent compounds
were measured as indices of lipid peroxidation. High-affinity Ca 2+-ATPase activity and ATP-dependent Ca 2+-influx were determined to document neuronal nuclear membrane function. Hyperoxia resulted in increases in lipid peroxidation,
high-affinity Ca 2+-ATPase activity, ATP-dependent Ca 2+-influx, and Bax/Bcl-2 ratio in the cortical neuronal nuclei of newborn piglets. We conclude that hyperoxia results in modification
of neuronal nuclear membrane function leading to increased nuclear Ca 2+-influx, and propose that hyperoxia-induced increases in intranuclear Ca 2+ activates the Ca 2+/calmodulin-dependent protein kinase pathway, triggering increased CREB protein-mediated apoptotic protein expression in hyperoxic
neurons. 相似文献
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