Ionization and Fragmentation of Butanone Clusters Irradiated by Photons at 355 and 118 nm

Time-of-flight(TOF) mass spectra of molecular butanone clusters were measured under the irradiation of photons at 355 and 118 nm. Butanone molecular parent ion and several series of butanone cluster fragments such as (CH<,3>COC<,2>H<,5>)<,n>H<'+>, (CH<,3>COC<,2>H<,5>)nC<,2>H<,5><'+>, (CH<,3>COC<,2>H<,5>)<,n>CH<,3>CO<'+> and (CH<,3>COC<,2>H<,5>)<,n>C<,2>H<,5>CO<'+> were observed. Odd-even variation pattern in the intensity of (CH<,3>COC<,2>H<,5>)<,n>CH<,3>CO<'+> is obvious from n=4 to 8. A connection is es- tablished between the fragment clusters (CH<,3>COC<,2>H<,5>)<,n>CH<,3>CO<'+> and the neutral clusters (CH<,3>COC<,2>H<,5>)<,n+1> based on the consideration of butanone cluster dissociation mainly by losing a radical C<,2>H<,5>. The stability variation of the neu- tral clusters calculated via the HF-B3LYP method based on DFT is in agreement with the observed phenomena expe- rimentally, indicating (CH<,3>COC<,2>H<,5>)<,n+1>(n+1=5,7) with a ring structure are with higher stability over the adjacent even-number clusters.     

Red flags and religious coping: identifying some religious warning signs among people in crisis

Particulate and soluble (1-3)-beta-glucans are effective in preventing infections by enhancing macrophage and neutrophil functions. However, the mechanisms triggering these enhanced cellular responses are essentially unknown. We recently demonstrated that zymosan, a particulate (1-3)-beta-glucan receptor agonist, caused an influx of Ca2+ in NR8383 rat alveolar macrophages (AMs) and a resulting increase in intracellular Ca2+ (Zhang et al., J. Leukoc. Biol. 62 (1997) 341-348). Since Ca2+ is important in mediating leukocyte responses, we investigated whether other (1-3)-beta-glucans also alter Ca2+ mobilization in AMs. Particulate and soluble (1-3)-beta-glucans derived from Saccharomyces cerevisiae were used in these studies. Like zymosan, particulate (1-3)-beta-glucan (WGPs) caused a concentration-dependent increase in [Ca2+]i, which was inhibited by removal of extracellular Ca2+ and by SKF96365, an inhibitor of receptor-operated Ca2+ channels. When three different soluble (1-3)-beta-glucans, with molecular weights of approximately 11,000, 150,000, and 1,000,000 Da, were tested alone for effects on Ca2+ responses, the low molecular weight (1-3)-beta-glucan produced no effect and the intermediate and high molecular weight (1-3)-beta-glucans caused only a small increase in [Ca2+]i. Interestingly, however, all three soluble (1-3)-beta-glucans could significantly reduce the Ca2+ responses induced by a subsequent exposure to either WGPs or zymosan. These results demonstrate that: 1) particulate (1-3)-beta-glucan activates Ca2+ influx in NR8383 macrophages through receptor-operated Ca2+ channels; 2) soluble (1-3)-beta-glucans do not strongly activate Ca2+ influx in these cells; and 3) soluble (1-3)-beta-glucans significantly inhibit Ca2+ influx induced by WGPs or zymosan. Soluble (1-3)-beta-glucans are likely to prevent Ca2+ influx by competitively binding to the (1-3)-beta-glucan receptors recognizing zymosan and WGPs. The smaller Ca2+ influx induced by soluble (1-3)-beta-glucans may represent only a partial activation of post-receptor signal transduction pathways necessary for inducing Ca2+ influx.     

Impact of knowledge and age on tip-of-the-tongue rates

The modulation of IA K+ current by ten trivalent lanthanide (Ln3+) cations spanning the series with ionic radii ranging from 0.99 A to 1.14 A was characterized by the whole-cell patch clamp technique in bovine adrenal zona fasciculata (AZF) cells. Each of the ten Ln3+s reduced IA amplitude measured at +20 mV in a concentration-dependent manner. Smaller Ln3+s were the most potent and half-maximally effective concentrations (EC50s) varied inversely with ionic radius for the larger elements. Estimation of EC50s yielded the following potency sequence: Lu3+ (EC50 = 3.0 microM) approximately Yb3+ (EC50 = 2.7 microM) > Er3+ (EC50 = 3.7 microM) >/= Dy3+ (EC50 = 4.7 microM) > Gd3+ (EC50 = 6.7 microM) approximately Sm3+ (EC50 = 6.9 microM) > Nd3+ (EC50 = 11.2 microM) > Pr3+ (EC50 = 22.3 microM) > Ce3+ (EC50 = 28.0 microM) > La3+ (EC50 = 33.7 microM). Ln3+s altered selected voltage-dependent gating and kinetic parameters of IA with a potency and order of effectiveness that paralleled the reduction of IA amplitude. Ln3+s markedly slowed activation kinetics and shifted the voltage-dependence of IA gating such that activation and steady-state inactivation occurred at more depolarized potentials. In contrast, Ln3+s did not measurably alter inactivation or deactivation kinetics and only slightly slowed kinetics of inactivated channels returning to the closed state. Replacement of external Ca2+ with Mg2+ had no effect on the concentration-dependent inhibition of IA by Ln3+s. In contrast to their action on IA K+ current, Ln3+s inhibited T-type Ca2+ currents in AZF cells without slowing activation kinetics. These results indicate that Ln3+ modulate IA K+ channels through binding to a site on IA channels located within the electric field but which is not specific for Ca2+. They are consistent with a model where Ln3+ binding to negative charges on the gating apparatus alters the voltage-dependence and kinetics of channel opening. Ln3+s modulate transient K+ and Ca2+ currents by two fundamentally different mechanisms.     

改性纳米二氧化钛分离富集电感耦合等离子体原子发射光谱法测定地质样品中金钯铑

纳米TiO2用二苯基硫脲修饰后得到改性纳米TiO2,改性纳米TiO2对Au3+、Pd2+和Rh3+有很强的吸附能力,被用于Au3+、Pd2+和Rh3+分离富集。将该分离富集方法与电感耦合等离子体原子发射光谱法(ICP AES)相结合建立了测定地质样品中Au、Pd和Rh的新方法。考察了溶液酸度、洗脱条件和干扰离子等因素对分析物的分离富集影响。结果表明,在pH 40,Au3+、Pd2+和Rh3+可被改性纳米TiO2定量富集,吸附率在95%以上;而K+、Na+、Ca2+、Mg2+、Zn2+、Ni2+、Ba2+、Co2+、Cd2+和Mn2+不被吸附,Fe2+、In3+和Ga3+部分被吸附,但对测定没有影响。吸附的贵金属离子可用20 g/L CS(NH2)2 和 2 mol/L HCl溶液完全洗脱。在优化的实验条件下,吸附剂对Au3+、Pd2+ 和Rh3+的吸附容量分别为2163 mg /g, 1282 mg/g和1956 mg/g。本法对Au3+、Pd2+和Rh3+的检出限(3σ)分别为：061 ng/mL, 058 ng/mL和189 ng/mL,样品测定结果的相对标准偏差(RSD)分别为17%, 26%和18 (n=11)。该法应用于标准样品(GBW07293)中Au3+、Pd2+和Rh3+的测定,测定值与认定值相符。     

Preparation and Luminescent Properties of BAM Blue Phosphor forPDP and CCFL

The Bax-0.05MgAl10O16 x :Eu0.05^2 (0.88≤ x≤ 1.02) phosphors with different Ba^2 content and the Ba0.85MgAl10O16.94:Eu0.05^2 phosphors with different fluxes (BaF2, MgF2, AlF3, BaCl2, MgCl2, AlCl3, H3BO3)were prepared by high temperature solid-state reaction method and their luminescence characteristics were studied under 254 nm excitation and vacuum ultraviolet (VUV) excitation. With the increase of the Ba^2 content, there is an increase in the emission intensity, and when x = 0.94, it reaches a maximum. Then, as the Ba^2 content increases, the emission intensity slowly falls. The fluorides have better flux-effects than chlorides and H3BO3. The possible mechanism in the process of particle growth was discussed when fluorides were used as fluxes. The effect of the activator concentration on this system was also investigated. The quenching concentration is 0.13 mol in per mole host.     

Fe-Ni-O-C体系中Fe、Ni的固态还原机理

运用差示扫描量热法、采用XRD检测等手段探讨研究了Fe-Ni-O-C体系中Fe、Ni的还原行为,样品主要包括NiO+C、Fe₂O₃+C、NiFe₂O₄+C、NiO+Fe₂O₃+C和Ni+Fe₂O₃+C等5种体系.结果表明:NiO+Fe₂O₃体系中由于NiFe₂O₄及Fe-Ni合金的生成使得该体系被还原的反应开始温度高于纯NiO,且最大反应速率对应的温度及还原反应结束温度均高于纯NiO但低于纯Fe₂O₃物质;相对于NiO+Fe₂O₃,NiFe₂O₄被C还原的开始及结束温度均更高,且还原速率更小;Fe₂O₃被C还原可分为三个阶段,金属Ni的存在能够明显促进铁氧化物的还原,主要是促进了Fe的各种氧化物形式(Fe₂O₃、Fe₃O₄和FeO)直接向金属Fe形式的转换;数据显示C还原NiFe₂O₄的过程也基本可分为三个阶段,不同阶段中产物的形态和种类均存在一定差别.     

Study on Separation of Lanthanum from Praseodymium Complexes with IMDA by Gel and Macroporous Anion Exchangers

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The effects of starch and protein degradation rates, hay sources, and feeding frequency on rumen microbial fermentation in a continuous culture system

Six continuous culture fermenters were used in three experiments to study the effects of dietary starch and protein degradability combination, hay sources, and feeding frequency on fermentation by rumen microorganisms. Experiments 1 and 2 used a 3 x 2 factorial design in which six diets were formulated to contain low (LS), medium (MS), or high starch degradability (HS) in combination with low (LP) or high protein degradability (HP). The dietary combinations were (1) LS + HP, (2) LS + LP, (3) MS + HP, (4) MS + LP, (5) HS + HP, and (6) HS + LP. In experiment 1, pangola was used as the hay source, and in experiment 2, alfalfa hay was used. In experiment 3, two starch degradabilities (LS, MS) and two hay sources (alfalfa, A; pangola, P) were combined with two feeding frequencies (2 X/d, 12 X/d). The dietary combinations were (1) LS + A + 12 X/d, (2) MS + A + 12 X/d, (3) LS + A + 2 X/d, (4) MS + A + 2 X/d, (5) LS + P + 12 X/d, and (6) MS + P + 12 X/d. A CRD design was used for experiment 3. Two rumen-cannulated Holstein cows fed alfalfa hay ad lib were used as donors of rumen fluid for all experiments. Each period was 6 d in length, with 5 d for adaptation and 1 d for sampling. In experiments 1 and 2, the effects of starch degradability on the composition of rumen microorganisms were significant. The MS or HS with HP had the highest total bacterial and protozoal density (P < 0.05). As for VFA, pH and nitrogen products, the effects of starch and protein degradability were not significant. There was no interaction between starch and protein degradability on most of microbial composition (ammonia-N, microbial nitrogen). In experiment 3, 12 X/d feeding frequency (MS + A + 12 X/d vs. MS + A + 12 X/d) resulted in higher pH, which tended to increase bacterial and protozoal density and starch and protein digestibilities. Different hay sources altered the starch and protein synchronization effect on the ammonia-N concentration (mg/dl) and non-ammonia N content (% DM) in the continuous culture system.     

Viscosities of ternary systems Y（NO_3）_3＋La（NO_3）_3＋H_2O,La（NO_3）_3＋Ce（NO_3）_3＋H_2O,La（NO_3）_3＋Nd（NO_3）_3＋H_2O and their binary subsystems at different temperatures

Viscosities were measured for the ternary systems Y(NO3)3+La(NO3)3+H2O, La(NO3)3+Ce(NO3)3+H2O, and La(NO3)3+Nd(NO3)3+ H2O and their binary subsystems Y(NO3)3+H2O, La(NO3)3+H2O, Ce(NO3)3+H2O, and Nd(NO3)3+H2O at 293.15, 298.15 and 308.15 K. The results were used to test the applicability of simple equations for the viscosity of the mixed solutions. The predictions agreed well with measured values, implying that the viscosities of the examined electrolyte solutions could be related to those of their constituent binary solutions using these simple equations.     

Biochemical and functional heterogeneity of rat cerebrum microsomal membranes in relation to SERCA Ca(2+)-ATPases and Ca2+ release channels

Rat cerebrum microsomes were subfractionated on isopycnic linear sucrose (20-42%) density gradients. The Ca2+ loading/release properties and the distribution of intracellular Ca2+ store channels, inositol 1,4,5-trisphosphate (IP3) receptor and ryanodine (Ry) receptor, and SERCA pumps, were monitored in each subfraction by ligand binding and 45Ca2+ loading/release assays. Three different classes of vesicles were identified: (i) heavy density vesicles with high content of Ry receptors and Ca2+ pumps and high thapsigargin (TG)-sensitivity of Ca2+ loading; (ii) intermediate sucrose density vesicles with high content of IP3 receptor, high IP(S)3-sensitivity of Ca2+ loading and low content of Ry receptors; and (iii) light sucrose density vesicles with high content of Ry receptors, low content of IP3 receptors and low content of SERCA pumps highly sensitive to TG. Isolation of molecularly heterogeneous rat cerebrum microsomes and identification of specific Ca2+ loading/release properties support the presence of multiple, potentially active, heterogeneous rapidly exchanging Ca2+ stores in rat cerebrum.     

Mechanism and specificity of lanthanide series cation transport by ionophores A23187, 4-BrA23187, and ionomycin

A23187, 4-BrA23187, and ionomycin transport several lanthanide series trivalent cations at efficiencies similar to Ca2+, when compared at cation concentrations of approximately 10(-5) M, ionophore concentrations of approximately 10(-6) M, and a pH of 7.00. Selectivity sequences and the range of relative rates are as follows: A23187, Nd3+ > La3+ > Eu3+ > Gd3+ > Er3+ > Yb3+ > Lu3+ (approximately 34-fold); 4-BrA23187, Nd3+ > Eu3+ > Gd3+ > La3+ > Er3+ > Yb3+ > Lu3+ (approximately 34-fold); ionomycin, La3+ > Yb3+ > Nd3+ > Lu3+ > Er3+ > Eu3+ > Gd3+ (approximately 4-fold). At concentrations between 9 and 250 microM, La3+ is transported by an electroneutral mechanism, predominately through mixed complexes of the type (ionophore)2La-OH (A23187 and 4-BrA23187) or (ionophore)La-OH (ionomycin), when no membrane potential is present. For all three ionophores, an induced potential of approximately 160 mV accelerates transport by approximately 50-100%. However, measured values of H+/La3+ exchange indicate that only 4-BrA23187 displays a significant electrogenic activity under these conditions. At a La3+ concentration of 17 mM, transport by all three ionophores is electroneutral and apparently occurs through complexes of type (ionophore)3La (A23187 and 4-BrA23187) or (ionophore)La-OH (ionomycin). Analysis of these patterns in a context of comproportionation equilibria involving the transporting species and free La3+ indicates that the species containing three ionophore molecules are formed on the membrane when aqueous phase solution conditions would strongly favor a 1:1 complex, based upon previous studies in solution. The implications of this and other findings are discussed.     

Studies on synthesis and fluorescent property of rare earth complexes RE（ABMF）2AA and copolymers RE（ABMF）2AA-co-MMA

Four new complexes RE(ABMF)2AA (RE=Sm, Eu, Tb, Dy) were synthesized by the reaction of RECl3·6H2O with acrylic acid (HAA) and 1-(2-furyl)-3-phenyl-1,3-propanedione (ABMF). The copolymerization of the rare earth complexes with methyl methacrylate was studied by using 2,2-azobis-isobutyronitrile as an initiator. The composition and structure of the four complexes were characterized by elemental analysis, UV-vis and FTIR. The glass transition temperature and molecular weight of the copolymers were determined. Photoluminescent measurement showed that ligand ABMF could efficiently transfer the energy to Sm3+ and Eu3+ ions in the complexes and sensitize the luminescence of the rare earth ions, but could not sensitize Tb3+ and Dy3+ ions. As a result, both Sm3+ and Eu3+ complexes emitted the characteristic fluorescence of Sm3+ and Eu3+ ions due to the f-f transitions. The four copolymers could emit strong fluorescence of the rare earth ions.     

Structural determinants of Ca2+ exchange and affinity in the C terminal of cardiac troponin C

The C terminal of cardiac troponin C (TnC) has two Ca2+-Mg2+ sites which exhibit approximately 20-fold higher Ca2+ affinity than the two C-terminal Ca2+ specific sites in calmodulin (CaM). Substitution of the third EF-hand of TnC for the corresponding EF-hand of CaM produced a mutant (CaM[3TnC]) with a 10-fold higher C-terminal Ca2+ and Mg2+ affinity. Substitution of loop 3 of TnC for loop 3 of CaM produced a mutant (CaM[loop3TnC]) with a 10-fold faster Ca2+ on rate and a 5-fold faster Ca2+ off rate than CaM. A mutant CaM (CaM[loop3X, Z]) which contained the identical coordinating amino acids and X and Z acid pairs of TnC loop 3 had a 3-fold higher C-terminal Ca2+ affinity without the increased Ca2+ exchange rates exhibited by CaM[loop3TnC]. Thus, loop factors other than the acid pairs must be responsible for the rapid Ca2+ exchange rates of CaM[loop3TnC]. Helix 6 and helix 5 in the third EF-hand of TnC support the rapid Ca2+ on rate of TnC's loop 3 and produce an approximately 4-fold reduction in its Ca2+ off rate, explaining the high Ca2+ affinity of the third EF-hand of TnC. Exchanging loop 3 or helix 5 of TnC into CaM increased the Mg2+ affinity by decreasing the Mg2+ off rate. Our results are consistent with the high Ca2+ and Mg2+ affinity of the third EF-hand of TnC resulting from the two (X and Z) acid pairs in loop 3, coupled with the greater hydrophobicity of helix 6 and helix 5 compared to that of the third EF-hand of CaM.     

Rapid activation and partial inactivation of inositol trisphosphate receptors by inositol trisphosphate

During superfusion of permeabilized hepatocytes, submaximal concentrations of inositol 1,4,5-trisphosphate (InsP3) evoked quantal Ca2+ mobilization: a rapid acceleration in the rate of 45Ca2+ release abruptly followed by a biphasic decline to the basal rate before the InsP3-sensitive stores had fully emptied. During the fast component of the decay, the Ca2+ permeability of the stores fell rapidly by 40% (t1/2 = 250 ms) to a state indistinguishable from that evoked by preincubation with InsP3 under conditions that prevented Ca2+ mobilization. This change was accompanied by a decrease in the InsP3 dissociation rate: the response declined more quickly when InsP3 was removed during the initial stages of a response than later. We suggest that InsP3 directly causes its receptor to rapidly switch (t1/2 = 250 ms) between a low-affinity (Kd approximately 1 microM) active, and a higher-affinity (Kd approximately 100 nM) less active, conformation, and that this transition underlies the fast component of the decaying phase of Ca2+ release. Ca2+ continues to leak through the unchanging less active state of the receptor until those stores that responded initially are completely empty, accounting for the slow phase of the response. The requirements for activation of InsP3 receptors are more stringent (InsP3 and then Ca2+ binding) than those for partial inactivation (InsP3 binding); rapid inactivation is therefore likely to determine whether the cytosolic [Ca2+] reaches the threshold for regenerative Ca2+ signals.     

Inositol trisphosphate and cyclic ADP-ribose-mediated release of Ca2+ from single isolated pancreatic zymogen granules

In pancreatic acinar cells low (physiological) agonist concentrations evoke cytosolic Ca2+ spikes specifically in the apical secretory pole that contains a high density of secretory (zymogen) granules (ZGs). Inositol 1,4,5-trisphosphate (IP3) is believed to release Ca2+ from the endoplasmic reticulum, but we have now tested whether the Ca(2+)-releasing messengers IP3 and cyclic ADP-ribose (cADPr) can liberate Ca2+ from AGs. In experiments on single isolated ZGs, we show using confocal microscopy that IP3 and cADPr evoke a marked decrease in the free intragranular Ca2+ concentration. Using a novel high resolution method, we have measured changes in the Ca2+ concentration in the vicinity of an isolated AG and show that IP3 and cADPr cause rapid Ca2+ release from the granule, explaining the agonist-evoked cytosolic Ca2+ rise in the secretory pole.     

Ca2+-dependent inactivation of a store-operated Ca2+ current in human submandibular gland cells. Role of a staurosporine-sensitive protein kinase and the intracellular Ca2+ pump

Stimulation of human submandibular gland cells with carbachol, inositol trisphosphate (IP3), thapsigargin, or tert-butylhydroxyquinone induced an inward current that was sensitive to external Ca2+ concentration ([Ca2+]e) and was also carried by external Na+ or Ba2+ (in a Ca2+-free medium) with amplitudes in the order Ca2+ > Ba2+ > Na+. All cation currents were blocked by La3+ and Gd3+ but not by Zn2+. The IP3-stimulated current with 10 microM 3-deoxy-3-fluoro-D-myo-inositol 1,4,5-triphosphate and 10 mM 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid in the pipette solution, showed 50% inactivation in <5 min and >5 min with 10 and 1 mM [Ca2+]e, respectively. The Na+ current was not inactivated, whereas the Ba2+ current inactivated at a slower rate. The protein kinase inhibitor, staurosporine, delayed the inactivation and increased the amplitude of the current, whereas the protein Ser/Thr phosphatase inhibitor, calyculin A, reduced the current. Thapsigargin- and tert-butylhydroxyquinone-stimulated Ca2+ currents inactivated faster. Importantly, these agents accelerated the inactivation of the IP3-stimulated current. The data demonstrate that internal Ca2+ store depletion-activated Ca2+ current (ISOC) in this salivary cell line is regulated by a Ca2+-dependent feedback mechanism involving a staurosporine-sensitive protein kinase and the intracellular Ca2+ pump. We suggest that the Ca2+ pump modulates ISOC by regulating [Ca2+]i in the region of Ca2+ influx.     

Brain beta-endorphin immunoreactivity as an index of cocaine and combined cocaine-ethanol toxicities

OBJECTIVE: IP3-induced Ca2+ release from the intracellular stores plays a role in the production of vasoactive substances in the endothelium. In many cells, Ca2+ release is accompanied by an inward movement of K+ whose function may be to dissipate the potential difference created by the loss of positive charge from the internal stores. The existence of such a mechanism in endothelial cells was investigated. METHODS: Using saponin-permeabilised bovine aortic endothelial (BAE) cells, the effects of K+ on the IP3-induced 45Ca2+ release were investigated. RESULTS: Replacement of K+ with NMG inhibited IP3 (3 microM)-induced 45Ca2+ release by 55%. The ability of other ions to allow IP3-induced 45Ca2+ release was found to be K+ = Na+ > Cs+ > Rb+ > Co2+. The K+ channel blockers TEA, 4AP and 3,4-DAP were found to significantly inhibit IP3-induced 45Ca2+ release by 16%, 36% and 27%, respectively. CONCLUSIONS: The data suggest that Ca2+ release from intracellular stores is partly dependent on a movement of K+ through K+ channels in the store membranes. In contrast, 9AA (400 microM) and substitution with Co2+ abolished the response. Therefore, K+ is important for IP3-induced 45Ca2+ release, but other ions are also likely to act as counter-ions. 9AA and Co2+ probably act on sites other than those involving ER monovalent cation channels. The possibility that a counter-ion system plays a role in the activation of endothelial cells is discussed.     

Differential expression of gangliosides and galactolipids in fetal human oligodendrocytes and astrocytes in culture

The phenotypic expression of gangliosides and galactolipids was investigated using primary cultures of fetal human oligodendrocytes and astrocytes. These glial cells were isolated from fetal human brains of 12-18 weeks' gestation. Expression of gangliosides and galactolipids in oligodendrocytes and astrocytes was investigated by double labeling immunocytochemistry using rabbit antibodies specific for galactocerebroside (GalC, a cell type-specific marker for oligodendrocyte) and glial fibrillary acidic protein (GFAP, a cell type-specific marker for astrocyte) in combination with a panel of mouse monoclonal antibodies which react with specific gangliosides or galactolipids. A considerable number of GalC+ oligodendrocytes expressed intense immunoreactivities specific for GM3 (19%) and GM2 (45%) gangliosides. Approximately 11% of GalC+ oligodendrocytes expressed GM4 immunoreactivity, and smaller numbers of GalC+ oligodendrocytes expressed GD3 (4%), GD2 (1%), GT1b (5%) and A2B5 (3%) immunoreactivities. However, GalC+ oligodendrocytes did not express GM1, GD1a, GT1b or GQ1c. Major populations of GalC+ oligodendrocytes immunolabeled by rabbit anti-GalC antibody reacted with anti-GalC mAb (Ranscht mAb, 81%) or by anti-sulfatide mAb (O4 mAb, 91%). A considerable number of GFAP+ astrocytes expressed intense GM2 (26%) and GD2 (15%) immunoreactivities, while a smaller population expressed intense GM3 (3%), GD3 (6%) and GM4 (4%) immunoreactivities. Weak immunoreactions specific for GD1b, A2B5 and sulfatide were found in less than 1% each of GFAP+ astrocytes, while GFAP+ astrocytes did not express GM1, GD1a, GT1a, GT1b or GQ1b. These results indicate that GM3, GM2 and sulfatide are expressed in a major population of GalC+ oligodendrocytes, while GM3, GM2, GD3, GD2, and GM4 are expressed in a small but distinctive population of GFAP+ astrocytes. Our results suggest that GM4, GM1 and GD3, which are utilized as markers for adult human oligodendrocytes and myelin, are not the major ganglioside constituents in cultured fetal human oligodendrocytes.     

Properties of the Ca2+ influx reveal the duality of events underlying the activation by vanadate and fluoride of the Gárdos effect in human red blood cells

The properties of the 45Ca2+ influx by human red blood cells (RBC) induced by NaVO3 or NaF were compared. The NaVO3-induced 45Ca2+ influx was slower and less extensive than that induced by NaF. Both processes were saturable with Ca2+. Substitution of Na+ by K+ inhibited the 45Ca2+ influx induced by NaVO3 but stimulated that by NaF. The NaVO3-induced Ca2+ influx was sensitive to nifedipine (IC50 = 50 mol/l), Cu2+ (IC50=9 mol/l), DTNB (5,5'-dithiobis-(dinitrobenzoic acid)) (IC50 = 12 mol/l) (maximal inhibition 16%, 18%, and 28%, respectively, if NaF was used as inducer). On the other hand, tetrodotoxin (TTX) and cyclosporin A inhibited only the NaF-induced 45Ca2+ influx (IC50 = 21 mol/l and 28 mol/l, respectively). Pig RBC, known not to display the NaVO3-induced Ca2+ influx, exhibited Ca2+ influx induced by NaF. The results show that NaVO3 activates the Ca2+ influx via a pathway homologous to the L-type Ca2+ channel while the NaF-induced Ca2+ influx is mediated via the TTX-sensitive Na+ channel in the presence of NaF with possible participation of calcineurin or cyclophilin. Thus, the Gardos effect induced by NaVO3 and NaF represents two phenomena activated by different mechanisms present in the cryptic state in the RBC membrane.     

沉金后液中金、铂、钯、碲的组态特征及其碲捕集稀贵金属机制

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