Effect of angiotensin II receptor blocker on angiotensin II stimulated dna synthesis of cultured human aortic smooth muscle cells

To examine the role of the renin-angiotensin system on human vascular smooth muscle cell (VSMC) replication, we studied the effect of DUP753, an angiotensin II (ANG II) type 1 receptor antagonist, on ANG II stimulated tritiated-thymidine (³H-Tdr) incorporation into cultured human aortic VSMC. ANG II stimulated DNA synthesis of VSMC in a dose-dependent manner as estimated by ³H-Tdr incorporation (control; 2993 ± 486 cpm, 10⁻⁸M; 3360 ± 350 cpm, 10⁻⁷M; 3474 ± 516 cpm, 10⁻⁶M; 4889 ± 320 cpm, P < 0. 01). The effects of ANG II were clearly inhibited by 10⁻⁶M DUP 753 (ANG II 10⁻⁸M; 3360 ± 350 vs 509 ± 39 cpm, 10⁻⁷M; 3474 ± 516 vs 661 ± 36 cpm, 10⁻⁶M; 4889 ± 320 vs 806 ± 76 cpm, each P < 0. 01). This receptor antagonist decreased the basal ³H-Tdr incorporation of VSMC from 2933 ± 486 to 411 ±78 cpm (P < 0. 01). Furthermore, DUP 753 decreased 10⁻⁷M ANG II-stimulated ³H-Tdr incorporation of VSMC in a dose-dependent manner (control; 2627 ± 256 cpm, 10⁻⁹M; 2145 ± 143 cpm, 10⁻⁸M; 1047 ± 543 cpm, 10⁻⁷M; 639 ± 169 cpm, 10⁻⁶M; 642 ± 59 cpm, P < 0. 01). These observations suggest that, in human VSMC, ANG II type 1 receptors are important for the regulation of both stimulated and basal cell proliferation. It may therefore be worth while to examine the clinical usefulness of DUP 753 for preventing abnormal VSMC growth.     

Evaluation of crystalline amino acids,betaine and AMP as food attractants of the giant tiger prawn (Penaeus monodon)

Laboratory observations of substrate probing by the chelate walking legs (chelipeds), antennular flicking rate and maxilliped activity of the prawn Penaeus monodon were used to evaluate various chemicals at seven different concentrations between 10⁻¹M and 10⁻⁷M as feeding stimulants. Exposure to amino acids (alanine, arginine, glutamine, glycine, isoleucine, serine and taurine) and betaine resulted in higher rates of substrate probing, antennular flicking and maxilliped activity in P. monodon at higher pipette concentrations (>10⁻²M) than at lower concentrations. Least response occurred in prawns which were exposed to nucleotide, adenosine 5′-monophosphate. Glutamine, betaine and taurine were the most effective single compounds tested, and stimulated significantly higher activities (p < 0.05) in prawns at concentrations above 10⁻⁶M than did controls (seawater only).An equimolar mixture of amino acids and betaine was also found to be an effective stimulant to P. monodon at concentrations above 10⁻⁶M and continued to elicit search responses in prawns at concentrations lower than that of any of the single chemicals. Such a strong response is consistent with synergistic interactions of the mixtures. All four molt stages tested (C, D₀, D₁, D₂) were equally responsive to food attractants.     

C2-ceramide primes specifically for the superoxide anion production induced by N-formylmethionylleucyl phenylalanine (fMLP) in human neutrophils

Activated sphingomyelinases release ceramide molecules believed to be involved in intracellular signalling. The present study investigated whether soluble C₂-ceramide modulates some of the effects of N-formylmethionylleucyl phenylalanine (fMLP) and other agonists on human neutrophils (or polymorphonuclear leukocytes-PMN); principally superoxide anion (O₂⁻) production. The preincubation of PMN for 15 min with C₂-ceramide increased by up to almost 3-fold the amounts of O₂⁻ generated in response to 0.1 and 1 μM fMLP. Priming was detected at C₂-ceramide concentrations of 2 μM to 4 μM per million PMN. Though less potent than C₂-ceramide, C₆-ceramide (N-hexanoylsphingosine) could prime for O₂⁻ generated in response to 0.1 μM fMLP, with maximal effects obtained at 10–20 μM. In contrast, micromolar concentrations of sphingosine, dihydroceramide, and ceramide-phosphate, failed to exert any potentiating effect on fMLP-induced O₂⁻ generation. As expected, TNF-α (1000 U/ml), also primed for fMLP-induced O₂⁻ production; however, the combination of TNF-α and C₂-ceramide showed no additive effect. Moreover, S. aureus sphingomyelinase (0.1 U/ml), was unable to reproduce the priming effects of C₂-ceramide and TNF-α. C₂-ceramide at 2 μM did not enhance the production of O₂⁻ induced by 100 nM recombinant human interleukin-8 (IL-8), leukotriene B₄ (LTB₄), platelet-activating factor (PAF) or 20 mM sodium fluoride (NaF). Furthermore, C₂-ceramide (2 μM) did not enhance the mobilization of calcium, the release of arachidonic acid or the accumulation of phosphatidylethanol, induced by 100 nM fMLP. This suggests that probably neither phospholipases C, A₂ or D (PLC, PLA₂, PLD) were involved in the priming effect by C₂-ceramide. However, C₂-ceramide inhibited in a dose-related manner the production of O₂⁻ induced by phorbol 12-myristate 13-acetate (PMA) and mezerein. Furthermore, PMA-stimulated PLD activity was also significantly reduced by a preincubation of PMN with C₂-ceramide. The priming O₂⁻ production by C₂-ceramide could involve yet unidentified mechanisms specific for fMLP, or it might imply that cytokines such as TNF-α have different mechanisms than C₂-ceramide.     

Exogenous phosphatidic acid with saturated short-chain fatty acyl groups induces superoxide anion release from guinea pig peritoneal polymorphonuclear leukocytes by three different mechanisms

Treatment of suspensions of guinea pig peritoneal polymorphonuclear leukocytes (PMN) with four species of phosphatidate (PA) containing short-chain fatty acids induced sustained superoxide anion (O₂⁻) production after a lag time. The rank order of efficiency of these PAs in triggering O₂⁻ production was PA_8:0 [1,2-dioctanoyl-sn-glycerol-3-phosphate (GP)]>PA_10:0 (1,2-didecanoyl-GP)>PA_6:0 (1,2-dicaproyl-GP)≫PA_12:0 (1,2-dilauroyl-GP). The O₂⁻ release from PMN stimulated with PA_10:0 or PA_12:0, but not with PA_6:0 or PA_8:0, was lowered by the addition of 1 mM extracellular Ca²⁺. Studies with various inhibitors showed that the mechanism of multiphasic O₂⁻ production induced by PA_8:0 depended on its concentration: 1 and 3 μM PA_8:0 induced O₂⁻ production constantly after a lag time through a protein kinase-dependent mechanism that was inhibited by 100 nM staurosporine. With concentrations of PA of 10 μM or more, an additional mechanism that was independent of protein kinase became operative and predominant over the protein kinase-dependent one. This protein kinase-independent mechanism was inhibited selectively by 80 μM TMB-8. Concentrations of 30, 60 and 100 μM PA first elicited transient O₂⁻ production via another protein kinase-dependent mechanism that was more sensitive to H-7 than to staurosporine, and then sustained O₂⁻ production, mainly driven by the protein kinase-independent mechanism. Metabolism of exogenously added [¹⁴C]PA_8:0 in intact PMN was examined in the presence and absence of propranolol. Results suggest that PA itself is more important rather than its degradation products such as diacylglycerol, in inducing O₂⁻ production via three different mechanisms described above.     

Hypoxia inverts the negative chronotropic response to norepinephrine in normoxia in cultured neonatal rat cardiac myocytes: role of the α1 adrenergic signal transduction system

In the present study, we investigated the effect of hypoxia on the chronotropic response to norepinephrine (NE) of cultured neonatal rat ventricular myocytes. We measured beating of myocytes with the Fotonic sensor^TM, using a newly developed method for a noncontact displacement measurement. The beating rate counted with the sensor had a high correlation coefficient with that counted visually under a microscope (r = 0.997, P < 0.01). NE concentrations of 10⁻⁸–10⁻⁴ M caused negative chronotropy dose dependently in the presence of 5×10⁻⁷ M propranolol. NE-induced chronotropy was completely antagonized by 10⁻⁶ M prazosin. Three hours hypoxia decreased the spontaneous beating rate 40% (P < 0.01). Negative chronotropy induced by 10⁻⁴ M NE in normoxia was inverted to positive and was antagonized by prazosin. Hypoxia increased the basal level of inositol 1,4,5-trisphosphate (Ins(1,4,5)P₃) to 190% (P < 0.01), while NE-stimulated Ins(1,4,5)P₃ production was significantly suppressed. Immunoblotting analysis of G protein subunits demonstrated no quantitative changes in Giα, Gqα, Goα and G_βcommon subunits in hypoxia. In a saturation binding assay with [³H]prazosin, K_d values were increased to 152% by hypoxia (P < 0.05) without significant change in B_max. Basal activity of low K_m-GTPase was increased to 122% by hypoxia (P < 0.05). These results suggest that the hypoxia-induced increase in low-K_m GTPase activity, which could stimulate phospholipase C by an activated α_GTP subunit of G protein and consequently induce receptor-independent increase in Ins(1,4,5)P₃, may be responsible for the inversion of the NE-induced negative chronotropic response in normoxia.     

Effects of adrenergic drugs on the activity of tryptophan hydroxylase in midbrain raphe slices of the rat

The effects of α- and ß-adrenergic drugs on the activity of tryptophan hydroxylase were investigated in rat midbrain raphe slices. The tryptophan hydroxylase activity in slices was estimated by measuring the formation of 5-hydroxytryptophan (5-HTP) under inhibition of aromatic l-amino acid decarboxylase using 3-hydroxy-4-bromobenzyloxyamine (NSD 1055). Isoproterenol, a ß-adrenergic stimulant, significantly increased 5-HTP formation to 122% (P < 0.05) of control at 10⁻⁶ M and this effect was prevented by 10⁻⁶ M of propranolol, a ß-adrenergic blocker. 5-(1-Hydroxy-2-isopropylaminobutyl)-8-hydroxycarbostryril hydrochloride hemihydrate (OPC 2009), a ß-adrenergic stimulant which does not contain a catechol group, increased 5-HTP formation to 145% at 10⁻⁶ M. A-23187 at 5 × 10⁻⁷ M further enhanced the isoproterenol-stimulated 5-HTP formation to 156% of control. Dibutyryl cAMP at 10⁻² M, however, did not enhance it. 8-Bromo cAMP did not enhance the OPC 2009-stimulated 5-HTP formation, either. An α-adrenergic stimulant, clonidine, had no effect on 5-HTP formation. But an α-adrenergic blocker, yohimbine, reduced 5-HTP formation to 78% at 10⁻⁶ M. These results suggest that the activity of tryptophan hydroxylase can be controlled by a ß-adrenergic receptor coupled with adenylate cyclase via an intracellular cAMP-dependent process.     

Dynamic reorganization of the alkaline phosphatase-containing compartment during chemotactic peptide stimulation of human neutrophils imaged by backscattered electrons

Scanning electron microscopy (EM) and cytochemical techniques were used to examine the alkaline phosphatase-containing compartment in human neutrophils after stimulation with nanomolar concentrations of N-formylmethionyl-leucyl-phenylalanine (10^–8M fMLP). Alkaline phosphatase (AlkPase) activity was demonstrated with a lead-based metal capture cytochemical method. The reaction product was visualized with the backscattered electron imaging mode of scanning EM, and analyzed by electron probe X-ray microanalysis. Alkaline phosphatase activity was detected only in fMLP-stimulated neutrophils; unstimulated neutrophils displayed no activity. Stimulation of human neutrophils with 10^–8 M fMLP induced a time-dependent intracellular redistribution of irregular round or tubular granules containing alkaline phosphatase activity, as seen by backscattering. The intracellular redistribution of alkaline phosphatase activity was accompanied by increased cytochemical activity on the cell surface. The reaction product was localized preferentially on ridges and folds of polar neutrophils. Reorganization of the AlkPase-containing compartment correlated with changes induced by fMLP in cell shape, ie, membrane ruffling and front-tail polarity, as observed with the secondary electron image mode of scanning EM. These findings demonstrate the intracellular reorganization, increase, and asymmetric distribution of alkaline phosphatase activity on the plasma membrane of human neutrophils after stimulation by chemotactic peptides.     

Interactions between cAMP- and cGMP-dependent protein kinase inhibitors and phosphodiesterase IV inhibitors on arachidonate release from human monocytes

The effects of specific inhibitors of cAMP-dependent protein kinase (PKA) and cGMP-dependent protein kinase (PKG) on the inhibitory activity of phosphodiesterase (PDE) type IV inhibitors and of the cell permeable analogue of cAMP, db-cAMP, were investigated on fMLP-induced arachidonate release from human monocytes. When monocytes were preincubated with the combined PKA/PKG inhibitor H8 (10⁻⁶ to 10⁻⁴ M) or the selective PKG inhibitor Rp-8-cpt-cGMPs (10⁻⁶ to 10⁻⁴ M) a concentration-dependent reduction of the inhibitory effect of db-cAMP (10⁻ M), rolipram (10⁻⁵ M) and Ro 20-1724 (10⁻⁵ M) was noted. When monocytes were preincubated with the selective PKA inhibitor H89 (10⁻⁶ to 10⁻⁴ M), only a small inhibition of the effect of db-cAMP and no inhibition of the effects of rolipram and Ro 20–1724 were observed. The present data indicate that db-cAMP and PDE IV inhibitors elicit an in vitro anti-inflammatory activity by a PKA-independent mechanism, which do not appear to be mainly mediated via the PKG activation.     

The effect of nitrogen containing bisphosphonates,zoledronate and alendronate,on the production of pro-angiogenic factors by osteoblastic cells

Bisphosphonates (BPs) have been shown to influence angiogenesis. This may contribute to BP-associated side-effects such as osteonecrosis of the jaw (ONJ) or atypical femoral fractures (AFF). The effect of BPs on the production of angiogenic factors by osteoblasts is unclear. The aims were to investigate the effect of (1) alendronate on circulating angiogenic factors; vascular endothelial growth factor (VEGF) and angiopoietin-1 (ANG-1) in vivo and (2) zoledronate and alendronate on the production of VEGF and ANG-1 by osteoblasts in vitro. We studied 18 post-menopausal women with T score ⩽ −2 randomized to calcium/vitamin D only (control arm, n = 8) or calcium/vitamin D and alendronate 70 mg weekly (treatment arm, n = 10). Circulating concentrations of VEGF and ANG-1 were measured at baseline, 3, 6 and 12 months. Two human osteoblastic cell lines (MG-63 and HCC1) and a murine osteocytic cell line (MLO-Y4) were treated with zoledronate or alendronate at concentrations of 10⁻¹²–10⁻⁶ M. VEGF and ANG-1 were measured in the cell culture supernatant. We observed a trend towards a decline in VEGF and ANG-1 at 6 and 12 months following treatment with alendronate (p = 0.08). Production of VEGF and ANG-1 by the MG-63 and HCC1 cells decreased significantly by 34–39% (p < 0.01) following treatment with zoledronate (10⁻⁹–10⁻⁶ M). Treatment of the MG-63 cells with alendronate (10⁻⁷ and 10⁻⁶) led to a smaller decrease (25–28%) in VEGF (p < 0.05). Zoledronate (10⁻¹⁰–10⁻⁶ M) suppressed the production of ANG-1 by MG-63 cells with a decrease of 43–49% (p < 0.01). Co-treatment with calcitriol (10⁻⁸ M) partially reversed this zoledronate-induced inhibition. BPs suppress osteoblastic production of angiogenic factors. This may explain, in part, the pathogenesis of the BP-associated side-effects.     

Activation of phosphoinositide-specific phospholipase C of rat neutrophils by the chemotactic aldehydes 4-hydroxy-2,3-trans-nonenal and 4-hydroxy-2,3-trans-octenal

A comparison has been made between the effects of 4-hydroxy-2,3-trans-nonenal (HNE) and 4-hydroxy-2,3-trans-octenal (HOE), two lipid peroxidation products, on the basal and GTPgammaS-stimulated activities of phosphoinositide-specific phospholipase C (PL-C) of rat polymorphonuclear leukocytes. PL-C activity was determined in vitro by measuring the hydrolysis of [³H] phosphatidylinositol-4,5-bis-phosphate (PtdIns-P₂) added as exogenous substrate to neutrophil plasma membranes. PL-C was activated by concentrations of HNE ranging from 10^?8 to 10^?6 M both in the presence and in the absence of 2 × 10^?5 M GTPgammaS; HOE stimulated the enzymatic activity between 10^?11 and 10^?8 M ; maximal stimulation was given by 10^?11 M HOE plus GTPgammaS. The aldehyde concentrations able to accelerate PtdIns-P₂ breakdown displayed a good correspondence with those which have been reported to stimulate the oriented migration of rat neutrophils. Pretreatment of neutrophils with pertussis toxin prevented the stimulation of PL-C by 10^?11 M HOE and by HOE plus GTPgammaS. Our results suggest that the chemotactic action of HNE and HOE might depend on the activation of PL-C; furthermore a regulatory G protein appears to be involved in the acceleration of PtdIns-P₂ turnover by HOE.     

Cocaine,amphetamine and cathinone,but not nomifensine and pargyline increase calcium inward current in internally perfused neurons

The influence of cocaine, amphetamine, cathione, pargyline and nomifensine on inward calcium current was studied using internally perfused neurons of the snail Lymnaea Stagnalis. While nomifensine and pargyline inhibited inward calcium current in the concentrations 10⁻⁷-10⁻⁴ M and did not affect them in the concentrations 10⁻⁹-10⁻⁸ M, cocaine, amphetamine and cathinone had a biphasic action on inward calcium current, causing activation (10–30 percent) at 10⁻⁹-10⁻⁷ M, and inhibition at higher concentrations. Only cathione caused a shift of the I–V characteristics of the membrane along the potential axis. It is suggested that drugs of abuse affect membrane excitability and inward calcium current in neurons directly.     

Substance induces migration of capillary endothelial cells: A novel NK-1 selective receptor mediated activity

Substance P (SP) has been indicated as a main mediator of neurogenic inflammation, leading to vasodilation, increase in vascular permeability and modulation of immune cell function. Certain vascular effects produced by SP are endothelium mediated. We have studied the effect of SP and of selective NK-1, NK-2 and NK-3 receptor agonists on migration of cultured capillary endothelial cells of bovine origin. Our results indicate that SP (10⁻¹⁴–10⁻⁶ M) induces a concentration-dependent migration of endothelial cells with maximal activity at 10⁻¹⁰ M. This effect was mimicked by the selective NK-1 receptor agonist which showed a similar concentration-dependent curve, while selective NK-2 and NK-3 receptor agonists were ineffective. Our conclusions are that endothelial cells possess specific receptors for SP of the NK-1 type which affect mobilization of capillary endothelial cells.     

S100 protein CP-10 stimulates myeloid cell chemotaxis without activation

Leukocyte recruitment to inflammatory foci is generally associated with cellular activation. Recent evidence suggests that chemotactic agents can be divided into two classes, “classical chemoattractants” such as FMLP, C5a, and IL-8, which stimulate directed migration and activation events and “pure chemoattractants” such as TGF-β1 which influence actin polymerisation and movement but not oxidative burst and associated granular enzyme release. The studies reported here demonstrate that the murine S100 chemoattractant protein, CP-10, belongs to the “non-classical” group. Despite its potent chemotactic activity for neutrophils and monocytes/macrophages, CP-10 failed to increase [Ca²⁺]_i in human or mouse PMN, although chemotaxis was inhibited by pertussis toxin, confirming the suggestion of a novel Ca²⁺-independent G-protein-coupled pathway for post-receptor signal transduction triggered by “pure chemoattractants.” The co-ordinated up-regulation of Mac-1 and down-regulation of L-selectin induced by FMLP on human PMN in vitro was not observed with CP-10. Quantitative changes in immediate (30 s) actin polymerisation occurred with FMLP and CP-10-treated human PMN. The relative F-actin increases induced in WEHI 265 monocytoid cells by FMLP and CP-10 was optimal at 60 s and declined over 120 s. F-actin changes reflected the concentration and potencies of the agonists required to provoke chemotaxis. After 90 min, CP-10 profoundly altered cell shape and increased both cell size and F-actin within pseudopodia. These changes are typical of those mediating leukocyte deformability, and CP-10 may mediate leukocyte retention within microcapillaries and thereby contribute to the initiation of inflammation in vascular beds. © 1996 Wiley-Liss, Inc.     

C-terminal fragment of parathyroid hormone-related protein,PTHrP-(107–111), stimulates membrane-associated protein kinase C activity and modulates the proliferation of human and murine skin keratinocytes

Low concentrations of the C-terminal parathyroid hormone-related protein (PTHrP) fragments, PTHrP-(107–111) and PTHrP-(107–139), stimulated membrane-associated protein kinase Cs (PKCs), but not adenylyl cyclase or an internal Ca²⁺ surge, in early passage human skin keratinocytes and BALB/MK-2 murine skin keratinocytes. The fragment maximally stimulated membrane-associated PKCs in BALB/MK-2 cells at 5 × 10⁻⁹ to 10⁻⁸ M. The maximally PKC-stimulating concentrations of PTHrP-(107–111) also stopped or stimulated BALB/MK-2 keratinocyte proliferation depending on whether the cells were, respectively, cycling or quiescent at the time of exposure. Thus, just one brief (30-minute) pulse of 10 ⁻⁸ M PTHrP-(107–111) stopped the proliferation of BALB/MK-2 keratinocytes for at least 5 days. On the other hand, daily 30-minute pulses of 10⁻⁸ M PTHrP-(107–111) started and then maintained the proliferation of initially quiescent BALB/MK-2 cells. Similarly PTHrP-(107–111) inhibited DNA synthesis by cycling primary adult human keratinocytes, but it stimulated DNA synthesis by quiescent human keratinocytes. © 1996, Government of Canada. Exclusive worldwide publication rights in the article have been transferred to Wiley-Liss, Inc., in perpetuity.     

A comparison of the 8-hydroxydeoxyguanosine,chromosome aberrations and micronucleus techniques for the assessment of the genotoxicity of mercury compounds in human blood lymphocytes

We compared the mechanism of action of micronuclei (MN), unstable chromosome aberrations, and 8-hydroxydeoxyguanosine (8-OHdG) levels to evaluate the genotoxicity of methyl mercuric chloride (CH₃HgCl) and mercuric chloride (HgCl₂) in human peripheral lymphocytes. The chromosome aberrations in human peripheral lymphocytes exposed to various concentrations of CH₃HgCl or HgCl₂ increased in a concentration-dependent manner and were significantly higher than the control when the cells were incubated with 1 × 10⁻⁵ M (HgCl₂) or 2 × 10⁻⁶ M (CH₃HgCl). The increase in the incidence of micronucleated lymphocytes was significant among the exposed groups, being 2 × 10⁻⁵ M (HgCl₂) and 5 × 10⁻⁶ M (CH₃HgCl) compared with the control. CH₃HgCl was about 4-fold more potent than HgCl₂. We determined the 8-OHdG levels in human peripheral blood mononuclear cells(PBMC) and found that they were significantly higher in the exposed groups at 1 × 10⁻⁵ M (HgCl₂) and 5 × 10⁻⁶ M (CH₃HgCl) compared with the control. A detectable (p < 0.05) increase in the level of 8-OHdG was induced by CH₃HgCl at a concentration that was about 50% of the amount of HgCl₂ required to produce a similar response. The data confirmed the value of the MN and/or chromosome aberration assays for assessing of HgCl₂- and/or CH₃HgCl-induced genotoxicity, and indicated that they are about the same concentration as the 8-OHdG assay. The presence of genotoxic effects in peripheral blood lymphocytes exposed to the mercuric compounds indicated by the chromosome aberrations and the MN assays could be partly due either to the disturbance of the spindle mechanism, or to the elevated level of 8-OHdG brought by the generation of reactive oxygen species.     

Source analysis and health risk of heavy metals in the different seasons from Taizihe River,China

Twenty five water samples were collected along the Taizihe River, the concentration and health risks of Zn, Cu, Pb, Cr and Cd were detected and evaluated, and the pollution sources was analyzed through principal components analyses. The results indicated that the order of average concentration of heavy metals was follows: Pb > Cr > Cu > Zn and Cd. Among that, the concentrations of Zn, Cu and Cr were at the permissible levels, but Pb and Cd exceeded grade V standard at some sites. The concentrations of Zn and Cu in the wet season were significant higher than that in the dry season (p < 0.05), but the average concentrations of Pb, Cr and Cd were not significantly different in the two seasons (p > 0.05). The annual average risks of human health caused by Cd and Cr were 10⁻³/a and 10⁻⁴/a, respectively, which were higher than the recommended maximum acceptable risk level. The human health risk values of Zn, Pb and Cu were all concentrated at 10⁻⁸/a or 10⁻⁹/a levels, which did not exceed the recommended standard. On the whole, Cd and Cr were the main health risk pollutants of Taizihe River. Pollution sources of Pb was different from other heavy metals in wet and dry season, Cd and Cr were similar in the wet and dry season. The mainly pollution source of heavy metals was industry, especially mining, metal smelting and electroplating industry.     

The pharmacology of the isolated foregut of the locust schistocerca gregaria—I. the effect of a range of putative neurotransmitters

1. Isolated locust foreguts exhibited little or no spontaneous contractile activity.2. Proctolin (10⁻⁹m-10⁻⁶m) caused rapid and powerful contraction of the tissue while the response to similar doses of l-glutamate was much weaker.3. 5-HT (10⁻⁸M-5 × 10⁻⁶M), acting at ketanserin-sensitive receptors, was the most powerful tissue relaxant tested.4. Relaxation caused by octopamine (10⁻⁷M-10⁻⁵M), acting at ketanserin-insensitive receptors was less than 50% of that caused by similar concentrations of 5-HT.5. ACh (10⁻⁵M-10⁻³M) induced relaxation, mimicked by nicotine and antagonised by d-tubocurarine, was seen only in the presence of the anti-cholinesterase neostigmine.     

The effect of gramicidin on ATP synthesis in pea chloroplasts: two modes of phosphorylation

The effect of gramicidin on the phosphorylation rate, electron flow and light-induced H²⁺ uptake (ΔH⁺) in chloroplasts with methyl viologen (MV) or phenazine methosulfate (PMS) added has been studied. In the presence of MV low concentrations of gramicidin (~10⁻⁹ M) were shown to inhibit the phosphorylation rate up to 80–90% of the initial value, without changing either the electron transport rate or ΔH⁺ value. Two components of phosphorylation have been identified in the presence of PMS - the first is DCMU-sensitive, which was suppressed by low gramicidin concentrations (< 10⁻⁹ M) and the second - DCMU-insensitive component, which was suppressed by high gramicidin concentrations (~10⁻⁷ M) exclusively, the high gramicidin concentration inducing the ΔH⁺ value fo fall.     

Histamine stimulates human lung fibroblast migration

Histamine is a potent mediator in allergic inflammatory processes and is released by basophils and mast cells. The aim of this study was to investigate the effect of histamine on in vitro migration of human fetal lung fibroblasts (HFL-1) to human plasma fibronectin (HFn), a chemoattractant. Using the blindwell chamber technique, histamine alone had no chemotactic activity. However, histamine augmented HFn-induced HFL-1 migration at concentrations ranging between 0 and 10^?7 M (290.6 ± 20.8%) (P < 0.05). The concentration-response was bell-shaped. The effect of histamine increased with time. The stimulatory effect of histamine on HFL-1 migration was inhibited by an H4 receptor antagonist, JNJ7777120 (10^?5 M). Histamine’s effect was also inhibited by pertussis toxin (50 ng/ml), showing that the effect was mediated by the H4 receptor. This study demonstrated that histamine has the potential to stimulate human lung fibroblast migration, and thus may contribute to regulation of wound healing and the development of fibrotic disorders of the lung.     

Differential lytic and agglutinating activity of the anti-Lewisx monoclonal antibody FC-2.15 on human polymorphonuclear neutrophils and MCF-7 breast tumor cells. In vitro and ex vivo studies

The Lewis^x (Le^x) trisaccharide (CD15) linked to proteins and glycolipids is highly expressed on the surface of normal human polymorphonuclear neutrophils (PMN) and several human neoplasias, such as breast and gastrointestinal carcinomas and chronic myeloid leukemias. FC-2.15 is an IgM murine mAb that specifically recognizes Le^x and has been previously shown to mediate the in vitro lysis of Le^x(+) cells by human complement. In a phase I clinical trial of FC-2.15, a temporary neutropenia was the main toxicity, and antitumor responses were observed. In order to characterize FC-2.15 further and determine the physiological relevance of Le^x binding, the reactivity of FC-2.15 on PMN was investigated under several conditions. Flow cytometry revealed a strong reactivity of FC-2.15 with almost 100% of PMN, and Scatchard analysis demonstrated an affinity constant of 5.14 × 10⁹ M⁻¹ and 1.11 × 10⁶ antigen sites/cell. In vitro, the binding of Le^x epitopes by FC-2.15 induced PMN homotypic aggregation, only 28.4 ± 4.1% remaining as single cells. When PMN and the Le^x(+) MCF-7 breast cancer cells were co-incubated, FC-2.15 induced heterotypic aggregation. In ⁵¹Cr-release assays employing human complement, FC-2.15 lysed 93.4 ± 7.9% of PMN and 87.8 ± 10.7% of MCF-7 cells. However, when the effect of FC-2.15 was tested in ex vivo circulating blood, no lytic activity against PMN was detected, whereas MCF-7 cells were still lysed. Blood smears demonstrated that FC-2.15 induced PMN agglutination and heterotypic aggregates when MCF-7 cells were present. A pre-treatment of PMN with colchicine impaired PMN agglutination both in vitro (single PMN = 81.15 ± 4.35%) and in ex vivo circulating blood. In the latter condition, FC-2.15-lytic activity was restored, suggesting that PMN homotypic aggregation by FC-2.15, but not lysis, is dependent on microtubule integrity and that PMN agglutination hinders their lysis. Moreover, when ⁵¹Cr-release assays were performed following agglutination, FC-2.15 cytotoxicity was restricted to isolated PMN. It is suggested that crosslinking of Le^x epitopes by FC-2.15 induces PMN to form homotypic aggregates. It is suggested that the neutropenia observed in FC-2.15-treated patients would be due to PMN agglutination and margination, rather than lysis. In addition, FC-2.15 appears to be able to lyse Le^x(+) tumor cells in circulation. Received: 3 December 1998 / Accepted: 28 January 1999