scholarly journals Polyamine replacement by magnesium ions in BHK-21/C13 cells

1979 ◽  
Vol 178 (2) ◽  
pp. 391-395 ◽  
Author(s):  
Maureen A. L. Melvin ◽  
Hamish M. Keir
Keyword(s):  
Cell Growth ◽  
Ornithine Decarboxylase ◽  
Culture Medium ◽  
Inhibitory Effect ◽  
Molar Ratio ◽  
Magnesium Ions ◽  
Inhibitory Effects ◽  
Simultaneous Addition ◽  
Cellular Processes ◽  
Stimulation Of

Cultures of BHK-21/C13 cells, whose growth was inhibited by deprivation of serum, were stimulated to grow by addition of serum to the culture medium. Addition of MgCl2 to the medium, to increase the concentration of Mg2+ ions by 15mm, 30min before addition of serum, had no effect on the stimulation of cell growth, but inhibited the accumulation of cellular spermidine, so that the spermidine/spermine molar ratio was lower in these cultures than in cultures that had received no additional cations. The increase in the activity of ornithine decarboxylase that occurs 4–5h after serum ‘step-up’ was substantially diminished by increasing the concentration of Mg2+ ions, but not of Na+ or K+ ions, in the medium by 30mm, 30min before addition of serum, and this inhibition was maintained for at least 24h. Methylglyoxal bis(guanylhydrazone), added to serum-deprived cultures to a concentration of 20μm, 30min before addition of serum, severely inhibited the increase in cell growth. The inhibitory effects of the drug were prevented by simultaneous addition of spermidine to the medium (to 100μm), and were partly prevented by the simultaneous addition of Mg2+ ions (to 30mm). Mg2+ ions were particularly effective in overcoming the inhibitory effect of methylglyoxal bis(guanylhydrazone) on the synthesis of DNA. Thus although a certain lack of specificity for cations exists in BHK-21/C13 cells, in that Mg2+ ions can be substituted for polyamines, particularly spermidine, to some extent, there are cellular processes for which the requirement for polyamines as cations is specific.

Effects Of Aspirin And Sulfinpyrazone On Platelets, Vascular Cells And Their Interactions

1981 ◽  
Author(s):  
M R Buchanan ◽  
M J Vazquez ◽  
M A Gimbrone
Keyword(s):  
Growth Rate ◽  
Cell Growth ◽  
Dna Synthesis ◽  
Vessel Wall ◽  
Culture Medium ◽  
Platelet Adhesion ◽  
Thymidine Incorporation ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Final Density

Sulfinpyrazone (SUL) and aspirin (ASA) are potentially useful antithrombotic drugs. Both drugs are thought to exert this effect by inhibiting the platelet enzyme, cyclooxygenase (C-0), thus preventing thromboxane A2 synthesis. Recent data, however, suggest that these drugs also may affect vessel wall cells. To study this further, we examined the effects of SUL and ASA on i) the adhesion of 3H-adenine-labelled washed human platelets to cultured bovine endothelial (EC) and smooth muscle cells (SMC), ii) EC and SMC DNA synthesis (3H-thymidine incorporation) and iii) cell growth. Pretreatment of platelets with 100μM ASA or 250μM SUL (concentrations sufficient to inhibit C-0), did not affect platelet adhesion to untreated EC or SMC. However, adhesion of untreated, ASA- and SUL-platelets was increased 25,28 and 44% resp. when EC were pretreated with 650μM SUL for 24 hr. In contrast, adhesion of ASA-platelets to EC pretreated with lOOμM ASA (sufficient to inhibit prostacyclin), was unaffected. Platelet adhesion to SMC pretreated with 650μM SUL for 24 hr was decreased when platelets also were pretreated with ASA (20%, p<0.05) or SUL (27%, pc 0.02). Pretreatment of SMC with SUL for only 2 hr had no effect. DNA synthesis in EC and SMC treated with 62.5 and 250μM SUL for 24 hr, was inhibited >35% and >95% resp. Preliminary data suggest that this inhibitory effect may last longer in SMC. To study the effect of SUL on cell growth, EC and SMC were plated at 2 × 104 cells/ cm2 and fed with culture medium containing 0, 62.5 or 625uM SUL on day 0, 1, 3 and 4.5. EC growth rate and final density were unaffected over 7 days. SMC growth rate also was unaffected, but the final density of SMC treated with 650μM SUL was 31 μ 2% less than untreated SMC at 7 days (p<0.01). These data indicate that SUL has direct effects on EC and SMC that may influence i) platelet-vessel wall interactions and ii) vascular cell proliferation.

scholarly journals Epidermal growth factor inhibits growth of A431 human epidermoid carcinoma in serum-free cell culture.

1982 ◽  
Vol 93 (1) ◽  
pp. 1-4 ◽  
Author(s):  
D W Barnes
Keyword(s):  
Growth Factor ◽  
Cell Growth ◽  
Epidermal Growth Factor ◽  
Culture Medium ◽  
Cell Types ◽  
Inhibitory Effect ◽  
Free Cell ◽  
Bovine Insulin ◽  
A431 Cell ◽  
Epidermal Growth

A medium consisting of a rich basal nutrient mixture supplemented with bovine insulin (10 micrograms/ml), human transferrin (10 micrograms/ml), human cold-insoluble globulin (5 micrograms/ml), and ethanolamine (0.5 mM) supported the growth of the A431 human epidermoid cell line in the absence of serum with a generation time equal to that of cells in serum-containing medium. Addition of epidermal growth factor (EGF) to this culture medium at concentration mitogenic for other cell types resulted in a marked inhibition of A431 cell growth. Inhibitory effects of EGF were observed at 1 ng/ml and near-maximal effects were observed at 10 ng/ml. The inhibitory effect of EGF could be reversed by the omission of EGF in subsequent medium changes and could be prevented by the addition of anti-EGF antibody to the culture medium. Inhibition of A431 cell growth by EGF also could be demonstrated in serum-containing medium.

scholarly journals Afferent Stochastic Modulation of Crayfish Caudal Photoreceptor Units

1968 ◽  
Vol 51 (4) ◽  
pp. 534-551 ◽  
Author(s):  
Howard T. Hermann ◽  
Richard E. Olsen
Keyword(s):  
Inhibitory Effect ◽  
Fiber Optic Probe ◽  
Inhibitory Effects ◽  
Excitatory Effect ◽  
Multiple Pulses ◽  
Caudal Photoreceptor ◽  
Stochastic Modulation ◽  
The Mean ◽  
Optic Probe ◽  
Stimulation Of

When all roots to the sixth ganglion of the crayfish are cut, the caudal photoreceptor unit (PRU) fires at regular intervals. With an intact preparation, stimulation of caudal tactile hairs has predominantly inhibitory effects on the PRU: short bursts of afferent impulses, produced by momentary mechanical stimulation of tactile hairs, have (a) occasional immediate excitatory effect on the PRU, (b) prolonged inhibitory effect. The mean firing rate of the afferented and deafferented PRUs reacts similarly to a step increase in light, but the same unit fires faster after deafferentation. In the dark, deafferented units often fire paired or multiple pulses; the interval between pulses in a pair is similar to the short mode in afferented histograms. A fiber-optic probe of the caudal ganglion demonstrates the approximate location of the photosensitive element.

Failure of 16,16-dimethyl PGE2 to prevent inhibitory effect of ethanol on sodium transport in canine gastric mucosa

1985 ◽  
Vol 248 (3) ◽  
pp. G299-G306
Author(s):  
T. A. Miller ◽  
J. M. Henagan ◽  
Y. J. Kuo ◽  
L. L. Shanbour
Keyword(s):  
Gastric Mucosa ◽  
Sodium Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Inhibitory Effect ◽  
Gastric Epithelium ◽  
Bathing Solution ◽  
Inhibitory Effects ◽  
Stimulation Of

By use of an in vitro canine gastric mucosal preparation, we evaluated the effects of ethanol (2, 4, 6, and 8%, vol/vol) and indomethacin (2.2 X 10(-4)M), with and without 16,16-dimethyl PGE2 pretreatment, on net sodium transport (JNanet) (mucosal to serosal) across gastric epithelium. Although administration of 2 or 4% ethanol to the mucosal bathing solution had no appreciable inhibitory effects on sodium transport, 6 and 8% ethanol and indomethacin significantly inhibited JNanet when compared with untreated control mucosa. This effect was accompanied by inhibition of transmucosal potential difference (PD) and short-circuit current (Isc). In other mucosae exposed to dimethyl PGE2 (8 X 10(-6) M) in the serosal bathing solution, significant increases in JNanet, PD, and Isc were noted when compared with control mucosa. Addition of 6 or 8% ethanol to the mucosal solution of dimethyl PGE2-pretreated tissue resulted in significant decreases in PD, Isc, and JNanet below control values that were not significantly different from mucosa exposed to 6 and 8% ethanol without PG pretreatment. When indomethacin was added to the mucosal solution following dimethyl PGE2 pretreatment, only slight decreases in PD and Isc below control levels were observed, and the inhibitory effects on JNanet induced by indomethacin without such treatment were abolished. These findings suggest that stimulation of JNanet by prostaglandin may play a role in its ability to prevent indomethacin damage to gastric epithelium but does not appear to be of importance in mediating protection against ethanol damage.

scholarly journals A novel role for calmodulin: Ca2+-independent inhibition of type-1 inositol trisphosphate receptors

1998 ◽  
Vol 334 (2) ◽  
pp. 447-455 ◽  
Author(s):  
Thomas J. A. CARDY ◽  
Colin W. TAYLOR
Keyword(s):  
Spodoptera Frugiperda ◽  
Inhibitory Effect ◽  
Ip3 Receptors ◽  
Inhibitory Effects ◽  
Independent Manner ◽  
S 100 ◽  
High Concentrations ◽  
Type 3 ◽  
Stimulation Of

Calmodulin inhibits both inositol 1,4,5-trisphosphate (IP3) binding to, and IP3-evoked Ca2+ release by, cerebellar IP3 receptors [Patel, Morris, Adkins, O'Beirne and Taylor (1997) Proc. Natl. Acad. Sci. U.S.A. 94, 11627–11632]. In the present study, full-length rat type-1 and -3 IP3 receptors were expressed at high levels in insect Spodoptera frugiperda 9 cells and the effects of calmodulin were examined. In the absence of Ca2+, calmodulin caused a concentration-dependent and reversible inhibition of [3H]IP3 binding to type-1 IP3 receptors by decreasing their apparent affinity for IP3. The effect was not reproduced by high concentrations of troponin C, parvalbumin or S-100. Increasing the medium free [Ca2+] ([Ca2+]m) inhibited [3H]IP3 binding to type-1 receptors, but the further inhibition caused by a submaximal concentration of calmodulin was similar at each [Ca2+]m. In the absence of Ca2+, 125I-calmodulin bound to a single site on each type-1 receptor subunit and to an additional site in the presence of Ca2+. There was no detectable binding of 125I-calmodulin to type-3 receptors and binding of [3H]IP3 was insensitive to calmodulin at all [Ca2+]m. Both peptide and conventional Ca2+–calmodulin antagonists affected neither [3H]IP3 binding directly nor the inhibitory effect of calmodulin in the absence of Ca2+, but each caused a [Ca2+]m-dependent reversal of the inhibition of [3H]IP3 binding caused by calmodulin. Camstatin, a peptide that binds to calmodulin equally well in the presence or absence of Ca2+, reversed the inhibitory effects of calmodulin on [3H]IP3 binding at all [Ca2+]m. We conclude that calmodulin specifically inhibits [3H]IP3 binding to type-1 IP3 receptors: the first example of a protein regulated by calmodulin in an entirely Ca2+-independent manner. Inhibition of type-1 IP3 receptors by calmodulin may dynamically regulate their sensitivity to IP3 in response to the changes in cytosolic free calmodulin concentration thought to accompany stimulation of neurones.

Neurotensin inhibition of canine intestinal motility in vivo via α-adrenoceptors

1984 ◽  
Vol 62 (4) ◽  
pp. 403-411 ◽  
Author(s):  
Y. Sakai ◽  
E. E. Daniel ◽  
J. Jury ◽  
J. E. T. Fox
Keyword(s):  
Acetylcholine Release ◽  
Contractile Activity ◽  
Inhibitory Effect ◽  
Inhibitory Effects ◽  
Maximal Inhibition ◽  
Contractile Responses ◽  
Adrenergic Antagonists ◽  
Distal Site ◽  
Stimulation Of

Neurotensin given intra-arterially in bolus doses to the canine small intestine inhibited field-stimulated, atropine-sensitive contractile responses in the duodenum (mean effective dose (ED50) = 3.2 × 10−11 mol) and in the ileum (mean ED50 = 2.1 × 10−11 mol). Norepinephrine (ED50 = 3 × 10−9 mol) also inhibited these contractile responses. Phenylephrine (ED50 = 1.3 × 10−8 mol) was one-fourth as potent as norepinephrine and clonidine (ED50 = 8 × 10−10 mol) was at least as potent as norepinephrine, while isoproterenol (up to 8 × 10−8 mol) failed to show any inhibitory effects. Phentolamine (2 mg/kg) increased significantly the ED50 of neurotensin and norepinephrine. Prazosin (2 mg/kg) increased significantly the ED50 of norepinephrine in the duodenum but had no effect on the ED50 of neurotensin. Yohimbine (2 mg/kg) increased the ED50 values of neurotensin and adrenergic agonists. Both neurotensin and norepinephrine in doses causing maximal inhibition of field-stimulated responses decreased (by 40 to 60%) contractile responses to 9 × 10−10 mol (approximately the intra-arterial ED50 dose) of acetylcholine. Reserpine pretreatment markedly diminished the inhibition of spontaneous or field-stimulated phasic contractions by distention or field stimulation of a distal site. Reserpine also diminished the ED50 for neurotensin from 1 × 10−11 to 2 × 10−11 mol (p < 0.02), but did not abolish neurotensin's inhibitory effect. Tetrodotoxin (10–15 μg, intra-arterially) increased the dose of neurotensin required to inhibit spontaneous activity in the ileum but after this toxin, as after adrenergic antagonists or reserpine, maximal inhibition could still be obtained. These results suggested that neurotensin inhibited contractile activity of canine intestine by acting on neural receptors to release norepinephrine. Norepinephrine activated primarily α2-adrenoceptors and ultimately inhibited acetylcholine release. Neurotensin also inhibited contractions by activating a second, less sensitive receptor on smooth muscle.

scholarly journals Chitosan Inhibits Helicobacter pylori Growth and Urease Production and Prevents Its Infection of Human Gastric Carcinoma Cells

Marine Drugs ◽  
2020 ◽  
Vol 18 (11) ◽  
pp. 542
Author(s):  
Shun-Hsien Chang ◽  
Pei-Ling Hsieh ◽  
Guo-Jane Tsai
Keyword(s):  
Helicobacter Pylori ◽  
Culture Medium ◽  
Fluorescent Microscopy ◽  
Inhibitory Effect ◽  
Carcinoma Cells ◽  
Inhibitory Effects ◽  
Urease Production ◽  
Decreasing Ph ◽  
H Pylori ◽  
Human Gastric Carcinoma Cells

This study investigated the effects of shrimp chitosan with 95% degree of deacetylation (DD95) in combination with clinical antibiotics on the growth and urease production of Helicobacter pylori. The inhibitory effect of DD95 on the adherence of H. pylori to the human intestinal carcinoma cells (TSGH9201) was also investigated. Five strains of H. pylori, including three standard strains and two strains of clinical isolates were used as the test strains. The inhibitory effects of DD95 on growth and urease production of various strains of H. pylori increased with increasing DD95 concentration and decreasing pH values from pH 6.0 to pH 2.0. Urease activity of H. pylori at pH 2.0 in the presence of 4000 μg/mL of DD95 decreased by 37.86% to 46.53%. In the presence of 50 μg/mL antibiotics of amoxicillin, tetracycline, or metronidazole at pH 6.0 and pH 2.0, H. pylori counts were decreased by 1.51–3.19, and 1.47–2.82 Log CFU/mL, respectively. Following the addition of 4000 μg/mL DD95 into the 50 μg/mL antibiotic-containing culture medium with pH 6.0 and pH 2.0, overall H. pylori counts were strongly decreased by 3.67–7.61 and 6.61–6.70 Log CFU/mL, respectively. Further, DD95 could inhibit the adherence of H. pylori on TSGH 9201 cells, as evidenced by fluorescent microscopy and thus may potentially protect against H. pylori infection.

Electrical stimulation of cell growth and neurogenesis using conductive and nonconductive microfibrous scaffolds

2019 ◽  
Vol 11 (6) ◽  
pp. 264-279
Author(s):  
Simon Grossemy ◽  
Peggy P Y Chan ◽  
Pauline M Doran
Keyword(s):  
Electrical Stimulation ◽  
Cell Growth ◽  
Electric Fields ◽  
Neural Differentiation ◽  
Culture Medium ◽  
Sheet Resistivity ◽  
Differentiation Markers ◽  
Cytotoxic Effects ◽  
Neurite Development ◽  
Stimulation Of

Abstract The effect of exogenous electrical stimulation on cell viability, attachment, growth, and neurogenesis was examined using PC12 cells in microfibrous viscose-rayon scaffolds immersed in culture medium. The scaffolds were applied either in their nonconductive state or after coating the fibres with 200 nm of gold to give a scaffold sheet resistivity of (13 ± 1.3) Ω square−1. The cells were treated for 12 days using direct current electrical stimulation of 2 h per day. No cytotoxic effects were observed when up to 500 mV (8.3 mV mm−1) was applied to the scaffolds without gold, or when up to 100 mV (1.7 mV mm−1) was applied to the scaffolds with gold. Compared with unstimulated cells, whereas electrical stimulation significantly enhanced cell growth and attachment in the nonconductive scaffolds without gold, similar effects were not found for the conductive scaffolds with gold. Neural differentiation in the presence of nerve growth factor was improved by electrical stimulation in both scaffolds; however, neurite development and the expression of key differentiation markers were greater in the nonconductive scaffolds without gold than in the scaffolds with gold. Application of the same current to scaffolds with and without gold led to much higher levels of neurogenesis in the scaffolds without gold. This work demonstrates that substantial benefits in terms of cell growth and neural differentiation can be obtained using electric fields exerted across nonconductive microfibrous scaffolds, and that this approach to electrical stimulation can be more effective than when the stimulus is applied to cells on conductive scaffolds.

Inhibition of dorsal-horn cell responses by stimulation of the Kölliker-Fuse nucleus

1986 ◽  
Vol 65 (6) ◽  
pp. 825-833 ◽  
Author(s):  
Charles J. Hodge ◽  
A. Vania Apkarian ◽  
Richard T. Stevens
Keyword(s):  
Brain Stem ◽  
Biogenic Amines ◽  
Dorsal Horn ◽  
Inhibitory Effect ◽  
Control Mechanisms ◽  
Inhibitory Effects ◽  
Content Type ◽  
Cell Responses ◽  
The Brain ◽  
Stimulation Of

✓ The Kölliker-Fuse nucleus (KF) in the dorsolateral pons has been shown to be the major source of catecholamine innervation of the spinal cord. This has important implications in terms of pain control mechanisms, since catecholamine-mediated mechanisms are essential for the expression of opiate and other varieties of antinociception. This study examines the effects of KF stimulation on responses of dorsal-horn cells to innocuous and noxious cutaneous stimuli in anesthetized cats. Stimulation of the KF potently inhibits the responses of dorsal-horn cells to both noxious and innocuous stimuli. The threshold for the inhibitory effect is significantly lower for responses to noxious stimuli as opposed to innocuous stimuli. The inhibitory effect is specific to the stimulus site, as evidenced by a marked decrease in the effect following small changes in the position of the stimulating electrode in the brain stem. The latency of the effects indicates a bulbospinal conduction velocity of 4 to 5 m/sec, which is much slower than usual reticulospinal effects and is consistent with a catecholamine-mediated system. The dependence of KF-spinal inhibition on intact biogenic amines was tested by depleting the animals of these amines with reserpine pretreatment. Depletion of biogenic amines resulted in a significant decrease in the KF spinal inhibitory effects, suggesting their dependence on intact noradrenergic stores. The results of these studies are consistent with the idea that the KF-spinal system plays an important noradrenergic-dependent role in the brain-stem modulation of spinal processing of noxious, potentially painful stimuli.

scholarly journals Inhibitory effect of curcuminoids and tetrahydrocurcuminoids on equine activated neutrophils and myeloperoxidase activity

2008 ◽  
pp. 577-587
Author(s):  
T Franck ◽  
S Kohnen ◽  
S Grulke ◽  
P Neven ◽  
Y Goutman ◽  
...  
Keyword(s):  
Chemical Structure ◽  
Inhibitory Effect ◽  
Original Method ◽  
Polymorphonuclear Neutrophils ◽  
Myeloperoxidase Activity ◽  
Ros Production ◽  
Inhibitory Effects ◽  
Inflammatory Reactions ◽  
Activated Neutrophils ◽  
Stimulation Of

In the horse, the inflammation response to various pathologies (intestinal strangulations, laminitis, etc.) involves an excessive stimulation of the polymorphonuclear neutrophils releasing reactive oxygen species (ROS) and myeloperoxidase (MPO). The aim of the present work was to study the effect of natural polyphenols, curcuminoids and tetrahydrocurcuminoids (THC) on isolated stimulated equine neutrophils and on the activity of purified MPO. The ROS production and the release of MPO by activated neutrophils were measured by chemiluminescence and ELISA techniques, respectively. The activity of purified MPO was measured by studying its nitration, chlorination or oxidation capacity and by using an original method called SIEFED allowing the study of drug interaction with the enzyme without interferences of the medium. Curcuminoids and THC had dosedependent inhibitory effects on ROS production and MPO release by activated neutrophils and on purified MPO activity. We suggest that the higher efficacy of curcuminoids versus THC could be explained, at least partially, by its chemical structure: the conjugated double bounds and the plane structure of curcuminoids made easier the neutralization of the radical species generated by activated neutrophils and the interaction of the drug with the active site of MPO. These inhibitory effects of curcuminoids on the oxidant activity of equine neutrophils and on MPO activity open therapeutic perspectives in equine pathologies with excessive inflammatory reactions.

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