Effects of ATP on ligand recognition of platelet fibrinogen receptor on GPIIb-IIIa

1994 ◽  
Vol 267 (3) ◽  
pp. H1098-H1106
Author(s):  
M. P. Gawaz ◽  
P. Mayinger ◽  
F. J. Neumann
Keyword(s):  
Binding Sites ◽  
Solid Phase ◽  
Atp Binding ◽  
Dependent Manner ◽  
Modulate Function ◽  
Glycoprotein Complex ◽  
Fibrinogen Receptor ◽  
Activated Platelets ◽  
Dose Dependent

The recent discovery of 8-azido-ATP binding sites on the platelet fibrinogen receptor glycoprotein complex GPIIb-IIIa suggests that extracellular ATP may directly modulate function of GPIIb-IIIa. In this study we investigated the effect of ATP on ligand binding to GPIIb-IIIa. Fibrinogen-mediated aggregation of washed platelets was inhibited by ATP and 8-azido-ATP in a dose-dependent manner, independent of the agonist (thrombin, collagen, epinephrine, phorbol 12-myristate 13-acetate) used to induce platelet activation. In addition, 8-azido-ATP and ATP inhibited binding of 125I-labeled fibrinogen to thrombin- and phorbol ester-activated platelets. Interaction of nonstimulated platelets with solid-phase fibrinogen was also reduced by 8-azido-ATP and ATP. Moreover, fibrinogen mimetic peptide-induced conformational change of GPIIb-IIIa on resting platelets was reduced in the presence of both nucleotides. Finally, photoincorporation of 8-azido-[gamma-32P]ATP into GPIIb-IIIa was suppressed by GRGDSP but not by the biologically inactive GRGESP peptide. Thus interaction of ATP with 8-azido-ATP binding sites present on GPIIb-IIIa modulate receptor function, which may play a role in regulation of in vivo platelet aggregation.

scholarly journals Continuous activation and deactivation of integrin CD11b/CD18 during de novo expression enables rolling neutrophils to immobilize on platelets

Blood ◽  
1996 ◽  
Vol 87 (12) ◽  
pp. 5040-5050 ◽  
Author(s):  
S Sheikh ◽  
GB Nash
Keyword(s):  
De Novo ◽  
Shape Change ◽  
Second Phase ◽  
Dependent Manner ◽  
Activated Platelets ◽  
Low Concentrations ◽  
Onward Migration ◽  
Dose Dependent

In an in vitro flow model, unstimulated neutrophils rolled steadily over a surface coated with platelets, until superfusion of the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (fMLP) caused a dose-dependent (10(-11) to 10(-7) mol/L) transition from rolling to stationary attachment in seconds, followed more slowly by neutrophil shape change and spreading on the surface, However, at low concentrations of Ca2+ and Mg2+ (0.1 mmol/L and 0.05 mmol/L, respectively, rather than physiologic 1 mmol/L and 0.5 mmol/L), neutrophils first halted but then started to roll again and to detach from the surface over 5 to 10 minutes. At the low cation concentration, stopping was largely inhibited by antibodies to the neutrophil integrins CD18 or CD11b, but not CD11a. When neutrophils were pretreated with antibodies to CD11b or CD18 in 1 mmol/L Ca2+ 0.5 mmol/L Mg2+, stopping was not prevented but delayed. However, if antibodies were also included with the superfused fMLP, stopping was inhibited, and detachment followed. This indicates that CD11b/CD18 was newly expressed during shape change and mediated the second phase of neutrophil immobilization and spreading in a cation-dependent manner. Prestimulated neutrophils also bound to platelets and spread, but immobilization was blocked if they were perfused with antibody to CD18 or CD11b or with low Ca2+ and Mg2+. Examining the cation-dependence further, it was evident that the presence of Mg2+ was essential for integrin-mediated adhesion and that the Mg2+ concentration determined whether immobilization could be maintained or was transient. Continuous superfusion of fMLP was also essential for maintenance of stable adhesion and spreading. Thus, activation of constitutive CD11b/CD18 rapidly and reversibly converted rolling to stationary attachment, whereas maintenance of adhesion and neutrophil spreading required continual expression of additional CD11b/CD18 that was only functional at physiologic Mg2+. Continual activation and deactivation of CD11b/CD18 during de novo expression could mediate immobilization and onward migration of neutrophils in vivo, and activated platelets appear capable of supporting this process as well as endothelial cells.

Effects of NO-Donors on Thrombus Formation and Microcirculation in Cerebral Vessels of the Rat

1996 ◽  
Vol 76 (01) ◽  
pp. 111-117 ◽  
Author(s):  
Yasuto Sasaki ◽  
Junji Seki ◽  
John C Giddings ◽  
Junichiro Yamamoto
Keyword(s):  
Blood Flow ◽  
Thrombus Formation ◽  
Dependent Manner ◽  
Red Cell ◽  
Cell Velocity ◽  
Red Cell Velocity ◽  
The Mean ◽  
Wall Shear ◽  
Dose Dependent

SummarySodium nitroprusside (SNP) and 3-morpholinosydnonimine (SIN-1), are known to liberate nitric oxide (NO). In this study the effects of SNP and SIN-1 on thrombus formation in rat cerebral arterioles and venules in vivo were assessed using a helium-neon (He-Ne) laser. SNP infused at doses from 10 Μg/kg/h significantly inhibited thrombus formation in a dose dependent manner. This inhibition of thrombus formation was suppressed by methylene blue. SIN-1 at a dose of 100 Μg/kg/h also demonstrated a significant antithrombotic effect. Moreover, treatment with SNP increased vessel diameter in a dose dependent manner and enhanced the mean red cell velocity measured with a fiber-optic laser-Doppler anemometer microscope (FLDAM). Blood flow, calculated from the mean red cell velocity and vessel diameters was increased significantly during infusion. In contrast, mean wall shear rates in the arterioles and venules were not changed by SNP infusion. The results indicated that SNP and SIN-1 possessed potent antithrombotic activities, whilst SNP increased cerebral blood flow without changing wall shear rate. The findings suggest that the NO released by SNP and SIN-1 may be beneficial for the treatment and protection of cerebral infarction

A Comparison of the Effect of Decorsin and Two Disintegrins, Albolabrin and Eristostatin, on Platelet Function

1995 ◽  
Vol 74 (05) ◽  
pp. 1316-1322 ◽  
Author(s):  
Mary Ann McLane ◽  
Jagadeesh Gabbeta ◽  
A Koneti Rao ◽  
Lucia Beviglia ◽  
Robert A Lazarus ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Sequence Similarity ◽  
Platelet Aggregation Inhibitors ◽  
Antiplatelet Drug ◽  
Rgd Sequence ◽  
Fibrinogen Receptor ◽  
Activated Platelets

SummaryNaturally-occurring fibrinogen receptor antagonists and platelet aggregation inhibitors that are found in snake venom (disintegrins) and leeches share many common features, including an RGD sequence, high cysteine content, and low molecular weight. There are, however, significant selectivity and potency differences. We compared the effect of three proteins on platelet function: albolabrin, a 7.5 kDa disintegrin, eristostatin, a 5.4 kDa disintegrin in which part of the disintegrin domain is deleted, and decorsin, a 4.5 kDa non-disintegrin derived from the leech Macrobdella decora, which has very little sequence similarity with either disintegrin. Decorsin was about two times less potent than albolabrin and six times less potent than eristostatin in inhibiting ADP- induced human platelet aggregation. It had a different pattern of interaction with glycoprotein IIb/IIIa as compared to the two disintegrins. Decorsin bound with a low affinity to resting platelets (409 nM) and to ADP-activated platelets (270 nM), and with high affinity to thrombin- activated platelets (74 nM). At concentrations up to 685 nM, it did not cause expression of a ligand-induced binding site epitope on the (β3 subunit of the GPIIb/IIIa complex. It did not significantly inhibit isolated GPIIb/IIIa binding to immobilized von Willebrand Factor. At low doses (1.5-3.0 μg/mouse), decorsin protected mice against death from pulmonary thromboembolism, showing an effect similar to eristostatin. This suggested that decorsin is a much more potent inhibitor of platelet aggregation in vivo than in vitro, and it may have potential as an antiplatelet drug.

scholarly journals Anti-tumor activity of a novel proteasome inhibitor D395 against multiple myeloma and its lower cardiotoxicity compared with carfilzomib

2021 ◽  
Vol 12 (5) ◽  
Author(s):  
Xuxing Shen ◽  
Chao Wu ◽  
Meng Lei ◽  
Qing Yan ◽  
Haoyang Zhang ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Proteasome Inhibitor ◽  
Osteoclast Differentiation ◽  
Dependent Manner ◽  
Serum Enzyme ◽  
Herg Channels ◽  
Anti Tumor Activity ◽  
Dose Dependent

AbstractCarfilzomib, a second-generation proteasome inhibitor, has significantly improved the survival rate of multiple myeloma (MM) patients, but its clinical application is still restricted by drug resistance and cardiotoxicity. Here, we identified a novel proteasome inhibitor, D395, and assessed its efficacy in treating MM as well as its cardiotoxicity at the preclinical level. The activities of purified and intracellular proteasomes were measured to determine the effect of D395 on the proteasome. CCK-8 and flow cytometry experiments were designed to evaluate the effects of D395 on cell growth and apoptosis. The effects of D395 and carfilzomib on serum enzyme activity, echocardiography features, cardiomyocyte morphology, and hERG channels were also compared. In our study, D395 was highly cytotoxic to MM cell lines and primary MM cells but not normal cells, and it was well tolerated in vivo. Similar to carfilzomib, D395 inhibited osteoclast differentiation in a dose-dependent manner. In particular, D395 exhibited lower cardiotoxicity than carfilzomib in all experiments. In conclusion, D395 is a novel irreversible proteasome inhibitor that has remarkable anti-MM activity and mild cardiotoxicity in vitro and in vivo.

scholarly journals Effect of Synchronous Versus Sequential Regimens on the Pharmacokinetics and Biodistribution of Regorafenib with Irradiation

Pharmaceutics ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 386
Author(s):  
Tung-Hu Tsai ◽  
Yu-Jen Chen ◽  
Li-Ying Wang ◽  
Chen-Hsi Hsieh
Keyword(s):  
Stereotactic Body Radiation Therapy ◽  
In Vivo Studies ◽  
Control Group ◽  
High Dose ◽  
Dependent Manner ◽  
Hep G2 ◽  
Time Curve ◽  
Dose Dependent

This study was performed to evaluate the interaction between conventional or high-dose radiotherapy (RT) and the pharmacokinetics (PK) of regorafenib in concurrent or sequential regimens for the treatment of hepatocellular carcinoma. Concurrent and sequential in vitro and in vivo studies of irradiation and regorafenib were designed. The interactions of RT and regorafenib in vitro were examined in the human hepatoma Huh-7, HA22T and Hep G2 cell lines. The RT–PK phenomenon and biodistribution of regorafenib under RT were confirmed in a free-moving rat model. Regorafenib inhibited the viability of Huh-7 cells in a dose-dependent manner. Apoptosis in Huh-7 cells was enhanced by RT followed by regorafenib treatment. In the concurrent regimen, RT decreased the area under the concentration versus time curve (AUC)regorafenib by 74% (p = 0.001) in the RT2 Gy × 3 fraction (f’x) group and by 69% (p = 0.001) in the RT9 Gy × 3 f’x group. The AUCregorafenib was increased by 182.8% (p = 0.011) in the sequential RT2Gy × 1 f’x group and by 213.2% (p = 0.016) in the sequential RT9Gy × 1 f’x group. Both concurrent regimens, RT2Gy × 3 f’x and RT9Gy × 3 f’x, clearly decreased the biodistribution of regorafenib in the heart, liver, lung, spleen and kidneys, compared to the control (regorafenib × 3 d) group. The concurrent regimens, both RT2Gy × 3 f’x and RT9Gy × 3 f’x, significantly decreased the biodistribution of regorafenib, compared with the control group. The PK of regorafenib can be modulated both by off-target irradiation and stereotactic body radiation therapy (SBRT).

Papaya shoot tip associated endophytic bacteria isolated from in vitro cultures and host–endophyte interaction in vitro and in vivo

2007 ◽  
Vol 53 (3) ◽  
pp. 380-390 ◽  
Author(s):  
Pious Thomas ◽  
Sima Kumari ◽  
Ganiga K. Swarna ◽  
T.K.S. Gowda
Keyword(s):  
Culture Medium ◽  
Carica Papaya ◽  
In Vitro Cultures ◽  
Dependent Manner ◽  
16S Rdna Sequence ◽  
16S Rdna Sequence Analysis ◽  
Single Organism ◽  
Dose Dependent

Fourteen distinct bacterial clones were isolated from surface-sterilized shoot tips (~1 cm) of papaya (Carica papaya L. ‘Surya’) planted on Murashige and Skoog (MS)-based papaya culture medium (23/50 nos.) during the 2–4 week period following in vitro culturing. These isolates were ascribed to six Gram-negative genera, namely Pantoea ( P. ananatis ), Enterobacter ( E. cloacae ), Brevundimonas ( B. aurantiaca ), Sphingomonas , Methylobacterium ( M. rhodesianum ), and Agrobacterium ( A. tumefaciens ) or two Gram-positive genera, Microbacterium ( M. esteraromaticum ) and Bacillus ( B. benzoevorans ) based on 16S rDNA sequence analysis. Pantoea ananatis was the most frequently isolated organism (70% of the cultures) followed by B. benzoevorans (13%), while others were isolated from single stocks. Bacteria-harboring in vitro cultures often showed a single organism. Pantoea, Enterobacter, and Agrobacterium spp. grew actively on MS-based normal papaya medium, while Microbacterium, Brevundimonas, Bacillus, Sphingomonas, and Methylobacterium spp. failed to grow in the absence of host tissue. Supplying MS medium with tissue extract enhanced the growth of all the organisms in a dose-dependent manner, indicating reliance of the endophyte on its host. Inoculation of papaya seeds with the endophytes (20 h at OD550 = 0.5) led to delayed germination or slow seedling growth initially. However, the inhibition was overcome by 3 months and the seedlings inoculated with Pantoea, Microbacterium, or Sphingomonas spp. displayed significantly better root and shoot growths.

Triphenyltin chloride induces spindle microtubule depolymerisation and inhibits meiotic maturation in mouse oocytes

2014 ◽  
Vol 26 (8) ◽  
pp. 1084 ◽  
Author(s):  
Yu-Ting Shen ◽  
Yue-Qiang Song ◽  
Xiao-Qin He ◽  
Fei Zhang ◽  
Xin Huang ◽  
...  
Keyword(s):  
Polar Body ◽  
Meiotic Maturation ◽  
Dependent Manner ◽  
Germinal Vesicle Breakdown ◽  
Mouse Oocytes ◽  
First Polar Body ◽  
Triphenyltin Chloride ◽  
Dose Dependent

Meiosis produces haploid gametes for sexual reproduction. Triphenyltin chloride (TPTCL) is a highly bioaccumulated and toxic environmental oestrogen; however, its effect on oocyte meiosis remains unknown. We examined the effect of TPTCL on mouse oocyte meiotic maturation in vitro and in vivo. In vitro, TPTCL inhibited germinal vesicle breakdown (GVBD) and first polar body extrusion (PBE) in a dose-dependent manner. The spindle microtubules completely disassembled and the chromosomes condensed after oocytes were exposed to 5 or 10 μg mL–1 TPTCL. γ-Tubulin protein was abnormally localised near chromosomes rather than on the spindle poles. In vivo, mice received TPTCL by oral gavage for 10 days. The general condition of the mice deteriorated and the ovary coefficient was reduced (P < 0.05). The number of secondary and mature ovarian follicles was significantly reduced by 10 mg kg–1 TPTCL (P < 0.05). GVBD decreased in a non-significant, dose-dependent manner (P > 0.05). PBE was inhibited with 10 mg kg–1 TPTCL (P < 0.05). The spindles of in vitro and in vivo metaphase II oocytes were disassembled with 10 mg kg–1 TPTCL. These results suggest that TPTCL seriously affects meiotic maturation by disturbing cell-cycle progression, disturbing the microtubule cytoskeleton and inhibiting follicle development in mouse oocytes.

scholarly journals The Antiinfective Effects of Velvet Antler of Formosan Sambar Deer (Cervus unicolor swinhoei) onStaphylococcus aureus-Infected Mice

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Ting-Yeu Dai ◽  
Chih-Hua Wang ◽  
Kun-Nan Chen ◽  
I-Nung Huang ◽  
Wei-Sheng Hong ◽  
...  
Keyword(s):  
Lipoteichoic Acid ◽  
Lavage Fluid ◽  
Dependent Manner ◽  
Protective Mechanisms ◽  
Velvet Antler ◽  
Sambar Deer ◽  
Dose Dependent ◽  
Cervus Unicolor

We assayed the effects of velvet antler (VA) of Formosan sambar deer (Cervus unicolor swinhoei) and its extracts on the anti-infective activity against pathogenicStaphylococcus aureus in vitroandin vivoin this study.In vitrodata indicated that the VA extracts stimulated the proliferation of resting splenocytes and macrophages in a dose-dependent manner up to the highest concentration used (150 μg mL−1). The production of proinflammatory cytokines (TNF-α, IL-6, IL-12) by lipoteichoic acid was significantly suppressed after being cocultured with the VA extracts in a dose-dependent manner. Animal test inS. aureus-infected mice demonstrated that the numbers of bacteria determined in the kidneys and peritoneal lavage fluid ofS. aureus-infected mice were significantly higher than those found in the same organs of mice pretreated with the VA samples. Moreover, the highly enhanced phagocytic activity of macrophages was further verified afterin vitrotreatment with the VA samples. The protective mechanisms of the VA samples might include an immune enhancer and an inflammatory cytokine suppressor.

Immunomodulatory activities of whey fractions in efferent prefemoral lymph of sheep

1996 ◽  
Vol 63 (2) ◽  
pp. 257-267 ◽  
Author(s):  
Chun W. Wong ◽  
Geoffrey O. Regester ◽  
Geoffrey L. Francis ◽  
Dennis L. Watson
Keyword(s):  
Immune Responses ◽  
Bovine Milk ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Milk Whey ◽  
Significant Difference ◽  
Lymphocyte Phenotypes ◽  
Dose Dependent

SummaryStudies on the immunomodulatory activities of ruminant milk and colostral whey fractions were undertaken. By comparing with boiled colostral whey in a preliminary experiment, a putative heat-labile immunostimulatory factor for antibody responses was found to be present in ovine colostral whey. Studies were then undertaken in sheep in which the efferent prefemoral lymphatic ducts were cannulated bilaterally, and immune responses in the node were measured following subcutaneous injection in the flank fold of whey protein preparations of various purities. A significant sustained decline of efferent lymphocyte output was observed following injection with autologous crude milk whey or colostral whey preparations, but no changes were observed in interferon-gamma levels in lymph plasma. Two bovine milk whey fractions (lactoperoxidase and lactoferrin) of high purity were compared in bilaterally cannulated sheep. A transient decline over the first 6 h was seen in the efferent lymphocyte output and lymph flow rate after injection of both fractions. A significant difference was seen between the two fractions in interferongamma levels in lymph at 6 h after injection. However, no significant changes in the proportion of the various efferent lymphocyte phenotypes were seen following either treatment. Whereas both fractions showed a significant inhibitory effect in a dose-dependent manner on the proliferative response of T lymphocytes, but not B lymphocytes, to mitogenic stimulation in vitro, no similar changes were seen following in vivo stimulation with these two fractions.

Role Of Cyclic Amp In The Inhibition Of Human Platelet Functions By Quercetin, A Flav0N0Id That Potentiates PGI2 Effect

1981 ◽  
Author(s):  
J P Cazenave ◽  
A Beretz ◽  
A Stierlé ◽  
R Anton
Keyword(s):  
Maximum Level ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Pde Inhibitors ◽  
Pde Inhibition ◽  
Induced Aggregation ◽  
Camp Levels ◽  
Dose Dependent

Injury to the endothelium (END) and subsequent platelet (PLAT)interactions with the subEND are important steps in thrombosis and atherosclerosis. Thus,drugs that protect the END from injury and also inhibit PLAT function are of interest. It has been shown that some flavonoids(FLA), a group of compounds found in plants, prevent END desquamation in vivo, inhibit cyclic nucleotide phosphodiesterases(PDE)and inhibit PLAT function. We have studied the structure-activity relationships of 13 purified FLA on aggregation and secretion of 14c-5HT of prelabeled washed human PLAT induced by ADP, collagen(COLL) and thrombin(THR). All the FLA were inhibitors of the 3 agents tested. Quercetin(Q), was the second best after fisetin. It inhibited secretion and aggregation with I50 of 330µM against 0.1 U/ML.THR, 102µM against 5µM ADP and 40 µM against COLL. This inhibitory effect is in the range of that of other PDE inhibitors like dipyridamole or 3-isobutyl-l- methylxanthine. The aggregation induced by ADP, COLL and THR is at least mediated by 3 mechanisms that can be inhibited by increasing cAMP levels. We next investigated if Q, which is a PDE inhibitor of bovine aortic microsomes,raises PLAT cAMP levels. cAMP was measured by a protein-binding method. ADP- induced aggregation(5µM) was inhibited by PGI2 (0.1 and 0.5 nM) . Inhibition was further potentiated(l.7 and 3.3 times) by lOµM Q, which alone has no effect on aggregation. The basal level of cAMP(2.2 pmol/108PLAT) was not modified by Q (50 to 500µM). Using these concentrations of Q,the rise in cAMP caused by PGI2(0.1 and 0.5nM) was potentiated in a dose dependent manner. Q potentiated the effect of PGI2 on the maximum level of cAMP and retarded its breakdown. Thus Q and possibly other FLA could inhibit the interaction of PLAT with the components of the vessel wall by preventing END damage and by inhibiting PLAT function through a rise in cAMP secondary to PDE inhibition and potentiation of the effect of vascular PGI2 on PLAT adenylate cyclase.

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