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At least 577 records · Page 32Linked to original sources
PubMed1994

Estimates of antagonist affinities at P2X purinoceptors in rat vas deferens.

In functional studies pyridoxalphosphate-6-azophenyl-2',5'-disulphonic acid (iso-PPADS), suramin, GR200282 (4,4'-[carbonyl-bis(imino-3- benzoylimino)]-bis[5-hydroxy-naphthalene-2,7-disulfonic acid] tetrapotassium salt), cibacron blue, trypan blue and congo red, each produced specific antagonism of the contractile responses of isolated rat vas deferens, induced by alpha,beta-methylene ATP (alpha,beta-meATP), with antagonist pKB estimates of 6.6 +/- 0.3, 5.5 +/- 0.2, 5.1 +/- 0.3, 5.8 +/- 0.2, 4.7 +/- 0.2 and 4.6 +/- 0.2, respectively. In radioligand binding studies, iso-PPADS, suramin, cibacron blue, GR200282, trypan blue and congo red competed for the high affinity [3H]alpha,beta-meATP binding sites in rat vas deferens membranes with pKi estimates of 5.6 +/- 0.04, 5.5 +/- 0.08, 5.6 +/- 0.15, 5.6 +/- 0.04, 4.3 +/- 0.06 and 4.9 +/- 0.10, respectively. Comparison of pKB and pKi estimates revealed a good agreement between the two approaches for estimating measures of affinity for the putative antagonists, except in the case of iso-PPADS. However, we found that two populations of [3H]alpha,beta-meATP binding sites can be identified by iso-PPADS, 26.4% of these having low affinity (pKi of 4.4 +/- 0.2), and 73.6% having high affinity (pKi of 6.5 +/- 0.02) for iso-PPADS. The pKi of 6.5 obtained at the high affinity sites identified by iso-PPADS was close to the equivalent pKB value of 6.6 from functional studies. These studies therefore show a good agreement between pKB and pKi estimates for several antagonists, and suggest that the high affinity binding sites labelled with [3H]alpha,beta-meATP in rat vas deferens represents binding to functional P2X purinoceptors.

Adenosine Triphosphate↗
PubMed1978

A survey of the effect of some drugs, chemicals, and enzymes on calcium oxalate precipitation in the rat kidney.

A single intraperitoneal injection of sodium oxalate was used to induce intrarenal tubular precipitation of calcium oxalate in rats. This experimental model was used to screen the efficacy of hydrochlorothiazide, orthophosphate, methylene blue, trypan blue, retinal folic acid, neuraminidase, and lysozyme in retarding intratubular calcium oxalate precipitation. Orthophosphate caused a 53 per cent reduction in calcium oxalate precipitation relative to the control animals.

Animals↗
PubMed1993

Bis-azo dyes interference with effector activation of antibodies.

Azo dyes (Congo Red, Evans Blue, Trypan Blue) were used to study the relation between antigen binding and effector activity in SRBC rabbit anti-SRBC IgG system. Antigen binding was tested in this study by agglutination and effector activity by complement fixation. Antibodies induced by the antigen binding appeared to become structurally susceptible for interaction with the dye. The dyes cause the enhancement of antigen binding by antibodies and inhibition of their effector activity. The intensity of both effects caused by binding the dye seems correlated. The increase of antibody concentration makes the effector activity of immune complexes more resistant to dye inhibition indicating that the influence of antigen binding may be exerted on assembling of antibody in the immune complex rather than on structural modulation of Fc. Also the analysis of dye effects on antibody derivatives deprived of effector activity (Fab)2, IgG with split interheavy chain disulphides supplied evidence that the induced by the antigen long distance structural effects may play the role of immune signal by influencing the assembling of antibodies and stability of immune complex.

Agglutination Tests↗
PubMed1993

Bis azo dyes--studies on the mechanism of complex formation with IgG modulated by heating or antigen binding.

The mechanism of binding of azo dyes (bis azo) to immunoglobulin G of altered conformation, induced by heating or interaction with antigen was analysed in this work. Azo dyes: Congo Red, Evans Blue and Trypan Blue were selected for these studies. The molecules of Congo Red and Evans Blue associate readily in water and exist as polymolecular micellar species of liquid crystalline organization. Such organization of molecules appeared necessary for these dyes to interact with antibodies and to affect the formation of immune complex. It was proved by studying the properties of isomeric dyes Evans Blue and Trypan Blue, whose ability to form polymolecular conglomerates in water differs, being high for Evans Blue and low for Trypan Blue. The dyes seem to influence the formation of the immune complex generally by interacting with individual immunoglobulin molecules. The rate of exchange of dye molecules in conglomerate bound to protein varies and is the lowest for the portion of molecules which are engaged directly in the complex with protein. Electron microscopic studies also confirmed the polymolecular form of the dye in the dye-protein complex. The computational simulation of dye-dye and dye-protein interaction was performed in a model system. The micelle in the system was represented by three molecules of Congo Red. The peptide loop composed of amino acids 68-88 originating from VL IgG domain, was selected to represent protein. Amino acid side chains of this fragment were reduced to C beta. The best fitness was found for peptide chains of twisted beta conformation and independently optimized conformation of the dye in a form of "twisted ribbon" micelle. It was concluded that the IgG domains become accessible for penetration of the dye after being relaxed in the result of heating or interaction with the antigen.

Agglutination Tests↗
PubMed1996

Effects of P2-purinoceptor antagonists on degradation of adenine nucleotides by ecto-nucleotidases in folliculated oocytes of Xenopus laevis.

The aim of the present study was to examine the effects of a number of P2-purinoceptor antagonists on degradation of adenine nucleotides by Xenopus laevis oocyte ecto-nucleotidase. Folliculated oocytes readily metabolize all three naturally-occurring nucleotides, the order of preferential substrates being ATP >ADP > AMP. The degradation of ATP and ADP was decreased significantly in the presence of several P2X- and P2Y-purinoceptor antagonists, including suramin, PPADS, Cibacron blue, Coomassie Brilliant blue, Evans blue, Trypan blue, Congo red, and PIT (each compound was used at 100 microM). All these compounds inhibited the degradation of ATP by up to 60%, whereas the hydrolysis of ADP was inhibited by Congo red and PIT by 75-80%. In addition, DIDS (100 microM) and TNP-ATP (100 microM) selectively inhibited the breakdown of ATP, and sodium azide (10 mM) selectively inhibited the breakdown of ADP. The enzymatic breakdown of either ATP or ADP was unaffected by 8-pSPT (100 microM), an antagonist of P1-purinoceptors, or by oxidized ATP (100 microM), an antagonist of P2Z-purinoceptors. The degradation of AMP was prevented completely by PIT (100 microM) and ingibited significantly by Congo red (100 microM). In conclusion, the present study shows that most of currently available antagonists of P2-purinoceptors inhibit the enzymatic breakdown of extracellular ATP and ADP. The inhibitory effect on ecto-nucleotidase activity should be taken into account when these antagonists are used in pharmacological experiments.

Adenine Nucleotides↗
PubMed2002

Nucleotide-evoked relaxation of rat vas deferens: possible mechanisms.

ATP causes relaxation of the K(+)-contracted rat vas deferens. Possible sites of action were investigated. ATP and adenosine relaxed the vas deferens precontracted with 80 mM K(+); EC(50) values and maximal relaxations averaged, respectively, 760 microM and 56% for ATP and 74 microM and 30% for adenosine. The adenosine P1 receptor antagonist 8-(para-sulfophenyl)theophylline (8-SPT) reduced relaxations caused by adenosine and low concentrations of ATP, as did the Rp-diastereomer of adenosine 3',5'-cyclic phosphorothioate (Rp-cAMPS), an inhibitor of protein kinase A. The phosphodiesterase inhibitor 4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (Ro 20-1724) augmented responses to adenosine and low concentrations of ATP. alpha,beta-Methylene ADP, an inhibitor of 5'-nucleotidase, reduced relaxations caused by ATP to a similar extent as did 8-SPT. In the presence of an almost saturating concentration of adenosine, ATP caused further relaxation. Conversely, in the presence of ATP, adenosine had little effect. Like ATP, UTP and other nucleoside triphosphates relaxed the vas deferens. The P2 receptor antagonists reactive blue 2, acid blue 25 and 4,4'-diisothiocyanotostilbene-2,2'-disulphonate (DIDS) attenuated the relaxation caused by ATP; suramin, pyridoxalphosphate-6-azophenyl-2',4'-disulphonate (PPADS), Evans blue, trypan blue, reactive red 2 and brilliant blue G had no effect. Three non-selective inhibitors of protein kinases, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), staurosporine and (8R*,9S*,11S*)-(-)-9-hydroxy-9-carboxy-8-methyl-2,3,9,10-tetrahydro-8,11-epoxy-1H,8H,11H-2,7b,11a-triazadibenzo[a,g]cycloocta[cde]trinden-1-one (K-252b), markedly reduced the relaxation caused by ATP. The results indicate that adenosine, derived from enzymatic dephosphorylation, contributes to the relaxant effect of ATP, presumably by activation of a smooth muscle adenosine receptor linked to the accumulation of cAMP and activation of protein kinase A. Yet, the main part of the response to ATP is mediated by a site distinct from the adenosine receptor. The pharmacological properties of this site differ from known P2 receptor subtypes. Possibly, the nucleotide-evoked relaxation is due to a phosphoryl transfer catalyzed by an ecto-protein kinase.

4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone↗
PubMed2004

Trypan blue-assisted vitrectomy.

PURPOSE: To evaluate the efficacy of trypan blue dye for the staining and removal of the internal limiting membrane, epiretinal membranes, and the posterior hyaloid during pars plana vitrectomy. METHODS: The authors retrospectively reviewed a consecutive series of 26 eyes of 26 patients in whom trypan blue 0.15% dye was used to stain intraocular tissues during vitrectomy surgery. RESULTS: The cases reviewed included the following diagnoses: epiretinal membrane (13), macular hole (9), proliferative vitreoretinopathy (2), chronic pseudophakic cystoid macular edema (1), and chronic diabetic macular edema (1). The application of trypan blue resulted in a useful and consistent bluish staining, facilitating the identification, delineation, and removal of the epiretinal membrane, internal limiting membrane, or posterior hyaloid in all patients. Six months after the surgery, visual acuity was better or the same in 21 of the 26 patients. There were no clinical signs of retinal toxicity in any patients. CONCLUSION: Trypan blue staining of the internal limiting membrane, epiretinal membranes, and the posterior hyaloid is a useful adjunct in vitreoretinal surgery and improves the efficiency and safety of membrane identification and removal.

Aged↗
PubMed2004

Functional outcome after trypan blue-assisted vitrectomy for macular pucker: a prospective, randomized, comparative trial.

PURPOSE: To evaluate functional outcome after the intraoperative application of 0.06% trypan blue during vitrectomy for macular pucker. DESIGN: Prospective, randomized, comparative study. METHODS: Forty-three eyes of 43 consecutive patients, 30 women and 13 men, were incorporated in the study. Patients were randomized into two groups: group 1 (n = 22) with trypan blue (0.06%) staining, and group 2 (n = 21) without trypan blue staining. Functional outcome (best-corrected visual acuity, Goldmann perimetry) was evaluated 1 day before surgery, at 6 weeks, and at intervals of 3, 6, and 12 or more months postoperatively. Only patients with an idiopathic macular pucker were included. In all patients, a standard three-port pars plana vitrectomy with peeling of an epiretinal membrane (ERM) and the internal limiting membrane was performed. No other modification of the surgical procedure, except the use of trypan blue was made between the two groups. RESULTS: Mean age was 68.9 years in group 1 (with trypan blue) and 69.4 in group 2 (without trypan blue). Median best-corrected visual acuity was 20/63 in both groups (range, 20/200-20/40; P >.5) before surgery. Mean follow-up time was 5.8 months in group 1 and 5.3 months in group 2. After surgery, median visual acuity had increased to 20/40 in both groups (range, 20/500 to 20/20 in group 1 and 20/100 to 20/20 in group 2; P <.001 for both groups). The difference between both groups was not statistically significant (P >.5). An improvement of visual acuity (gain of 2 or more lines) was seen in 16 patients of both groups. No postoperative visual field defects were noted. CONCLUSIONS: Trypan blue-assisted vitrectomy for macular pucker leads to good functional results with no dye-related adverse effects after short follow-up. Trypan blue might be especially applicable in cases in which the borders of the ERM are difficult to define. Hypothetical advantages, such as fewer recurrences of ERMs after trypan blue staining, will have to be evaluated during further follow-up of patients.

Aged↗
PubMed2006

Increase in intracellular Ca2+ concentration is not the only cause of lidocaine-induced cell damage in the cultured neurons of Lymnaea stagnalis.

PURPOSE: To determine whether the increase in intracellular Ca2+ concentration induced by lidocaine produces neurotoxicity, we compared morphological changes and Ca2+ concentrations, using fura-2 imaging, in the cultured neurons of Lymnaea stagnalis. METHODS: We used BAPTA-AM, a Ca2+ chelator, to prevent the increase in the intracellular Ca2+ concentration, and Calcimycin A23187, a Ca2+ ionophore, to identify the relationship between increased intracellular Ca(2+) concentrations and neuronal damage without lidocaine. Morphological changes were confirmed using trypan blue to stain the cells. RESULTS: Increasing the dose of lidocaine increased the intracellular Ca2+ concentration; however, there was no morphological damage to the cells in lidocaine at 3 x 10(-3) M. Lidocaine at 3 x 10(-2) M increased the intracellular Ca2+ concentration in both saline (from 238 +/- 63 to 1038 +/- 156 nM) and Ca2+-free medium (from 211 +/- 97 to 1046 +/- 169 nM) and produced morphological damage and shrinkage, with the formation of a rugged surface. With the addition of BAPTA-AM, lidocaine at 3 x 10(-2) M moderately increased the intracellular Ca2+ concentration (from 150 +/- 97 to 428 +/- 246 nM) and produced morphological damage. These morphologically changed cells were stained dark blue with trypan blue dye. The Ca2+ ionophore increased the intracellular Ca2+ concentration (from 277 +/- 191 to 1323 +/- 67 nM) and decreased it to 186 +/- 109 nM at 60 min. Morphological damage was not observed during the 60 min, but became apparent a few hours later. CONCLUSION: These results indicated that the increase in intracellular Ca2+ concentration is not the only cause of lidocaine-induced cell damage.

Anesthetics, Local↗
PubMed1985

A sensitive assay of cytotoxicity applicable to mixed cell populations.

The fluorescent vital dye, Hoechst 33342, was used to stain cultured cells prior to assay of antibody dependent complement mediated cytotoxicity. The fluorescence of nonviable dye stained cells is quenched by cellular uptake of trypan blue, but trypan blue excluding cells remain intensely fluorescent. Detection by fluorescence microscopy of one viable prestained cell per 10(5) unstained cells was accurate and reliable. The technique was found to have sensitivity equal to a clonogenic assay for measuring cytotoxicity. The dye stained cell assay may be used to measure depletion of a selected cell type, when those cells are stained prior to mixing with another cell population. This technique may prove useful to study model systems for depletion of tumor cells or T-cells from bone marrow.

Antibody-Dependent Cell Cytotoxicity↗