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PubMed1989

Thrombogenicity of canine free internal mammary artery autografts.

Early patency of free internal mammary artery (IMA) grafts for coronary artery bypass (CAB) is lower than that of in situ IMA grafts, and proximal anastomotic problems have been implicated in the pathogenesis of graft occlusion. To determine whether thrombotic phenomena might account for proximal graft narrowing, we examined platelet and fibrinogen deposition in 23 free IMA grafts in a canine model of CAB. Twelve animals had no antiplatelet therapy and were controls. Eleven animals received dipyridamole, 55 mg p.o. daily, 2 days before and each day after operation; aspirin, 325 mg p.o. daily, was given after CAB. Six of the 12 untreated dogs and 5 of the 11 treated dogs were sacrificed at 1 day after surgery; the remainder of each group was sacrificed on the 14th postoperative day. Platelet and fibrinogen depositions were quantitated by indium-111 tropolone and Iodine-125 labeling, respectively. Grafts were sectioned into five parts: proximal anastomosis (PA), proximal graft (PG), midgraft (MG), distal graft (DG), and distal anastomosis (DA). Platelet deposition was highest at the PA of free IMA grafts, and fibrinogen deposition was high at both anastomoses. Antiplatelet therapy significantly reduced platelet deposition at the PA at 14 days, but not at 1 day; fibrinogen deposition was significantly reduced at the DA at 1 day, and at both the PA and DA at 14 days. The ratio of fibrinogen molecules per platelet was unaffected by antiplatelet therapy, but was observed to increase with time at the DG and DA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Amperometric detection of low concentrations of dopamine receptor agonists after liquid chromatographic on-column sample enrichment: effect of o-methylation on brain concentrations of dipropyl-5,6-ADTN and dipropyl-6,7-ADTN.

A sensitive and selective method of determination of N,N-dipropylamino-5, 6-dihydroxytetralin and its 6,7-dihydroxy isomer in rat plasma and brain tissue is described. The method is based on isolation of these dopamine receptor agonists from the biological samples on small Sephadex G-10 columns, followed by reversed phase high performance liquid chromatography with amperometric detection. Large volume (2 ml) injections result in on-column sample enrichment without a subsequent loss in column efficiency. Using this method the very low detection limit of 4 pmol/g was achieved in brain tissue. It was found that the lower in vivo potency as a centrally acting dopamine agonist of the 6,7-compared with the 5,6-isomer is almost entirely due to the lower brain concentrations achieved after peripheral administration of equimolar doses. This difference is mainly caused by different rates of O-methylation by catechol-O-methyltransferase, which follows from the fact that inhibition of this enzyme by tropolone leads to almost equal brain concentrations of the two isomers.

Animals↗
PubMed1985

A motility test of leukocytes under agar.

A migration test under agar for leukocytes was developed. Leukocytes moved quite a distance under anaerobic Blood Agar Base (blood agar), a Gibco product. Migration on stained and coloured plates was visualized by projection with a profile projector, making the use of a light microscope superfluous. A migration index was defined. Reproducibility was good enough to allow paired comparisons of leukocyte populations subjected to different treatments. Migration was the result of spontaneous and chemotactically directed migration. Cell-labelling complexes as 111In-oxinate and 111In-tropolonate--ligand concentration 3.5 micrograms/mL in the ultimate cell preparation--did not affect leukocyte migration. 111In-pyrithionate (mercapto pyridine-N-oxide) significantly impaired cell motility. The motility test described could be used as retrospective analysis in abscess localization studies using 111In labelled leukocytes.

Agar↗
PubMed1983

A survey of the available colorimetric indicators for Ca2+ and Mg2+ ions in biological experiments.

The binding of Ca2+ and Mg2+ ions to commercially available and easily synthesizable metallochromic indicators has been systematically examined at pH 7.35, temperature 37 degrees C, ionic strength 0.16, the conditions of blood plasma. The pCa and pMg midpoints of the colour changes of all the useful indicators are reported. In addition to the well-known indicators arsenzazo III, chlorophosphonazo III, antipyrylazo III, and murexide for Ca2+, and Eriochrome Black T and Eriochrome Blue SE for Mg2+, we draw attention to the values of oxyacetazo I, carboxyazo III, tropolone, methylthymol blue, Mordant Black 32, and the tetracyclines.

Azo Compounds↗
PubMedDate not supplied

In vitro phenoloxidase activity in the blood of Ciona intestinalis and other ascidians.

The presence and activation of phenoloxidase in the blood of Ciona intestinalis and other ascidians was investigated in vitro. In C. intestinalis, phenoloxidase was found to exist in the cells as a proenzyme and to be activated by proteases. The microbial carbohydrates, LPS or laminarin, also enhanced enzyme activity but a similar effect was not achieved with other sugars. Calcium was not essential for enzyme activity and no enzyme suppression was seen at high calcium concentrations. Prophenoloxidase activation by LPS was further found to be dose related and inhibited by PTU and tropolone. Since benzamidine and STI reduced phenoloxidase activity in cell lysate supernatants, activation may involve other factors, possibly a serine protease. Lastly, as phenoloxidase activity was detected in the blood cells (usually the morula cells) of eight other ascidian species, it appears that it is widely distributed in the blood of this group of invertebrates.

Animals↗
PubMed1987

The value of indium-labelled leucocytes in clinical practice.

Following intravenous injection, autologous 111In labelled-leucocytes migrate to sites of inflammation, where they can be imaged with the gamma camera. The principle underlining the labelling technique is exposure of a population of leucocytes or purified granulocytes to a lipophilic 111In complex, such as 111In oxine or 111In tropolonate. As a result of cell activation, the in vitro manipulation to which the leucocytes are subjected modifies their biodistribution early after re-injection. Separation and labelling in plasma-enriched media, however, limits this activation and promotes early migration into inflammatory foci.

Humans↗
PubMed1994

Neuroprotective effects of colchicine in the gerbil model of cerebral ischaemia.

The tropolonic alkaloid colchicine significantly reduces the behavioural, electroencephalographic and histological damage seen after a 6-min occlusion of the two common carotid arteries of the Mongolian gerbil if the compound is administered at 2 or 4 mg/kg i.p. immediately upon reperfusion. A 45% increase in high-frequency ECoG activity and significant reduction of 80% in the hypermotility of the gerbils, with 63% less faults in a passive avoidance paradigm, were observed in conjunction with considerable protection of the hippocampus, after a single dose of 4 mg/kg colchicine. No adverse effects of colchicine treatment on animal movement and body weight were observable. Colchicine's possible mode of action, via inhibition of cellular transport systems, is discussed.

Animals↗
PubMed1984

The effect of various chelating agents on the mobilization of iron from reticulocytes in the presence and absence of pyridoxal isonicotinoyl hydrazone.

The chelating agent pyridoxal isonicotinoyl hydrazone (PIH) has recently been shown to mobilize 59Fe from reticulocytes loaded with non-heme 59Fe. In this study, various chelating agents were tested for their ability to effect the mobilization of iron from reticulocytes by PIH. They fall into several groups. The largest group includes chelators such as citrate, ethylenediaminetetracetic acid and desferrioxamine, which fail to affect PIH-induced iron mobilization and do not mobilize iron per se. Either these chelators do not enter reticulocytes or they do not take up iron from PIH-Fe complexes. The second group includes chelators such as 2,2'-bipyridine, 1,10-phenanthroline, bathophenanthroline sulfonate and N,N'-ethylenebis(o-hydroxyphenylglycine) which inhibit PIH-induced iron mobilization from reticulocytes and, when added together with PIH, induce radioiron accumulation in an alcohol-soluble fraction of reticulocytes. It appears that these chelators enter the cell and compete with PIH for 59Fe(II), but having bound iron are unable to cross the cell membrane. Spectral analysis suggests that Fe(II) chelators such as 2,2'-bipyridine and 1,10-phenanthroline remove iron from Fe(II)PIH but are not able to do so from Fe(III)PIH. Then there are compounds such as 2,3-dihydroxybenzoic acid and catechol which potentiate PIH-induced iron mobilization although they are unable to mobilize iron from reticulocytes by themselves. Lastly, there is a group of miscellaneous compounds which include chelators that either potentiate the iron-mobilizing effect of PIH as well as mobilizing iron from reticulocytes by themselves (tropolone), or that reduce PIH-induced iron mobilization while themselves having an iron-mobilizing effect (N,N'-bis(2,3-dihydroxybenzoyl)-1,6-diaminohexane). In further experiments, heme was found to stimulate globin synthesis in reticulocytes, the heme synthesis of which was inhibited by PIH, suggesting that PIH is probably not toxic to the cells.

2,2'-Dipyridyl↗
PubMed1991

Comparison of sulphur-mode and tin-mode flame photometric detectors for the gas chromatographic determination of organotin compounds.

A comparison of sulphur-mode (393 nm) and tin-mode (610 nm) flame photometric detectors for the gas chromatographic determination of butyl- and phenyltin compounds is described. The chromatographic peaks of the butyl- and phenyltin compounds were well separated, and high sensitivity was achieved in both modes; however, the tin-mode was more specific for tin compounds than the sulphur-mode. The absolute detection limits with the sulphur-mode and the tin-mode were 3.9-7.6 pg and 2.6-5.1 pg as tin, respectively. The application of the tin-mode gas chromatographic method to the determination of organotin compounds in fish is presented. For this application, organotins are extracted (as chloride) with hydrochloric acid and n-hexane-benzene (3:2, containing 0.05% tropolone) and the extracts are pentylated by a Grignard reagent prior to gas chromatography. The absolute recoveries of butyl- and phenyltin compounds added to fish samples ranged from 68.5 to 84.4% (the coefficients of variation were less than 6.6% for all substances, n = 8). Significant amounts of three organotin compounds (di- and tributyltin and triphenyltin) in fish samples were detected by this method. This technique may have application for other organotin compounds and the monitoring of butyl- and phenyltin compounds in the environment.

Animals↗
PubMed1993

Gas chromatographic determination of inorganic tin in rat urine after a single oral administration of stannous chloride and mono-, di-, and triphenyltin chloride.

A method is described for the determination of inorganic tin by gas chromatography with flame photometric detection. The inorganic tins, stannous and stannic, were extracted with hydrochloric acid and n-hexane-benzene in the presence of 0.05% tropolone, and both inorganic tins were pentylated to tetrapentyltin with a Grignard reagent prior to gas chromatography. The absolute limit of detection for tetrapentyltin was 3 pg as tin. The recovery of stannous chloride added to rat urine samples was 80.2 +/- 2.4% (mean +/- S.D., n = 8). The application of this method to the study of urinary excretion of inorganic tin and organotin compounds in rats following oral administration of tin compounds is presented. The urinary excretion of tin compounds was observed over a period of 96 h following administration of stannous chloride or phenyltin compounds. Most of the inorganic tin was excreted into urine within 24 h after administration of stannous chloride. In the experiments on organotin administration, the level of the excretion as total tin for monophenyltin reached a maximum ca. 0-24 h after administration, whereas the maxima for di- and triphenyltin were found after 24-48 h and 48-72 h, respectively. The predominant excretion product of these tin compounds found in urine was monophenyltin.

Administration, Oral↗
PubMed1996

Oxymetric and spectrophotometric study of the ascorbate oxidase activity shown by frog epidermis tyrosinase.

Many studies concerning the effect of ascorbic acid on the action of tyrosinase on several substrates have been carried out with contradictory results. The results shown in this work comprise a hypothetical reaction mechanism, which explains the ascorbate oxidase activity of frog epidermis tyrosinase. The reaction between frog epidermis tyrosinase and L-ascorbic acid was studied by oxymetric and spectrophotometric assays. The activity was linearly related to enzyme concentration, with a Michaelis constant for L-ascorbic acid of 0.160 +/- 0.009 mM and Vmax of 90 +/- 4 nM/s. Maximum activity was obtained at pH 7.5. The stoichiometry of the reaction was calculated by measuring the substrate (O2 and L-ascorbic acid) consumption as well as the initial rates of the consumption of oxygen and the disappearance of L-ascorbic acid. The stoichiometry was found to be 1:2 (O2:L-ascorbic acid). The action of the tyrosinase inhibitor tropolone was also studied. All the results present evidence concerning the ascorbate oxidase activity of frog epidermis tyrosinase and a possible reaction mechanism based on the different enzymatic forms of tyrosinase to explain such activity.

Animals↗
PubMed2005

Arachidonate 12-lipoxygenases with reference to their selective inhibitors.

Lipoxygenase is a dioxygenase recognizing a 1-cis,4-cis-pentadiene of polyunsaturated fatty acids. The enzyme oxygenates various carbon atoms of arachidonic acid as a substrate and produces 5-, 8-, 12- or 15-hydroperoxyeicosatetraenoic acid with a conjugated diene chromophore. The enzyme is referred to as 5-, 8-, 12- or 15-lipoxygenase, respectively. Earlier we found two isoforms of 12-lipoxygenase, leukocyte- and platelet-type enzymes, which were distinguished by substrate specificity, catalytic activity, primary structure, gene intron size, and antigenicity. Recently, the epidermis-type enzyme was found as the third isoform. Attempts have been made to find isozyme-specific inhibitors of 12-lipoxygenase, and earlier we found hinokitiol, a tropolone, as a potent inhibitor selective for the platelet-type 12-lipoxygenase. More recently, we tested various catechins of tea leaves and found that (-)-gallocatechin gallate was a potent and selective inhibitor of human platelet 12-lipoxygenase with an IC50 of 0.14 microM. The compound was much less active with 12-lipoxygenase of leukocyte-type, 15-, 8-, and 5-lipoxygenases, and cyclooxygenases-1 and -2.

Animals↗
PubMed2006

Demonstration of a true phenoloxidase activity and activation of a ProPO cascade in Pacific oyster, Crassostrea gigas (Thunberg) in vitro.

The prophenoloxidase (ProPO) system is the origin of melanin production and is considered to be an innate defence mechanism in invertebrates. In different bivalve species, phenoloxidase (PO) is present in the haemolymph as an inactive form of ProPO. The present study focuses on the Pacific adult oyster, Crassostrea gigas, an economically important bivalve species along French coasts. The results indicate that many factors may inhibit the PO-like activity. These include: phenylthiourea (PTU), sodium diethylthiocarbamate (DETC), beta-mercaptoethanol and tropolone, which repressed the spontaneous PO activity. The activation of PO-like activity in C. gigas acellular fraction by lipopolysaccharide (LPS) involved participation of other factors, including at least one serine protease. PO was present as proPO in the acellular fraction of haemolymph and haemocytes of C. gigas and could be activated by an exogenous protease (trypsin-N-tosyl-l-phenylalanine chloromethyl ketone) when used at 1 gL(-1). Treatment of acellular fractions with other modulators/activators namely LPS (1 gL(-1)), zymosan (0.6 gL(-1)) or laminarin (0.6 gL(-1)) also increased PO-like activity but to a less important way. The study demonstrated the evidence of a true phenoloxidase activity in Pacific oyster, C. gigas (Thunberg). The activation of a proPO system by non-self molecules suggests the role played by PO in vivo in the internal defence mechanisms. Understanding the activation of the ProPO system could enable the evaluation of the health of oyster stocks.

Animals↗
PubMed2006

Interaction of the bacteria Xenorhabdus nematophila (Enterobactericeae) and Bacillus subtilis (Bacillaceae) with the hemocytes of larval Malacosoma disstria (Insecta: Lepidoptera: Lasiocampidae).

Malacosoma disstria larvae are a pest of deciduous trees. Little is known on the interaction of bacteria with the immediate hemocytic antimicrobial responses of these insects. Incubating dead Xenorhabdus nematophila and Bacillus subtilis with a mixture of serum-free granular cells and plasmatocytes in vitro revealed differential bacterial-hemocyte adhesion and differential discharge of lysozyme and phenoloxidase but not total protein. Although active phenoloxidase adhered equally to both bacterial species, X. nematophila limited enzyme activation whereas B. subtilis enhanced activation. Serum with active phenoloxidase (as opposed to tropolone-inhibited phenoloxidase) and purified insect lysozyme increased bacterial-hemocyte adhesion of both bacterial species. An apolipophorin-III-like protein when incubated with hemocytes, limited their responses to glass slides and bacterial adhesion. However, initial binding of the protein to both bacteria increased granular cell levels with bacteria while lowering the plasmatocyte levels with adhering procaryotes. The protein also increased lysozyme and phenoloxidase activities. Although B. subtilis in vivo elicited a nodulation-based decline in total hemocyte counts and did not affect hemocyte viability, dead X. nematophila elevated hemocyte counts and damaged the hemocytes as lipopolysaccharide levels increased and X. nematophila emerged into the hemolymph. Apolipophorin-III-like protein once bound to the bacteria slowed their removal from the hemolymph.

Animals↗
PubMed2005

Oxidation of the flavonoid eriodictyol by tyrosinase.

A pathway is proposed for the oxidation of the flavonoid eriodictyol by mushroom tyrosinase. In it, the enzymatic oxidation of eriodictyol leads to the formation of eriodictyol-o-quinone, which undergoes the nucleophilic attack of another eriodictyol unit to yield a dimer. This dimer is then oxidized by the eriodictyol-o-quinone. The reaction was followed by recording the time course of formation of this second o-quinone at 475 nm. Progress curves at this wavelength showed the appearance of a lag, the length of which varied with enzyme and substrate concentrations, and which must have been caused by the chemical reactions taking place after the enzymatic reaction. When eriodictyol oxidation was studied in the presence of 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH), which competes with the substrate in the reaction with eriodictyol-o-quinone, the lag disappeared. The kinetic parameters were similar with and without MBTH. Eriodictyol oxidation was inhibited by tropolone, which behaved as a slow-binding inhibitor.

Enzyme Inhibitors↗
PubMed1984

Technique of leukocyte harvesting and labeling: problems and perspectives.

Mixed leukocyte suspensions obtained after gravity sedimentation of red cells and labeled with 111In lipophilic chelates are now widely used clinically for abscess localization at many medical centers. So far, labeling with 111In-oxine or tropolone has been more successful than any 99mTc method. More sophisticated approaches are available for isolation and labeling of specific leukocyte cell types, to study their migration in vivo. The most significant advances in cell harvesting include newer density gradients for isopyknic centrifugation (nonionic contrast media such as Nycodenz and Percoll, PVP-coated colloidal silica), centrifugal elutriation, and flow cytometry. Unlike current radioactive agents which label many cell types indiscriminately, more selective ligands are being developed which bind to specific cell surface receptors. These will label certain leukocyte populations or subtypes while not reacting with others, thereby avoiding laborious separation techniques. Monoclonal antibodies against leukocyte cell-surface antigens appear particularly promising as agents for selective cell labeling.

Abscess↗
PubMed1999

Platelet kinetic studies in patients with idiopathic thrombocytopenic purpura.

PURPOSE: To determine the value in diagnosis and treatment of mean platelet life, platelet production, and major sites of platelet destruction in patients with idiopathic thrombocytopenic purpura (ITP). PATIENTS AND METHODS: Sternal or posterior superior iliac spine bone marrow aspiration was performed in 141 patients. Platelet kinetic studies with Indium-111 tropolonate labeled autologous platelets were utilized to determine platelet production. RESULTS: Two subgroups of patients could be defined. The first group (n = 81, 58%) had normal or increased platelet production and increased peripheral platelet destruction. These patients fulfilled the conventional criteria for ITP, including reduced platelet survival time (mean +/- SD, 1.6 +/- 1.4 days). Forty-eight (59%) of these patients had increased splenic sequestration and 30 (88%) of the 34 patients who underwent splenectomy had a complete or partial remission. The second group (n = 60, 42%) had decreased platelet production, with significantly greater platelet survival times (3.6 +/- 2 days, P <0.0001). In this group, the proportion of patients with complete or partial response to splenectomy (62%) was somewhat lower (P = 0.09). These patients mainly had ineffective platelet production in the bone marrow. CONCLUSIONS: Platelet kinetic studies suggest that ITP is a heterogeneous disease that comprises two subgroups. Further studies are needed to validate these findings and to determine their effect on the choice and outcome of therapy.

Adult↗
PubMedDate not supplied

Phenoloxidase and cytotoxicity in the compound ascidian Botryllus schlosseri.

The vacuoles of morula cells (MC) of the colonial ascidian Botryllus schlosseri contain phenoloxidase (PO). As the release of their vacuolar content at the border of incompatible contacting colonies is associated with the formation of necrotic masses which characterize the rejection reaction, the role of PO in Botryllus cytotoxicity was investigated. When hemocytes are incubated with blood plasma from incompatible (heterologous) colonies, MC degranulate and, after 60 min, the cytotoxicity index becomes significantly greater than that observed in controls incubated with autologous plasma. The rise in cell mortality is completely inhibited by the addition of PO inhibitors sodium benzoate, tropolone and phenylthiourea, and serine protease inhibitors phenylmethylsulfonyl fluoride, benzamidine, N-tosyl-L-phenylalanine chloromethyl ketone and N-tosyl-L-lysine chloromethyl ketone. The addition of either reducing agents L-cysteine and ascorbic acid or reactive oxygen species scavenger enzymes superoxide dismutase and catalase has a similar effect. Significant inhibition of cytotoxicity is also observed with the quinone scavenger, 3-methyl-2-benzothiazolinone hydrazone. In the presence of sodium benzoate and phenylthiourea, there is a significant reduction in the number, size and color intensity of necrotic masses along the contact border of incompatible colonies. A significant increase in superoxide anion production, completely inhibited by sodium benzoate, is observed when hemocytes are incubated with heterologous blood plasma. These results indicate that: (i) PO is the enzyme responsible for the cytotoxicity observed in both hemocyte cultures and rejection reactions; (ii) PO is present inside MC vacuoles as a proenzyme which is activated, upon release, by humoral proteases; (iii) cytotoxicity appears to be mainly due to oxidative stress generated by PO during oxidation of polyphenols to quinones without the involvement of other oxidases such as NADPH oxidase and peroxidase.

Animals↗