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PubMed1980

The multifunctional actions of beta-thujaplicin on the oxidative energy transformations as a consequence of its lipophilic and chelating properties.

The influence of the fungicidic compound beta-thujaplicin (beta-isopropyl-tropolone) on the energy transformation processes of oxidative phosphorylation was investigated in isolated rat liver mitochondria with succinate (plus rotenone) as substrate. To elucidate the observed strong inhibition of active respiration by beta-thujaplicin three possibilities were assayed: the inhibition of 1) transport processes across the inner mitochondrial membrane for inorganic phosphate, adenine nucleotides, or succinate, 2) electron flux along the respiratory chain, and 3) mitochondrial ATPase. In this respect a remarkable inhibition of both Pi transport and the translocation of adenine nucleotides could not be observed. However, the effective suppression of the DNP-induced ATPase by beta-thujaplicin explains the pronounced inhibition of active respiration. An impairment of succinate transport and the measured partial inhibition of the terminal respiratory chain at the level of cytochrome oxidase contribute to the less marked inhibition of the uncoupled respiration. The ability of beta-thujaplicin to extract mitochondrial Mg++ and the prevention of the effects of beta-thujaplicin by an excess of Mg++ in the medium suggest a common mode of action of beta-thujaplicin as a lipophilic chelator of Mg++ and other divalent cations.

Adenosine Diphosphate↗
PubMed1981

Catechol-O-methyl transferase activity in human mononuclear cells.

Catechol-O-methyl transferase (COMT) activity was investigated in human peripheral mononuclear cells and in human lymphoblastoid cells lines. In any case, we have detected enzymatic activity in the membrane fraction of the cells. Km was found to be 4-9 10(-6) M and the enzyme was inhibited by tropolone and the lack of magnesium. The eventual association of COMT with adrenergic receptor-adenylate cyclase system in mononuclear cells is discussed.

Adult↗
PubMed1980

Rat liver regeneration in the presence of nonbenzenoid aromatic agents: ferrocenes and cycloheptatrienes.

The extent of liver regeneration in partially hepatectomized rats was increased over a period of 10 days on feeding a basal diet supplemented with 1,1'-diacetylferrocene at 0.15% by weight but the respective differences over the controls were not significant with diets containing ferrocene (0.10 and 0.30%) and acetylferrocene (0.10%) or on sc injection of these agents in peanut oil solution. Tropolone and colchicine supplemented at 750 and 100 PPM, respectively, depressed the regenerative process. The wet and dry liver weight percentages were increased in intact rats fed acetylferrocene (0.15%) or diacetylferrocene (0.060%) but not with ferrocene (0.20%) or with the three injected by the sc route. Hepatic iron deposition was extensive in operated rats fed ferrocene and diacetylferrocene but was far lower in the intact animals on these diets or in the groups injected with the agents.

Animals↗
PubMed1979

The selection and evaluation of new chelating agents for the treatment of iron overload.

A large-scale systematic evaluation of potential iron chelators for the treatment of hemosiderosis was conducted. The compounds were identified and evaluated using a hypertransfused mouse screen in which deferrioxamine B was a standard. This screen was designed to measure iron depletion in the tissues as well as iron excretion. Groups of 10 previously hypertransfused BDF1 male mice received a single daily i.p. injection of either vehicle, standard, or test compound for 7 days. Iron in daily urine pools and individual spleen and liver homogenates was determined by atomic absorption. More than 70 chelators were evaluated, including natural and synthetic hydroxamic acids, phenols, catechols and tropolones known to have a high affinity for iron (III) in vitro. Ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid) was shown to be considerably more effective than deferrioxamine B (i.p.) and, in addition, was orally active. Factors determining the efficacy of this and other chelating agents are discussed.

Animals↗
PubMed1994

Tentative evidence of a rosmarinic acid peroxidase in cell cultures from lavandin (Lavandula x intermedia) flowers.

The oxidative stability of rosmarinic acid (alpha-O-caffeoyl-3,4-dihydroxyphenyllactic acid) in lavandin (Lavandula x intermedia) cell cultures was studied in an attempt to explain the decrease in the rosmarinic acid content of aging cell cultures, a process which is associated with the appearance of brown pigments. The oxidation of rosmarinic acid by a partially purified protein fraction was followed spectrophotometrically and by HPLC. The results showed that rosmarinic acid oxidation was almost totally dependent on the presence of H2O2 and protein, and that brownish products were the results of this oxidation, resembling those shown by aging cell cultures. Since this protein fraction contains peroxidase activities and shows the total absence of tropolone-sensitive polyphenoloxidase (catecholase) and laccase activities, rosmarinic acid oxidation is tentatively proposed to be caused by a peroxidase-like activity. These results support the existence of a rosmarinic acid peroxidase in cell cultures of lavandin flowers, which may be involved in the oxidative destruction of rosmarinic acid, and which may also be responsible for the formation of brown pigments during aging, lowering the yields of rosmarinic acid.

Cells, Cultured↗
PubMed1976

Inactivation of neural and exogenous norepinephrine in rat tail artery studied by the oil immersion technique.

The inactivation of exogenous and neural norepinephrine (NE) by helical strips of rat tail artery was studied with a combination of the techniques of transmural stimulation and oil immersion. A steady-state contraction was elicited either by adding low concentrations of NE to the bath or by low frequency transmural stimulation. The aqueous bath solution was then replaced with mineral oil and relaxation was monitored. A prolongation of the rate of relaxation of the strip at a given concentration of exogenous NE or frequency of transmural stimulation indicates that inactivation of NE has been slowed. The major known processes for inactivation of NE were inhibited by pharmacological agents used singly or in various combinations (uptake by cocaine, uptake by corticosterone, catechol-O-methyltransferase by tropolone and monoamine oxidase by iproniazid). Cocaine was the only agent which alone caused a marked shift in the relaxation curve. A modest and equivocal effect on relaxation after inhibition of extraneuronal uptake (uptake), or catabolism of NE (catechol-O-methyltransferase and monoamine oxidase) was only demonstrated under special circumstances (high concentrations of NE, combinations of inhibitors, or uptake simultaneously inhibited). The data suggest that low concentrations of NE, both exogenous and neural, are preferentially inactivated in rat tail artery by neuronal uptake and storage.

Animals↗
PubMed1997

Phenoloxidase-dependent cytotoxic mechanism in ascidian (Styela plicata) hemocytes active against erythrocytes and K562 tumor cells.

The cytotoxic activity against rabbit erythrocytes (RE) and human K562 tumor cells by Styela plicata hemocytes was significantly related to the phenoloxidase (PO) which converts phenols to quinone and initiates the melanogenic pathway. The effector hemocyte population, separated in a Percoll density gradient band, enriched in a granulocyte type named "morula cells", was examined with RE in a hemocyte cytotoxic assay and plaque forming cell assay. Inhibition experiments with the copper chelating agents 1-phenyl-2-thiourea and tropolone, the substrate analogue sodium benzoate and sodium ascorbate support the notion that hemocyte cytotoxic activity is a PO-dependent mechanism. Treatments of hemocytes with the antioxidant enzymes, superoxide dismutase and catalase rule out oxy radicals produced by the melanogenic process as responsible of erythrolysis. Such a result suggests that quinone compounds derived from the melanogenic pathway might be the cytotoxic molecules. The PO-dependent anti-RE activity was also shown in a plaque forming assay in which "morula cells", containing polyphenols and PO, were identified as cytotoxic.

Animals↗
PubMed1996

Porcine model of stent thrombosis: platelets are the primary component of acute stent closure.

Acute stent thrombosis remains a major concern of coronary stent implantation. Animal studies using stents do not adequately mimic this clinical problem, since stent placement is rarely associated with acute closure. The purpose of this study was to develop and characterize a porcine model of stent thrombosis. Improved understanding through such a model may be useful toward preventing and treating acute stent closure. Whole blood was drawn from domestic crossbred swine one day before study. Platelets were isolated, labeled with 111-In tropolone, and reinjected within 18 hr of the study. Bilateral carotid arteries were exposed, and severe injury induced by a series of mechanical crushes. This method produced histologic injury similar to human coronary angioplasty, with medial disruption and large dissections protruding into the lumen. Stenting was performed in standard fashion with 3.5-mm JJIS stents. Local platelet deposition was measured and recorded as 111-In radioactivity using a miniaturized scintillation detector (Dosimeter Corp.) mounted directly at the artery injury site. This measurement was made in real time at 1-min intervals. Similarly, volumetric blood flow was measured in real time by Doppler flowmeter. Eighteen arteries of nine pigs were studied. In nine arteries from nine pigs, crush injury only was performed and monitored. In the contralateral artery, crush injury was followed immediately by placement of a 3.5-mm Palmaz-Schatz (coronary) stent. Blood flow decreased rapidly following injury in both groups and followed a cyclic pattern. Eight arteries of the crush alone and two arteries of the crush plus stent groups were totally occluded 1 hr after crush. 111-In counts normalized to baseline were significantly higher at 1 hr in both groups compared to baseline; in the stented group, counts were higher than in the unstented group. Blood flow was higher in the stented group than in unstented group for 1 hr. Histopathologic observation of the thrombi forming in both crush-only and crush-stent injuries showed severe medial dissections with obstructing medial flap formation. The thrombi forming in both groups were highly platelet rich. This model of stent and arterial thrombosis showed rapid formation of platelet-rich thrombus, cyclic blood flow variations, and acute occlusion in 20% of cases. Stent placement at arterial injury sites is associated with thrombus that is predominantly platelet rich. Stent placement at injury sites enhances platelet deposition over crush injury alone. Despite greater numbers of platelets, as shown by increased 111-In counts, stenting improved vessel patency. These were likely due to higher volumetric blood flow, continuous deposition, and embolization of labeled platelets.

Acute Disease↗
PubMed2000

Chiral photochemistry within zeolites

Chiral induction of chemical reactions continues to be one of the main concerns of chemists. While basic rules of chiral induction of thermal reactions have been reasonably established, the same is not true of photochemical reactions. Short excited state lifetime and low activation energies for reactions in the excited state(s) leave very little room for manipulating the diastereomeric transition states. Yet impressive chiral induction of photochemical reactions in the solid state has been achieved. On the other hand, chiral induction of photoreactions of organic molecules in solution continues to be inefficient at ambient conditions. We are exploring the possibility of employing zeolites as a media for achieving chiral induction during photoreactions. The motivating force for such an attempt is the fact that chiral chemistry in the solid state is not completely general due to the fact that not all molecules crystallize. To achieve chiral induction one needs a chiral perturber. Zeolites are not chiral and therefore the perturber is added to the medium. Thus the medium for a photoreaction is a chirally modified zeolite. Of the several reactions investigated, results on photoelectrocylization of tropolone alkyl ethers are discussed at length. The confined space offered by the zeolite supercage forces a reactant and the chiral inductor to interact intimately to yield enantiomerically enriched product. Due to the transitory nature of the reaction cavity in solution such close interactions are less likely in isotropic solvent media. The examples discussed herein show negligible chiral induction in solution, whereas in a zeolite one obtains induction as high as 90%.

Journal Article↗
PubMed1984

Kinetics and distribution of platelets in man.

51Cr sodium-chromate, though having been widely used in the last two decades for labeling platelets, suffers from several serious drawbacks, ie, low labeling efficiency, long physical half-life, and low gamma photon yields. 111In-oxine and 111In-tropolone overcome these shortcomings and have the potential of precise determination of platelet kinetics as well as visualization and in vivo quantification of the temporal and spatial distribution of platelets in man. Computer analysis of platelet kinetics reveals that the multiple-hit model fits the survival curve better than the linear or the exponential model. The multiple-hit model provides not only the mean platelet survival time but also information on the initial recovery and the shape of the survival curve. The application of these techniques in normal and disease states should greatly enhance our understanding of the physiology and pathophysiology of platelets.

Blood Platelets↗
PubMed1988

A selective ion monitoring assay for tributyltin and its degradation products.

Tributyltin (TBT) is a biocide which has been shown to enter the aquatic environment by release from antifouling paints. TBT is acutely toxic to some marine organisms at concentrations near 1 microgram l-1 and physiological changes may occur at low nanogram per liter concentrations. Gas chromatography/mass spectrometry (GC/MS) (methane chemical ionization) has been used for identification (full scanning) and quantification (selected ion monitoring) of TBT, dibutyltin (DBT) and monobutyltin (MBT). The butyltins were extracted from environmental water samples with hexane/0.2% tropolone and derivatized with hexyl magnesium bromide to form hexylbutyltins. Selected ion monitoring was at m/z 319 (TBT) and m/z 347 (DBT, MBT and tripentyltin, the internal standard). Calibration curves prepared in natural water were linear and detection limits were less than 2 ng l-1. GC/MS and GC with flame photometric detection were compared as quantification methods for environmental samples and were shown to give similar results at the low nanogram per liter levels.

Gas Chromatography-Mass Spectrometry↗
PubMed2005

Activation of catechol-O-methyltransferase in astrocytes stimulates homocysteine synthesis and export to neurons.

Elevation of the total homocysteine (tHcy) concentration in plasma has been implicated in neurodegeneration in patients with stroke, dementia, Alzheimer disease, and Parkinson disease. Because the mechanisms controlling brain tHcy are unknown, the present study investigated its synthesis and transport in primary rat brain cell cultures. We found that the catechol-O-methyltransferase (COMT) substrate 3,4-dihydroxybenzoic acid (DHB) increased export of tHcy in astrocytes, but not in neurons. The export mechanism was selective for tHcy over cyst(e)ine, total glutathione (tGSH) or cysteinylglycine (Cys-Gly). tHcy export from astrocytes was also induced by the COMT substrates levodopa (L-DOPA), dopamine and quercetin, and it was blocked by the COMT inhibitors tropolone and entacapone. This export was associated with increased synthesis of tHcy because both intracellular and extracellular tHcy concentrations rose during COMT activation. Incubation in cyst(e)ine-deficient medium inhibited the tHcy export response to COMT activation. Exogenous tHcy (100 muM) was accumulated into neurons, but not into astrocytes. We conclude that activation of COMT causes sustained synthesis of Hcy in astrocytes and transport of this amino acid to neurons.

Amino Acids↗
PubMed1980

Differential pulse polarographic determination of colchicine.

A differential pulse polarographic method for the analysis of colchicine-containing dosage forms is described. The reduction of the tropolone carbonyl is useful for quantitative analysis in that the relationship of the colchicine concentration to the current is linear over the concentration range of 0 to approximately 50 micrograms/ml, with a slight negative deviation at higher concentration. The procedure involves no preliminary treatment, is simple and specific, and is applicable to the assay of composite tablets, individual tablets, and injectable solutions. Polarography is conduction on a solution of colchicine in pH 1.81 Britton-Robinson buffer with 0.01% alkylphenoxy polyethoxyethanol. The quantitative analysis is achieved using the method of standard addition. A relative standard deviation of 3.2% was obtained for tablets. The results agree with those obtained using the USP XIX method.

Colchicine↗
PubMed2005

Delocalization of spin projection in weak exchange linear chains, evidenced by multi-frequency HF-EPR spectroscopy.

High-field electron paramagnetic resonance (HF-EPR) spectroscopy was used to investigate the unusual temperature and frequency dependence of the powder spectrum of the Gd(HBPz3)2 tropolonate complex (GdTrp). A new type of H/T effect is evidenced. This effect is interpreted in terms of the formation of spin projection states delocalized and quasidelocalized along linear chains of Gd3+ ions in high magnetic fields due to the competition between the weak dipole and exchange spin-spin interaction and the particular structure of the molecular complex. The number of ions in the chain depends strongly on the orientation of the magnetic field and on the relaxation processes.

Journal Article↗
PubMed2000

Initial conditions for carbon-13 MAS NMR 1D exchange involving chemically equivalent and inequivalent nuclei

A major problem in dynamic 1D (13)C MAS NMR concerns the exchange between magnetically inequivalent, but chemically equivalent sites, whose signals are not resolved in the regular 1D spectrum. This difficulty may be overcome by properly preparing the initial nonequilibrium state of the spin system in the exchange experiments. In the present paper we discuss the advantages and limitations of several such experiments already in use and propose a new sequence, which we term SELDOM-ODESSA. Unlike the other 1D-exchange methods, this experiment yields pure absorption spectra that can more readily be analyzed quantitatively. The experiment is a hybrid comprising a SELDOM sequence, for selective excitation of one of the spinning sideband manifolds in the spectrum, followed by the ODESSA sequence, which induces alternate polarization in the excited sideband manifold. The evolution of the spectrum following this sequence provides information on both the exchange between congruent sites belonging to the same group of equivalent nuclei, and the exchange between inequivalent sites. Results are presented for a tropolone sample specifically enriched in carbon-13 at the carbonyl and hydroxyl sites. The dominant exchange mechanism in this sample involves spin diffusion. The various spin exchange processes in this sample, in the presence and absence of proton decoupling during the mixing time, are measured and discussed. Copyright 2000 Academic Press.

Journal Article↗
PubMed1998

The Strong Duschinsky Effect and the Intensity of Transitions in Non-Totally Symmetric Vibrations in the Electronic Spectra of Polyatomic Molecules

The effect of strong Duschinsky type mixing of two normal coordinates Q1 and Q2 on the intensity of transitions in non-totally symmetric vibrations in electronic spectra is examined. Using a Fermi resonance type theory, expressions are derived for the intensity of transitions such as 1(1)02(0)1 and 1(1)02(1)0 which gain significant intensity when mixing of coordinates is strong. The results are applied to the 288-nm electronic spectrum of styrene, the 370-nm spectrum of tropolone, and the 281-nm spectrum of 1,4-benzodioxan, all of which provide examples of strong mixing between a pair of normal coordinates. In some cases the theoretical predictions are in general agreement with the observed intensity pattern, if a suitable choice is made of the relevant mixing coefficient. In others there is a divergence which may be related to the importance of other factors such as electrical and mechanical anharmonicity. Copyright 1998 Academic Press. Copyright 1998Academic Press

Journal Article↗
PubMed1996

Reduction of Platelet Thrombi and Emboli by L-Arginine during Cardiopulmonary Bypass in a Pig Model.

We wanted to test the hypothesis that NO generation by L-arginine (LA) infusion will be beneficial in increasing blood flow to all organs to counteract the process of global ischemia during cardiopulmonary bypass (CPB) and to reduce platelet emboli by platelet inhibition. The effect of LA infusion on NO formation, vasodilation, and reduction of thromboembolic burden in organs and tissues after CPB was quantified with In-111-labeled autologous platelets in two major groups: 180 minutes CPB (CPB) and 90 minutes CPB plus 90 minutes reperfusion (RP). Platelets labeled with In-111 tropolone (650-780 µCi) were administered 24 hours before CPB and LA infusion (bolus, 10 mg/kg and infusion at 2 mg/kg/min, 21 pigs for 180 minutes CPB) in 8 groups of 30 Yorkshire pigs (30-35 kg, 6 pigs; LA 2 mg/kg/min, 3 pigs; sham-thoracotomy control, 6 pigs; unoperated control, 6 pigs). Two groups of 9 pigs (control CPB, 6 pigs; LA 2 mg/kg/min, 3 pigs) underwent 90 minutes of CPB and 90 minutes of reperfusion. All pigs were heparinized (ACT > 400 seconds); CPB was instituted with a roller pump, an oxygenator (OX: Bentley Univox, 1.8 m2), and an arterial filter (AF: 0.25 m2, Bentley) at a blood flow of 2.5-3.5 l/min. Radioactive thrombi in OX and AF and emboli in viscera, brain, and connective tissues were imaged with a gamma camera and were finally measured with an ion chamber and a gamma counter. The percent of injected platelets (mean +/- SD) in the organs and tissues of all pigs was calculated. Cerebral emboli were mapped in 25 regions of both hemispheres of pig brain. Flow cytometry with antibodies to CD61 (GPIIIa) and CD62P (GMP-140:control) of porcine platelets was carried out with blood samples taken before, during, and after CPB. Coronary bypass with LA infusion decreased the amount of adherent thrombi in OX and AF (p < 0.07). The embolic burden in brain and lung also decreased. Regional cerebral mapping of In-111 platelets showed reduced emboli in almost all regions, including the medulla, hip pocampus, and posterior cerebral cortex in both LA-treated groups. Flow cytometry of blood samples demonstrated the shift of equilibria from single platelet to platelet-aggregate-microparticle during CPB and steady-state level after the first 5-10 minutes of initiation of CPB. The L-arginine infusion reduced thrombi and emboli during CPB in the pig model.

Journal Article↗
PubMed1996

Effect of Thoracotomy and Cardiopulmonary Bypass on Activated Platelet and Neutrophil Dynamics and Platelet Emboli in a Pig Model.

The effects of thoracotomy and components of extracorporeal circuits on dynamics of platelets and neutrophils were quantified with autologous In-111-labeled platelets (INPLT) and neutrophils (INN) during cardiopulmonary bypass (CPB) operations in Yorkshire pigs. Cardiopulmonary bypass was carried out with a hollow-fiber oxygenator and an arterial filter in 48 pigs (30-35 kg; 12 unoperated controls for platelets and neutrophils; 12 sham operated controls; 12 with 180 minutes of CPB with platelets and neutrophils; 12 with 90 minutes of CPB and 90 minutes of reperfusion at 2.5-3.5 one/min. Platelets and neutrophils were labeled with In-111 tropolone and were injected intravenously: platelets at 24 hours and neutrophils at 15 minutes before CPB. All pigs were systemically heparinized [activated coagulation time (ACT) > 400 seconds]; CPB was instituted with a roller pump, oxygenator (OX; Bentley Univox, 1.8 m2), and arterial filter (AF; 0.025 m2) for durations of 180 minutes and 90 minutes of bypass, followed by 90 minutes of reperfusion. The kinetics and pooling of platelets and neutrophils were monitored by a Geiger probe. The adherent thrombi and neutrophils in the OX, AF, viscera, and brain were imaged with a gamma camera and were measured with an ion chamber and a gamma counter. The percentile distribution of labeled platelets and neutrophils expressed as the mean +/- standard deviation of injected dose in eight groups was calculated and statistical analyses were performed (ANOVA and paired t-test). Sham operation alone increased platelet retention in the lung, heart, and brain significantly (p < 0.001) over that of unoperated pigs. Neutrophil margination to lung immediately after injection was high; CPB and reperfusion altered the distribution in blood, viscera, and connective tissues. During CPB, an equilibrium among single platelets, platelet thrombi, and emboli was reached in the blood, oxygenator, arterial filter, perfused organs, and tissues. After CPB, the pulmonary neutrophil retention increased significantly (p < 0.001). Reperfusion of 90 minutes following 90 minutes of CPB decreased the level of neutrophils and increased the level of platelets in the lung. Only a small amount of platelets and neutrophils was retained in the oxygenator and arterial filter. Neutrophil retention in the OX and AF was higher than that of platelets. The small amount of retained neutrophils in the heart, kidneys, and brain suggested that cytokines, rather than marginated neutrophils alone, may play a major role in inflammatory insult to these organs during and after CPB. OX thrombi increased with the time of CPB; AF thrombus in both groups was almost similar. During CPB, AF functioned minimally as a thrombus trap with a small percent of retained thrombi; reperfusion post-CPB did not change the amount. Thoracotomy alone has a significant effect on platelet and neutrophil kinetics, and on the subsequent effect of thrombus formation, embolization, and neutrophil margination in organs during the CPB procedure.

Journal Article↗