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PubMed1986

Indium-111 platelet kinetics in normal human subjects: tropolone versus oxine methods.

The effect of labeling media on the kinetics of[111In]platelets was evaluated by performing a paired crossover study in eight normal human subjects using tropolone and oxine methods. Platelets were labeled in autologous plasma with [111In]tropolone (In-tr) and in ACD-saline with [111In]oxine (In-ox) and reinjected. Starting at 1 hr, ten blood samples were obtained over an 8-day period. The in vivo platelet recovery was higher at 1 hr and throughout the 8 days of study with In-tr and the gamma camera images showed less uptake in liver and spleen than with In-ox. When platelet life-span (PLS) was estimated using all ten samples, only linear regression showed that the platelet life-span was longer with In-tr (10.7 +/- 1.5) than with In-ox (9.5 +/- 0.8). When the PLS was estimated excluding the 1-hr sample point, the life-span of platelets was significantly longer with In-tr than with In-ox based on three out of four models of curve fitting. These results demonstrate that platelets labeled with In-tr in plasma are preserved better in circulation and have equal or longer life-span than platelets labeled with In-ox in ACD-saline.

Adult↗
PubMed1988

In vivo red blood cell compatibility testing using indium-113m tropolone-labeled red blood cells.

In vivo radionuclide crossmatch is a method for identifying compatible blood for transfusion when allo- or autoantibodies preclude the use of conventional crossmatching techniques. A technique for labeling small volumes of donor red blood cells with [113mIn]tropolone is reported. The use of 113mIn minimizes the accumulation of background radioactivity and the radiation dose especially so when multiple crossmatches are performed. Labeling red cells with [113mIn]tropolone is faster and easier to perform than with other radionuclides. Consistently high labeling efficiencies are obtained and minimal 113mIn activity elutes from the labeled red blood cells. A case study involving 22 crossmatches is presented to demonstrate the technique. The radiation dose equivalent from 113mIn is significantly less than with other radionuclides that may be used to label red cells.

Adult↗
PubMed1983

Imaging of inflammation with indium-111 tropolonate labeled leukocytes.

Indium-111 tropolonate has recently been introduced as a new cell-labeling agent. It has the interesting property of labeling cells in plasma with high efficiency, and may therefore promote an improvement in viability of labeled cells. This paper describes our initial experience with In-111 tropolonate as a leukocyte label for abscess imaging. Pure populations of separated granulocytes, as well as crude leukocyte preparations, have been labeled. Of 101 studies performed, 51 were positive (no false positives) and 50 negatives, of which only two were false negatives. Localization in sites of inflammation was prominent and rapid. Of 36 positive studies, 27 were already positive at 40 min following injection and an additional nine at 3 hr. Of the other 15 positive studies, 11 were scanned for the first time at 3 hr, when they were positive. Granulocytes labeled with this agent in plasma showed minimal sequestration in lungs and liver, interpreted as indicating improved viability in comparison with cells displaying prolonged lung sequestration.

Abdomen↗
PubMed1997

Dynamic Hydrogen Disorder in Solid Tropolone. A Single-Crystal NMR Study of the Hydroxyl Deuterons

The orientation and temperature dependences of the deuterium NMR spectrum and spin-lattice relaxation time of the hydroxyl deuterons in single crystals of tropolone-d 1 are reported. The results are interpreted in terms of a dynamic hydrogen disorder model in which the hydrogen nuclei move in an asymmetric double well potential. According to this model, the hydrogen-bonded dimer structure as determined by X-ray diffraction constitutes a majority species in the tropolone crystal, comprising more than 98% of the molecules at room temperature. However, there also exists a tautomeric minority species formed by a concerted back and forth shifting of the hydroxyl hydrogens (deuterons) along the hydrogen bonds to the nearby carbonyl oxygens. This process results in a modulation of the electric field gradient tensor at the site of the deuterons, thus providing an efficient relaxation mechanism. The concentration of the minority species is too low and its lifetime is too short to make its direct observation possible. Still, structural information about this species and kinetic and thermodynamic parameters of the hydrogen shift process can be derived by fitting the measured T 1 values to the above model.

Journal Article↗
PubMed1988

Effect of Iron Limitation on "Pseudomonas plantarii" Growth and Tropolone and Protein Production.

The addition of iron to an iron-deficient medium markedly enhanced the growth of "Pseudomonas plantarii" and the production of red crystals. However, it markedly reduced the amount of dissolved tropolone, a product of the bacterium and an iron chelator, and the production of an iron-regulated protein (78 kilodaltons). The red crystal was complex, composed of tropolone and iron, the ratio being 3:1.

Journal Article↗
PubMed1993

Mechanism of thrombocytopenia in liver cirrhosis: kinetics of indium-111 tropolone labelled platelets.

Using indium-111 tropolone-labelled platelets, a study of platelet kinetics was performed on the basis of the relationship between platelet count, platelet survival time, platelet dynamics, platelet-associated immunoglobulin G (PA-IgG) and splenic volume in 31 patients with liver cirrhosis and a platelet count of less than 100 x 10(9)/l. The mean platelet count was 46.6 +/- 25.3 x 10(9)/l, and the mean platelet survival time was 6.50 +/- 1.33 days. The mean uptake into the spleen was 43.2% +/- 14.8% on the 1st day, and 53.7% +/- 14.3% on the 7th day. The mean PA-IgG level was 107.6 +/- 66.0 ng/10(7) platelets in five patients with chronic active hepatitis who were studied as controls, the mean platelet count was 197 +/- 30 x 10(9)/l, the mean platelet survival time 9.33 +/- 0.78 days, and the mean PA-IgG 21.2 +/- 2.9 ng/10(7) platelets. The former two parameters were significantly higher (P < 0.05), and the latter significantly lower (P < 0.05). In liver cirrhosis, the platelet count showed a positive correlation with the platelet survival time and a negative correlation with PA-IgG and the splenic volume. These results suggest that the increases in both the splenic platelet pool and platelet destruction in the spleen through immunological mechanisms may influence thrombocytopenia in liver cirrhosis.

Blood Platelets↗
PubMed1979

Antithyroid and antiperoxidase activity of tropolone and 3-hydroxy-4-pyrone.

Tropolone (TR) and 3-hydroxy-4-pyrone were investigated for antithyroid activity following the finding that the 2-hydroxy-oxo pyridine, 3-hydroxy-4(1H)-pyridone (DHP, I), is goitrogenic. Both compounds inhibited the thyroidal uptake of radioiodine in rats and resembled the thioamide drugs in inhibiting the organic binding of iodine by the thyroid gland rather than the trapping of iodide, but were weaker binding inhibitors than 6-methyl-2-thiouracil (MeTU). Both compounds also inhibited the iodination of bovine serum albumin and thyroglobulin, catalyzed by thyroidperoxidase (TPO), lactoperoxidase (LPO), chloroperoxidase (CPO) and horseradish peroxidase (HPO) in vitro. The inhibitory effect of TR but not that of 3-hydroxy-4-pyrone was antagonized by ferrous ions. When fed to mice at levels of intake expected to produce goitre both compounds were toxic and caused severe liver damage. Thyroid enlargement was not observed in any of these feeiding experiments, but the thyroids of mice fed 0.1% TR showed moderate hyperplasia. It was concluded that both compounds are weakly goitrogenic. Hyperactivity was observed in the mice fed TR which may be associated with inhibition of catechol methyl transferase (COMT).

Animals↗
PubMed1990

Optimized radiolabelling of pig granulocytes with indium-111 tropolonate.

Standard labelling methods using 111In-tropolonate in plasma resulted in lower labelling efficiency (LE) with pig granulocytes than with human cells. Addition of acid-citrate-dextrose (ACD) to cell-free plasma in a ratio of 1:10 tripled the LE to a value which was not significantly different from that obtained in saline. Under optimized conditions, LE was 67 +/- 2% (mean +/- SE) with pig granulocytes, which remained lower than that obtained with human cells but was adequate for nuclear imaging studies of granulocyte deposition in the pig.

Animals↗
PubMed1983

Indium-111 tropolonate leucocyte scanning in the detection of intra-abdominal abscesses.

Indium-111 leucocyte scanning is established as an accurate method for localising intra-abdominal abscesses. With the currently available cell labelling techniques there is a variable and significant delay in localisation of abscesses which is a major disadvantage in comparison with ultrasound or computed tomography. We have examined the speed and accuracy of localisation of leucocytes labelled in plasma with a new chelating agent, indium-111 tropolonate, in 90 patients with suspected intra-abdominal abscess. In 50 patients a comparison with ultrasound was made. Nineteen patients had abscesses. The sensitivity and specificity of labelled leucocytes were 95% and 99%, respectively. Comparative results for ultrasound were 60% and 83%. In nine out of 10 patients with abscesses scanned sequentially from 40 min after return of the labelled cells, activity corresponding to the abscess was already visible on the 40 min scan. These results demonstrate that indium-111 plasma labelled leucocyte scanning is both rapid and an accurate method of detecting abscesses.

Abdomen↗
PubMed2001

Synthesis and biological evaluation of O-alkylated tropolones and related alpha-ketohydroxy derivatives as ribonucleotide reductase inhibitors.

A series of O-alkylated tropolones and related alpha-ketohydroxy compounds were evaluated for their biological activities and were shown to present an expected ribonucleotide reductase inhibition and cytotoxicity against some cancer cell lines but no antitubulin activity. Pharmacomodulation studies were realised to understand and enhance the observed activities. These original benzylic, heterocyclic and allylic compounds have been synthesised by a phase-transfer catalysed O-alkylation developed in our laboratories.

Animals↗
PubMed1992

Synthesis and antitumor activity of tropolone derivatives. 7. Bistropolones containing connecting methylene chains.

Bistropolone derivatives (4-12) containing differing lengths of linkage between the two tropolone rings were prepared and examined for their antitumor activity in in vitro (KB cell) and in vivo (leukemia P388 in mice) systems. Parent compound 3, related compounds previously prepared, and the new compounds 4-12 were evaluated for inhibitory activity against ribonucleotide reductase by indirect means to measure their effects on the dNTP pool imbalance. Present structure-activity relationship results would suggest that potently active bistropolones in vivo inhibit intracellular ribonucleotide reductase through chelating with the two irons at the two active sites of the enzyme.

Animals↗
PubMed1986

Synthesis and antitumor activity of tropolone derivatives. 3.

As part of a study on the antitumor activities of tropolone derivatives prepared from hinokitiol, which naturally occurs in the plants of Chamaecyparis species, effects of aromatic substituents of alpha,alpha-bis(7-hydroxy-5-isopropyltropon-2-yl)toluenes on the activity were examined. Several of the compounds showed high potency in the P388 leukemia assay. 4-Hydroxy analogue 4d showed the most potent activity (T/C = 195%) at a 5 mg/kg dose. The introduction of large-size substituents, of which the steric influence prevents coplanarity of the substituted aromatic function, resulted in a remarkable decrease in the potency. X-ray structural analysis of highly potent 4-methoxy analogue 4b was undertaken.

Animals↗
PubMed1984

Synthesis and antitumor activity of tropolone derivatives.

Treatment of tropolones with benzaldehyde diethyl acetals gave monotropolone (12) and bistropolone (13) derivatives at the benzylic position, whereas the related 1-ethoxyisochroman and the diethyl acetals of crotonaldehyde and cinnamaldehyde gave only the monotropolone derivatives (5, 10, or 11). The monotropolone derivatives (5, 10, 11, and 12) had poor potency against P388 leukemia in mice, but the bistropolone derivatives (13 and 14) showed significant potency and prolongation of life.

Animals↗
PubMed1987

Synthesis and antitumor activity of tropolone derivatives. 5.

As part of a study on the structure-activity relationship of antitumor-active tropolone derivatives, a series of bistropone analogues, related to potently active bistropolone 1a, were synthesized and tested for their antitumor activity in in vitro (KB cell) and in vivo (leukemia P388 in mice) systems. The methoxytropones 3 and 5, hydroxytropothione 10, and (N-methylamino)tropones 12 and 13 were inactive in both systems. Methoxytropone 6 exhibited weak activity, whose potency was equal to that of monotropolone 2a.

Animals↗
PubMed1999

Studies toward the biomimetic synthesis of tropolone natural products via a hetero Diels-Alder reaction.

Analogues of the tropolone natural products pycnidione and epolone B were synthesized via a hetero Diels-Alder reaction of benzotropolone 10 with humulene. The quinone methide benzotropolone 13 was generated in situ by thermalisation of benzotropolone 10. Benzotropolone 10 was derived from phthalic acid via carbonyl ylide 8a followed by an intramolecular 1,3-dipolar cycloaddition and subsequent acid-catalyzed ring opening.

Fungi↗
PubMed1977

Effects of pharmacologic alterations of adrenergic mechanisms by cocaine, tropolone, aminophylline, and ketamine on epinephrine-induced arrhythmias during halothane-nitrous oxide anesthesia.

The purpose of this study was to examine the effects of pharmacologic alterations of adrenergic terminating mechanisms by cocaine, tropolone, aminophylline, and ketamine on the ability of epinephrine to induce arrhythmias during halothane-nitrous oxide anesthesia in dogs. Because the first three drugs inhibit intraneuronal uptake of catecholamines, extraneuronal catechol-O-methyl transferase (COMT), and phosphodiesterase, respectively, they might be expected to potentiate epinephrine-induced arrhythmias. To evaluate this possibility, the authors devised a technique for determining the minimal arrhythmic dosage of epinephrine that permitted graded assessment of changes in the sensitivity of the heart to epinephrine-induced arrhythmias. When the first three drugs were administered to the same dog in the order listed at intervals of 60 minutes, they sequentially increased the ability of epinephrine to induce arrhythmias. Ketamine, according to several investigators, also appears to block reuptake of catecholamines, and when studied was also found to enhance the arrhythmogenicity of epinephrine. The extent of enhancement was comparable to that seen with cocaine. These results indicate that drugs like cocaine and ketamine that interfere with intraneuronal uptake can facilitate the development of epinephrine-induced arrhythmias and that the successive pharmacologic interference of intraneuron uptake, COMT, and phosphodiesterase leads to a stepwise increase in the arrhythmogenicity of epinephrine.

Aminophylline↗
PubMed1993

Cytotoxic effect of hinokitiol and tropolone on the growth of mammalian cells and on blastogenesis of mouse splenic T cells.

Hinokitiol (I) and tropolone (II) showed characteristic cytotoxic effects in vitro on five kinds of human and murine cell lines and blastic lymphocytes from mouse splenocytes. The cytotoxic effect of I on the growth of murine and human tumor cell lines, including RL male-1, MH134, HL60, K562 and KATO-III was definite when examined by thymidine incorporation into DNA and its 50% inhibitory concentration (IC50) on all cells was 0.3-0.6 microgram/ml. Compound II also showed comparable cytotoxic effects on these cell lines, indicating a little lower activity when compared to I. Furthermore, I and II also completely suppressed the [3H]thymidine ([3H]TdR) incorporation of mitogen-induced blastic lymphocytes. The suppressive activity on mouse lymphocyte proliferative response to concanavaline-A was also found with both compounds at a low concentration of 0.32 microgram/ml. As compound I is known to be of fairly low toxicity (LD50: 453 + 24 mg/kg in mice), the antitumor and immuno-suppressive effect of hinokitiol (I) should be further investigated.

Animals↗
PubMed2003

Biological activity of tropolone.

Tropolone (1). showed strong insecticidal activity on Tyrophagus putrescentiae and Dermatophagoides farinae. The insecticidal effect of 1 on both insects was stronger than that of hinokitiol (2, 4-isopropyltropolone: major component of Thujopsis dolabrata SIEB. et ZUCC. hondai MAKINO). The insecticidal activity of both compounds was higher than that of N,N-diethyl-m-toluamide (DEET), used as a positive control. Compound 1 had potent insecticidal activity against Coptotermes formosanus, although its activity was much lower than that of commercial chloropyrifos. Like 2, 1 showed the inhibitory activity toward metalloproteases such as carboxypeptidase A, collagenase and thermolysin and their inhibitory activities were much higher than that of 1,10-phenanthroline, used as a positive control. The inhibitory activity of 1 on carboxypeptidase A was especially high, its 50% inhibitory concentrations (IC(50)) being 2.73 x 10(-6) M. This inhibitory activity was as high as that of 2 (IC(50): 2.76 x 10(-6) M). Compound 1 inhibited the growth of seven kinds of plant-pathogenic fungi and their minimum inhibitory concentration (MIC) values were in the range of 6.0-50.0 microg/ml. In particular, 1 showed strong antifungal activity on Pythium aphanidermatum IFO-32440 (MIC: 6.0 microg/ml).

Animals↗