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PubMed1998

Characterisation of beta2-adrenoceptors, using the agonist [11C]formoterol and positron emission tomography.

The agonist radioligand N-[2-hydroxy-5-[1-hydroxy-2-[[2-(4-[11C]-methoxyphenyl)-1-methylethyl]am ino]ethyl]phenyl]formamide ([11C]formoterol) was synthesised in order to test its ability to visualise pulmonary beta2-adrenoceptors in vivo, with positron emission tomography (PET). Formoterol was labelled via reaction of a dibenzyl-protected precursor with [11C]CH3I. Subsequent deprotection with Pd/C and H2 yielded [11C]formoterol in 5-15% (corrected for decay) and the specific activity ranged from 5.5-22.2 TBq mmol (150-600 Ci mmol(-1)), 60-70 min after end of bombardment. Biodistribution studies with [11C]formoterol were performed in male Wistar rats which were either untreated or predosed with (D,L)-propranolol hydrochloride (2.5 mg kg(-1), beta-adrenoceptor antagonist), erythro-DL-1-(7-methylindan-4-yloxy)-3-isopropylaminobuta n-2-ol hydrochloride (ICI 118551, 0.15 mg kg(-1), beta2-adrenoceptor antagonist), isoprenaline (15 mg kg(-1), non-subtype selective beta-adrenoceptor agonist) or (+/-)-(2-hydroxy-5-[2-((2-hydroxy-3-(4-((1-methyl-4-trifluoromethyl)1H-i midazol-2-yl-)phenoxy)propyl)amino)ethoxy]benzamide)monomethane sulfonate (CGP 20712A, 0.15 mg kg(-1), beta1-adrenoceptor antagonist). Lungs, heart, liver and plasma were analysed for radioactive metabolites. The kinetics of [11C]formoterol in the lungs of male Wistar rats were investigated by means of a dynamic PET study. The biodistribution studies showed significant specific binding in tissues known to contain beta2-adrenoceptors (lungs, spleen, and heart). Binding in these organs was blocked by ICI 118551 and isoprenaline, but not by CGP 20712A. [11C]Formoterol was rapidly metabolised in rats but lungs and heart did not substantially take up the labelled metabolites. The binding of [11C]formoterol in various tissues of rats is consistent with the beta2-selectivity of formoterol. Whether [11C]formoterol selectively binds to the high affinity state of beta2-adrenoceptors remains to be elucidated. [11C]Formoterol is potentially useful for studying beta2-adrenoceptors with PET and this radioligand may provide new insights in the mechanisms underlying prolonged sympathomimetic action.

Adrenergic beta-Agonists↗
PubMed1999

Effects of the orally active non-peptide bradykinin B2 receptor antagonist, FR173657, on plasma extravasation in guinea pig airways.

We investigated the effect of the orally active non-peptide bradykinin B2 receptor antagonist, FR173657 (E)-3-(6-acetamido-3-pyridyl)-N-[N-[2.4-di-chloro-3-[(2-methyl-8-quinoli nyl)oxymethyl]phenyl]-N-methy-laminocarbonylmethyl] acrylamide), on plasma extravasation mediated by activation of sensory nerves in guinea pig airways. Plasma extravasation was assessed by the photometric measurement of the extravasated Evans blue after formamide extraction. We found that the increase in Evans blue dye extravasation evoked by an aerosol of bradykinin (0.1 mM, 2 min) in the presence of phosphoramidon (2.5 mg/kg, i.v.) was abolished completely by FR173657 (20 mg/kg, p.o.) in the trachea and main bronchi. In sensitized guinea pigs pretreated with phosphoramidon, FR173657 (20 mg/kg, p.o.) inhibited plasma extravasation evoked by ovalbumin aerosol (5%, 2 min) by 77+/-14.2% in the trachea and 65+/-11.2% in the main bronchi. FR173657 (20 mg/kg, p.o.) did not affect the plasma extravasation caused by aerosolised capsaicin. These findings suggest that FR173657 is an orally active, promising anti-inflammatory agent for kinin-dependent inflammation following antigen challenge.

Administration, Oral↗
PubMed1997

An AU at the first base pair of helix 3 elevates the catalytic activity of hepatitis delta virus ribozymes.

A mutational analysis of the helix 3 (H3) region of hepatitis delta virus (HDV) ribozymes disclosed that an AU at the first base pair of H3 elevates the catalytic activity of various cis- and trans-acting HDV ribozymes. A GC to AU substitution at this position of H3, which is located at the junction of three of the four helices of the pseudoknot-like structure model, altered the structure of HDV ribozymes. This substitution in the H3 did not change the independence of the cleavage rate to pH nor the sensitivity to formamide treatment of the ribozymes.

Base Sequence↗
PubMed2000

Synthesis and evaluation of some new fluorinated hydroquinazoline derivatives as antifungal agents.

The key intermediate octahydroquinazoline (1) was obtained in one pot synthesis by a modification of the Biginelli reaction. Compound 1 was allowed to react with phenacyl bromide and bromomalononitrile to furnish thiazolo[2,3-b]quinazoline 3 and 12, respectively. Interaction of compound 12 with formamide, formic acid and phenyl isothiocyanate yielded the corresponding pyrimidino[4',5':4.5]thiazolo[2,3-b] quinazolines 13, 14 and 17, respectively. The structure of the synthesized compounds were elucidated by elemental analyses and spectroscopic analyses. Some of the prepared compounds were tested for their antifungal activity in comparison with tioconazole as a reference fungicide.

Antifungal Agents↗
PubMedDate not supplied

Quinazoline derivatives with antitubercular activity.

4-Quinazolinol was prepared by the reaction of anthranilic acid and formamide. The hydroxy group was converted into the thiol function by treatment with phosphorus(V)sulfide, and the subsequent alkylation of the thiol group was carried out with alkylhalides under the conditions of phase-transfer catalysis. The structure of the substances was confirmed by 1H, 13C NMR, IR, and MS. Most of the synthesized compounds exhibited antimycobacterial activity against the strains of Mycobacterium tuberculosis, Mycobacerium avium, Mycobacterium fortuitum, Mycobacterium kansasii and Mycobacterium intracellulare. 4-(S-Butylthio)quinazoline (3c) was even more active than isoniazide against atypical strains of mycobacteria.

Alkylation↗
PubMed2000

Synthesis of some new thiazolo[3,2-a]pyridines and related heterocyclic systems.

New 2,7-disubstituted 5-amino-6,8-dicyano-2,3-dihydro-3-oxo thiazolo[3,2-a]pyridines have been prepared. Their cyclization with formamide, nitrous acid and triethylorthoformate afforded a series of polycyclic heterocycles containing condensed pyrimidine and triazine rings. Antifungal tests were also performed.

Antifungal Agents↗
PubMed2000

Capillary electrochromatography of proteins and peptides with a cationic acrylic monolith.

For the separation of proteins and peptides by capillary electrochromatography (CEC), columns with a monolithic stationary phase were prepared from silanized fused-silica capillaries of 50 microm I.D. by in situ copolymerization of glycidyl methacrylate, methyl methacrylate and ethylene glycol dimethacrylate in the presence of propanol and formamide as porogens. The epoxide groups at the surface of the porous monolith were reacted with N-ethylbutylamine to form fixed tertiary amino functions with ethyl- and butyl-chains. A mixture of ribonuclease A, insulin, alpha-lactalbumin and myoglobin was separated isocratically by counterdirectional CEC with hydro-organic mobile phases containing acetonitrile and sodium phosphate buffer, pH 2.5. The separation of four angiotensin type peptides by CEC was also achieved under similar conditions. The elution order of proteins was similar to that obtained in reversed-phase chromatography. Plots of the migration factors for proteins and peptides against the acetonitrile concentration exhibit opposite trends. This is most likely due to the greater chromatographic retention and lower electrophoretic migration velocity of proteins than that of peptides in the counterdirectional CEC system. From this it is concluded that the separation is governed by a dual mechanism that involves the complex interplay between selective chromatographic retention and differential electrophoretic migration.

Acetonitriles↗
PubMed2000

Sub-microliter DNA sequencing for capillary array electrophoresis.

DNA sequencing from sub-microliter samples was demonstrated for capillary array electrophoresis by optimizing the analysis of 500 nl reaction aliquots of full-volume reactions and by preparing 500 nl reactions within fused-silica capillaries. Sub-microliter aliquots were removed from the pooled reaction products of 10 microl dye-primer cycle-sequencing reactions and analyzed without modifying either the reagent concentrations or instrument workflow. The impact of precipitation methods, resuspension buffers, and injection times on electrokinetic injection efficiency for 500 nl aliquots were determined by peak heights, signal-to-noise ratios, and changes in base-called readlengths. For 500 nl aliquots diluted to 5 microl in 60% formamide-1 mM EDTA and directly injected, a five-fold increase in signal-to-noise ratios was obtained by increasing injection times from 10 to 80 s without a corresponding increase in peak widths or reduction in readlengths. For 500 nl aliquots precipitated in alcohol, 80 +/- 5% template recovery and a two-fold decrease in conductivity was obtained, resulting in a two-fold increase in peak heights and 50 to 100 bases increase in readlengths. In a comparison of aliquot volumes and precipitation methods, equivalent readlengths were obtained for 500 nl, 4 microl, and 8 microl aliquots by simply adjusting the electrokinetic injection conditions. To ascertain the robustness of this methodology for genomic sequencing, 96 Arabidopsis thaliana subclones were sequenced, with a yield of 38 624 bases obtained from 500 nl aliquots versus 30 764 bases from standard scale reactions. To demonstrate 500 nl sample preparation, reactions were performed in fused-silica capillary reaction chambers using air-based thermal cycling. A readlength of 690 bases was obtained for the polymerase chain reaction product of an Arabidopsis subclone without modifying the reagent concentrations, post-reaction processing or electrokinetic injection workflow. These results demonstrated the fundamental feasibility of small-volume DNA sequencing for high-throughput capillary electrophoresis.

Arabidopsis↗
PubMed2001

Rapid separation of peptides and proteins by isocratic capillary electrochromatography at elevated temperature.

The use of capillary electrochromatography (CEC) for the separation by isocratic elution of synthetic peptides, proteins as well as the tryptic digest of cytochrome c has been demonstrated. The monolithic porous stationary phase was prepared from silanized fused-silica capillaries of 75 microm I.D. by in situ copolymerization of vinylbenzyl chloride and ethylene glycol dimethacrylate in the presence of propanol and formamide as the porogens. The chloromethyl groups at the surface of the porous monolith were reacted with N,N-dimethylbutylamine to form a positively charged chromatographic surface with fixed n-butyl chains. Results of studies on the influence of temperature and mobile phase composition on the retention and selectivity of separation by CEC demonstrated the feasibility of rapid polypeptide analysis and tryptic mapping at elevated temperature with high resolution and efficiency. Typically the chromatography of a tryptic digest of cytochrome c took about 5 min at 55 degrees C and 75 kV/m with hydro-organic mobile phases containing acetonitrile in 50 mM phosphate buffer, pH 2.5. For peptides and proteins plots of logarithmic k'cec against acetonitrile concentration were nonlinear, whereas Arrhenius plots for the mobilities were nearly linear. Comparison of the separation of such samples under conditions of CEC and capillary zone electrophoresis (CZE) indicates that the mechanism of separation in CEC is unique and leads to a chromatographic profile different from that obtained by CZE.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed1976

Studies on digitalis. IV. A method for thin-layer chromatographic separation and determination of digitoxin and cardioactive metabolites in human blood and urine.

A thin-layer chromatographic method for the separation of digitoxin and its cardioactive metabolites in one system is described. Pre-coated silica gel plates impregnated with 15% formamide solution in acetone were developed twice in the same direction (running distance 18cm) with ethyl methyl ketone-xylene (50:50) as solvent. The system showed no border-zone effects, and the reproducibility was good. Samples (5 ml) of serum or urine were extracted with dichloromethane, the extracts were evaporated, the residues were dissolved in 70% ethanol, the ethanol solutions were washed twice with light petroleum and then evaporated, and the residues were dissolved in chloroform-methanol for application to the thin-layer plates. After development, the metabolites were scraped from the plates and analyzed by means of a modified rubidium-86 method. The recovery for the whole procedure was 59%, and the sensitivity of the method permitted the determination of down to 0.5 ng per spot. The method will facilitate the study of digitoxin metabolism in patients undergoing treatment with the drug.

Chromatography, Thin Layer↗
PubMed2001

Detection of DNA adducts of benzo[a]pyrene using immunoelectrophoresis with laser-induced fluorescence. Analysis of A549 cells.

Detection of benzo[a]pyrene diol epoxide (BPDE)-damaged DNA in a human lung carcinoma cell line (A549) has been performed using free zone affinity capillary electrophoresis with laser-induced fluorescence (LIF). Using BPDE as a model carcinogenic compound, the speed, sensitivity and specificity of this technique was demonstrated. Under free zone conditions, an antibody bound adduct was baseline-resolved from an unbound adduct in less than 2 min. The efficiencies of separation were in excess of 6 x 10(5) and 1 x 10(6) plates per meter for the antibody-bound and unbound adducts, respectively. Separation using a low ionic strength buffer permitted the use of a high electric field (830 V/cm) without the loss of resolving power. Using LIF detection, a concentration detection limit of roughly 3 x 10(-10) M was achieved for a 90-mer oligonuleotide containing a single BDPE. The use of formamide in the incubation buffer to enhance denaturing of DNA did not affect the stability of the complex between the antibody and the adducts. Using a fluorescently labeled BPDE-modified DNA adduct probe, a competitive assay was established to determine the levels of BPDE-DNA adducts in A549 cells.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed2003

Exfoliation and immobilization of anionic iron porphyrin in layered double hydroxides.

Mg-Al layered double hydroxide (LDH) intercalated with glycinate anions was synthesized through co-precipitation and exfoliated in formamide and the single-layer suspension was reacted with an aqueous iron porphyrin (FeTDFSPP) solution. The new composite was characterized by powder X-ray diffraction, UV-vis, FTIR, and electron paramagnetic spectroscopies and thermal analyses (simultaneous TG/DSC). The analyses demonstrated that glycinate anions continue to be intercalated and the anionic iron porphyrin is adsorbed at the surface of the layered double hydroxide crystals.

Journal Article↗
PubMed1983

Structure of partially denatured Escherichia coli 23 S ribosomal RNA determined by electron microscopy.

The secondary structure of 23 S ribosomal RNA was analyzed by electron microscopy after partial denaturation. A reproducible pattern of loops was seen when molecules were spread for electron microscopy in 50% formamide solutions containing various concentrations of Mg2+ and Na+. Some loops were stabilized more than others by Na+ or by Mg2+; but in general, small amounts of Mg2+ (0.5 to 1.0 mM) markedly stabilized all the major loops, as did much greater amounts of Na+ (100 mM). However, at all levels of Mg2+ examined, increasing levels of Na+ destabilized loop structures. These data are consistent with the known salt dependence of double-stranded DNA and transfer RNA structure. The four most frequently observed loops correspond, within the limits of measurement error, to the major loops in the secondary structure models of Noller et al. (1981) and Glotz et al. (1981). These four loops are, in length and position of their midpoints along the 23 S rRNA molecule: 490 +/- 50 at 250 +/- 40; 350 +/- 50 at 1860 +/- 80; 400 +/- 70 at 2330 +/- 150; and 570 +/- 100 at 2350 +/- 100. Three of the four have base-paired stems with delta G0 values among the lowest of all the loops in the two indirect models. At least two are also among the most stable loops found in computer searches of the 23 S rRNA sequence for dyad symmetry. These results demonstrate that partial denaturation mapping can both identify prominent features of secondary structure in rRNA and estimate their relative stability.

Escherichia coli↗
PubMed1990

Hemodynamic effect of the metallopurpurin SnET2 and light on transplantable FANFT induced bladder tumor.

Changes in blood flow to transplantable N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide induced bladder tumors growing subcutaneously in the flanks of Fischer CDF (F344/CrlBR) rats were measured after photodynamic therapy with the photosensitizer tin (II) etiopurpurin dichloride using the radioactive microsphere technique. As with the other photosensitizers, hematoporphyrin derivative and chloroaluminum tetrasulfophtalocyanine, tin (II) etiopurpurin dichloride and light caused a rapid decrease in tumor blood flow in this tumor model. The decrease in blood flow occurred whether the vehicle for photosensitizer delivery was an emulsion or a liposome. Systemic heparinization of animals prior to light treatment did not alter changes in tumor blood flow.

Animals↗
PubMed1987

A dose response analysis of purpurin derivatives used as photosensitizers for the photodynamic treatment of transplantable FANFT induced urothelial tumors.

Rats engrafted with transplantable N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT) induced urothelial tumors were treated with purpurin derivatives and red light (greater than 590 nm., 360 joules/cm.2). Treated and control tumors were harvested 12 days after treatment and dry weights compared. At doses of 5.0 micrograms./gm. and 2.5 micrograms./gm. body weight, the purpurins designated NT1 and NT2, when combined with light, caused statistically significant (p less than 0.02) tumor regression when compared to light shielded controls. At 1.0 micrograms./gm. body weight, NT1 and light also induced significant tumor regression (p less than 0.02). Purpurins, which have strong absorption bands above 650 nm. and can be synthesized with a high degree of purity, appear to have potential as photosensitizers for photodynamic therapy.

Animals↗
PubMed1986

Photodynamic treatment of transplantable bladder tumors in rodents after pretreatment with chloroaluminum tetrasulfophthalocyanine.

Chloroaluminum tetrasulfophthalocyanine (AlPCS) was used as a photosensitizer for the photodynamic treatment of transplantable N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT) induced urothelial tumors. Two groups of six rats each were injected with AlPCS (three micrograms./gm. body weight) and 24 hours after injection underwent photodynamic treatment with red light (greater than 590 nm., 360 joules/cm.2). Tumors examined four hours (Group I) and 24 hours (Group II) after the completion of phototreatment showed extensive hemorrhagic necrosis. Tumors treated with AlPCS alone showed no changes. In two other groups of six rats each, blood flow to tumors treated with AlPCS alone (Group III) and AlPCS plus light (Group IV) was measured using the radioactive microsphere technique. AlPCS plus light resulted in a significant decrease (p less than .05) in tumor blood flow within 10 minutes of completion of phototreatment while AlPCS alone had no effect on tumor blood flow. These findings are similar to those observed when higher doses (10 micrograms./gm. to 20 micrograms./gm. body weight) of hematophorphyrin derivative (HpD) and light were used for phototreatment of FANFT induced tumors. AlPCS is a stable sulfonated derivative of tetraazotetrabenzoporphyrin which absorbs maximally in the red portion of the visible spectrum, a region with good tissue penetration properties. These studies suggest the AlPCS may be a useful new agent for photodynamic therapy of cancer.

Animals↗
PubMed1985

In vitro and in vivo activity of two second generation platinum analogs in murine bladder cancer.

The activity of cis-diamminedichloroplatinum(II) was compared to two second generation platinum analogs, cis-diammine-1,1-cyclobutane dicarboxylate platinum(II) and cis-dichlorotransdihydroxybisisopropylamine platinum(IV) in the N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide-induced murine bladder tumor model and a tumor colony assay. Murine drug testing revealed that all three drugs were active against the MBT-2 tumor line, although cis-diamminedichloroplatinum(II) was more active than its analogs. All drugs produced enhanced inhibition of clonal growth with increasing drug exposure times. Cis-diamminedichloroplatinum(II) was more active against MBT-2 cells in the plateau growth phase versus the log growth phase after a one hour drug exposure. Similar differential activity depending upon the proliferative state of MBT-2 was not seen with the two platinum analogs. These two platinum analogs have somewhat less activity in vivo and in vitro than cis-diamminedichloroplatinum(II) and would be predicted to be less effective clinically in human bladder cancer than the parent compound.

Animals↗
PubMed1985

Hematoporphyrin derivative photochemotherapy of experimental bladder tumors.

Recent studies have shown that disruption of tumor blood flow is a major consequence of hematoporphyrin derivative photochemotherapy. A series of experiments was undertaken on the transplantable N-(4-(5-nitro-2-furyl)-2-thiazolyl)-formamide induced urothelial tumor in Fischer 344 rats to determine a dose response for both hematoporphyrin derivative and light. Tumor blood flow was used as the biologic criteria of response. Hematoporphyrin derivative doses of 10 micrograms./gm. body weight or above were necessary to cause a significant decrease in tumor blood flow when the tumors were illuminated with 360 joules/cm.2 of noncoherent red light (greater than 590 nm.). With a constant hematoporphyrin derivative dose of 20 micrograms./gm. body weight, significantly lower tumor blood flows were observed with fluences of 240 joules/cm.2 and above. In order to correlate dose response to tumor regression, experiments were done in which tumor dry weights were determined 3 weeks after completion of photochemotherapy (360 joules/cm.2). Hematoporphyrin derivative doses of 10 micrograms./gm. body weight or above were necessary to induce tumor regression. These studies support the hypothesis that disruption of tumor blood flow is a tumoricidal mechanism of hematoporphyrin derivative photochemotherapy.

Animals↗