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PubMed1995

Isolation and biochemical characterization of highly purified Escherichia coli molecular chaperone Cpn60 (GroEL) by affinity chromatography and urea-induced monomerization.

Isolated Escherichia coli molecular chaperone Cpn60 (GroEL) has been further purified from tightly bound substrate polypeptides by two different procedures: (i) group-specific affinity chromatography by using the triazine dye Procion yellow HE-3G as affinity ligand, and (ii) urea-induced monomerization and subsequent chromatography. Procion yellow binds specifically to aromatic amino-acid side chains present in the majority of proteins, but has no affinity to GroEL because of its low content of aromatic residues. Some GroEL-bound polypeptides are buried within the aqueous cavity of the GroEL oligomer, whereas others are exposed on its surface and available for affinity-ligand interactions and the complex is thereby retarded on Procion yellow columns. Pure substrate-free GroEL was obtained after ion-exchange chromatography of GroEL monomers followed by reassembly of the purified monomers into functional GroEL oligomers. The final preparation contained no substrate polypeptides bound to GroEL as judged by electrophoretic analysis and lack of tryptophan fluorescence. GroEL preparations also displayed two equally strong bands on native electrophoresis suggesting the presence of two conformers. Monomers of GroEL showed heterogeneity with respect to isoelectric point and molecular mass when analysed by MALDI-MS and electrophoresis under native and denaturing conditions respectively. By use of MALDI-MS, highly accurate molecular masses of wild-type and a truncated form of GroEL were determined and verified, by comparison with their respective gene sequences.

Amino Acid Sequence↗
PubMed1996

Biomimetic-dye affinity chromatography for the purification of mitochondrial L-malate dehydrogenase from bovine heart.

Seven biomimetic anthraquinone triazinyl dye-ligands, bearing as triazine-linked terminal moiety (keto)carboxylated structures mimicking substrates and inhibitors of malate dehydrogenase (MDH), were immobilised on cross-linked agarose Ultrogel A6R. These biomimetic ligands are terminal-ring analogues of commercial nonbiomimetic Cibacron blue 3GA (CB3GA) and parent Vilmafix blue A-R (VBAR). The biomimetic-dye adsorbents, along with nonbiomimetic adsorbents bearing immobilised CB3GA and VBAR, were evaluated for their ability to purify mitochondrial malate dehydrogenase (mMDH) from bovine heart. All but two biomimetic-dye adsorbents displayed higher purifying ability for MDH, compared to nonbiomimetic-dye adsorbents. Furthermore, immobilised anthraquinone-dyes were able to discriminate between the mitochondrial and the cytoplasmic MDH isoenzymes, binding only to the former. One immobilised biomimetic-dye (BM5), bearing as biomimetic terminal moiety 4-aminophenyloxanylic acid, showed the highest purifying ability. This affinity adsorbent was exploited in the purification of mMDH from unpretreated bovine heart extract in one-step. The procedure afforded mMDH at 54% overall yield and of specific activity approx. 1300 U mg-1 (25 degrees C), using step-elution with a mixture containing 0.1 mM beta-nicotinamide adenine dinucleotide (NAD+) and 1.5 mM sulphite. Commercial analytical-grade bovine heart mitochondrial MDH, when assayed under identical conditions, gave a specific activity not exceeding 950 U mg-1. The well-known adsorbent Cibacron blue 3GA-agarose exhibited 8% lower recovery and 25% lower purification for mMDH. The product obtained from the procedure based on the BM5-adsorbent was free of cytoplasmic MDH, glutamic-oxaloacetic transaminase (GOT) and fumarase, and since it has also shown high specific activity, it should be suitable for analytical applications.

Acetone↗
PubMed1983

Antiallergic activity profile in vitro of RHC 2963 and related compounds.

RHC 2963 (7-methyl-pyrido (3',2':4,5)-thieno (3,2-d)-1,2,3 triazine-4(3H)-one and 20 related compounds have been investigated for their antiallergic activities in 3 in vitro models of anaphylaxis and for their effects on cyclic nucleotide phosphodiesterases (cNUC-PDE) from purified rat mast cells (RMC). Nine compounds were potent (I50 less than or equal to 80 microM) inhibitors of antigen-induced release of histamine (AIR) from RMC, 2 compounds inhibited anti-IgE-induced release of histamine from human basophils (I50 less than or equal to 60 microM) and one compound inhibited AIR from guinea pig lung slices (I50 = 55 microM). RHC 2963 was 18 times more potent than disodium cromoglycate (DSCG) as inhibitor of AIR from RMC and had an activity profile identical to that of DSCG in the following respects: loss of inhibitory activity with increasing preincubation time, tachyphylactic properties and inability to inhibit non-immunologic release of histamine induced by compound 48/80. Neither RHC 2963 nor DSCG had any effect on anti-IgE-induced release of histamine from human basophils or IgG1-mediated release of histamine from guinea pig lung. Twelve of the compounds in this chemical series were more potent than theophylline as inhibitors of cyclic AMP and/or cyclic GMP phosphodiesterase (PDE) from RMC. Paired regression analysis of the I50 values for inhibition of AIR and cNUC-PDE from RMC revealed no statistically significant correlation between the inhibition of AIR and inhibition of cAMP- or cGMP-PDE. We conclude: (1) RHC 2963 and some of the related compounds are potent inhibitors of immunologic release of histamine from RMC with a mechanism of action similar to that of DSCG, and (2) inhibition of cAMP- or cGMP-PDE by these compounds is not the biochemical mechanism by which they inhibit AIR from RMC.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1984

Chronic toxicity, reproductive, and teratogenic studies of hexazinone.

Hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine 2,4(1H,3H)-dione; CAS 51235-04-2] was tested for oral toxicity in rats (both 90-day and 2-year feeding studies), mice (8-week and 2-year feeding studies), and dogs (90-day feeding study). The teratogenic potential was evaluated in rabbits and rats and functional reproductive capacity was studied in rats. Ninety-day feeding of up to 1000 ppm produced no signs of a toxic response in rats. Rats fed 5000 ppm had growth curves slightly inferior to those of the controls as the only detectable difference. Extending the feeding period to 2 years produced decreased body weights in males fed 2500 ppm (top level tested) and in females fed either 1000 or 2500 ppm. All other indices of response, including the type and distribution of tumors, were similar in the test and control rats with the no-effect level being 200 ppm. Eight-week feeding of up to 10,000 ppm in mice produced increased liver weight only at the highest level without any other changes. Two-year feeding of either 200, 2500, or 10,000 ppm resulted in sloughing of the distal tip of the tail and increased liver weights among mice fed 10,000 ppm. Hypertrophy of centrilobular hepatocytes and hyperplasic nodules were increased in mice fed either 2500 or 10,000 ppm. No evidence of a tumorigenic response was evident. The no-effect level was 200 ppm. Dogs fed 5000 ppm for 90 days had decreased rate of body weight gain with clinical enzyme changes suggestive of liver damage. Microscopic examination of the liver failed to reveal any alterations and dogs fed either 200 or 1000 ppm were indistinguishable from controls. The no-effect level in the dog was 1000 ppm. No evidence of a teratogenic response was seen in either rats or rabbits and reproduction capacity in rats fed up to 2500 ppm for three generations was unaffected.

Animals↗
PubMed1990

Toxic interactions of the munitions compounds TNT and RDX in F344 rats.

The potential toxic interactions in F344 rats of the munitions compounds trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) were examined following their coadministration in the diet. Groups of 10 rats per sex received TNT at doses of 5 or 125 mg/kg/day, RDX at doses of 30, 100, or 300 mg/kg/day, and combinations thereof for 13 weeks. Thirty rats per sex served as controls. Toxicologic endpoints included clinical observations, body weight, food consumption, hematology, clinical chemistry, organ weights, and tissue morphology. The major toxic effects following dietary administration of TNT to rats included anemia, hypercholesterolemia, and hepatomegaly, splenomegaly, and testicular atrophy with their accompanying histologic lesions. RDX intoxication in rats included hypotriglyceridemia, behavioral changes, and mortality. Most of the toxic effects of these chemicals were partially antagonized following their coadministration.

Anemia↗
PubMed1986

Effects of chitin synthesis inhibitors on incorporation of nucleosides into DNA and RNA in a cell line from Manduca sexta (L).

Five putative chitin synthesis inhibitors (CSI) were tested to determine if they inhibited nucleoside incorporation into acid precipitable material in a cell line from Manduca sexta (L.). The results varied. Diflubenzuron (DFB) (100 micron) inhibited cytidine incorporation by 38%; EL-494 (100 micron) inhibited adenosine incorporation by 43%; Bay Sir 8514 (100 micron) inhibited uridine incorporation by 24%. Superdiflubenzuron (100 micron) was the worst inhibitor overall (18-22%) for the benzoylphenyl urea CSI. The triazine CSI, CGA 19255, was the best inhibitor tested with 60% inhibition for cytidine and 49% for adenosine incorporation into DNA and RNA. Examination of cells incubated with diflubenzuron by scanning electron microscopy revealed distinct external morphological changes. Transmission electron microscopy showed that crystalline structures accumulated in the cytoplasm of cells treated with DFB. The crystalline structures were assumed to be diflubenzuron and they persisted even after diflubenzuron was removed from the medium.

Animals↗
PubMed1989

Degradation of plasma bilirubin by a bilirubin oxidase derivative which has a relatively long half-life in the circulation.

To enhance degradation of unconjugated bilirubin in hyperbilirubinemic subjects, we synthesized a bilirubin oxidase (EC 1.3.3.5) (BO) derivative (PEGBO) by covalently linking (2,4-bis[O-methoxy(polyethyleneglycol)]-6-chloro-s-triazine) (PEG) to the enzyme. Intravenously injected BO in rats disappeared from the circulation with a half-life of 2.5 min; the half-life of PEGBO was 190 min. Intravenously injected BO minimally and transiently decreased plasma bilirubin levels in jaundiced Gunn rats and in bile-duct-ligated jaundiced rats. In contrast, PEGBO rapidly and substantially decreased plasma bilirubin levels and the effect persisted for longer than 3 h. Renal dysfunction often occurs in patients with liver diseases. To study the role of bilirubin toxicity for the kidney, functions of transtubular transport for organic anions was measured in bile-duct-ligated jaundiced animals before and after treatment with PEGBO. Bile duct ligation decreased urinary excretion of phenolsulfophthalein (PSP), an organic anion used for renal function test. Treatment of the jaundiced animals with PEGBO increased the rate of PSP disappearance from the circulation and normalized its urinary excretion. Thus, PEGBO might be useful for the study of bilirubin toxicity in jaundiced animals.

Animals↗
PubMed1986

Hexamethylmelamine: a critical review of an active drug.

Hexamethylmelamine is an s-triazine that began clinical trials during the 1960s based on its level of antitumor activity in murine tumor models. Phase I studies were performed using an oral formulation given in divided doses for varying numbers of days. The most frequently reported toxicities included nausea, vomiting, abdominal cramps, anorexia, weight loss and malaise. Less frequently reported toxicities were anemia, thrombocytopenia, leucopenia and peripheral neuropathy. Clinical antitumor activity was noted in the phase I studies in a variety of tumor types. Since then a large number of studies have been performed using hexamethylmelamine as a single agent and in a variety of combinations. Unfortunately, almost none of these studies sought to define the utility of this drug relative to other treatments for the diseases in which it showed activity, or to define the contribution of this drug to the activity of any given combination. Thus its role in the treatment of patients with malignancies remains undefined.

Altretamine↗
PubMed1989

Results of combination chemotherapy and thoracic radiation therapy for unresectable non-small cell carcinoma of the lung.

From October 1979 to December 1982, 126 patients with locally advanced unresectable or inoperable Stage II (7 patients), Stage IIIA (81 patients), and Stage IIIB (38 patients) non-small cell carcinoma of the lung were treated in a prospective randomized trial using five cycles of CAP (Cytoxan, Adriamycin, and cisplatin), T-CAP (triazinate plus CAP), or V-CAP (VP-16 plus CAP) chemotherapy with thoracic radiation therapy (TRT). TRT consisted of 40 Gy in 10 fractions (split-course) with cycles 3 and 4 of chemotherapy. The treatment field included the primary tumor, ipsilateral hilum, mediastinum, and ipsilateral supraclavicular fossa. All patients were followed until death or for a minimum of 5 years for survivors. The evaluable subgroup consisted of 102 patients who completed TRT. Median and 5-year survivals for the entire group were 14.0 months and 10%, respectively; for the evaluable subgroup, they were 14.8 months and 12%, respectively. There was a trend toward better survival with V-CAP plus TRT than with CAP plus TRT (p = 0.08). Median and 5-year survivals were 16.2 months and 18%, respectively, with V-CAP plus TRT. Of eight prognostic variables analyzed for their association with survival, only Eastern Cooperative Oncology Group performance status (0,1 versus 2) (p = 0.02) and weight loss (less than or equal to 10% versus greater than 10%) (p = 0.05) were significant. Sex, age, T stage, N stage, overall stage, and histologic type were not significantly associated with survival. Failure analysis revealed 83 patients (81%) with identifiable first failures. The median time to first failure was 9.8 months, and the median survival after first failure was 4.7 months. Failure patterns included local failure alone (19%), local and distant (20%), and distant alone (43%). Nineteen percent of patients had no documented progression. Total failure patterns were local in 39% and distant in 63%. Twenty-three patients (23%) had failure in the brain; they accounted for 31% of all distant failures. In 20 of these patients (20% of all patients), this was the only site of failure. There were eight (8%) initial nodal failures in 96 untreated contralateral supraclavicular fossae. No initial failures were seen in any of 101 untreated contralateral hila. The data suggest the following: (a) Combined treatment with V-CAP and TRT yielded excellent results (median survival, 16.2 months; 5-year survival, 18%).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1989

Structure-activity relationships for benzotriazine di-N-oxides.

SR 4233 (3-amino-1,2,4-benzotriazine 1,4-dioxide) is a bioreductive agent that selectively kills and radiosensitizes hypoxic mammalian cells in vitro and murine tumors in vivo. In an attempt to better understand the mechanism of action of the drug, and to determine whether a superior analog may exist, 15 benzotriazine-di-N-oxide analogs of SR 4233 have been evaluated to date for the following properties: hypoxic and aerobic toxicity toward CHO cells in vitro, drug-induced stimulation of oxygen consumption by incubation with respiration-inhibited cells, and acute LD50 evaluated in BALB/c mice. We noted several correlations between these biological properties of the drugs and some of their physicochemical characteristics. Both the hypoxic cytotoxicity and stimulation of oxygen consumption by respiration-inhibited cells were positively correlated with E1/2, the polarographic half-wave reduction potential, and a measure of electron affinity. The air-to-nitrogen differential cytotoxicity reached a maximum (corresponding to SR 4233) and then declined with increasing E1/2. The acute LD50 of each analog in mice decreased with increasing E1/2. One new compound, SR 4482, was found to be more toxic to hypoxic cells in vitro, but less toxic to mice, than SR 4233. It is similar in structure to SR 4233, but lacks any substituent in the 3-position of the triazine ring. This promising drug may represent a member of a new subseries of 1,2,4-benzotriazines with different structure-activity relationships.

Animals↗
PubMed1992

An in vitro investigation of the action of lamotrigine on neuronal voltage-activated sodium channels.

Lamotrigine (LTG), 6-(2,3-dichlorophenyl)-1,2,4-triazine-3,5-diamine, is a novel antiepieptic drug structurally unrelated to the major anticonvulsants in current use. Previous studies of LTG in rodents revealed efficacy in maximal electroshock test, pentylenetetrazol test and kindling models of seizures suggesting potential utility in the treatment of partial and generalized (tonic-clonic) seizures. In the present study, LTG was found to block sustained repetitive firing of sodium-dependent action potentials in mouse spinal cord cultured neurons and inhibit [3H]batrachotoxinin A 20-alpha-benzoate binding in rat brain synaptosomes suggesting a direct interaction with voltage-activated sodium channels.

Action Potentials↗
PubMed1994

Thromboxane A2 biosynthesis inhibitors: synthesis and evaluation of pyrazolotriazinyl alkanoic acids.

A novel series of (6-aryl-4-oxo-pyrazolo 2,3-d] [1,2,5] triazin-3-yl) alkanoic acids was synthesized and evaluated in vitro as thromboxane A2 (TXA2) biosynthesis inhibitors. The experiments were carried out using arachidonic acid (32.8 microM) as a substrate and horse platelet microsomes (HPM) as sources of TXA synthetase. TXB2, a stable breakdown product of TXA2, was determined by radioimmunoassays (RIA). The substances under study, at concentrations ranging from 1.10(-6) M to 1.10(-4) M, significantly inhibited the biosynthesis of TXA2 in vitro. This activity was found to be dose-dependent, the potency of which could be related to structural features of the molecules. Compound 3b, bearing a butanoic side chain in the 3-position and a 4-chloro phenyl ring in the 6-position of the bicyclic system, was the most active derivative in in vitro enzyme inhibition (ID50 = 2.81 x 10(-5) M). Comparison of the spatial configurations of prostaglandin H2 (PGH2 and 3b displayed a good correlation between essential structural moieties of both molecules. In addition, conceptual model for the PGH2 and TX synthetase interactions was applied to compound 3b.

Animals↗
PubMed1994

Stable analogues of the antitumour agent trimelamol retain in vitro cytotoxicity in drug-sensitive and resistant rodent and human cell lines.

In spite of clinical activity in heavily-pretreated ovarian cancer, the antitumour s-triazine trimelamol [TM; tris(hydroxymethyl)-tris(methyl)melamine] had to be withdrawn from further clinical studies due to formulation difficulties related to instability. A synthetic programme has produced tris(hydroxymethyl) analogues containing electron-withdrawing groups in place of methyl-triscyanomethyl CB 7669, tristrifluoroethyl CB 7639, CB 7529 and trispropargyl CB 7547, all showing markedly superior stability to TM. Chemosensitivity testing of analogues (MTT assay, continuous exposure) using a panel of rodent and human cell lines showed activity close to that of TM, e.g. for the CH1 human ovarian cancer cell line. IC50 values were TM 23.4 microM, CB 7639 30.5 microM, CB 7529 29.5 microM, CB 7547 28.5 microM and CB 7669 27.3 microM. CB 7669 and CB 7639 required prolonged exposure (> 12 h) in order to exhibit equivalent cytotoxicity to a 2-h exposure to TM. Thus, rather than administration as a single daily dose, the stable analogues may be more suited to prolonged infusion, which was suggested as being a more beneficial regimen in clinical trials with TM. In line with clinical observations indicating the efficacy of TM in platinum-refractory ovarian cancer, we saw no significant cross-resistance to TM or CB 7529 in a range of platinum-sensitive and acquired-resistant cell line pairs or in an alkylating-agent resistant cell line, despite TM's ability to crosslink DNA. Data obtained using cell lines with acquired resistance to TM, CB 7669 and formaldehyde (released in the breakdown of TM) suggest a pivotal role for formaldehyde and a more minor role for alkylating activity in the mechanism of action of the N-(hydroxymethyl)melamines in vitro. Further clinical trials of these compounds are eagerly awaited, and their usefulness as second-line chemotherapy for heavily pretreated ovarian cancer deserves further investigation.

Animals↗
PubMed2006

Optimized dyeing conditions of immunoprotein with reactive dye Procion Blue MX-7RX.

For investigating the feasibility of using reactive dyes as an immunoassay marker, a dichlorine triazine dye, Procion Blue MX-7RX, was employed to stain the antibody against human serum albumin (anti-HSA). With the color intensity revealed in the immunochromatographic test strip as the objective variables, the optimal dyeing conditions were found as follows: pH 11.4, temperature 35.7 degrees C, molar ratio 188 (mol dye/mol antibody), and reaction time 45.6 min. The dyed-anti-HSA revealed a maximal color intensity of 8738 without apparent loss of antigen binding affinity.

Antibodies↗
PubMed2006

Multiple synergistic interactions between atovaquone and antifolates against Plasmodium falciparum in vitro: a rational basis for combination therapy.

The use of synergistic drug combinations for the treatment of drug-resistant malaria is a major strategy to slow the selection and spread of Plasmodium falciparum resistant strains. In order to investigate synergistic compounds, with different modes of action, as alternative candidates for combination therapy, we used standard in vitro P. falciparum cultures and an established synergy testing method to define interactions among dapsone (DDS), atovaquone (ATQ), chlorproguanil (CPG) and its triazine metabolite chlorcycloguanil (CCG). Strong synergy was observed in the combinations DDS/CCG and ATQ/CPG. Multiple combination of these drugs, DDS/CCG/CPG/ATQ also exhibited high synergy although not higher than that of either of the two drug combinations separately. The use of this triple combination DDS/CPG/ATQ, even without an increase in synergy over their double combinations, ATQ/CPG and DDS/CCG, would contribute towards slowing the selection pressure since these drugs act against different targets and would delay the selection of parasites resistant to the three drugs, extending the useful therapeutic life of these valuable compounds.

Animals↗
PubMed2004

The interactive effects of the antifouling herbicides Irgarol 1051 and Diuron on the seagrass Zostera marina (L.).

The herbicides Irgarol 1051 (2-(tert-butylamino)-4-cyclopropylamino)-6-(methylthio)-1,3,5-triazine) and Diuron (3-(3',4'-dichlorophenyl)-1,1-dimethylurea) are commonly incorporated into antifouling paints to boost the efficacy of the compound towards algae. Previous investigations have identified environmental concentrations of these herbicides as being a threat to non-target organisms, such as seagrasses. Their individual toxicity has been assessed, but they can co-occur and interact, potentially increasing their toxicity and the threat posed to seagrass meadows. Chlorophyll fluorescence (Fv:Fm) and leaf specific biomass ratio (representing plant growth) were examined in Zostera marina L. after a 10-day exposure to the individual herbicides. The EC20 for each herbicide was determined and these then used in herbicide mixtures to assess their interactive effects. Irgarol 1051 was found to be more toxic than Diuron with lowest observable effect concentrations for Fv:Fm reduction of 0.5 and 1.0 +/- microg/l and 10-day EC50 values of 1.1 and 3.2 microg/l, respectively. Plants exposed to Irgarol 1051 and Diuron showed a significant reduction in growth at concentrations of 1.0 and 5.0 microg/l, respectively. When Z. marina was exposed to mixtures, the herbicides commonly interacted additively or antagonistically, and no significant further reduction in photosynthetic efficiency was found at any concentration when compared to plants exposed to the individual herbicides. However, on addition of the Diuron EC20 to varying Irgarol 1051 concentrations and the Irgarol 1051 EC20 to varying Diuron concentrations, significant reductions in Fv:Fm were noted at an earlier stage. The growth of plants exposed to Diuron plus the Irgarol 1051 EC20 were significantly reduced when compared to plants exposed to Diuron alone, but only at the lower concentrations. Growth of plants exposed to Irgarol 1051 and the Diuron EC20 showed no significant reduction when compared to the growth of plants exposed to Irgarol 1051 alone. Despite the addition of the EC20 not eliciting a further significant reduction when compared to the herbicides acting alone for most of the mixtures, the lowest observable significant effect concentration for growth and photosynthetic efficiency decreased to 0.5 microg/l for both herbicides. Irgarol 1051 and Diuron have been shown to occur together in concentrations above 0.5 microg/l, suggesting that seagrasses may be experiencing reduced photosynthetic efficiency and growth as a result.

Analysis of Variance↗
PubMed2004

Blockade of adenosine A2A receptors reverses short-term social memory impairments in spontaneously hypertensive rats.

Spontaneously hypertensive rats (SHR) exhibit impairment across several cognitive domains such as attention, short-term memory and spatial reference memory. These cognitive deficits have been variously attributed to disrupted dopaminergic, cholinergic and adenosinergic neurotransmitter function. However, social memory in SHR has not been investigated. In the present study, we therefore evaluated whether SHR exhibit altered short-term social memory abilities compared to normotensive Wistar rats (WIS) through two experimental paradigms (social recognition and habituation-dishabituation tests). We also compared the performance of SHR and WIS rats in the object recognition test. SHR exhibited significantly impaired performance in both models of social memory, but not in the object recognition test, demonstrating a selective deficit in the ability to recognize a juvenile rat after a short period of time. The administration of acute doses of the non-selective adenosine receptor antagonist caffeine (3.0 or 10.0 mg/kg, i.p.) and the adenosine A2A receptor antagonist 4-(2-[7-amino-2-[2-furyl][1,2,4]triazolo-[2,3-a][1,3,5]triazin-5-yl-amino]ethyl) phenol (ZM241385, 0.5 or 1.0 mg/kg, i.p.) but not the adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 1.0 or 3.0 mg/kg, i.p.) reversed this social memory impairment in SHR, but these treatments did not alter the hypertension state. These results demonstrate an impairment of short-term social memory in SHR and the involvement of the adenosine A2A receptors in this alteration.

Adenosine A2 Receptor Antagonists↗
PubMed2004

A novel inhibitor that protects apoptotic DNA fragmentation catalyzed by DNase gamma.

The internucleosomal cleavage of genomic DNA is the biochemical hallmark of apoptosis. DNase gamma, a Ca(2+)/Mg(2+)-dependent endonuclease, has been suggested to be one of the apoptotic endonucleases. We identified here 4-(4,6-dichloro-[1,3,5]-triazin-2-ylamino)-2-(6-hydroxy-3-oxo-3H-xanthen-9-yl)-benzoic acid (DR396) as a novel and potent DNase gamma inhibitor using stable HeLa S3 transfectants of DNase gamma (HeLa-gamma cells). DR396 inhibited apoptotic DNA fragmentation in HeLa-gamma cells induced by staurosporine (STS) and in rat splenocytes exposed to gamma-ray irradiation in a dose-dependent manner. This compound potently and selectively inhibited DNase gamma activity with an IC(50) value of 3.2 microM. DR396 did not delay the apoptotic processes as judged by the morphological changes and the cleavage of a death substrate, poly(ADP-ribose) polymerase (PARP). Furthermore, the compound did not prevent apoptotic DNA fragmentation in Jurkat cells induced by anti-Fas antibody (Ab), which is catalyzed by caspase-activated DNase (CAD). These findings clearly indicate that DR396 exerts chemical knockdown effect of DNase gamma on cells, suggesting that the compound could be an attractive tool for understanding of the physiological significance of DNase gamma.

Animals↗