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PubMed2025

DNA damage repair gene alterations influence the tumor immune microenvironment in advanced non-small cell lung cancer.

PURPOSE: DNA damage response and repair (DDR) gene alterations contribute to genomic instability and increased tumor immunogenicity, yet their clinical significance in non-small cell lung cancer (NSCLC) remains unclear. Using a large real-world dataset, we evaluated the prevalence of DDR alterations and their relation to the tumor immune microenvironment in metastatic NSCLC. EXPERIMENTAL DESIGN: We retrospectively analyzed real-world data from patients with metastatic NSCLC using the Tempus AI database. Tumors were sequenced with Tempus xT DNA and xR RNA assays and classified based on the presence (DDRmt) or absence (DDRwt) of a pathogenic somatic alteration or copy number deletion in a DDR pathway gene. Associations between DDR alterations and immune cell infiltration, PD-L1 immunohistochemistry, tumor mutational burden (TMB), and microsatellite instability (MSI-H) were examined. RESULTS: Among 14,127 patients (median age = 67, 49% female), 5,276 (37%) were DDRmt. There was a higher prevalence of current/former smokers in the DDRmt group (86% vs. 82%; p<0.001). DDRmt tumors were more likely to have higher levels of TMB (median: 5.4 vs. 4.6; p<0.001), MSI-H (1.1 % vs. <0.1 %; p<0.001), and infiltrating CD8+ T cells (p=0.003) compared to DDRwt tumors. A lower frequency of macrophages (p<0.001) were observed among DDRmt compared with DDRwt tumors with no difference in PDL1 positivity. CONCLUSIONS: Among patients with metastatic NSCLC, 37% present with DDRmt tumors characterized by higher TMB, frequency of MSI-H, and changes in immune cell infiltrates. These findings provide insight into the immunogenic landscape of DDR-altered NSCLC and may inform biomarker selection and therapeutic strategies.

Humans↗

PubMed2005

In vitro and in vivo evaluation of pyridinium oximes: mode of interaction with acetylcholinesterase, effect on tabun- and soman-poisoned mice and their cytotoxicity.

The increased concern about terrorist use of nerve agents prompted us to search for new more effective oximes against tabun and soman poisoning. We investigated the interactions of five bispyridinium oximes: K027 [1-(4-hydroxyiminomethylpyridinium)-3-(4-carbamoylpyridinium) propane dibromide], K048 [1-(4-hydroxyiminomethylpyridinium)-4-(4-carbamoylpyridinium) butane dibromide], K033 [1,4-bis(2-hydroxyiminomethylpyridinium) butane dibromide], TMB-4 [1,3-bis(4-hydroxyiminomethylpyridinium) propane dibromide] and HI-6 [(1-(2-hydroxyiminomethylpyridinium)-3-(4-carbamoylpyridinium)-2-oxapropane dichloride)] with human erythrocyte acetylcholinesterase (AChE; E.C. 3.1.1.7) and their effects on tabun- and soman-poisoned mice. All the oximes reversibly inhibited AChE, and the enzyme-oxime dissociation constants were between 17 and 180 microM. Tabun-inhibited AChE was completely reactivated by TMB-4, K027 and K048, with the overall reactivation rate constants of 306, 376 and 673 min(-1)M(-1), respectively. The reactivation of tabun-inhibited AChE by K033 reached 50% after 24h, while HI-6 failed to reactivate any AChE at all. Soman-inhibited AChE was resistant to reactivation by 1mM oximes. All studied oximes protected AChE from phosphorylation with both soman and tabun. In vivo experiments showed that the studied oximes were relatively toxic to mice; K033 was the most toxic (LD50=33.4 mg/kg), while K027 was the least toxic (LD50=672.8 mg/kg). The best antidotal efficacy was obtained with K048, K027 and TMB-4 for tabun poisoning, and HI-6 for soman poisoning. Moreover, all tested oximes showed no cytotoxic effect on several cell lines in concentrations up to 0.8mM. The potency of the oximes K048 and K027 to protect mice from five-fold LD50 of tabun and their low toxicity make these compounds leading in the therapy of tabun poisoning. The combination of HI-6 and atropine is the therapy of choice for soman poisoning.

Acetylcholinesterase↗

PubMed2003

Capillary electrophoretic enzyme immunoassay with electrochemical detection for thyroxine.

A capillary electrophoretic enzyme immunoassay with electrochemical detection (CE-EIA-ED) has been developed. In this method, antigen (Ag) competes with horseradish peroxidase (HRP)-labeled antigen (HRP-Ag) for a limited number of antibody (Ab) binding sites. The free HRP-Ag and the bound HRP-Ag-Ab complex are separated by capillary electrophoresis in a separation capillary. Then they catalyze the oxidation of their enzyme substrate 3,3',5,5'-tetramethylbenzide (TMB (reduced form)) with H(2)O(2) in a reaction capillary, which follows the separation capillary. The reaction product (TMB (oxidized form)) is amperometrically determined using a carbon fiber microdisk bundle electrode at the outlet of the reaction capillary. Due to the amplification of the enzyme, the concentration of TMB(Ox) is much higher than those of free HRP-Ag and the bound HRP-Ag-Ab complex. Therefore, the limit of detection (LOD) of CE-EIA-ED is very low. The method has been used to determine thyroxine in human serum. A concentration of LOD of 3.8 x 10(-9)mol/L, which corresponds to a mass LOD of 23.2 amol, was achieved.

Electrochemistry↗

PubMed1997

Antiemetic inhibits conditioned taste aversion, but not the hypophagia induced by epinephrine.

It has been shown that relatively high doses of epinephrine (E) injected intraperitoneally (IP) produce hypophagia and conditioned taste aversion (CTA) in rats. We examined the possibility that E effects involve malaise. For this purpose, changes in saccharin preference induced by E injected IP (100 microg/kg) were determined after a previous administration of trimethobenzamide (TMB, 5 mg/kg), an antiemetic agent. E alone decreased saccharin preference by 54% (p < 0.01), but only by 16% (not significant) in the presence of TMB. In contrast, the injection of 75 or 100 microg/kg E reduced food intake by 50 and 85%, respectively (p < 0.01), regardless of previous injection of TMB. In conclusion, the results suggest that E-induced malaise is not the direct cause of the hypophagia it elicits.

Animals↗

PubMedDate not supplied

The treatment of Soman poisoning and its perspectives.

Soman is a highly toxic organophosphorus chemical warfare nerve agent which is characterized by (1) extremely rapid ageing of the phosphonylated enzyme, (2) poor reactivation of inhibited AChE due to a steric factor, (3) pronounced CNS effects, and (4) tentative direct toxic biochemical effects. By studies of Soman and its thiocholine-like analog (which yield the same type of phosphonylated enzyme), it has been established that (1) the steric factor is at least as responsible as ageing in the failure of oximes to reactivate effectively AChE inhibited by Soman, (2) that its dealkylation is catalyzed by the anionic site of the enzyme, and (3) that the velocity of reactivation and ageing of AChE is dependent on the orientation of the phosphonyl group at the enzyme surface. It has been found that PiMeP-Cl (O-pinacolyl methylphosphonochloridate) may serve as a good model in the evaluation of Soman toxicity and in the selection of adequate oximes in the treatment of its poisoning. The opposite effects of TMB-4 and HI-6, as group representatives, on PiMeP-Cl toxicity in mice (strong potentiation by TMB-4 and antagonism by HI-6) were mainly ascribed to the rates of decomposition of their corresponding O-pinacolyl methylphosphonylated products formed in vivo. They are considered to be slow with potentiators and instantaneous with antagonists, respectively. This assumption was confirmed by the finding that the most powerful oximes in Soman poisoned mice were HI-6, HGG-42 and BDB-27, which, contrary to TMB-4, possess an oxime group in position 2 and the CH2-O-CH2 linking chain. The remarkable influence of diazepam and sodium n-dipropylacetate on the survival time in Soman poisoned rats treated by atropine and bis-pyridinium oximes points to their antagonistic action at the biochemical level (decrease of elevated cGMP in CNS), not possessed by atropine. Essential antidotes in experimental treatment of Soman poisoning today are the powerful reactivators of Soman-inhibited AChE (e.g. HI-6, HGG-42 and BDB-27) and atropine. The treatment may be further improved by the use of symptomatic agents capable of counteracting biochemical changes in Soman poisoning not antagonized by atropine (e.g. diazepam), and theoretically for now, by retardation of ageing and by overcoming steric disturbances.

Animals↗

PubMed2002

Asiatic acid, a triterpene, induces apoptosis through intracellular Ca2+ release and enhanced expression of p53 in HepG2 human hepatoma cells.

Asiatic acid (AA), a triterpene, decreased viability and induced apoptosis of HepG2 human hepatoma cells in a dose-dependent manner. AA also markedly increased intracellular Ca(2+) level, which was blocked by TMB-8 and dantrolene, intracellular Ca(2+) release blockers, but not by EGTA, an extracellular Ca(2+) chelator. Moreover, AA-induced apoptosis was significantly suppressed by treatment with TMB-8 and dantrolene, suggesting that intracellular Ca(2+) release may play an essential role in the AA-induced apoptosis. In addition, AA profoundly increased protein level of p53, which was also inhibited by BAPTA/AM, an intracellular Ca(2+) chelator, TMB-8 and dantrolene. Treatment with A23187, a Ca(2+) ionophore, or thapsigargin, a Ca(2+)-ATPase inhibitor, alone enhanced p53 nuclear accumulation, indicating that p53 accumulation is dependent on intracellular Ca(2+) increase. Furthermore, the viability of Hep3B, p53-null cells, was much higher than that of HepG2, p53-wild type cells, when treated with AA. Taken together, these results suggest that AA induced apoptosis through increased intracellular Ca(2+), which, in turn, enhanced p53 expression in HepG2 cells. These results further suggest that AA may be a valuable agent for the therapeutic intervention of human hepatomas.

Antineoplastic Agents↗

PubMed1997

Thapsigargin does not affect phenylephrine-induced contractions in the anococcygeus muscle of rats.

1. The aims of the present study were to investigate the contribution of intracellular calcium and to evaluate the effect of the antagonists of the intracellular calcium stores, thapsigargin and [8-(Diethylamino)-octyl-3,4,5-trimethoxybenzoate, HC1] TMB-8, on phenylephrine-stimulated contractions of rat anococcygeus smooth muscle, using functional studies. 2. Phenylephrine induced concentration-related contractions in both 2.5 mM Ca2(+)-free EGTA media. 3. In Ca2(+)-free media phenylephrine stimulated successive contractions, and the contractile response was abolished only after approximately 26 stimulations. 4. In Ca2(+)-free media, after incubation with 10 microM TMB-8 for 30 min, phenylephrine induced concentration-response curves that shifted to the right. The EC50 values were not changed, and the maximum contractile response was reduced by 39.2 +/- 7.6% in relation to phenylephrine-stimulated responses in absence of TMB-8. 5. Thapsigargin (1 microM) did not alter phenylephrine-stimulated contractions in Ca2(+)-free media. 6. These results indicate that intracellular Ca2+ plays an important role on phenylephrine-stimulated contractions on rat anococcygeus muscle and that the phenylephrine-sensitive intracellular Ca2+ store is not sensitive to thapsigargin.

Animals↗

PubMed2002

Theoretical mechanistic basis of the toxic effects and efficacy of AZT in HIV: AIDS.

Toxic effects and efficacy of azidothymidine (AZT) in human immunodeficiency virus were evaluated by theoretical mechanistic biochemistry (TMB) techniques based on the structure of AZT and on the structure of HIV. AZT was positive (1+) for epoxide; (2+) for hydroxl free radical (*OH); (1+) for (*N(3)) azide free radical and (1+) for azide (N(3-)) generations, respectively. AZT was negative (-) for areneimine, and nitroso generations, respectively, for toxic effects totalling 5+ compared with dideoxycytidine (ddc) of 3+ and artesunate (At) of 0. Therefore for toxic effects the trend is AZT(5+) > ddc(3+) > At(0). TMB efficacy of AZT was based on the generations of *OH from the 1-NH (1+) and the 3(1)-azido (N(3))(1+) and azide free radical (*N(3)), (1+) totalling 3+ compared with ddc of 1+ and At of 1+. Therefore for efficacy, the trend is AZT(3+) > ddc(1+) = At(1+). In combination drug therapy, TMB postulates the following for HIV : AIDS: At(1+) + AZT(3+) + ddc(1+) > AZT(3+) + ddc(1+) = AZT(3+) + At(1+) > AZT(3+) > At(1+) + ddc(1+) > ddc(1+) = At(1+).

Acquired Immunodeficiency Syndrome↗

PubMed1999

11B magnetic resonance imaging and MAS spectroscopy of trimethylborate-treated radiata pine wood.

Boron-11 nuclear magnetic resonance imaging and spectroscopy have been used to characterise the nature and distribution of boron compounds after preservative treatment of radiata pine wood with trimethylborate (TMB). One day after treatment, 11B magnetic resonance imaging microscopy showed significant differences in the morphological distribution of boron species, with there apparently being no treatment penetration of the latewood. 11B MAS NMR spectroscopy of freshly preservative-treated radiata pine wood, which had been separated into latewood and earlywood, showed the only boron species present in the latewood to be boric acid while in the earlywood both TMB and boric acid were initially present. Due to quadrupolar broadening and a short T2 value, the boric acid signal relaxed too quickly to be observable and this caused the apparent lack of 11B in the image when only boric acid was present. TMB undergoes hydrolysis to form boric acid and in radiata pine latewood, this hydrolysis reaction is rapid.

Borates↗

PubMed2003

Capillary electrophoretic enzyme immunoassay with electrochemical detection using a noncompetitive format.

A capillary electrophoretic enzyme immunoassay with electrochemical detection (CE-EIA-ED) using a noncompetitive format has been developed. In this method, antigen (Ag) reacts with an excess amount of horseradish peroxidase (HRP)-labeled antibody (Ab*). The free Ab* and the bound Ag-Ab* complex produced in the solution are separated by capillary zone electrophoresis in a separation capillary. Then they catalyze enzyme substrate 3,3',5,5'-tetramethylbenzide (TMB(Red)) and H(2)O(2) in a reaction capillary following the separation capillary. The reaction product, TMB(Ox), can be determined using amperometric detection on a carbon fiber microdisk bundle electrode at the outlet of the reaction capillary. Due to the amplification of the enzyme, a significant amount of TMB(Ox) can be produced for detection. Therefore, the limit of detection (LOD) of CE-EIA-ED is very low. A tumor marker (CA15-3) was used as a model, in order to test the method. The concentration LOD of CA15-3 is 0.024 U/ml, which corresponds to a mass detection limit of 1.3x10(-7) U.

Electrochemistry↗

PubMed1991

Roles of ring C oxygens in the binding of colchicine to tubulin.

The roles of the oxygens in ring C of colchicine in its binding to tubulin were probed by a study of the interactions of two allocolchicine biphenyl analogues, 2,3,4,4'-tetramethoxy-1,1'-biphenyl (TMB) and 2,3,4-trimethoxy-4'-acetyl-1,1'-biphenyl (TKB), the first one containing a methoxy group in position 4', the second a keto group. Both analogues were found to bind specifically to the colchicine-binding site on tubulin in a rapidly reversible equilibrium. The standard free energies of binding at 25 degrees C were delta G zero (TKB) = 7.19 +/- 0.11 kcal mol-1 and delta G zero (TMB) = -6.76 +/- 0.22 kcal mol-1. The binding of TKB induced the same perturbation in protein circular dichroism at 220 nm as colchicine and allocolchicine, as well as quenching of protein tryptophan fluorescence. Binding of TMB did not affect the protein CD spectrum within experimental error and induced only a marginal quenching of protein fluorescence. Comparison with the binding properties of allocolchicine and its des(ring B) analogue 2,3,4-trimethoxy-4'-carbomethoxy-1,1'-biphenyl (TCB) [Medrano et al. (1989) Biochemistry 28, 5589-5599] has shown that the binding properties of the 4'-keto analogue (TKB) were closer to those of allocolchicine, even though the substituent in the 4'-position of TCB is identical with that of allocolchicine. It has been proposed that binding in the ring C subsite on tubulin, which is stabilized thermodynamically by stacking interactions, can be modulated in a nonidentical fashion by the carbonyl and the ether oxygens in the para position of ring C.

Binding, Competitive↗

PubMed2005

Reactions of chlorine atoms with a series of aromatic hydrocarbons.

Aromatic hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs), are present in urban and rural atmospheres. Reactions of PAHs with Cl atoms may occur in the marine boundary layer and in coastal regions. To assess the importance of these reactions and to investigate whether any unique chlorine-containing products are formed from these reactions, we have measured the rate constants for the gas-phase reactions of Cl atoms with toluene-d8, 1,3,5-trimethylbenzene (1,3,5-TMB), naphthalene, 1-methylnaphthalene-d10 (1-MN-d10), 1- and 2-methylnaphthalene (1- and 2-MN), 1- and 2-ethylnaphthalene (1- and 2-EN), and the dimethylnaphthalenes (DMNs) at 296 +/- 2 K. A relative rate technique was used, and, using our measured rate constant forthe reaction of Cl atoms with 1,3,5-TMB of 2.42 x 10(-10) cm3 molecule(-1) s(-1), the rate constants (in units of 10(-10) cm3 molecule(-1) s(-1)) are as follows: naphthalene, < or = 0.0091 +/- 0.0003; 1-MN, 1.21 +/- 0.16; 2-MN, 1.05 +/- 0.13; 1-EN, 2.12 +/- 0.35; 2-EN, 1.38 +/- 0.27; 1,2-DMN, 3.61 +/- 0.68; 1,3-DMN, 2.90 +/- 0.22; 1,4-DMN, 2.93 +/- 0.30; 1,5-DMN, 2.31 +/- 0.19; 1,6-DMN, 2.15 +/- 0.20; 1,7-DMN, 3.05 +/- 0.34; 1,8-DMN, 3.07 +/- 0.44; 2,3-DMN, 2.93 +/- 0.49; 2,6-DMN, 2.34 +/- 0.18; and 2,7-DMN, 2.00 +/- 0.22, where the indicated errors are two standard deviations and do not include the uncertainty in the rate constant for 1,3,5-TMB. The measured deuterium isotope effects for the toluene-d8 and 1-MN-d10 reactions indicate that the reactions proceed by initial H- (or D-) atom abstraction. The products identified and quantified from the toluene and 1-MN reactions using gas chromatography and in situ direct air sampling atmospheric pressure ionization tandem mass spectrometry were benzaldehyde (84% +/- 7% yield) and benzyl alcohol (11% +/- 2% yield) from toluene and 1-naphthaldehyde (approximately 36%, lower limit to yield) and 1-naphthyl alcohol (approximately 12%, lower limit to yield) from 1-MN. These products confirm that H-atom abstraction is the dominant, if not sole, reaction pathway for the alkylbenzenes and alkylnaphthalenes, consistent with the 100-fold lower rate constant measured for naphthalene compared to the alkylnaphthalenes and with the measured deuterium isotope effects.

Atmosphere↗

PubMed2005

Blue luminescent 2-(2'-pyridyl)benzimidazole derivative ligands and their orange luminescent mononuclear and polynuclear organoplatinum(II) complexes.

Five new 2-(2'-pyridyl)benzimidazole derivative ligands, 1,4-bis[2-(2'-pyridyl)benzimidazolyl]benzene (1,4-bmb), 4,4'-bis[2-(2'-pyridyl)benzimidazolyl]biphenyl (bmbp), 1-bromo-4-[2-(2'-pyridyl)benzimidazolyl]benzene (Brmb), 1,3-bis[2-(2'-pyridyl)benzimidazolyl]benzene (1,3-bmb), and 1,3,5-tris[2-(2'-pyridyl)benzimidazolyl]benzene (tmb), have been synthesized by Ullmann condensation methods. The corresponding mononuclear and polynuclear PtII complexes, Pt2(1,4-bmb)Ph4 (1), Pt2(bmbp)Ph4 (2), Pt(Brmb)Ph2 (3), Pt2(1,3-bmb)Ph4 (4), and Pt3(tmb)Ph6 (5), have been obtained by the reaction of the appropriate ligand with [PtPh2(SMe2)]n. The structures of the free ligands 1,4-bmb, bmbp, and tmb, as well as the complexes 1-3, were determined by single-crystal X-ray diffraction. All ligands display fluorescent emissions in the purple/blue region of the spectrum at ambient temperature and phosphorescent emissions in the blue/green region at 77 K, which are attributable to ligand-centered pi --> pi* transition. No ligand-based emission was observed for the PtII complexes 1-5. All PtII complexes display orange/red emissions at 77 K in a frozen solution or in the solid state, attributable to metal-to-ligand charge transfers (MLCT). Variable-temperature 1H NMR experiments establish that complexes 1, 4, and 5 exist in isomeric forms in solution at ambient temperature due to the hindered rotation of the square PtC2N2 planes in the complexes.

Journal Article↗

PubMed2002

Activation of peroxidase-catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine with poly(salicylic acid 5-aminodisulfide).

5-Aminosalicylic acid (5-ASA) inhibited by a mixed mechanism the peroxidase catalyzed oxidation of tetramethylbenzidine (TMB) in 0.015 M phosphate-citrate buffer (pH 6.4) supplemented with 5% DMSO and 5% DMF. Poly(salicylic acid 5-aminodisulfide) (poly(SAADS)) in 0.01 M phosphate buffer (pH 6.2-7.4) supplemented with 5% DMSO and 5% DMF effectively activated the peroxidase-catalyzed oxidation of TMB. The activation was quantitatively characterized by coefficients alpha (M-1) determined at different pH values: alpha increased linearly with increase in pH up to the maximal value of 2.44*105 M-1 at pH 7.0. The activating effect of poly(SAADS) on the peroxidase-catalyzed oxidation of TMB is explained by the activator properties of polyelectrolyte, with its anionic form interacting with peroxidase sites responsible for the acid-base catalysis.

Antioxidants↗

PubMed2002

Photochemical properties of the triplet pi,pi* state, anion and ketyl radicals of 5,12-naphthacenequinone in solution studied by laser flash photolysis: electron transfer and phenolic H-atom transfer.

Photochemical properties of the lowest triplet pi,pi* state of 5,12-naphthacenequinone (5,12-NQ) have been investigated in solution by means of nanosecond laser flash photolysis at 295 K. The transient absorption spectrum of triplet 5,12-NQ was measured in CCl4 and the molar absorption coefficient was determined. In CCl4, triplet 5,12-NQ is shown to be quenched by the ground-state 5,12-NQ. In acetonitrile, triplet 5,12-NQ is quenched by 1,2,4,5-tetramethoxybenzene (TMB) via electron transfer to produce the TMB cation and 5,12-NQ anion radicals. The absorption spectrum and the molar absorption coefficient of the 5,12-NQ anion radical were determined based on those of the TMB cation radical. Although triplet 5,12-NQ does not abstract H-atom of ethanol or cyclohexane, H-atom transfer occurs from phenol and p-phenylphenol to triplet 5,12-NQ, producing the 5,12-NQ ketyl radical. The absorption spectrum and the molar absorption coefficient of the 5,12-NQ ketyl radical were determined based on those of the p-phenylphenoxyl radical. It is shown that the quenching rate constants by phenol for triplet 5,12-NQ and other triplet paraquinones previously reported obey a Rehm-Weller relationship. The mechanism for the phenolic H-atom transfer to triplet paraquinones is interpreted in terms of coupled electron and proton transfer.

Anions↗

PubMed1992

Adenosine stimulates Ca2+ fluxes and increases cytosolic free Ca2+ in cultured rat mesangial cells.

Adenosine has been associated with cellular Ca2+ metabolism in some cell types. Since adenosine is able to contract glomerular mesangial cells in culture, and since Ca2+ is the main messenger mediating contractile responses, we studied the effect of adenosine on 45Ca2+ movements into and out of mesangial cells and on the cytosolic free Ca2+ concentration ([Ca2+]i). Adenosine at 0.1 mM increased 45Ca2+ uptake (basal, 9993 +/- 216; + adenosine, 14823 +/- 410 d.p.m./mg; P less than 0.01) through verapamil-sensitive Ca2+ channels. These channels seem to be of the A1-adenosine receptor subtype. Adenosine also stimulated 45Ca2+ efflux from 45Ca(2+)-loaded mesangial cells. This effect was accompanied by a net depletion of intracellular 45Ca2+ content under isotopic equilibrium conditions (basal, 24213 +/- 978; + adenosine, 18622 +/- 885 d.p.m./mg; P less than 0.05). The increase in 45Ca2+ efflux was inhibited by a Ca(2+)-free medium or in the presence of 10 microM-verapamil. However, the intracellular Ca(2+)-release blocker TMB-8 (10 microM) only partially inhibited the adenosine-stimulated 45Ca2+ efflux. In addition, adenosine induced an elevation in [Ca2+]i in mesangial cells with an initial transient peak within 15 s (basal, 113 +/- 7; adenosine, 345 +/- 46 nM), and a secondary increase which was slower (3-4 min) and of lower magnitude than the initial peak (250 +/- 21 nM). In summary, adenosine elevates [Ca2+]i and stimulates both Ca2+ uptake from the extracellular pool and Ca2+ efflux from intracellular pools in mesangial cells. The Ca2+ release from internal stores is produced by a combination of a TMB-8-inhibitable and a non-TMB-8-inhibitable mechanism, and seems to be dependent on Ca2+ influx.

Adenosine↗

PubMed2000

Spore-forming, Desulfosporosinus-like sulphate-reducing bacteria from a shallow aquifer contaminated with gasoline.

Previous studies on the geochemistry of a shallow unconfined aquifer contaminated with hydrocarbons suggested that the degradation of some hydrocarbons was linked to bacterial sulphate reduction. There was attenuation of naphthalene, 1,3,5-trimethylbenzene (TMB), toluene, p-xylene and ethylbenzene in the groundwater with concomitant loss of sulphate. Here, the recovery of eight strains of sulphate-reducing bacteria (SRB) from the contaminated site is reported. All were straight or curved rod-shaped cells which formed endospores. Amplification and sequencing of the 16S rDNA indicated that the strains were all sulphate reducers of the Gram-positive line of descent, and were most closely related to Desulfosporosinus (previously Desulfotomaculum) orientis DSM 8344 (97-98.9% sequence similarity). The strains clustered in three phylogenetic groups based on 16S rRNA sequences. Whole cell fatty acid compositions were similar to those of D. orientis DSM 8344, and were consistent with previous studies of fatty acids in soil and groundwater from the site. Microcosms containing groundwater from this aquifer indicated a role for sulphate reduction in the degradation of [ring-UL-14C]toluene, but not for the degradation of [UL-14C]benzene which could also be degraded by the microcosms. Adding one of the strains that was isolated from the groundwater (strain T2) to sulphate-enriched microcosms increased the rate of toluene degradation four- to 10-fold but had no effect on the rate of benzene degradation. The addition of molybdate, an inhibitor of sulphate reduction, to the groundwater samples decreased the rate of toluene mineralization. There was no evidence to support the mineralization of [UL-14C]benzene, [ring-UL-14C]toluene or unlabelled m-xylene, p-xylene, ethylbenzene, TMB or naphthalene by any of the strains in pure culture. Growth of all the strains was completely inhibited by 100 micromol l-1 TMB.

Benzene↗

PubMed2003

Variations in cell signaling pathways for different vasoconstrictor agonists in renal circulation of the rat.

BACKGROUND: Major cell signaling pathways involved in agonist-induced vasoconstriction are recognized to be Ca2+ mobilization via inositol-1,4,5 triphosphate (IP3), Ca2+ influx through l-type channels, activation of protein kinase C (PKC), and of Rho-associated kinase (ROK). However, their contribution for renal vasoconstriction induced by different agonists is not well characterized. METHODS: Increasing doses of angiotensin II (Ang II), norepinephrine, and arginine vasopressin (AVP) were infused into the left renal artery of anesthetized rats to reduce renal blood flow from a threshold value to about 50%. Rightward shift of the dose-response curves due to coinfusion of inhibitors served to assess contribution of different pathways: trimethoxybenzoate (TMB-8) against Ca2+ mobilization, nifedipine against Ca2+ influx, staurosporine and Ro-318220 against PKC, and Y-27632 and HA-1077 against ROK. Effects of inhibitors were also determined for renal response to a single dose of U-46619, a thromboxane A2 agonist. Composite response to U-46619 consisting of a fast and slow component did not permit determination of dose-response curves. RESULTS: Inhibition of ROK by Y-27632 or HA-1077 had the largest effect on renal responses to agonists. They shifted dose-response curves of Ang II, norepinephrine, and AVP to sevenfold and higher values. Staurosporine, nifedipine, and TMB-8 had variable effect on agonist responses. They attenuated effects of Ang II and norepinephrine in an additive manner, and each of them increased effective dose values about fourfold. TMB-8 did not attenuate response to AVP and U-46619. Staurosporine and nifedipine diminished effects of AVP in a nonadditive manner, and attenuated additively the fast component of U-46619 response. CONCLUSION: In contrast to other cell signaling pathways, ROK plays a common role for all vasoconstrictor agonistsis in renal circulation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗