LJ-2698, a highly potent human A3 adenosine receptor antagonist with nucleoside structure, was designed to have a minimal species dependence. For further pre-clinical studies, analytical method for the detection of LJ-2698 in rat plasma was developed by liquid chromatography-tandem mass. Plasma samples were processed by protein precipitation method with acetonitrile, using losartan as the internal standard (IS). Chromatographic separation was carried out using a Kinetex C18 column (100 × 4.6 mm; 100 Å; 2.6 μ) with acetonitrile/water with 0.2% (v/v) formic acid (65:35, v/v) in the isocratic mode at a flow rate of 0.4 mL/min. Mass spectrometric detection in multiple reaction monitoring mode was performed with positive electrospray ionization. The mass transitions of LJ-2698 and IS were m/z 412.3 → 294.1 and m/z 423.1 → 207.2, respectively. The calibration curves were linear in the range 5.00-5000 ng/mL (r 2 ≥ 0.998). The lower limit of quantification was established as 5.00 ng/mL. Within- and between-run precisions were <7.01%, as relative standard deviation; and accuracies were in the range 3.37-3.64%, as relative error. The validated method was successfully applied to its pharmacokinetic evaluation after intravenous and oral administration in rats, and the dose-dependent pharmacokinetic behavior of LJ-2698 was elucidated for the first time.

The conformational properties of diastereomeric P-modified nucleotides are reported as reflected by different NMR parameters. Some conformational trends can be rationalized by consideration of the (3) J(C4\',P)()and (3) J(C2\',P) coupling values of the isomers and the nature of the substituent on the phosphorus. Configurational assessment of the phosphorus is inferred from NOE experiments. The effects of temperature, solvent and size of substituents are presented.

S-Adenosyl-L-methionine (SAM) and its metabolites S-adenosyl-L-homocysteine (SAH) and methyl-thioadenosine (MTA) are endogenous compounds that are heavily involved in a variety of biochemical processes, and have therefore been the target for several assays in body fluids and tissues. Reversed-phase chromatographic behaviour of SAM and its metabolites has been studied by using Supelcosil LC-ABZ column, specially designed for analysis of acidic, basic, zwitterionic and neutral compounds, and on a Hypersil ODS column as a function of mobile phase pH. The retentions of the compounds, expressed by the capacity ratio (k\'), are measured on both column with mobile phases comprised of 10% acetonitrile and 10 mM ammonium formate buffer with pH values ranging from 2 to 9. Higher selectivity is observed on Supelcosil LC-ABZ within pH range 4-6. Different retention properties are observed at very low pH and seemed as if the Supelcosil LC-ABZ column reduced the effect of the mobile phase pH by about 1 pH unit. Whilst the Supelcosil column can be recommended for the routine analysis of SAM and its related metabolites in biological fluids by using mobile phase pH 5, the Hypersil ODS column may be suggested for use with mobile phase pH values of 3-4.

Two hundred twenty eligible patients with metastatic colorectal carcinoma were treated with a combination of beta-2\'-deoxythioguanosine (BTG), plus methyl-CCNU or mitomycin. There was no significant difference in overall response (CR/PR + stable) among fully evaluable patients between the mitomycin plus BTG arm 19/96 (19.7%) and the MeCCNU arm 26/87 (29.8%). Median survival of eligible patients was 19 weeks with mitomycin plus BTG versus 21 weeks with MeCCNU plus BTG: no difference. Median survival of responders (40 weeks) and patients with stable disease (35 weeks) was significantly better than patients with increasing disease (17 weeks): p + 0.001.

The Southeastern Cancer Study Group conducted a post-remission induction randomized trial in adult acute myelogenous leukemia to assess the efficacy of alternate drug therapy during consolidation and of immunotherapy during maintenance. Of 508 evaluable patients entered into the study, 335 (66%) achieved a complete remission treated with a 7-day infusion of cytosine arabinoside at a dose of 100 mg/sq m/day and 3 days of daunorubicin at a dose of 45 mg/sq m/day. Those in remission were randomized to receive 3 courses of 1 of 3 consolidation regimens: (A) a continuous infusion of 5-azacytidine, 150 mg/sq m/day for 5 days; (B) 5-azacytidine plus beta-deoxythioguanosine, 300 mg/sq m/day for 5 days; or (C) cytosine arabinoside, 100 mg/sq m/day intravenously, and thioguanine, 100 mg/sq m orally every 12 hr, plus daunorubicin, 10 mg/sq m every 24 hr daily for 5 days. There was no difference in relapse rate among the 3 arms. Those completing consolidation and remaining in remission were randomized to 1 of 3 maintenance regimens: (D) chemotherapy, 5-day infusion of cytosine arabinoside and 2 days of daunorubicin (same doses as induction) given every 13 wk for 1 yr; (E) BCG given twice weekly for 1 mo and then monthly for 1 yr; or (F) the combination of regimens D and E. The median duration of remission was significantly better on regimen D (17.4 versus 9.4 and 9.5 mo), and median survival was 29 mo compared to 21 mo for the other regimens. Those given different drugs during consolidation than used for induction (regimens A and B) and subsequent chemotherapy for maintenance (regimen D) had the longest remission durations and survival. Immunotherapy was not as good as intensive chemotherapy for maintenance.

The metabolism of the two methionine precursors, L-homocysteine and 5\'-deoxy-5\'-methylthioadenosine was compared to the ability of these compounds to support cell growth in a Met-free medium, in the following mammalian cell lines: Raji, CCL 39 and BHK cells. These three cell lines metabolized L-homocysteine and 5\'-deoxy-5\'-methylthioadenosine into methionine, S-adenosyl-L-methionine and proteins. However there was a discrepancy between metabolic and growth studies: Raji cells could grow on L-homocysteine and on 5\'-deoxy-5\'-methylthioadenosine, BHK cells could grow on L-homocysteine but not on 5\'-deoxy-5\'-methylthioadenosine, and CCL 39 cells could not grow either on L-homocysteine or on 5\'-deoxy-5\'-methylthioadenosine. The metabolism of exogenous methionine, and of methionine endogenously synthesized from 5\'-deoxy-5\'-methylthioadenosine was studied in CCL 39 and Raji cells, incubated with 25 microM [methyl-14c] methionine + 25 microM 5\'-deoxy-5\'-methylthioadenosine or 25 microM [methyl-14c] 5\'-deoxy-5\'-methylthioadenosine + 25 microM methionine: there was no difference between the metabolism of exogenous and endogenous methionine in either type of cell. Our results indicate that i) \"methionine dependence\" initially described for L-homocysteine [Hoffman, R.M. and Erbe, R.W. (1976) Proc. Natl. Acad. Sci. USA 73, 1523], can also be observed with the other precursor of methionine, ie 5\'-deoxy-5\'-methylthioadenosine; ii) \"methionine-dependence\" can not be considered as the inability of a cell to grow on methionine endogenously synthesized from a precursor, but depends on the precursor used, and possibly, on a toxic effect of the precursor in the absence of methionine.

Phase II trials of several single agents demonstrated only minimal objective response rates in patients with pancreatic carcinoma and measurable tumors: hexamethylmelamine (7%; four responses among 55 patients); dianhydrogalactitol (2.5%; one response among 40 patients); razoxane (7%; two responses among 29 patients); and beta-2\'-deoxythioguanosine (6%; two responses among 32 patients). Among patients with a good performance status (0-2) and no prior chemotherapy, response rates were 8% for hexamethylmelamine (two responses among 26 patients); 8% for dianhydrogalactitol (one response among 13 patients); 8% for razoxane (one response among 12 patients); and 10% for beta-2\'-deoxythioguanosine (two responses among 20 patients). None of these agents given by the methods of this study offers substantive benefit to the patient with advanced pancreatic cancer.

Intracellular recordings were performed in a pontine slice preparation of the rat brain containing the locus coeruleus (LC). Adenosine (100, 300 mumol/l) and its structural analogues, namely (-)-N6-(R-phenylisopropyl)-adenosine (R-PIA; 3-30 mumol/l) and S-PIA (10, 30 mumol/l), as well as 5\'-N-ethylcarboxamido-adenosine (NECA; 3-30 mumol/l) inhibited the firing rate of spontaneous action potentials and produced hyperpolarization; their rank order of potency was R-PIA congruent to NECA greater than S-PIA greater than adenosine. When applied by superfusion, all agonists strongly desensitized the LC cells; the hyperpolarization never surmounted 6 mV. Upon pressure ejection of adenosine 10 mmol/l from a micropipette positioned close to an LC neurone, the membrane potential was raised by 14 mV and the apparent input resistance decreased by 20%. When the membrane potential was hyperpolarized by current injection to a similar extent as adenosine did, the fall in input resistance was only 7%. The adenosine uptake inhibitor S-(p-nitrobenzyl)-6-thioguanosine (NBTG) 30 mumol/l decreased the frequency of action potentials alone; on simultaneous bath-application with adenosine 300 mumol/l it potentiated the hyperpolarization caused by the purine derivative. 8-Cyclopentyl-1,3-dipropylxanthine (CPDPX) 0.1 mumol/l had no effect on its own, but it antagonized both R-PIA 30 mumol/l and NBTG 30 mumol/l. A higher concentration of CPDPX (1 mumol/l) facilitated the spontaneous firing. In conclusion, both exogenous and endogenous adenosine activates somatic and/or dendritic A1-receptors of LC neurones leading to an enhancement of potassium conductance and thereby to a decreased firing rate and a hyperpolarization.

The Eastern Cooperative Oncology Group assessed the activity of diglycoaldehyde (DGA), VP-16-213, and the combination of methyl-CCNU and beta-2\'-deoxythioguanosine in previously treated patients with advanced colorectal cancer. Objective responses were seen in two of 40 evaluable patients receiving methyl-CCNU and beta-2\'-deoxythioguanosine and in one of 35 patients receiving DGA. None of 33 patients responded to VP-16-213, but one death related to sepsis and bone marrow failure occurred. Survival of patients whose previous chemotherapy included a nitrosourea was markedly shortened compared to those who had not been exposed to nitrosoureas. With the possible exception of DGA, further treatment of patients with colorectal cancer with these therapies is not warranted.

In a randomized multi-institutional trial of the Eastern Cooperative Oncology Group, 316 patients with advanced measurable colorectal adenocarcinoma were treated with a weekly schedule of 5-fluorouracil given orally and intravenously with oral-5-fluorouracil in combination with cyclophosphamide or 6-thioguanine, or with oral Methyl CCNU administered once every eight weeks. On failure or progression, 133 protocol patients crossed-over to a secondary therapy, while 116 other patients previously treated with 5-fluorouracil off protocol were randomized to treatment with Methyl CCNU or B-2\'-deoxythioguanosine. Response rates among patients who had received no prior chemotherapy were 18% to oral 5-FU, 15% to intravenous 5-FU and to MeCCNU, 12% to 5-FU and 6-thioguanine and 5% to cyclophosphamide and 5-FU, with little activity (3% response rate) in crossover or previously treated patients. Treatment with 5-FU, particularly oral 5-FU was associated with the least drug-related toxicity. Hematologic toxicity was greatest with Methyl CCNU, but was no more frequent in previously treated than in untreated patients. A tendency toward cumulative bone marrow depression was noted. 5-FU was effective only in ambulatory patients, whereas responses among non-ambulatory patients were seen only in the group treated with Methyl-CCNU.