Bevacizumab and irinotecan for recurrent oligodendroglial tumors.

BACKGROUND: Treatment with a regimen of bevacizumab-irinotecan has been shown to be effective in recurrent grade 3 and 4 gliomas, but the effect of this regimen against recurrent oligodendroglial tumors has not been specifically studied. METHODS: The bevacizumab-irinotecan regimen was retrospectively evaluated in a consecutive series of 25 patients with recurrent oligodendroglial tumors. All patients had not responded to previous treatment with radiation therapy and at least one line of temozolomide chemotherapy. Bevacizumab (10 mg/kg) and irinotecan (125 or 340 mg/m(2) according to the antiepileptic regimen) were administered every 14 days. Response was measured clinically and on monthly MRI. RESULTS: The objective response rate was 72% (20% complete response, 52% partial response). After a median follow up of 202 days, the median progression-free survival was 140 days (95% confidence interval [CI] 116-infinity), and overall survival had not been reached. The 6-month progression-free survival was 42% (95% CI 26%-67%). Among the 17 patients in whom the status of the main molecular alterations of gliomas could be evaluated (search for deletions of chromosomes 1p, 19q, 9p, and 10q and amplification of epidermal growth factor receptor, mouse double-minute gene, and cyclin-dependent kinase 4 gene), no relation could be found between the response rate and the type of genetic change (including 1p-19q codeletion). The profile of tolerance was fair, with treatment discontinuation in 20% of patients. Intratumoral hemorrhages occurred in 6 patients (24%), but the treatment had to be discontinued because of symptomatic bleeding in only 1 patient (4%). CONCLUSIONS: This regimen is effective in recurrent oligodendrogliomas, and the overall tolerance is acceptable.

2-Amino-4-methylpyridine as a potent inhibitor of inducible NO synthase activity in vitro and in vivo.

1. The ability of 2-amino-4-methylpyridine to inhibit the catalytic activity of the inducible NO synthase (NOS II) enzyme was characterized in vitro and in vivo. 2. In vitro, 2-amino-4-methylpyridine inhibited NOS II activity derived from mouse RAW 264.7 cells with an IC50 of 6 nM. Enzyme kinetic studies indicated that inhibition is competitive with respect to arginine. 2-Amino-4-methylpyridine was less potent on human recombinant NOS II (IC50 = 40 nM) and was still less potent on human recombinant NOS I and NOS III (IC50 = 100 nM). NG-monomethyl-L-arginine (L-NMMA), N6-iminoethyl-L-lysine (L-NIL) and aminoguanidine were much weaker inhibitors of murine NOS II than 2-amino-4-methylpyridine but, unlike 2-amino-4-methylpyridine, retained similar activity on human recombinant NOS II. L-NMMA inhibited all three NOS isoforms with similar potency (IC50S 3-7 microM). In contrast, compared to activity on human recombinant NOS III, L-NIL displayed 10 x selectivity for murine NOS II and 11 x selectivity for human recombinant NOS II while aminoguanidine displayed 7.3 x selectivity for murine NOS II and 3.7 x selectivity for human recombinant NOS II. 3. Mouse RAW 264.7 macrophages produced high levels of nitrite when cultured overnight in the presence of lipopolysaccharide (LPS) and interferon-gamma. Addition of 2-amino-4-methylpyridine at the same time as the LPS and IFN-gamma, dose-dependently reduced the levels of nitrite (IC50 = 1.5 microM) without affecting the induction of NOS II protein. Increasing the extracellular concentration of arginine decreased the potency of 2-amino-4-methylpyridine but at concentrations up to 10 microM, 2-amino-4-methylpyridine did not inhibit the uptake of [3H]-arginine into the cell. Addition of 2-amino-4-methylpyridine after the enzyme was induced also dose-dependently inhibited nitrite production. Together, these data suggest that 2-amino-4-methylpyridine reduces cellular production of NO by competitive inhibition of the catalytic activity of NOS II, in agreement with results obtained from in vitro enzyme kinetic studies. 4. When infused i.v. in conscious unrestrained rats, 2-amino-4-methylpyridine inhibited the rise in plasma nitrate produced in response to intraperitoneal injection of LPS (ID50 = 0.009 mg kg-1 min-1). Larger doses of 2-amino-4-methylpyridine were required to raise mean arterial pressure in untreated conscious rats (ED50 = 0.060 mg kg-1 min-1) indicating 6.9 x selectivity for NOS II over NOS III in vivo. Under the same conditions, L-NMMA was nonselective while L-NIL and aminoguanidine displayed 5.2 x and 8.6 x selectivity respectively. All of these compounds caused significant increases in mean arterial pressure at doses above the ID50 for inhibition of NOS II activity in vivo. 5. 2-Amino-4-methylpyridine also inhibited LPS-induced elevation in plasma nitrate after either subcutaneous (ID50 = 0.3 mg kg-1) or oral (ID50 = 20.8 mg kg-1) administration. 6. These data indicate that 2-amino-4-methylpyridine is a potent inhibitor of NOS II activity in vitro and in vivo with a similar degree of isozyme selectivity to that of L-NIL and aminoguanidine in rodents.

Design and synthesis of 1-heteroaryl-3-(1-benzyl-4-piperidinyl)propan-1-one derivatives as potent, selective acetylcholinesterase inhibitors.

Herein is described the synthesis and structure--activity relationship of a novel series of aromatic and heteroaromatic 3-(1-benzyl-4-piperidinyl)propan-1-one derivatives that display potent and selective inhibition of the enzyme acetylcholinesterase (AChE). 1-(2-Methyl-6-benzothiazolyl)-3-(N-benzyl-4-piperidinyl)propan-1-one hydrochloride, 6d, is one of the most active compounds within this series exhibiting an IC50 for the inhibition of the AChE enzyme equal to 6.8 nM. Compound 6d has shown a dose-dependent elevation of total acetylcholine (ACh) levels in the mouse forebrain with an oral ED50 = 9.8 mg/kg. In addition, in vivo microdialysis experiments in the rat demonstrate that 6d increases extracellular ACh (100% over basal) 1-3 h postdose with an oral ED50 = 4.8 mg/kg.

Activation of the mitogen-activated protein kinase pathway in Triton X-100 disrupted NIH-3T3 cells by p21 ras and in vitro by plasma membranes from NIH 3T3 cells.

We describe a novel Triton-disrupted mammalian cell system wherein the pathways for activation of mitogen-activated protein (MAP) kinases (MAPKs) are capable of direct biochemical manipulation in vitro. MAPKs p42mapk and p44mapk are activated in signal transduction cascade(s) initiated by occupancy of plasma membrane receptors for peptide growth factors, hormones, and neurotransmitters. One likely activation pathway for MAPKs consists of sequential activations of c-ras, c-raf-1, and a protein-tyrosine/threonine kinase, MAP kinase kinase. Triton-disrupted cells retained capacity for activation of the pathway by both peptide growth factors and by addition of GTP-loaded p21 rasVal12. Incubation of disrupted cells with an antibody that neutralized the function of c-ras (Y13-259) abolished receptor-mediated stimulation of MAPK as did acute addition of 200 microM azatyrosine. Activation of the pathway was reconstituted in a cell-free system using high-speed supernatants generated from Triton-disrupted cells together with purified plasma membranes from parental cells and as a heterogeneous system using purified plasma membranes from v-ras-transformed cells. These systems will allow biochemical dissection in vitro of the interaction(s) between c-ras and the MAPK pathway in mammalian cells.

Molecular structure of a protein-tyrosine/threonine kinase activating p42 mitogen-activated protein (MAP) kinase: MAP kinase kinase.

MAP kinases p42mapk and p44mapk participate in a protein kinase cascade(s) important for signaling in many cell types and contexts. Both MAP kinases are activated in vitro by MAP kinase kinase, a protein-tyrosine and threonine kinase. A MAP kinase kinase cDNA was isolated from a rat kidney library by using peptide sequence data we obtained from MAP kinase kinase isolated from rabbit skeletal muscle. The deduced sequence, containing 393 amino acids (predicted mass, 43.5 kDa), is most similar to byr1 (Bypass of ras1), a yeast protein kinase functioning in the mating pathway induced by pheromones in Schizosaccharomyces pombe. An unusually large insert is present in MAP kinase kinase between domains IX and X and may contribute to protein-protein interactions with MAP kinase. Major (2.7 kilobases) and minor (1.7 kilobases) transcripts are widely expressed in rat tissues and appear to be derived from a single gene.

Activation of mitogen-activated protein kinase kinase by v-Raf in NIH 3T3 cells and in vitro.

Mitogen-activated protein (MAP) kinases are 42- and 44-kD serine-threonine protein kinases that are activated by tyrosine and threonine phosphorylation in cells stimulated with mitogens and growth factors. MAP kinase and the protein kinase that activates it (MAP kinase kinase) were constitutively activated in NIH 3T3 cells infected with viruses containing either of two oncogenic forms (p35EC12, p3722W) of the c-Raf-1 protein kinase. The v-Raf proteins purified from cells infected with EC12 or 22W viruses activated MAP kinase kinase from skeletal muscle in vitro. Furthermore, a bacterially expressed v-Raf fusion protein (glutathione S-transferase-p3722W) also activated MAP kinase kinase in vitro. These findings suggest that one function of c-Raf-1 in mitogenic signaling is to phosphorylate and activate MAP kinase kinase.

Ring contraction of oleandrose on the macrolide antibiotic oleandomycin with [(Methoxycarbonyl)sulfamoyl]triethylammonium hydroxide inner salt.

Ring contraction of the neutral oleandrose sugar in the 14-membered-ring macrolide antibiotic oleandomycin (2) has been accomplished using [(methoxycarbonyl)sulfamoyl]triethylammonium hydroxide inner salt (1). The product of this interesting rearrangement, after methanolic hydrolysis of the 2'-acetate, is the 11-acetyl-3-O-(3"-methoxy-4"-vinylfuranosyl)oleandomycin (12). The in vitro activity of furanoside 12 is only moderately less than that of 11-acetyloleandomycin (13).