Toxicity and toxicokinetics of a phosphorothioate oligonucleotide against the c-myc oncogene in cynomolgus monkeys.

A 2-week toxicity and toxicokinetic study of a 15-mer phosphorothioate oligonucleotide, INX-3280, against the c-myc oncogene was performed in cynomolgus monkeys. As this oligonucleotide readily adopts an aggregate structure, a quadruplex, which may be associated with adverse physiologic effects, this study was performed using INX-3280 that had been converted to its monomeric form. Animals received intravenous (i.v.) infusions of monomeric INX-3280 three times per week for 2 weeks at doses of 3 or 15 mg/kg per administration. The monkeys were examined for clinical signs: changes in hematology, serum chemistry, coagulation, and urinalysis parameters; complement activation; macroscopic findings at necropsy; and histopathologic alterations. In addition, the toxicokinetics of INX-3280 were evaluated, using a validated HPLC assay, after the first and last (sixth) doses. No treatment-related clinical signs of any adverse effects were observed, and there were no test article-related changes in hematology, serum chemistry, or complement activation parameters. The only alteration in clinical pathology parameters was a minor (30%) prolongation of the activated partial thromboplastin time (aPTT), reflecting slight inhibition of the intrinsic coagulation pathway, which was less than that reported with other oligonucleotides given at similar doses. Treatment-related histopathologic alterations consisted of characteristic accumulation of basophilic material in the cytoplasm of tubular epithelial cells in the kidney, resident macrophages in the lymph nodes, and Kupffer cells in the liver. These changes were graded as minimal in all cases. The basophilic material is believed to reflect accumulation of the oligonucleotide or metabolites or both. The pharmacokinetic parameters of INX-3280 were identical on the first and sixth administrations and were similar to those reported for other phosphorothioate oligonucleotides. Maximum concentration (Cmax) values for INX-3280 (101-119 microg/ml) were in excess of the threshold plasma concentrations reported to trigger complement activation by phosphorothioate oligonucleotides. It is concluded that the safety profile of monomeric INX-3280 in cynomolgus monkeys is quite favorable relative to the known effects of other phosphorothioate oligonucleotides, particularly with respect to the blood level-related toxicities of this class of compounds, including complement activation and inhibition of coagulation. This study found no toxicities that were expected to be clinically significant.

Development of a pediatric burn pain and anxiety management program.

To facilitate effective management of pain and anxiety, and to permit more objective assessment of changes in this management, a pain and anxiety guideline was developed and has been followed uniformly for 3 years. The guideline describes four patient care categories: (1) ventilated acute, (2) nonventilated acute, (3) chronic acute, and (4) reconstructive. A small and consistent formulary was emphasized. A specific guideline for background, procedural, and transition pain and anxiety management was developed for each patient care category. All pain and anxiety medications given to all acutely burned children admitted to the Institute for 12 consecutive months were recorded, and daily pain and anxiety discomfort scores were noted using a 5-level action-based bedside scoring system. Doses of individual pain and anxiety medications were calculated as mg per kg per patient-day in each category, and all doses were found to be within guideline specifications. The efficacy of the guideline was judged by four discomfort scores: (1) background pain, (2) procedural pain, (3) background anxiety, and (4) procedural anxiety, and were adequate in all patient categories. There were no complications related to overmedication experienced during the interval. Our objective was to develop a guideline for pain and anxiety management that: (1) was safe and effective over a broad range of ages and injury acuities seen in the unit, (2) was explicit in its recommendations, (3) had a limited formulary to optimize staff familiarity with agents used, and (4) took advantage of the presence of a bedside nurse to continuously evaluate efficacy and intervene when needed through dose-ranging. Although many drugs are appropriate, our choices were based on institutional familiarity and simplicity. This process of developing a clear and consistent guideline can be duplicated in any unit.

Functional analysis of developmentally regulated chromatin-hypersensitive domains carrying the alpha 1-fetoprotein gene promoter and the albumin/alpha 1-fetoprotein intergenic enhancer.

During liver development, the tandem alpha 1-fetoprotein (AFP)/albumin locus is triggered at the AFP end and then asymmetrically enhanced; this is followed by autonomous repression of the AFP-encoding gene. To understand this regulation better, we characterized the two early developmental stage-specific DNase I-hypersensitive (DH) sites so far identified in rat liver AFP/albumin chromatin: an intergenic DH-enhancer site and the AFP DH-promoter site. Mutation-transfection analyses circumscribed the DH-enhancer domain to a 200-bp DNA segment stringently conserved among species. Targeted mutations, DNA-protein-binding assays, and coexpression experiments pinpointed C/EBP as the major activatory component of the intergenic enhancer. Structure-function relationships at the AFP DH-promoter site defined a discrete glucocorticoid-regulated domain activated cooperatively by HNF1 and a highly specific AFP transcription factor, FTF, which binds to a steroid receptor recognition motif. The HNF1/FTF/DNA complex is deactivated by glucocorticoid receptors or by the ubiquitous factor NF1, which eliminates HNF1 by competition at an overlapping, high-affinity binding site. We propose that the HNF1-NF1 site might serve as a developmental switch to direct autonomous AFP gene repression in late liver development. We also conclude that the intergenic enhancer is driven by C/EBP alpha primarily to fulfill albumin gene activation functions at early developmental stages. Factor FTF seems to be the key regulator of AFP gene-specific functions in carcinoembryonic states.