Low risk of inhibitor formation in haemophilia A patients following en masse switch in treatment to a third generation full length plasma and albumin-free recombinant factor VIII product (ADVATE®).

Previous studies have suggested that development of inhibitors in previously treated patients (PTPs) may be attributable to a switch in factor VIII (FVIII) therapeutic product. Consequently, it is widely recognized that inhibitor development must be assessed in PTPs following the introduction of any new FVIII product. Following a national tender process in 2006, all patients with haemophilia A in Ireland changed their FVIII treatment product en masse to a plasma and albumin-free recombinant full-length FVIII product (ADVATE(®)). In this study, we retrospectively reviewed the case records of Irish PTPs to evaluate risk of inhibitor formation following this treatment switch. One hundred and thirteen patients participated in the study. Most patients (89%) had severe haemophilia. Only one of 96 patients with no inhibitor history developed an inhibitor. Prior to the switch in his recombinant FVIII (rFVIII) treatment of choice, this child had only experienced three exposure days (EDs). Consequently, in total he had only received 6 EDs when his inhibitor was first diagnosed. In keeping with this lack of de novo inhibitor development, we observed no evidence of any recurrent inhibitor formation in any of 16 patients with previously documented inhibitors. Similarly, following a previous en masse switch, we have previously reported that changing from a Chinese hamster ovary cell-produced to a baby hamster kidney cell-produced rFVIII was also associated with a low risk of inhibitor formation in PTPs. Our cumulative findings from these two studies clearly emphasizes that the risk of inhibitor development for PTPs following changes in commercial rFVIII product is low, at least in the Irish population.

Successful outcome of patients with relapsed/refractor Hodgkin lymphoma treated with high dose chemotherapy at the National Adult Bone Marrow Transplant Unit at St. James's Hospital.

Patients with Hodgkin lymphoma who relapse or are refractory to first line multi-agent chemotherapy can be successfully salvaged with high dose therapy (HDT) and autologous stem cell transplant (ASCT). Twenty-six patients with relapsed or refractory Hodgkin lymphoma have been treated with HDT and ASCT at St James Hospital between 2000 and 2005. At day 100 post HDT-ASCT, 23 patients were in complete remission. This group included all 6 patients transplanted at first relapse, 8 of 9 with advanced disease and 9 of 11 with primary refractory disease. Patients treated in first relapse had the best outcome with an overall and progression free survival of 100% (median, 37 months). Patients with primary refractory disease had the poorest outcome with an overall survival of 76% (median, 28 months). All patients with primary refractory disease responsive to salvage chemotherapy were in remission at a median of 28 months. The presence of chemosensitive disease prior to transplantation was the most important determinant of outcome. PET-CT imaging is useful to assess chemosensititvity prior to HDT and thus predict which patients will do well post HDT-ASCT. No patient died of treatment related toxicity. The outcome of this patient series compares favourably with international figures.

The use of capnography in the air medical environment.

We can count on two things when we receive a call as part of an air medical transport team--the patient is in critical condition, and time is of the essence. Whether the patient has experienced trauma from a motor vehicle crash, has fallen, or has suffered an insult as a consequence of poor health, our technique, skill, and judgment are tested constantly. Fortunately, we have equipment at our disposal to make our job easier. One of the more difficult aspects and responsibilities of air medical transport teams is placement of an endotracheal tube (ET). Along with the techniques used for successful endotracheal intubation (ETI), available technology can maximize patients' ventilatory status using an instrument that detects expired carbon dioxide (CO(2)) levels.

Antiproliferative actions of inhalational anesthetics: comparisons to the valproate teratogen.

The antiproliferative potential of the volatile anesthetics isoflurane, enflurane and sevoflurane was determined and compared to the valproate teratogen. The in vitro system employed, a G1 phase proliferative arrest endpoint in C6 glioma, has served previously to discriminate agents with known teratogenic potential in vivo. Based on estimated IC(50) values that were within twice the estimated minimum aveolar concentration value, the rank antiproliferative potency of the inhalational anesthetics employed was isoflurane=enflurane>>sevoflurane. Flow cytometric analysis of growth-arrested cell populations failed to reveal specific accumulation in any cell cycle phase and the lack of a G1 phase-specific effect was confirmed by the absence of a transient, time-dependent sialylation event in synchronized cells. The antiproliferative mechanism of volatile anesthetics, and valproate, was mediated at hydrophobic binding sites, as increasing the hydration sphere of the drug-micelle complex, using the hygroscopic qualities of the dimethylsulfoxide vehicle, completely reversed this effect. Our findings suggest inhalational anesthetics lack the specific in vitro characteristics of the valproate teratogen.

Syntheses of benzoquinolizidine and benzoindolizidine derivatives as anti-amnesic agents.

Tacrine, one of the drugs available for Alzheimer's disease based on the cholinergic approach, suffers from considerable toxicity. Many analogues of tacrine have been prepared which retain the pharmacologically rich aminopyridine or aminoquinoline motifs. The current research was undertaken to produce an acetylcholinesterase inhibitor by employing 11-aminobenzoquinolizidines (4) and 10-aminobenzoindolizidines (5) as templates. Thus, we aimed to achieve three goals relative to tacrine: eliminate the pyridine and quinoline moieties and render the molecule less flat. Overall, the compounds we prepared were poorer inhibitors of acetylcholinesterase compared to tacrine. The single exception was compound 6f which exhibited an effect comparable to that of tacrine, but only at a dose of the order of 10(-3) M. However, despite the poor acetylcholinesterase inhibition by 6b, this compound proved to be an effective anti-amnesic agent at 45 mg/kg dose.

Syntheses of 1,2-diamino and 1,2-aminoalcohol derivatives in the piperidine and pyrrolidine series as anti-amnesic agents.

Tacrine, one of the drugs available for Alzheimer's disease based on the cholinergic approach, suffers from considerable toxicity. Many analogues of tacrine has been prepared which retain the pharmacologically rich aminopyridine or aminoquinoline motifs. The current research is a continuation of our efforts in the area of 11-aminobenzoquinolizidines (4) and 10-aminobenzoindolizidines (5) (cf. ref9). A serendipitous discovery led us to the biologically active open chain analogue 9, and we proceeded to elaborate on this molecule. Overall, the compounds we prepared were poor inhibitors of acetylcholinesterase as compared to tacrine. The single exception was compound 20 which exhibited an effect comparable to that of tacrine, but only at a dose in the order of 10(-3) M. However, despite the poor acetylcholinesterase inhibition by 9, this compound was found to be an effective antiamnesic agent.

Studies on the teratogen pharmacophore of valproic acid analogues: evidence of interactions at a hydrophobic centre.

Propyl-4-yn-valproic acid (2-propyl-4-pentynoic acid), an analogue of valproic acid with a triple bond in one alkyl side chain, potently induces exencephaly in mice. Given that propyl-4-yn-valproic acid is a branched chain carboxylic acid, we synthesized a series of analogues with n-alkyl side chains of increasing length and correlated their potential to induce neural tube defects and to inhibit proliferation and induce differentiation in cells of neural origin, the latter being crucial to the orderly structuring of the embryo. All analogues significantly increased the incidence of neural tube defects in the embryos of dams exposed to a single dose of 1.25 mmol/kg on day 8 of gestation. This effect occurred in a dose-dependent manner and the rate of exencephaly increased with the progressive increase in n-alkyl side chain length. Moreover, increasing chain length resulted in a dose-dependent inhibition of C6 glioma proliferation rate over a concentration range of 0-3 mM and this was independent of the cell type employed and mode of estimating proliferative rate. The antiproliferative action of these analogues was associated with profound shape change in neuro-2A neuroblastoma involving extensive neuritogenesis and an associated increase in neural cell adhesion molecule (NCAM) prevalence at points of cell-cell contact, the latter exhibiting a dose-dependent increase when the n-alkyl chain was extended to five carbon units. These results suggest an interaction with a specific site in which the n-alkyl side is proposed to serve as an 'anchor' within a hydrophobic pocket to facilitate the ionic and/or H-bonding of the carboxylic acid and high electron density of the carbon-carbon triple bond.

Cell proliferation, migration and CAM-dependent neurite outgrowth as developmental in vitro endpoints for screening teratogenic potential: Application to valproic acid and related analogues of varying potency.

The in vivo teratogenic potential of valproic acid (VPA) and related teratogenic and non-teratogenic analogues has been correlated with their effects on specific in vitro endpoints of cell proliferation, migration and CAM-dependent neurite outgrowth, as these events are common to crucial epochs of development. The (+/-)-2-n-propyl-4-pentynoic acid [(+/-)-4-yn-VPA] and S-2-n-propyl-4-pentynoic acid [S(-)-4-yn-VPA] analogues increased the incidence of neural tube defects in mouse embryos exposed to a single dose, whereas the E-2-n-propyl-2-pentenoic acid (E-2-en-VPA) analogue and R-2-n-propyl-4-pentynoic acid [R( + )-4-yn-VPA] enantiomer were without effect. VPA and related analogues tested exerted comparable G1 phase antiproliferative effects in C6 glioma and limb bud cells in a dose range of 0-3 mM; however, their relative potency did not correlate with in vivo teratogenicity. In contrast, VPA and all teratogenic analogues, at 3 mM, inhibited neuronal cell aggregation and limb bud chondrocyte differentiation in a manner that exhibited a reasonable correlation with their in vivo teratogenicity. The teratogenic S(-)-4-yn-VPA and non-teratogenic R( + )-4-yn-VPA enantiomers exhibited a differential inhibition of primary neurone outgrowth of neuntes stimulated by cell adhesion molecules [L1 and N-cadherin (NCAD)]. Half-maximal inhibition was observed at approximately 150 muM for the teratogenic S(-)-4-yn-VPA enantiomer, but not the non-teratogenic R( + )-4-yn-VPA form. These results suggest that in vitro perturbations of differentiation are likely to provide the greatest discriminatory power for in vivo teratogenicity.

Valproic acid suppresses G1 phase-dependent sialylation of a 65kDa glycoprotein in the C6 glioma cell cycle.

The influence of valproate on in vitro glycosylation events in C6 glioma has been investigated, as this major human teratogen restricts proliferation in the mid-G1 phase of the cycle and alters the prevalence and/or glycosylation state of cell surface glycoproteins with the potential to mediate cell-cell and cell matrix interactions critical to development. C6 glioma cultured continuously in the presence of 1 mM valproate exhibited a significant depression of exponential growth but attained confluency one day later, when the majority of cells entered the G1 phase of the cycle. Glycoprotein sialyltransferase, which exhibited a four-fold increase during exponential growth and a small decrease at confluency, was markedly attenuated in valproate-exposed cells in a manner which was indirect. This was associated with an inhibition of transient alpha2,3 sialylation of a 65 kDa glycoprotein expressed maximally at 4 hr into the G1 phase of the cell cycle. This effect was cell-cycle phase-specific, as exposure of synchronized cells to valproate inhibited transient sialylation at 4 and 5 hr into the G1 phase. Inhibition of the 65 kDa glycoprotein sialylation by valproate is suggested to arise from impaired signal transduction preceding the eventual arrest by the drug at a 5-6 hr G1 phase restriction point.

Correlation of in vitro anti-proliferative potential with in vivo teratogenicity in a series of valproate analogues.

The prediction that an anti-proliferative effect coupled with a pro-differentiative action will detect a neural tube teratogen has been validated by comparison of these in vitro endpoints with in vivo teratogenicity in a series of closely allied valproate structural analogues. The majority of the compounds significantly inhibited C6 glioma proliferation, the most potent compounds being ranked as octanoic acid > 2-propylhexanoic acid > or = 2-ethylhexanoic acid > or = valproic acid. The anti-proliferative potency of these compounds did not correlate strictly to their relative in vivo teratogenic potential. Valproic acid exhibited an anti-proliferative IC50 of 1.45 mM, whereas 2-propyl-2-pentenoic acid and 2-propyl-4-pentenoic acid were virtually indistinguishable, exhibiting significantly lower IC50 values of 2.5 and 2.55 mM, respectively. The concanavalin A lectin affinity assay was employed to establish whether an anti-proliferative action was coupled with an increased state of cell differentiation. In this lectin affinity assay, the most potent analogues to significantly attenuate the affinity of exposed C6 glioma cells for concanavalin A lectin-coated plastic included 2-butylhexanoic acid, 2-propyl-4-pentenoic acid, 2-propylhexanoic acid and 2-ethylhexanoic acid in a manner which can be related to their relative teratogenic potencies in vivo. All compounds screened positive in both the anti-proliferative and pro-differentiative assays exhibited in vivo exencephalic rates of 5-44%. These included valproic acid, 2-ethylhexanoic acid, 2-propylhexanoic acid and 2-butylhexanoic acid. It would appear that combined anti-proliferative and pro-differentiative screens provide a promising detection system for teratogenic status in a series of valproate analogues.