Drug-drug interactions in pediatric oncology patients.

BACKGROUND: Drug-drug interactions (DDIs) can negatively affect pharmacotherapy. However, pediatric DDI studies are scarce. We undertook an exploratory study to investigate prevalence and clinical relevance of DDIs between cytostatic and noncytostatic drugs in outpatient pediatric oncology patients. PROCEDURE: After informed consent and inclusion, the following information was collected: currently prescribed noncytostatic and cytostatic drugs, comorbidities, and use of over-the-counter (OTC) drugs, complementary and alternative medicines (CAMs), and dietary supplements. All medication was screened for DDIs according to two databases: Micromedex® Solutions and the Dutch drug database G-Standard. The researcher presented DDIs with an associated potential for adverse outcome and a proposal for intervention to three independent experts. If the experts considered a DDI to be potentially clinically relevant and requiring intervention, the physician was notified. RESULTS: Seventy-three patients were included (median age 8.9 years). A total of 67 different DDIs were counted (66 in Micromedex® Solutions, 14 in G-Standard, and 13 DDIs in both databases). The medication reviews resulted in 35 interventions related to 11 different DDIs. The majority of DDIs concerned noncytostatic drugs (25/35) and one third occurred between cytostatic and noncytostatic drugs (10/35). The use of QTc-interval-prolonging drugs resulted in one intervention. The use of OTC drugs, CAM, or dietary supplements did not lead to DDIs. CONCLUSIONS: This study resulted in a selection of 11 potentially clinically relevant DDIs for 73 outpatients in our pediatric oncology department. Interventions were formulated in close collaboration between physicians and clinical pharmacists. Future research should focus on assessing DDIs concerning QTc-interval prolongation.

Cigarette smoke suppresses in vitro allergic activation of mouse mast cells.

BACKGROUND: Mast cells are important effector cells in innate or acquired immunity that contribute to host defence. Excessive activation of mast cells can result in the development of allergic diseases, including atopic asthma. Mast cell activation by IgE and specific antigen induces the cells to release spasmogenic, vasoactive and pro-inflammatory mediators, which enhance airway smooth muscle contraction, vascular permeability and inflammatory cell recruitment. Recently, we have demonstrated that exposure of mast cells to cigarette smoke medium (CSM) triggered mast cells to produce chemokines. On the other hand, smoking may decrease the risk of allergic sensitization, which could be explained by a reduced IgE production or a diminished response of mast cells to activation of the IgE receptor. OBJECTIVE: In this study, we investigated the effect of CSM on the allergic activation of mast cells through IgE and antigen. METHODS: Primary cultured murine mast cells were exposed to CSM and activated with IgE and antigen or lipopolysaccharide (LPS). The release of granules, production of leukotrienes, chemokines and cytokines was determined in the supernatants by ELISA. The effect of CSM exposure on intracellular signalling, especially the nuclear factor (NF)-kappaB and extracellular signal-regulated kinase (Erk)1/2 pathways, was analysed by Western blotting. RESULTS: CSM suppressed IgE-mediated degranulation and cytokine release, but no effect was observed on leukotriene release. CSM induced phosphorylation of Erk1/2 in mast cells. In CSM-exposed mast cells, activating transcription factor (ATF)-1 was phosphorylated after stimulation with IgE/Ag. LPS-activated mast cells were not influenced by CSM. CONCLUSION: Our study suggests that exposure to cigarette smoke may lead to a reduced allergic activation of mast cells without affecting their response to activation via e.g. bacterial-derived LPS.

Pitfalls of the application of microdialysis in clinical oncology: controversial findings with docetaxel.

Microdialysis is a novel and minimally invasive sampling technique, based on the diffusion of analytes from the interstitial compartment through a semi-permeable membrane, and enables direct assessment of tissue disposition and penetration of drugs. Variable antitumor responses may be associated with differences in tumor vascularity, capillary permeability or tumor interstitial pressure resulting in variable delivery of anticancer agents. In preparation of pharmacokinetic studies, aimed at measuring docetaxel concentrations in healthy and malignant tissues in vivo, in pre-clinical as well as clinical studies, in vitro recovery experiments were performed. In contrast to published data, the recovery experiments suggest that docetaxel has a very low recovery as a result of non-specific binding to currently available microdialysis catheters. Here we discuss our findings with docetaxel in a historical perspective and we report on our experience using polysorbate 80 to eliminate the non-specific binding and its effects on the recovery of docetaxel.

Radiology of torture.

PURPOSE: Although there are different definitions of torture, there is no contradiction that torture exists. Changes resulting from torture are shown to demonstrate which findings can be visualized with X-rays. MATERIAL: The findings come from rehabilitation centers for victims of torture, collections of others and from personal observations. They are documented with plain films, scintigraphy, computed tomography, and MRI. RESULTS: On fingers, hand, and arm, and on toes, foot and leg, imaging can visualize changes and pathologies which are characteristic for preceding torture. On head, neck, and trunk, this is only rarely the case; this is understandable, when one considers that force having been directed against these regions of the body will more often be deadly than that applied on limbs only. Special forms of torture with the use of water and electricity are also described. It is pointed out that multiple forms of torture do not leave traces, which might be made visible by diagnostic imaging. The cases are part of a selection: the victims have survived (which means that these types of torture permitted survival; injuries of hand and foot do not endanger the survival as opposed to stab wounds to the head, chest, and abdomen, into the anus and the genitals, which are often mortal. Mutilation by torture motivates the torturer to eliminate any proof of his actions and to kill the victim. Public interest induces a selection of methods, which leave no traces. Possibly (and hopefully) some special forms of torture, which use chemical substances that act on the psyche and the central nervous system, might become visible by functional MRI in the near future. CONCLUSION: Torture is likely to occur when findings are seen to be typical or characteristic forms of torture, when age of fractures and pattern of beatings and other injuries corroborate the indications of the victim, and when these findings correspond to the procedures known from the region of application the organization/group/militia, which is said to have executed the torture.

Airway hyper-responsiveness in allergic asthma in guinea-pigs is mediated by nerve growth factor via the induction of substance P: a potential role for trkA.

BACKGROUND: The neurotrophin nerve growth factor (NGF) has been implicated as a mediator in allergic asthma. Direct evidence that inhibition of NGF-induced activation of neurotrophin receptors leads to improvement of airway symptoms is lacking. We therefore studied the effects of inhibitors of NGF signal transduction on the development of airway hyper-responsiveness (AHR) and pulmonary inflammation in a guinea-pig model for allergic asthma. METHODS: Airway responsiveness to the contractile agonist histamine was measured in vivo in guinea-pigs that were sensitized and challenged with ovalbumin (OVA). Inflammatory cell influx and NGF levels were determined in bronchoalveolar lavage fluid (BALF). Substance P, a key mediator of inflammation, was measured in lung tissue by radioimmunoassay, while substance P immunoreactive neurons in nodose ganglia were measured by immunohistochemistry. RESULTS: OVA challenge induced an AHR after 24 h in OVA-sensitized guinea-pigs. This coincided with an increase in the amount of NGF in BALF. Simultaneously, an increase in the percentage of substance P immunoreactive neurons in the nodose ganglia and an increase in the amount of substance P in lung tissue were found. We used tyrosine kinase inhibitors to block the signal transduction of the high-affinity NGF receptor, tyrosine kinase A (trkA). Treatment with the tyrosine kinase inhibitors (K252a or tyrphostin AG879) both inhibited the development of AHR, and prevented the increase in substance P in the nodose ganglia and lung tissue completely whereas both inhibitors had no effect on baseline airway resistance. Neither treatment with K252a or tyrphostin AG879 changed the influx of inflammatory cells in the BALF due to allergen challenge. CONCLUSIONS: We conclude that substance P plays a role in the induction of AHR in our model for allergic asthma which is most likely mediated by NGF. As both tyrosine kinase inhibitors AG879 and K252a show a similar inhibitory effect on airway function after allergen challenge, although both tyrosine kinase inhibitors exhibit different non-specific inhibitory effects on targets other than trkA tyrosine kinases, it is likely that the induction of substance P derived from sensory nerves is mediated by NGF via its high-affinity receptor trkA.

Potential for improvement of docetaxel-based chemotherapy: a pharmacological review.

Since the introduction of docetaxel, research has focused on various approaches to overcome treatment limitations and improve outcome. This review discusses the pharmacological attempts at treatment optimisation, which include reducing interindividual pharmacokinetic and pharmacodynamic variability, optimising schedule, route of administration, reversing drug resistance and the development of structurally related second-generation taxanes.

Calcium signaling inhibits interleukin-12 production and activates CD83(+) dendritic cells that induce Th2 cell development.

Mature dendritic cells (DCs), in addition to providing costimulation, can define the Th1, in contrast to the Th2, nature of a T-cell response through the production of cytokines and chemokines. Because calcium signaling alone causes rapid DC maturation of both normal and transformed myeloid cells, it was evaluated whether calcium-mobilized DCs polarize T cells toward a Th1 or a Th2 phenotype. After human monocytes were cultured for 24 hours in serum-free medium and granulocyte-macrophage colony-stimulating factor to produce immature DCs, additional overnight culture with either calcium ionophore (CI) or interferon gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and soluble CD40L resulted in phenotypically mature DCs that produced interleukin-8 (IL-8) and displayed marked expression of CD80, CD86, CD40, CD54, CD83, DC-LAMP, and RelB. DCs matured by IFN-gamma, TNF-alpha, and soluble CD40L were additionally distinguished by undetectable CD4 expression, marked secretion of IL-12, IL-6, and MIP-1beta, and preferential ability to promote Th1/Tc1 characteristics during T-cell sensitization. In contrast, DCs matured by CI treatment were distinguished by CD4 expression, modest or absent levels of IL-12, IL-6, and MIP-1beta, and preferential ability to promote Th2/Tc2 characteristics. Calcium signaling selectively antagonized IL-12 production by mature DCs activated with IFN-gamma, TNF-alpha, and soluble CD40L. Although the activation of DCs by calcium signals is largely mediated through calcineurin phosphatase, the inhibition of IL-12 production by calcium signaling was independent of this enzyme. Naturally occurring calcium fluxes in immature DCs, therefore, negatively regulate Dc1 differentiation while promoting Dc2 characteristics and Th2/Tc2 polarization. Calcium-mobilized DCs may have clinical usefulness in treating disease states with excessive Th1/Tc1 activity, such as graft-versus-host disease or autoimmunity.

The role of sensory nerve endings in nerve growth factor-induced airway hyperresponsiveness to histamine in guinea-pigs.

1. Nerve growth factor induces an airway hyperresponsiveness in vivo in guinea-pigs, as we have shown previously. Since antagonizing the neurokinin-1 (NK(1)) receptor can prevent this NGF-induced airway hyperresponsiveness and since sensory nerves release tachykinins, we investigated the role of sensory nerves in the NGF-induced airway hyperresponsiveness. 2. We used isolated tracheal rings from guinea-pigs to measure tracheal contractility. In these rings sensory nerve endings are present, but these endings lack any contact with their cell bodies. 3. In this in vitro system, NGF dose-dependently induced a tracheal hyperresponsiveness to histamine. The NK(1) receptor antagonist SR140333 could block the induction of tracheal hyperresponsiveness. 4. To further investigate the involvement of sensory nerve endings we used the cannabinoid receptor 1 (CB(1)) agonist R-methanandamide to inhibit excitatory events at the nerve terminal. The CB(1) receptor agonist was capable of blocking the tracheal hyperresponsiveness to NGF in the isolated system, as well as the airway hyperresponsiveness to NGF in vivo. 5. This indicates that NGF can induce an increase in airway responsiveness in the absence of sensory nerve cell bodies. NGF may act by increasing substance P release from sensory nerve endings, without upregulation of substance P in the neurons. Substance P in its turn is responsible for the induction of the NGF-induced airway hyperresponsiveness.

Emergent lung retransplantation after discovery of two primary malignancies in the donor.

A 50-year-old woman underwent single lung transplantation for advanced chronic obstructive pulmonary disease. Shortly after the procedure, it was discovered that the donor suffered from both a renal cell carcinoma and a spindle-cell sarcoma of the ascending aorta, which had metastasized to the spleen. The patient was emergently listed for a retransplantation and underwent bilateral lung transplantation after a new donor became available 4 days after the initial transplantation procedure. After 24 months, the patient is without evidence of malignancy. This case illustrates the role of immediate retransplantation for patients who have inadvertently received thoracic organs from donors harboring occult malignancies.

Calcium ionophore activation of chronic myelogenous leukemia progenitor cells into dendritic cells is mediated by calcineurin phosphatase.

We have previously demonstrated that Ph+ myeloid progenitor cells of patients with chronic myeloid leukemia (CML) can acquire characteristics of mature dendritic cells (DC) following calcium mobilization with calcium ionophore (A23187, CI). In this study we characterize the intracellular signaling pathway by which CI induces the acquisition of DC features in these leukemic cells. CI-induced activation of CML cells is attenuated by the calcineurin phosphatase inhibitor cyclosporin A (CsA) as well as the calmodulin (CaM) antagonist W-7. These cause ablation of both the CI-induced immunophenotypic expression of DC markers and immunostimulatory properties in mixed leukocyte responses (MLR). Minimal blocking effect was observed when Ca(2+)/CaM kinase II (281-301) inhibitor was added to the cultures. These findings suggest a Ca(2+)-dependent mechanism for the CI-induced activation of CML cells into antigen-presenting cells (APC), which is primarily mediated through the CaM/calcineurin pathway.

Granulocyte-macrophage colony-stimulating factor, interleukin-2, and interleukin-12 synergize with calcium ionophore to enhance dendritic cell function.

The authors previously showed that monocytes treated with calcium ionophore (CI) acquire characteristics of mature dendritic cells (DC) in part through a calcineurin-dependent pathway. In this study, the authors evaluated the ability of granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin-2 (IL-2), and interleukin-12 (IL-12) alone or in combination with CI to induce DC characteristics in peripheral blood monocytes. Monocytes obtained by leukapheresis and countercurrent centrifugal elutriation were cultured with calcium, cytokines, or both, profiled by flow cytometry, and assessed for antigen uptake and sensitization of autologous CD8+ T cells to antigen. Monocytes treated with the combination of GM-CSF, IL-2, and IL-12 resulted in immunophenotypic and antigen uptake profiles typical of immature DC, including loss of surface CD14 expression, de novo low-level expression of B7.1, negligible CD83 expression, marked enhancement of CD40 and ICAM-1, and high major histocompatibility complex class I and II levels. A high level of antigen uptake by macro-pinocytosis was observed. In contrast, CI treatment significantly up-regulates B7.1, B7.2, CD40, CD54, and CD83 and substantially down-regulates CD14 and macro-pinocytosis, a profile consistent with mature DC. Many CI-induced modulations, but none resulting from cytokine treatment alone, were inhibited by the calcineurin phosphatase inhibitor cyclosporin A. Compared with monocytes treated with CI alone, combined treatment of monocytes with GM-CSF, IL-2, IL-12, and CI augmented B7.1 and CD83 expression and enhanced sensitization of autologous CD8+ T cells to melanoma-antigen-derived peptides. These results suggest that several independent pathways of DC activation can cooperatively enhance the function of monocyte-derived DC.

Virus- and bradykinin-induced airway hyperresponsiveness in guinea pigs.

The involvement of bradykinin in virus-induced airway hyperresponsiveness (AHR) in guinea pig airways in vivo was determined with the B(2)-receptor antagonist Hoe 140. The efficacy of Hoe 140 treatment was assessed through its effect on the bradykinin-induced (up to 2.5 microgram/100 g B.W. administered intravenously) decrease in blood pressure (BP). Hoe 140 (0.1 micromol/kg), administered subcutaneously twice a day for 5 d almost completely blocked bradykinin-induced changes in BP. Four days after parainfluenza-3 (PI-3) virus infection, guinea pigs showed AHR; excessive airway contraction was found with histamine-receptor stimulation. This hyperresponsiveness was completely inhibited by pretreatment with Hoe 140 (0.1 micromol/kg) administered subcutaneously twice a day for five consecutive days, starting 1 d before virus inoculation. Interestingly, nebulized delivery of bradykinin itself to captopril-treated animals induced an AHR comparable to that observed in virus-treated guinea pigs. Viral infection also caused influx of bronchoalveolar cells into the lungs. Both histologic examinations and lung lavage experiments showed that this cell influx could not be inhibited by pretreatment with Hoe 140. In summary, the results of the study show that bradykinin is involved in a cascade of events leading to AHR after a viral infection in guinea pigs, without affecting bronchoalveolar cell influx.

Calcium signaling induces acquisition of dendritic cell characteristics in chronic myelogenous leukemia myeloid progenitor cells.

Effective host T lymphocyte sensitization to malignant cells depends on successful antigen presentation. In this study, we examined the capacity of malignant myeloid progenitor cells of patients in the chronic phase of chronic myelogenous leukemia (CML) to acquire characteristics of activated dendritic cells (DCs) after intracellular calcium mobilization, thereby bypassing a need for third-party antigen-presenting cells. Treatment of purified CD33(+) CML cells from 15 patients with calcium ionophore (CI) consistently resulted in de novo expression of the costimulatory molecules CD80 (B7.1) and CD86 (B7.2), CD40 and the DC-specific activation marker CD83, as well as marked up-regulation of MHC class I and II molecules and the adhesion molecule CD54. Most of these changes occurred within 24 hr of treatment. Morphologically, CI-treated CML cells developed long dendritic projections similar to those seen in mature DCs. Functionally, CI-treated CML cells provided stimulation of allogeneic T lymphocytes 10- to 20-fold that of untreated CML cells or untreated monocytes. Fluorescent in situ hybridization of CI-activated CML cells confirmed their leukemic origin by displaying the typical bcr/abl fusion signal. No difference in bcr/abl translocation percentages between untreated and CI-treated CML nuclei was observed. These observations indicate that calcium mobilization may constitute a valuable approach for rapidly and reliably generating CML-derived DCs for immunotherapy of CML.

Calcium ionophore-treated myeloid cells acquire many dendritic cell characteristics independent of prior differentiation state, transformation status, or sensitivity to biologic agents.

We previously reported that treatment of human peripheral blood monocytes or dendritic cells (DC) with calcium ionophore (CI) led to the rapid (18 hour) acquisition of many characteristics of mature DC, including CD83 expression. We therefore investigated whether less-mature myeloid cells were similarly susceptible to rapid CI activation. Although the promyelocytic leukemia line HL-60 was refractory to cytokine differentiation, CI treatment induced near-uniform overnight expression of CD83, CD80 (B7.1), and CD86 (B7. 2), as well as additional characteristics of mature DC. Several cytokines that alone had restricted impact on HL-60 could enhance CI-induced differentiation and resultant T-cell sensitizing capacity. In parallel studies, CD34(pos) cells cultured from normal donor bone marrow developed marked DC-like morphology after overnight treatment with either rhCD40L or CI, but only CI simultaneously induced upregulation of CD83, CD80, and CD86. This contrasted to peripheral blood monocytes, in which such upregulation could be induced with either CI or rhCD40L treatment. We conclude that normal and transformed myeloid cells at many stages of ontogeny possess the capacity to rapidly acquire many properties of mature DC in response to CI treatment. This apparent ability to respond to calcium mobilization, even when putative signal-transducing agents are inoperative, suggests strategies for implementing host antileukemic immune responses.

Nerve growth factor induces a neurokinin-1 receptor- mediated airway hyperresponsiveness in guinea pigs.

Because asthmatic patients show increased nerve growth factor (NGF) serum levels, we examined the effect of NGF on airway function. Intravenously administered NGF potentiates the histamine- induced bronchoconstriction with a maximum of over 200% in anesthetized spontaneously breathing guinea pigs. Doses of 8 ng and 80 ng NGF/kg body weight induce a significant hyperresponsiveness to histamine. NGF itself does not affect airway reactivity. Airway hyperresponsiveness is observed 30 min and 3 h after NGF administration, and has disappeared after 24 h. The neurokinin-1 receptor antagonist SR 140333 completely blocks the NGF-induced hyperresponsiveness, pointing to a role for tachykinins. This is the first report showing a direct relation between peripherally administered NGF and airway hyperresponsiveness. Taking into consideration that plasma NGF levels have been shown to be elevated in asthmatic patients, our result points to an important role for NGF in the pathogenesis of asthma.

Pharmacological inhibition of leukotriene actions.

Leukotrienes represent a group of lipid mediators that play a very important role in a wide variety of pathological conditions. The presence of leukotrienes in inflammatory sites has been extensively documented, and accordingly research efforts have been directed towards the development of drugs that interfere with the formation or effects of leukotrienes. Although clinical application of such drugs has been disappointing in the past, recent discoveries of more potent and selective drugs seem to be promising. This review attempts to highlight some of these exciting developments.

Sesame oil in injectable gold: two drugs in one?

To investigate the potential anti-inflammatory effects of sesame oil, which is present in the injectable gold preparation Auromyose, the synthesis of tumour necrosis factor alpha (TNF-alpha), prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) by in vitro stimulated blood cells was measured before, during and after 12 weeks of dietary supplementation with 18 g of sesame oil daily in 11 healthy male volunteers. Neither TNF-alpha, PGE2 nor LTB4 production levels showed statistically significant changes during the 12 weeks of dietary supplementation with sesame oil. These results do not suggest an anti-inflammatory effect of sesame oil as present in injectable gold preparations which are used in the treatment of rheumatoid arthritis.

Increased cAMP levels in stimulated neutrophils inhibit their adhesion to human bronchial epithelial cells.

Bronchial epithelial cells express the intercellular adhesion molecule-1 that mediates binding of activated neutrophils via interaction with Mac-1 and/or leukocyte function-associated antigen-1. In this study, we examined whether increased intracellular levels of adenosine 3',5'-cyclic monophosphate (cAMP) affected neutrophil adhesion to the human bronchial epithelial cells. It was found that the N-formylmethionyl-leucyl-phenylalanine (fMLP)-stimulated neutrophil adhesion was concentration dependently inhibited when the cAMP analogs dibutyryl adenosine 3',5'-cyclic monophosphate or 8-bromoadenosine 3',5'-cyclic monophosphate were present. The beta-adrenergic receptor agonists isoprenaline and salmeterol, in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX), were also able to inhibit the fMLP-stimulated adhesion of neutrophils to bronchial epithelial cells. These agonists in combination with IBMX significantly increased the intracellular cAMP level in both neutrophils and epithelial cells. Preincubation of neutrophils with the long-acting beta2-adrenergic receptor agonist salmeterol (in the presence of IBMX) inhibited their fMLP-stimulated adhesion to epithelial cells, whereas pretreatment of epithelial cells did not influence the adhesion process. When ethanol-fixed epithelium was used, salmeterol pretreatment also diminished the adhesion of stimulated neutrophils. Moreover, combinations of salmeterol or isoprenaline with IBMX inhibited fMLP-upregulated Mac-1 expression. Therefore, we conclude from these data that elevation of intracellular cAMP in the neutrophil inhibits stimulated neutrophil adhesion to bronchial epithelial cells via Mac-1.