cAMP accumulation in opioid-sensitive SH-SY5Y neuroblastoma cells is modified by estradiol and progesterone.

We have recently demonstrated that acute and chronic treatments with estradiol and progesterone induce changes in the responsiveness of endogenous opioid systems to painful stimulation. In the present study the neuroblastoma SH-SY5Y subclone known to contain predominantly mu opioid receptors was used as a model to characterize the gonadal steroid effect on this opioid receptor system. The function of opioid receptors was assessed by measuring prostaglandin E1 (PGE1)-induced cyclic AMP accumulation after various treatments with estradiol and progesterone. Differentiated SH-SY5Y cells respond to PGE1 with a dramatic increase in cAMP level. Morphine (MOR) inhibits by about 75% the stimulatory effect of PGE1 on cAMP. Pretreatment with 5 nM of estradiol for 6 days resulted in a significant increase of PGE1-stimulated cAMP accumulation. Exposure of cells for 48 h to estradiol in doses of 5 nM or 50 nM did not affect cell sensitivity to the PGE1 effect on cAMP. Moreover, neither dose of estradiol changed the inhibitory effect of morphine on PGE1-induced cAMP response. There was a significant increase in PGE1-stimulated cAMP accumulation after treatment with 100 nM progesterone for 1 h or 15 min and a marked elevation of cAMP levels was also measured after 15 min treatment with 10 nM progesterone. Exposure to either dose of progesterone for 8 h, 48 h or 6 days did not affect basal or PGE1-induced cAMP in neuroblastoma cells. Progesterone-treated groups responded to MOR with 56-67% inhibition of PGE1-stimulated cAMP accumulation. The potency of MOR-induced inhibition was comparable to the MOR effect in cells not treated with the steroid.(ABSTRACT TRUNCATED AT 250 WORDS)     

[Biocytin13]Dynorphin A 1-13 Amide: A Potential Probe for the κ-Opioid Receptor

A dynorphin A 1-13 amide (DYN) derivative biotinylated in position lysine 13 (B-DYN) has been prepared by automated solid-phase peptide synthesis. The derivative retained its ability to bind to avidin, and B-DYN–avidin complex showed a dissociated half-life of 10 hr at 37°C. Opioid receptor binding was measured in membrane preparations of rat brain (µ), NG-108-15 neuroblastoma–glioma hybrid cells (), and guinea pig cerebellum (). Biotinyl substitution of DYN either did not affect receptor binding () or slightly reduced binding affinity (µ and ). Binding of B-DYN to the receptor was very tight, with an IC₅₀ value in the low picomolar range, while binding to µ and sites was over two orders of magnitude lower. Preassociation of B-DYN with avidin resulted in a reduction of the affinities to the investigated opioid receptors by 100- to 1000-fold. However, the apparent affinity of B-DYN–avidin for the -opioid receptor is sufficient to suggest that B-DYN may be a useful tool for -opioid receptor assay, localization, and purification.     

Hereditary elliptocytosis with detection of a membrane protein defect of erythrocytes

It is reported on a 33-year-old patient whose diagnosis "hereditary elliptocytosis" has been ensured by typical findings. References to a structural defect of erythrocyte membrane proteins resulted from the SDS-gel electrophoresis. A splenectomy improved the subjective and objective symptoms distinctly.     

Binding affinities of rimexolone (ORG 6216), flunisolide and their putative metabolites for the glucocorticoid receptor of human synovial tissue

The relative binding affinities (RBA) of two locally used glucocorticoids, rimexolone and flunisolide have been measured for the glucocorticoid receptor of human synovial tissue. The non-fluorinated derivative rimexolone exhibited a binding affinity (RBA of 130) somewhat higher than that of dexamethasone (RBA of 100) but lower than that of flunisolide (RBA 190). Potential metabolites of rimexolone hydroxolated at the C₁₇ side-chain, showed decreased binding affinities, while the 6-hydroxy metabolite of rimexolone and flunisolide (its main metabolite) and the 4,5-dihydro metabolites of rimexolone hardly bound at all. These results support previous pharmacological findings that the high ratio of local to systemic effects of both compounds are due to a pronounced receptor affinity of the parent compounds and the fast systemic metabolism to derivatives with low pharmacodynamic activity.     

Induction of centrosome and chromosome aberrations by imatinib in vitro.

Imatinib (STI571, Gleevec/Glivec) is a potent selective tyrosine kinase inhibitor and is used successfully in the treatment of chronic myeloid leukemia (CML). While karyotype alterations, in addition to the Philadelphia chromosome, are a common phenomenon of progressing CML, the observation of BCR-ABL-negative leukemic clones with distinct aberrant karyotypes under an imatinib regimen is not yet understood. Here we test the hypothesis that such tumor clones may be induced de novo from normal cells by imatinib. In vitro experiments with varying drug concentrations (5-20 microM) were performed on normal human dermal fibroblasts (NHDF), Chinese hamster embryonal and Indian muntjak fibroblasts. After 3 weeks of treatment, analysis of cell cultures by centrosome immunostaining and conventional cytogenetics revealed that imatinib induced centrosome and chromosome aberrations in all cultures in a significant dose-dependent and species-independent manner. Moreover, the results of NHDF long-term culture experiments demonstrated that aberrant phenotypes, emerging under imatinib treatment for 12 weeks, were not reversible after prolonged propagation omitting the drug. These observations suggest a causative role of imatinib in the origin of centrosome and karyotype aberrations (genetic instability) and thus may explain the emergence of clonal chromosomal abnormalities in BCR-ABL-negative progenitor cells under imatinib therapy.     

Therapie von Hirnmetastasen und Meningeosis neoplastica

The continuous development of systemic chemotherapy of malignant tumors and the introduction of novel substances into the therapeutic regimen has not so far changed the therapeutic concept for cerebral metastases. Difficulties confounding the evaluation of these new substances are due to the fact that there are virtually no randomized studies which demonstrate the benefit of targeted therapies alone or in combination with other therapeutic modalities. The intention of this article is to review current data on the therapy of solid tumor brain metastases and to put them into relation to current therapeutic recommendations. Special emphasis is placed on the importance of multimodal concepts and the value of targeted therapies, as further development of therapeutic recommendations are to be expected in this field.     

Current concepts in pharmacokinetics and their implications for clinical medicine

The history of medicine provides ample evidence of the physicians' struggle with the subject of appropriate drug dosing. Recent studies indicate that drug-related mortality due to inadequate dosing principles still is a leading cause of death, only surpassed by cardiovascular diseases, cancer and stroke. In an effort to rationalize drug therapy, pharmacokinetic (PK) principles were introduced in medical practice in the early 1970s, mainly in the field of therapeutic drug monitoring (TDM). This measure was shown to reduce mortality. Several limitations in traditional PK, however, have led to the belief among many physicians that clinical PK is an unnecessary assignment of limited clinical relevance. Despite the perceived limitations of traditional PK research, remarkable developments have taken place in recent years and have made clinical PK a "physiological-mechanism based endeavor" with important implications for clinical medicine. Notably, the introduction of (1) PK-PD (pharmacokinetic-pharmacodynamic) modeling (2) target site PK (3) population PK and (4) pharmacogenomics has permitted better integration of PK principles into clinical drug therapy. The aim of the present article is to provide an overview of these developments and to discuss their impact on our understanding of clinical drug therapy.