Quantification of magnetic nanoparticles by magnetorelaxometry and comparison to histology after magnetic drug targeting.

Magnetic nanoparticles can be used in medicine in vivo as contrast agents and as a drug carrier system for chemotherapeutics. Thus local cancer therapy is performed with Magnetic Drug Targeting (MDT) and allows a specific delivery of therapeutic agents to desired targets, i.e., tumors, by using a chemotherapeutic substance bound to magnetic nanoparticles and focused with an external magnetic field to the tumor after intraarterial application. Important for this therapeutic principle is the distribution of the particles in the whole organism and especially in the tumor. Therefore we used magnetorelaxometry to quantify ferrofluids delivered after MDT. Tissue samples of some mm3 volume of a VX2 squamous cell carcinoma were measured by magnetic relaxation and the amount of iron was determined using the original ferrofluid suspension as a reference. From this the distribution of the magnetic particles within the slice of tumor was reconstructed. Histological cross-sections of the respective tumor offer the opportunity to map quantitatively the particle distribution and the vascularisation in the targeted tumor on a microscopic scale. Our data show that the integral method magnetorelaxometry and microscopic histological methods can complete each other efficiently.

Female sex hormones decrease constitutive endothelin-1 release via endothelial sigma-1/cocaine receptors: an action independent of the steroid hormone receptors.

Cardiovascular disease is rare in premenopausal women compared to men. The authors investigate sex hormone-induced endothelin-1 (ET-1) release and the involvement of classic sex hormone receptors as well as the ability of sigma-1/cocaine receptors to respond to sex hormones. ET-1 release was measured in the supernatant of endothelial cells after treatment with beta-estradiol, progesterone, testosterone, or combined with their antagonists, and with the sigma-1 receptor ligand ditolylguanidine (DTG), or haloperidol, a sigma-1 receptor antagonist. Binding assays were performed using 2.5 x 10(-8) M [3H]DTG. Female sex hormones decreased ET-1 release whereas testosterone increased it, sex hormone antagonists only slightly attenuated or had no effect on the respective hormone's effect. DTG totally blocked the female sex hormone-induced inhibition on ET-1 release, whereas testosterone-induced stimulation was not affected. However, haloperidol blocked both. [3H]DTG binding was displaced by beta -estradiol but not by testosterone. DTG-binding sites account for 513 +/- 114 per cell, KD 8.79 nM. These data suggest that besides classic steroid hormone receptors, sigma-1/cocaine receptors mediate the effects of female sex hormones on ET-1 release, an up to now unknown signalling pathway. Results also suggest that female and male sex hormones may bind to different sites on sigma-1 receptors, exerting opposite pharmacological effects.

[Chemokine directed homing of transplanted adult stem cells in wound healing and tissue regeneration]. / Chemokine-vermitteltes Homing von transplantierten adulten Stammzellen während der Wundheilung und Geweberegeneration.

A major challenge in stem cell biology is to study the underlying mechanisms of tissue specific homing and differentiation. Recent results suggest that bone marrow derived stem cells can give rise to multiple cell types. Because chemokines and chemokine receptors are associated with development, differentiation and homing of immune cells, we undertook efforts to study the chemokine receptor expression profile of human adult stem cells to identify their potential role in tissue specific homing prior to transdifferentiation. Using human bone marrow-derived stem cell lines, we could demonstrate functional chemokine receptor expression of various chemokine receptors. The expression of CXCR5 and CCR7, associated with secondary lymphoid organ homing as well as CXCR4 and CCR10, involved in organ specific homing and CXCR3, CCR5 and CCR1, which are involved in inflammation events, suggested a role of chemokine receptors in tissue specific homing of stem cells. To proof the specific homing of stem cells in vivo, we used murine stem cell lines, stably introduced green fluorescent protein under control of CMV promotor into the cells and injected them intravenously into mice. We demonstrate the homing of these stem cells to lymphnode and thymus as well as mucosal tissue, while stem cells home exclusively to a site of lesion during wound healing and tissue regeneration. Our data suggest that chemokine biology may play a pivotal role in the homing of stem cells to specific tissues and niches prior to (trans)differentiation, while the homing changes during tissue damage and other adequate lesions.

Heterogeneity of cardiac rat and human elongation factor 2.

Elongation factor 2 (EF-2) catalyses the last step of the elongation cycle, translocation, in the course of protein biosynthesis. A system for analyzing post-translational modifications of EF-2, which is a single polypeptide of 857 amino acids, is reported and its application to cytosolic extracts of cultured neonatal rat heart myocytes, neonatal and adult rat cardiac tissue, and extracts of human left ventricular myocardium is described. Comparing different pH ranges in immobilized pH gradient-isoelectric focusing (IPG-IEF), a range of pH 3 - 10 and 4 - 9 resulted in a highly defined and reproducible resolution of six different EF-2 variants of all extracts in the first dimension. These six variants were detected by the "imaging plate" (phosphor radiation image sensor) after specific labeling with Pseudomonas exotoxin A catalyzed [32P]ADP-ribosylation. This finding could be confirmed in Western blot analysis with a specific polyclonal rabbit antibody. Using two-dimensional polyacrylamide gel electrophoresis (2-D-PAGE), five to six EF-2 variants could be demonstrated in all extracts. By application of a second IPG indicator strip to the 2-D gel, they could be aligned with corresponding spots in a silver-stained 2-D separation of human myocardial tissue, revealing that the EF-2 variants belong to the group of low-abundance proteins.

[Determination of TAA-binding cells in peripheral blood of breast cancer patients (author's transl)]. / Bestimmung von TAA-bindenden Zellen im peripheren Blut von Mammakarzinom-Patienten.

Circulating human breast tumor-associated antigen (TAA) specific lymphocytes were detected in breast carcinoma patients by antigen specific rosette technique. About 60 percent of patients with breast cancer showed a positive reaction in our test system, the number of rosettes were considerably increased in comparison to the values of blood donors. Following operation normally the number of TAA specific rosettes decrease, contrary, in all cases with recidives, tested, we found positive test results. There is evidence, that our modification of the specific rosette-technique is suitable for detection of malignomas and can be important for the postoperative control of patients with breast carcinoma.