Die Jahrestagungen der Gesellschaft für Mineralstoffe und Spurenelemente e .V. (GMS) behandeln Themen an den Schnittstellen zwischen Medizin, Ernährung, Biologie, Chemie und Umwelt. Dieses Buch ...präsentiert die Beiträge zur 28. Jahrestagung der GMS am Karlsruher Institut für Technologie. Unter dem Motto „Nutzen-Risiko-Bewertung von Mineralstoffen und Spurenelementen: Biochemische, physikalische und toxikologische Aspekte“ wurden neueste Erkenntnisse aus dem Bereich der Spurenelemente präsentiert. Am Beispiel von Zink, Selen, Jod und Eisen wurden biochemische Funktionen, eine optimale Aufnahme/Versorgung sowie Interaktionen zwischen diesen Spurenelementen dargestellt. Andererseits müssen aber auch möglicherweise toxische Wirkungen von Spurenelementen infolge von Überversorgung, beispielsweise durch Nahrungsergänzungsmittel oder angereicherte Lebensmittel, in Betracht gezogen und durch entsprechende Grenzwertsetzung berücksichtigt werden. Toxische Wirkungen können zudem als Folge unphysiologischer Aufnahmewege auftreten; Beispiele sind die Neurotoxizität von Mangan und schädigende Wirkungen von Kupfer-basierten Nanopartikeln. Für Arsen standen der Metabolismus sowie die Speziesabhängigkeit toxischer Effekte im Fokus des Interesses. Die Zusammenschau analytischer, biochemischer und toxikologischer Aspekte liefert einen Eindruck über das spannende Forschungsgebiet der Spurenelemente.
The reliability of the assay of endogenous erythroid colony (EEC) formation in serum-free, cytokine-free collagen-based media was investigated in a multicentric study including 140 patients with ...polyglobuly (80 polycythemia vera (PV), 54 secondary erythrocytosis (SE), six idiopathic erythrocytosis (IE)) and 10 healthy donors. In each center, EEC assays were performed in parallel with progenitor cells from bone marrow (BM) and peripheral blood (PB); two commercialized media and 'low' and 'high' cell plating densities were tested. Negativity of EEC assays was considered certain only when sufficient BFU-E growth was obtained in control cultures with cytokines. In the two media, EEC formation was specific - never observed in cultures of healthy donors or SE patients - and comparable. BM EEC assays were positive (presence of eythroid colonies) for 75% ('low' plating) to 100% ('high' plating) of PV patients; PB EEC assays were positive for 83.3% ('low' plating) to 93.7% ('high' plating) of PV patients (differences not significant). Depending on the medium, 86.2-93.7% of patients with a positive BM EEC assay had a positive PB EEC assay. Hence, a standardized collagen-based EEC assay can be performed with either BM or PB progenitors; the EEC assay described here is positive for at least 75% of PV patients when a single EEC assay is performed, and for at least 94% of PV patients when both BM and PB EEC assays are performed.
We investigated the expression and functions of extracellular matrix receptors (or integrins) in the course of the differentiation of human megakaryocytes (Mks) leading to the formation of platelets. ...Integrins β1 or Very Late Antigens (VLA) are specialized transmembrane receptors allowing the attachment of the cells to collagen (VLA-2), fibronectin (VLA-4 and-5) and laminin (VLA-6). A proportion of committed megakaryocytic progenitor cells (CFU-MK) adhere to fibronectin but not to collagen or laminin. The early immature Mks are retained on fibronectin (30%) and laminin (12%) but not on collagen whereas large mature Mks are still adherent to fibronectin and laminin and also acquired the capacity to adhere to collagen. The expression of the different VLA in the maturation of Mks correlates well with their adhesive properties. Hence, VLA-2 is not expressed on immature Mks but is present on the mature polyploid cells. VLA-4 is detected only on immature Mks which do not seem to bear VLA-5, while this last integrin appears on late Mks. VLA-6 showed a broad distribution from the early to late stages of Mks differentiation.
Integrins β3 of the cytoadhesin family are represented by αIIbβ3 that is the receptor for fibrinogen and αVβ3 which mediates adhesion to vitronectin. αIIbβ3 is present on the CFU-MK and highly expressed throughout the Mks maturation stages while αVβ3 expression is much lower and seems to be detected only on the late Mks. The regulation of the expression of these receptors by cytokines and their respective roles in the maturation of Mks and the final production of platelets, are discussed. The development of efficient culture systems of human Mks in the presence of the recently cloned thrombopoietin will undoubtly help to shed more light on the molecular mechanisms of their interactions via integrins with the BM microenvironment.
We investigated the effects of two sex steroids (17
β estradiol and testosterone) on five human leukemia cell lines. We observed a statistically significant inhibition of proliferation, dose and time ...dependent, of the human monoblastic leukemia cell line U937. This inhibition was associated with a dose dependent decrease in the number of CFU-blasts in clonogenic cultures. Cytostatic effect was obtained with doses of 5 μM for estrogen and 10 μM for androgen and was not due to a non-specific cytotoxic effect, some cell viability remained high (>90%) even after 6 days of incubation. More accurately, we demonstrated that growth inhibition was associated with a cell cycle arrest, U937 cells accumulating in G2/M phase. This blockade was dose related with a maximum number of cells accumulating at day 4. Sensitivity of these cells to an S-phase specific agent (hydroxyurea) was not increased, suggesting that these cells were blocked in G2/M and did not undergo mitosis. Expression in U937 cells of high affinity nuclear receptors for estrogen and androgen was negative which was in favour of a type II estrogen binding site, mediated mechanism. Moreover, a small fraction of these cells underwent apoptosis or differentiation with about 12% apoptotic cells and a significant increase (more than 30%) of two myelomonocytic markers (CD13 and CD64). These results demonstrate that the proliferation of some leukemic cells may be inhibited by micromolar concentrations of sex steroids, independently of nuclear receptor expression. The main mechanism seems to be a block in cell cycle associated with modulation of apoptosis and differentiation. It provided additional evidence for the potential value of sex steroids and their analogues in the treatment of leukemias.
Rearrangement of chromosomal bands 1q21-23 is one of the most frequent chromosomal aberrations observed in hematological malignancy. The genes affected by these rearrangements remain poorly ...characterized. Typically, 1q21-23 rearrangements arise during tumor evolution and accompany disease-specific chromosomal rearrangements such as t(14;18) (BCL2) and t(8;14) (MYC), where they are thus thought to play an important role in tumor progression. The pathogenetic basis of this 1q21-23-associated disease progression is currently unknown. In this setting, we surveyed our series of follicular lymphoma for evidence of recurring 1q21-23 breaks and identified three cases in which a t(14;18)(q32;q21) was accompanied by a novel balanced t(1;22)(q22;q11). Molecular cloning of the t(1;22) in a cell line (B593) derived from one of these cases and detailed fluorescent in situ hybridization mapping in the two remaining cases identified the FCGR2B gene, which encodes the immunoreceptor tyrosine-based inhibition motif-bearing IgG Fc receptor, FcgammaRIIB, as the target gene of the t(1;22)(q22;q11). We demonstrate deregulation of FCGR2B leading to hyperexpression of FcgammaRIIb2 as the principal consequence of the t(1;22). This is evidence that IgG Fc receptors can be targets for deregulation through chromosomal translocation in lymphoma. It suggests that dysregulation of FCGR2B may play a role in tumor progression in follicular lymphoma.
The assay of endogenous erythroid colony formation (EEC), a characteristic of polycythemia vera and essential thrombocythemia, is not standardized. In this multicentric study, we tested four ...semisolid, serum-free, cytokine-free media based on either methylcellulose (M1, M2) or collagen (C1, C2) commercialized for the EEC assay.
Bone marrow mononuclear cells (BMMC) from 73 individuals (62 patients with either polycythemia vera (26), essential thrombocythemia (19), secondary polyglobuly (17) or chronic myeloid leukemia (2) and 11 healthy donors) were grown in parallel in the four media without, or with 0.01 U/ml erythropoietin (EPo).
In all four media EEC formation was specific, as it was not observed in cultures of patients with secondary polyglobuly or chronic myeloid leukemia, nor of healthy donors. Analysis of fresh or MGG-stained collagen gel cultures allowed detection of EEC formation significantly more frequently than methylcellulose-based media; addition of 0.01 U/ml of EPo had little or no effect on EEC formation. Collagen-based medium C1 gave better results than the other media tested: the 'C1' EEC assay was positive for 68.2% of polycythemia vera cultures with significantly higher median EEC numbers (6.5/10(5) BMMC for patients with one major criteria of polycythemia vera and 19 and 21/10(5) BMMC for patients with two or three major criteria, respectively). Medium C1 was also better for essential thrombocythemia cultures with 47.4% of positive results but with a low median EEC number (6.7/10(5) BMMC). When associated with the ELISA dosage of serum EPo, the 'C1' EEC assay allowed confirmation or elimination of the diagnosis of polycythemia vera for 91% (20/22) of polyglobulic patients.
We propose that serum-free collagen-based culture systems be considered to standardize the EEC assay, now part of the new criteria of polycythemia vera.
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