Multidentate 2-pyridyl-phosphine ligands – towards ligand tuning and chirality

The incorporation of a variety of alcohols into (amino)pyridyl-phosphine frameworks provides access to a library of multidentate (alkoxy)pyridyl-phosphines. Their coordination chemistry with Cu^I is explored.

Polarization of human hematopoietic progenitors during contact with multipotent mesenchymal stromal cells: effects on proliferation and clonogenicity

Establishment of a defined cell culture system that facilitates ex vivo expansion of isolated hematopoietic stem and progenitor cells (HSPCs) is a crucial issue in hematology and stem cell transplantation. Here we have evaluated the capacity of primary human multipotent mesenchymal stromal cells (MSCs) to support the ex vivo expansion of peripheral CD34(+)-enriched HSPCs. We observed that HSPCs co-cultured on MSCs showed a substantially higher total expansion rate compared to those growing without. Moreover, in addition to the expansion of CD34(+)CD133(+) and CD34(+)CD133(-) cells, a third population of CD133(+)CD34(-) stem cells became detectable after expansion. Direct contact between HSPCs and the feeder layer appears beneficial for the expansion of HSPCs harboring CD133(+) phenotype, i.e., CD34(+)CD133(+) and CD133(+)CD34(-), in contrast to CD34(+)CD133(-) cells. Interestingly, electron microscopy and immunofluorescence analyses revealed that adherent HSPCs display various morphologies; they are either round with, in some cases, the appearance of a microvillar pole or exhibit several distinct types of plasma membrane protrusions such as lamellipodium and magnupodium. CD133 is selectively concentrated therein, whereas CD34 is randomly distributed over the entire surface of HSPCs. Together, this co-culture offers a unique experimental system to further characterize the biology and role of markers of rare stem cell populations.

Comparative analysis of proliferative potential and clonogenicity of MACS-immunomagnetic isolated CD34+ and CD133+ blood stem cells derived from a single donor

A novel stem cell marker prominin-1 (CD133) has been shown to be expressed on a subpopulation of CD34(+) haematopoietic stem and progenitor cells. The aim of this study was to compare in parallel commercially available CD34(+) and CD133(+) isolation methods based on paramagnetic bead-coupled antibodies using clinical-grade samples of mobilized peripheral blood from 10 individual healthy donors under identical conditions. The CD133 negative fraction from the first selection was used for CD34(+) enrichment to obtain an additional CD34(+)/CD133(-) population. Although no significant difference in total cell expansion between cells isolated from the three procedures was observed in a 7-day cytokine-driven suspension culture, the long-term culture-initiating cell assay demonstrated that cells derived by CD34(+) isolation contain less primitive progenitors than those isolated based on CD133(+) selection. Interestingly, CD34(+)-enriched progenitors, especially the CD34(+)/CD133(-) fraction, contained a significantly higher proportion of erythroid colony-forming cells, whereas the highest content of myeloid colony-forming cells was concentrated in the CD133(+) selected cells. These subtle differences between CD34(+) and CD133(+) immunomagnetic selection will have to be explored for their potential clinical relevance.

Expression and regulation of NFAT (nuclear factors of activated T cells) in human CD34+cells: down-regulation upon myeloid differentiation

The calcineurin-dependent, cyclosporin A (CsA)-sensitive transcription factor nuclear factor of activated T cells (NFAT) represents a group of proteins, which is well-characterized as a central regulatory element of cytokine expression in activated T cells. In contrast, little is known about the expression or function of NFAT family members in myeloid cells; moreover, it is unclear whether they are expressed by hematopoietic stem/progenitor cells. Here, we show that NFATc2 (NFAT1) is expressed at high levels in CD34+ cells and megakaryocytes but not in cells committed to the neutrophilic, monocytic, or erythroid lineages. Cytokine-induced in vitro differentiation of CD34+ cells into neutrophil granulocytes results in the rapid suppression of NFATc2 RNA and protein. NFATc2 dephosphorylation/rephosphorylation as well as nuclear/cytoplasmic translocation in CD34+ cells follow the same calcineurin-dependent pattern as in T lymphocytes, suggesting that NFATc2 activation in these cells is equally sensitive to inhibition with CsA. Finally, in vitro proliferation, but not differentiation, of CD34+ cells cultured in the presence of fms-like tyrosine kinase 3 ligand (FLT3L), stem cell factor, granulocyte macrophage-colony stimulating factor (GM-CSF), interleukin-3, and G-CSF is profoundly inhibited by treatment with CsA in a dose-dependent manner. These results suggest a novel and unexpected role for members of the NFAT transcription factor family in the hematopoietic system.

Mesenchymal Stem Cells Can Be Differentiated Into Endothelial Cells In Vitro

Human bone marrow-derived mesenchymal stem cells (MSCs) have the potential to differentiate into mesenchymal tissues like osteocytes, chondrocytes, and adipocytes in vivo and in vitro. The aim of this study was to investigate the in vitro differentiation of MSCs into cells of the endothelial lineage. MSCs were generated out of mononuclear bone marrow cells from healthy donors separated by density gradient centrifugation. Cells were characterized by flow cytometry using a panel of monoclonal antibodies and were tested for their potential to differentiate along different mesenchymal lineages. Isolated MSCs were positive for the markers CD105, CD73, CD166, CD90, and CD44 and negative for typical hematopoietic and endothelial markers. They were able to differentiate into adipocytes and osteocytes after cultivation in respective media. Differentiation into endothelial-like cells was induced by cultivation of confluent cells in the presence of 2% fetal calf serum and 50 ng/ml vascular endothelial growth factor. Laser scanning cytometry analysis of the confluent cells in situ showed a strong increase of expression of endothelial-specific markers like KDR and FLT-1, and immunofluorescence analysis showed typical expression of the von Willebrand factor. The functional behavior of the differentiated cells was tested with an in vitro angiogenesis test kit where cells formed characteristic capillary-like structures. We could show the differentiation of expanded adult human MSCs into cells with phenotypic and functional features of endothelial cells. These predifferentiated cells provide new options for engineering of artificial tissues based on autologous MSCs and vascularized engineered tissues.

Sonographic quantification of the type IV reaction after intradermal application of recall antigens

20-MHz B-scan high-resolution sonography permits non-invasive, two-dimensional visualisation of micromorphological structures in vivo, and allows precise measurement of the depth and extent of inflammatory skin lesions. In 50 patients, the reactions following intradermal application of 8 recall antigens to the volar forearm were evaluated clinically and sonographically at various times (0, 24, 48, 72 h). In 30 patients, one of the inflammatory papules was excised after 48 h for complete histological work-up (serial sections) and subsequent comparison with the sonographic image. Infiltrates were characterised in the ultrasound scans by the almost regular occurrence of convexity of the skin surface, by a loosened structure (loss of echogenicity) of the corium and by protrusion of the corium into the subcutaneous fatty tissue. It was also possible to follow the dynamics of the type IV reaction with the measurement of echogenicity (densitometry). High-frequency ultrasound is an objective, exact and very sensitive tool for the measurement of type IV reactions after intradermal application of recall antigens and therefore superior to clinical evaluation. The B-scan was superior to the A-scan. However, for routine evaluation of tuberculin-like reactions, sonography is too time-consuming. Our results suggest that densitometry provides no additional or necessary information compared to sonometry.

Elicitation and habituation of the electrodermal orienting response in a short interstimulus interval paradigm

The present experiment was carried out to investigate elicitation and habituation of the electrodermal Orienting Response with stimulus trains utilising a short interstimulus interval (ISI) of 1.1 s. We sought evidence for within-train response decrement to repeated stimulus presentation, response recovery to a change stimulus and dishabituation following the change stimulus--the three properties necessary to unequivocally identify a decremental process as habituation. No autonomic study could be found using such a short ISI. Autonomic studies on this time scale are necessary if these measures are to be integrated with central event-related potential (ERP) measures of electrical brain function. Overcoming this paradigm gap required the development of novel measurement procedures to estimate the small electrodermal responses obtained, usually occurring on the recovery slope of the response to the previous stimulus in the train. With our novel measurement procedures, evidence was found indicating that electrodermal activity in such a paradigm exhibited the three classic criteria of habituation.

Antiestrogen and antiandrogen administration reduce bone mass in the rat

In mature female and male rats sex hormone deficiency was produced by surgical castration and by antiestrogen or antiandrogen administration. For the latter purpose we used the nonsteroidal antiestrogens tamoxifen, keoxifene (LY156758) and tetramethylhexestrol, and the steroidal antiandrogen cyproterone acetate. Dosages of 0.4 mg tamoxifen/rat/day and isomolar dosages of keoxifene and tetramethylhexestrol led to a bone mass reduction which was comparable to ovariectomized rats. Cyproterone acetate showed, at 10 mg/rat/day, a similar decrease in bone mass like orchidectomy. The often discussed intrinsic estrogen activity of the antiestrogens was present only in the highest dosage tested of tamoxifen. Keoxifene and tetramethylhexestrol showed no estrogenic effects, but this may be a dosage problem. Cyproterone acetate revealed no androgenic side-effects. These results indicate that antigonadal hormone drugs reduce bone mass to a varying extent.

[The unrecognized myocardial infarct in the aged--contribution to prognosis]

The poor prognosis of myocardial infarction in old people is based almost completely upon clinical observations. But in the case of patients of advancing years it seems likely that the percentage of undiagnosed infarctions-whether due to atypical symptoms or to the fact that the patient is not admitted to hospital-is considerable. To estimate the level of this percentage a clinical-autoptical analysis of 124 decreased with transmural myocardial scars was carried out (mean age of death: 80 years). This reveals that 80% of all myocardials scars had not hitherto been diagnosed. Only 35% of the electrocardiograms showed definite scars, mostly in the case of patients with known myocardial infarction. 22% of deceased had complained about angina pectoris, again mostly patients with known myocardial infarction. In comparison with other studies of people in the same age group, the results are not surprising. This is only explained in part by old people's poor powers of recollection and their limited ability to communicate. These results indicate that the over all prognosis of acute myocardial infarction in old people, which often does not occur in hospital without being diagnosed should be viewed in a more favourable light than clinical results would suggest.

[Survived brain infarction in old age - clinical and morphological findings. II. Risk factors (author's transl)]

208 hospitalized patients, nearly 80 years old, were investigated because of risk factors and complicating diseases. Hypertension (58.2%), typical myocardial infarctions (37.2%) and diabetes (45.2%) were twice often as in our comparable cases without stroke. Corresponding we found signs of left ventricular hypertrophy in more than 50% post mortem. The dimensions of heart failure by hypertension are visible in ECG indicating LVH with many dysrhythmias. Early mortality (40%) as survival time are dependent on the size of the stroke. Cardiovascular causes of death were found mainly. The differences to younger patients with brain infarction seem to be only of gradually nature and especially to refer to the more intensive damaged heart.

[Survived brain infarction in old age - clinical and morphological findings. part I: extracranial stenoses of carotis arteries (author's transl)]

By clinical and post mortem findings we searched for the risk factors, important for brain infarctions in people of nearly 80 years. We were especially interested in the conditions of the extracranial vessels such as the carotid arteries and the murmurs at this point. The number of arterial stenoses in this region, ascertained in younger people is similar in old age. Besides of others factors, caused by old age, the many cases of multiple extracranial stenoses are probably responsible for the overproportional big brain infarctions in this series. In nearly 50% of all stenoses we heard vascular murmurs, mostly in both of the carotid arteries. Despite of some uncertainly of the clinical importance - just in old age many cardiac murmurs of the ejection type with tendency to transmission have been heard - they should give rise to investigate carefully the region of the neck in symptomatic patients.