Efficient quenching sheds light on early stages of gold nanoparticle formation.

The formation mechanism of plasmonic gold nanoparticles (Au NPs) by fast NaBH4 induced reduction of the precursors is still under debate. In this work we introduce a simple method to access intermediate species of Au NPs by quenching the solid formation process at desired time periods. In this way, we take advantage of the covalent binding of glutathione on Au NPs to stop their growth. By applying a plethora of precise particle characterization techniques, we shed new light on the early stages of particle formation. The results of in situ UV/vis measurements, ex situ sedimentation coefficient analysis by analytical ultracentrifugation, size exclusion high performance liquid chromatography, electrospray ionization mass spectrometry supported by mobility classification and scanning transmission electron microscopy suggest an initial rapid formation of small non-plasmonic Au clusters with Au10 as the main species followed by their growth to plasmonic Au NPs by agglomeration. The fast reduction of gold salts by NaBH4 depends on mixing which is hard to control during the scale-up of batch processes. Thus, we transferred the Au NP synthesis to a continuous flow process with improved mixing. We observed that the mean volume particle sizes and the width of the particle size distribution decrease with increasing flow rate and thus higher energy input. Mixing- and reaction-controlled regimes are identified.

Determination of the yield, mass and structure of silver patches on colloidal silica using multiwavelength analytical ultracentrifugation.

Anisotropic nanoparticles offer considerable promise for applications but also present significant challenges in terms of their characterization. Recent developments in the electroless deposition of silver patches directly onto colloidal silica particles have opened up a simple and scalable synthesis method for patchy particles with tunable optical properties. Due to the reliance on patch nucleation and growth, however, the resulting coatings are distributed in coverage and thickness and some core particles remain uncoated. To support process optimization, new methods are required to rapidly determine patch yield, thickness and coverage. Here we present a novel approach based on multiwavelength analytical ultracentrifugation (MWL-AUC) which permits simultaneous hydrodynamic and spectroscopic characterization. The patchy particle colloids are produced in a continuous flow mixing process that makes use of a KM-type micromixer. By varying the process flow rate or metal precursor concentration we show how the silver to silica mass ratio distribution derived from the AUC-measured sedimentation coefficient distribution can be influenced. Moreover, through reasoned assumptions we arrive at an estimation of the patch yield that is close to that determined by arduous analysis of scanning electron microscopy (SEM) images. Finally, combining MWL-AUC, electrodynamic simulations and SEM image analysis we establish a procedure to estimate the patch thickness and coverage.

Aplastic crisis as primary manifestation of systemic lupus erythematosus.

Aplastic crisis is an unusual feature of systemic lupus erythematosus (SLE). We report the case of a 54-year-old woman presenting with both (extravascular) Coombs-positive hemolytic anemia and laboratory findings of bone marrow hyporegeneration with concomitant severe neutropenia. A bone marrow biopsy confirmed aplastic crisis. Diagnostic work-up revealed soaring titers of autoantibodies (anti-nuclear, anti-double-stranded DNA, anti-cardiolipin-IgM, and anti-ß2-glykoprotein-IgM antibodies), indicating a connective tissue disease as the most plausible reason for bone marrow insufficiency. As the criteria for SLE were fulfilled, we initiated an immunosuppressive therapy by steroids, which led to a rapid complete hematologic and clinical remission in our patient. In this case, we could report on one of the rare cases of SLE-induced aplastic crisis showing that this condition can be entirely reversed by immunosuppressive treatment and that SLE-induced aplastic crisis yields a good prognosis. In conclusion, in a case of aplastic crisis, physicians should be aware that SLE can be a rare cause that is accessible to specific treatment.

Dihydroorotate dehydrogenase inhibitor A771726 (leflunomide) induces apoptosis and diminishes proliferation of multiple myeloma cells.

Multiple myeloma is still an incurable disease; therefore, new therapeutics are urgently needed. A771726 is the active metabolite of the immunosuppressive drug leflunomide, which is currently applied in the treatment of rheumatoid arthritis, BK virus nephropathy, and cytomegaly viremia. Here, we show that dihydroorotate dehydrogenase (DHODH) is commonly expressed in multiple myeloma cell lines and primary multiple myeloma cells. The DHODH inhibitor A771726 inhibits cell growth in common myeloma cell lines at clinically achievable concentrations in a time- and dose-dependent manner. Annexin V-FITC/propidium iodide staining revealed induction of apoptosis of multiple myeloma cell lines and primary multiple myeloma cells. The 5-bromo-2'-deoxyuridine cell proliferation assay showed that inhibition of cell growth was partly due to inhibition of multiple myeloma cell proliferation. A771726 induced G(1) cell cycle arrest via modulation of cyclin D2 and pRb expression. A771726 decreased phosphorylation of protein kinase B (Akt), p70S6K, and eukaryotic translation initiation factor 4E-binding protein-1 as shown by Western blotting experiments. Furthermore, we show that the stimulatory effect of conditioned medium of HS-5 bone marrow stromal cells on multiple myeloma cell growth is completely abrogated by A771726. In addition, synergism studies revealed synergistic and additive activity of A771726 together with the genotoxic agents melphalan, treosulfan, and doxorubicin as well as with dexamethasone and bortezomib. Taken together, we show that inhibition of DHODH by A771726/leflunomide is effective in multiple myeloma. Considering the favorable toxicity profile and the great clinical experience with leflunomide in rheumatoid arthritis, this drug represents a potential new candidate for targeted therapy in multiple myeloma.

An ETV6-ABL1 fusion in a patient with chronic myeloproliferative neoplasm: Initial response to Imatinib followed by rapid transformation into ALL.

We report the case of a 26 year-old patient presenting with a persistent leukocytosis and CML-like marrow but no evidence of a BCR/ABL1 fusion. Molecular cytogenetics revealed that a portion of the ETV6 locus was inserted into the ABL1 locus. An ETV6/ABL1 fusion transcript could subsequently be confirmed. The patient was started on imatinib and went into complete cytomorphological remission. QRT-PCR measurements showed a 4 log reduction of the ETV6/ABL1 fusion. 15 months later, the disease transformed into ALL and the patient expired. Thus, an ETV6/ABL1 fusion positive MPN has the potential to transform very rapidly into ALL.

Necrotizing fasciitis in a young patient with acute myeloid leukemia - a diagnostic challenge.

BACKGROUND: Necrotizing fasciitis is characterized by a fulminant destruction of the soft tissue with an alarmingly high mortality rate. One of the main reasons for the continued high mortality is due to the challenge to punctual recognize and diagnose this disease, as specific cutaneous signs can vary or even be missing early in its evolution - especially in case of simultaneous first manifestation of an acute leukemia. CASE PRESENTATION: An untypical case of necrotizing fasciitis disease in a young patient with the first diagnosis of acute myeloid leukemia is presented. After her induction chemotherapy the only presenting clinical sign was fever in the presence of severe neutropenia without an evident infectious focus. After a few days a painless confluent, erythematous, pustular skin rash with a central necrosis on lateral thigh appeared. Escherichia coli was isolated from blood cultures. Surgical debridement was performed and showed subcutaneous tissue, fascia and underlying muscle around the site of initial cutaneous manifestation with typical necrosis on exploration. But, initially taken skin biopsy did not show any typical histopathological findings like bacteria or inflammatory cells confirming necrotizing fasciitis. Nevertheless, the intraoperative findings were impressive and highly indicative for a necrotizing soft tissue infection, so that the patient was treated according to clinical guidelines with extensive recurrent surgical debridement, broad-spectrum antibiotics and intensive care therapy. After recovering from NF, she successfully underwent further chemotherapy and stem cell transplantation. CONCLUSION: The presented case highlights the risk of potential misinterpretation, delayed diagnosis and treatment of necrotizing fasciitis in patients presenting with an untypical clinical and histopathological manifestation of necrotizing fasciitis as a result of severe neutropenia following chemotherapy for acute myeloid leukemia.