Disadvantages to the use of DMSO-d6 are its high viscosity, which broadens signals, and its hygroscopicity, which leads to an overwhelming H2O resonance in the 1H-NMR spectrum. It is often mixed with CDCl3 or CD2Cl2 for lower viscosity and melting points. DMSO is also used to dissolve test compounds in in vitro drug discovery and drug design screening programs, including high-throughput screening programs. This is because it is able to dissolve both polar and nonpolar compounds, can be used to maintain stock solutions of test compounds (important when working with a large chemical library), is readily miscible with water and cell culture media, and has a high boiling point (this improves the accuracy of test compound concentrations by reducing room temperature evaporation). One limitation with DMSO is that it can affect cell line growth and viability, with low DMSO concentrations sometimes stimulating cell growth, and high DMSO concentrations sometimes inhibiting or killing cells.DMSO is used as a vehicle in in vivo studies of test compounds too. It has, for example, been employed as a co-solvent to assist absorption of the flavonol glycoside Icariin in the nematode worm Caenorhabditis elegans. As with its use in in vitro studies, DMSO has some limitations in animal models. Pleiotropic effects can occur and, if DMSO control groups are not carefully planned, then solvent effects can falsely be attributed to the prospective drug.
More recently, the Group has suggested that values of 0.5x109 or 5%, respectively, may be more appropriate from a therapeutic viewpoint and therefore should be studied as a definitive criterion for the disease. A recent study supported this suggestion in finding that multiple myeloma patients with >5% circulating plasma cells had a prognosis much worse than that for multiple myeloma and similar to that for plasma cell leukemia. Flow cytometry immunophenotyping of blood cells to detect clonal phenotypes of plasma cells seen in multiple myeloma (e.g. the CD138+, CD38+, CD19−, CD45+/- phenotype) may be a more sensitive method to enumerate circulating clonal plasma cells and diagnose plasma cell leukemia. Treatments
Prior to the use of newly developed drugs and treatment regimens, median survival rates from the time of diagnosis for pPCL and sPCL were 8–11 months and 2–8 months, respectively, even when treated very aggressively with the VAD regimen of vincristine, doxorubicin, and dexamethasone or the VCMP regimen of vincristine, carmustine, melphalan, and prednisone alternating with vincristine, carmustine, doxorubicin, and prednisone. The treatment of PCL patients, particularly pPCL patients, with newer methods appears to have made modest improvements in survival rates. However, the rarity of these two leukemias has limited individual studies to case reports on a small number of patients or retrospective analyses of patient records. Randomized controlled trials on these patients have not been reported. One flaw of these methods is patient selection bias, i.e.