Optimal force evaluation for isotonic fatigue characterization in mouse Tibialis Anterior muscle

Skeletal muscle fatigue is most often studied as a response to repeated stimulations in isometric conditions and it is usually quantified as the progressive loss of force generating capability over time. However, physical dynamic activity is based on the shortening of skeletal muscles. Therefore, the condition that best mimics body movements is the isotonic one, in which muscle is allowed to shorten against a constant load. In the literature, the isotonic fatigue test is performed allowing the muscle to lift a load corresponding to one-third of the maximal isometric force (reference optimal force), as best representative of the force at which the tissue develops its maximum power. The goal of this study was to devise a new testing protocol in which each muscle was tested for isotonic fatigue by shortening against its own optimal force, i.e. the force at which it really developed the maximum power. Our hypothesis was that testing all the muscle at a standard reference value would introduce significant errors in the parameters associated to muscle fatigue and in their variance. The proposed protocol was based on the real-time measurement of the maximum power a muscle was able to generate through the application of the after-load technique and a mathematical interpolation to the Hill's equation, that therefore allowed to determine the experimental optimal force to be applied during the fatigue test. Experimental results showed that the muscles tested with the experimental optimal force had a fatigue time significantly lower than the control muscles tested with the reference optimal force. A decrease, even if not statistically significant, was also measured for the power and work generated during the fatigue test. Of note, for all these parameters a huge decrease in the measurement variance was reported, confirming that a precise assessment of the muscle experimental optimal force was needed to increase the accuracy of the measurements. On the other hand, the application of the protocol proposed in this work required an increase in the test duration, due to the application of the after-load technique, and a real time measurement of the power generated by the tissue

SELECTIVE INFLUENCES IN THE B-CELL RECEPTOR IMMUNOGLOBULIN HEAVY AND LIGHT CHAIN IN HAIRY CELL LEUKEMIA

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SELECTIVE INFLUENCES IN THE B-CELL RECEPTOR IMMUNOGLOBULIN HEAVY AND LIGHT CHAIN IN HAIRY CELL LEUKEMIA

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Large genomic aberrations detected by SNP array are independent prognosticators of a shorter time to first treatment in chronic lymphocytic leukemia patients with normal FISH

Background Genomic complexity can predict the clinical course of patients affected by chronic lymphocytic leukemia (CLL) with a normal FISH. However, large studies are still lacking. Here, we analyzed a large series of CLL patients and also carried out the so far largest comparison of FISH versus single-nucleotide polymorphism (SNP) array in this disease. Patients and methods SNP-array data were derived from a previously reported dataset. Results Seventy-seven of 329 CLL patients (23%) presented with a normal FISH. At least one large (>5 Mb) genomic aberration was detected by SNP array in 17 of 77 patients (22%); this finding significantly affected TTT. There was no correlation with the presence of TP53 mutations. In multivariate analysis, including age, Binet stage, IGHV genes mutational status and large genomic lesion, the latter three factors emerged as independent prognosticators. The concordance between FISH and SNP array varied between 84 and 97%, depending on the specific genomic locus investigated. Conclusions SNP array detected additional large genomic aberrations not covered by the standard FISH panel predicting the outcome of CLL patient

Correcting pervasive errors in RNA crystallography through enumerative structure prediction

Three-dimensional RNA models fitted into crystallographic density maps exhibit pervasive conformational ambiguities, geometric errors and steric clashes. To address these problems, we present enumerative real-space refinement assisted by electron density under Rosetta (ERRASER), coupled to Python-based hierarchical environment for integrated 'xtallography' (PHENIX) diffraction-based refinement. On 24 data sets, ERRASER automatically corrects the majority of MolProbity-assessed errors, improves the average Rfree factor, resolves functionally important discrepancies in noncanonical structure and refines low-resolution models to better match higher-resolution models

The SF3B1 inhibitor spliceostatin A (SSA) elicits apoptosis in chronic lymphocytic leukemia cells through downregulation of Mcl-1

The pro-survival Bcl-2 family member Mcl-1 is expressed in chronic lymphocytic leukemia (CLL), with high expression correlated with progressive disease. The spliceosome inhibitor spliceostatin A (SSA), is known to regulate Mcl-1 and so here we assessed the ability of SSA to elicit apoptosis in CLL. SSA induced apoptosis of CLL cells at low nanomolar concentrations in a dose- and time-dependent manner, but independently of SF3B1 mutational status, IGHV status and CD38 or ZAP70 expression. However, normal B and T cells were less sensitive than CLL cells (P=0.006 and P<0.001, respectively). SSA altered the splicing of anti-apoptotic MCL-1L to MCL-1s in CLL cells coincident with induction of apoptosis. Overexpression studies in Ramos cells suggested Mcl-1 was important for SSA-induced killing since its expression inversely correlated with apoptosis (P=0.001). IL4 and CD40L, present in patient lymph nodes, are known to protect tumor cells from apoptosis and significantly inhibited SSA, ABT-263 and ABT-199 induced killing following administration to CLL cells (P=0.008). However, by combining SSA with the Bcl-2/Bcl-xL antagonists ABT-263 or ABT-199, we were able to overcome this pro-survival effect. We conclude that SSA combined with Bcl-2/Bcl-xL antagonists may have therapeutic utility for CL