The protein folding problem would be considered "solved" when it will be possible to "read genes", i.e., to predict the native fold of proteins, their dynamics, and the mechanism of fast folding based solely on sequence data. The long-term goal should be the creation of an algorithm that would simulate the stepwise mechanism of folding, which constrains the conformational space and in which random search for stable interactions is possible. Here, we focus attention on the initial phases of the folding transition starting with the compact disordered collapsed ensemble, in search of the initial sub-domain structural biases that direct the otherwise stochastic dynamics of the backbone. Our studies are designed to test the "loop hypothesis", which suggests that fast closure of long loop structures by non-local interactions between clusters of mainly non-polar residues is an essential conformational step at the initiation of the folding transition of globular proteins. We developed and applied experimental methods based on time-resolved resonance excitation energy transfer (trFRET) measurements combined with fast mixing methods and studied the initial phases of the folding of Escherichia coli adenylate kinase (AK). A series of AK mutants were prepared, in which the ends of selected backbone segments that form long closed loops or secondary structure elements were labeled by donors and acceptors of excitation energy. The end-to-end distance distributions of such segments were determined under equilibrium and during the fast folding transitions. These experiments show that three out of seven long loops that were labeled in the AK molecule are closed very early in the transition. The N terminal 26-residue loop (loop I) is closed in < 200 μs after the initiation of folding, while the β strand included in loop I is still disordered. The closure of the second 44-residue loop (loop II, which starts at the end of loop I) is also complete within < 300 μs. Four other loops as well as five secondary structures of the CORE domain of AK (an α helix and four β strands) are formed at a late step, at a rate of 0.5 ± 0.3 s -1 , the rate of the cooperative folding of the molecule. These experiments reveal a hierarchically ordered pathway of folding of the AK molecule, ranging from microseconds to seconds. The results reviewed here, obtained mainly from studying a small number of model proteins, support the counterintuitive mechanism whereby non-local interactions are effective in the initiation of the folding pathways. The experiments presented demonstrate the importance of mapping the rates of sub-domain structural transitions along the folding transition, in situ, in the context of the other sections of the chain, whether folded or disordered. These experiments also show the power of the time-resolved FRET measurements in achieving this goal. A large body of data obtained by theoretical and experimental studies that support, or can accommodate, the loop hypothesis is reviewed. We suggest that mapping multiple sub-domain structural tr...
The life expectancy of patients with chronic myeloid leukemia (CML) approaches that of the age-matched population and quality of life (QOL) issues are becoming increasingly important. To describe patients’ characteristics and assess QOL, we delivered a 30-item core questionnaire, a 24-item CML-specific questionnaire, both from the European Organization for Research and Treatment of Cancer (EORTC), and additional health-related items to 350 patients. Among 193 patients who completed the questionnaires, 139 received either imatinib (n = 70, 33%), dasatinib (n = 45, 23%) or nilotinib (n = 24, 12%). Patients’ median age was 58 (range: 23 to 89) years and 86 (63%) were males. Stratifying patients by treatment, we recognized two distinct populations. In comparison to patients on dasatinib and nilotinib, patients on imatinib were two decades older, had a longer duration of disease and current treatment, experienced fewer limitations on daily activities (p = 0.02), less fatigue (p = 0.001), lower degree of impaired body image (p = 0.022) and less painful episodes (p = 0.014). Similarly, they had better emotional functioning, were less worried, stressed, depressed or nervous (p = 0.01) and were more satisfied with their treatment (p = 0.018). Not only does age associate with current treatments, but it also predicts how patients perceive QOL. Young patients express impaired QOL compared with elderly patients.
Background: Free Light Chain (FLC) assay is used for multiple myeloma screening, prediction of risk progression and response assessment as indicated by IMWG guidelines, particularly to define stringent complete response (sCR). The assay is also recommended in cases of unmeasurable (non-secretory, NS) or low values of M-protein (oligo-secretory, OS). Aims: Here we describe the value of FLC assay in predicting extramedullary relapse in four MM patients. Methods: During the course of therapy, FLC was monitored routinely on a monthly basis. Results: An OS MM IgG k patient (first case) started in May 2017 4 th line KRd therapy, due to new lytic lesions, with negative BM biopsy. During the course of therapy, sIFE remained negative, while sFLC continued to rise (May 2017 -March 2018: sFLC k 175 vs 340 mg/L, rFLC 4.2 vs 19.9). In March 2018 a right femur mass appeared and histology, confirmed EMD relapse. Patient underwent surgical removal and rFLC returned within normal range (1.3). Considering that it was the only site of disease, KRD regimen was restarted in June 2018 for four more cycles. Unfortunately, in November 2018 the knee mass reappeared, and, once again, sFLC was altered (FLC k 124 mg/L, ratio 25), with negative sIFE. Biopsy of the mass confirmed EMD relapse, BM biopsy remained negative. A patient with IgG k MM (second case) started in May 2017 2 nd line KRd therapy for disease progression, confirmed by BM biopsy. A partial response was obtained quickly, but since March 2018 a progressive rise of rFLC was noticed (March -September 2018: rFLC 0.67 vs 1.67), and it anticipated of 5 months the increase of MP (August 2018). In June 2018 patient complained vague gastrointestinal symptoms and in September a CT scan revealed hepatic nodularities, confirmed by biopsy as hepatic EMD. A LC MM l patient (third case) started in March 2017 KRd as 2 nd line treatment for disease progression (MP 0.7 g/dL, sFLC l 2000 mg/dL, rFLC 171), with positive BM biopsy. Patient obtained CR after the first cycle, but during the treatment in June 2018 sFLC started increasing and in July alteration of liver and bilirubin tests was noticed, without any clinical sign, always with negative sIFE. In October 2018 sIFE became positive and in November MP reappeared (0.37 g/dL) while both the sFLC (June -November 2018: sFLC l 53 vs 207 mg/dL; rFLC 6 vs 68) and the liver tests continued to rise. A solid hepatic mass was revealed and biopsy confirmed an EMD relapse. A MM IgA l patient (fourth case) diagnosed with biopsy of soft paravertebral tissues, was treated with 1 st line VMP treatment in September 2018. During the treatment the patient complained sight loss and a CT scan showed the presence of a right ocular mass. The MP was reduced while sFLC increased (September -October 2018: MP 2.4 vs 0.2 g/dL; sFLC l 158 vs 263 mg/dL; rFLC 5.7 vs 29.4). Biopsy confirmed an aggressive EMD relapse and the patient started 2 nd line KRD treatment in October 2018. A complete remission was obtained with ocular mass regression, negative sIFE and improvement of...
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