Significance of atomic-scale defects in flexible surfaces on local solvent and ion behaviour.

Many factors can affect the course of heterogeneous nucleation, such as surface chemistry, flexibility and topology, substrate concentration and solubility. Atomic-scale defects are rarely investigated in detail and are often considered to be unimportant surface features. In this work, we set out to investigate the significance of atomic-scale defects in a flexible self-assembled monolayer surface for the behaviour of clusters of Ca2+ and CO32- ions in water. To this end, we use molecular dynamics simulations to estimate the diffusion coefficients of ion clusters at different topological surface features and obtain ionic radial distribution functions around features of interest. Well-tempered metadynamics is used to gain insight into the free energy of ions around selected surface defects. We find that certain defects, which we refer to as active defects, can impair ionic surface diffusion, as well as affect the diffusion of ions in close proximity to the surface feature in question. Our findings suggest that this effect can result in an ability of such topological features to promote ion clustering and increase local ionic concentration at specific surface sites. The work reported here shows how the presence of small atomic-scale defects can affect the role of a surface in the process of heterogeneous nucleation and contributes towards a rational definition of surfaces as effective nucleating agents.

Identifying Conformational Isomers of Organic Molecules in Solution via Unsupervised Clustering.

We present a systematic approach for the identification of statistically relevant conformational macrostates of organic molecules from molecular dynamics trajectories. The approach applies to molecules characterized by an arbitrary number of torsional degrees of freedom and enables the transferability of the macrostates definition across different environments. We formulate a dissimilarity measure between molecular configurations that incorporates information on the characteristic energetic cost associated with transitions along all relevant torsional degrees of freedom. Such metric is employed to perform unsupervised clustering of molecular configurations based on the Fast Search and Find of Density Peaks algorithm. We apply this method to investigate the equilibrium conformational ensemble of Sildenafil, a conformationally complex pharmaceutical compound, in different environments including the crystal bulk, the gas phase, and three different solvents (acetonitrile, 1-butanol, and toluene). We demonstrate that while Sildenafil can adopt more than 100 metastable conformational configurations, only 12 are significantly populated across all of the environments investigated. Despite the complexity of the conformational space, we find that the most abundant conformers in solution are the closest to the conformers found in the most common Sildenafil crystal phase.

Time-independent free energies from metadynamics via mean force integration.

Inspired by thermodynamic integration, we propose a method for the calculation of time-independent free energy profiles from history-dependent biased simulations via Mean Force Integration (MFI). MFI circumvents the need for computing the ensemble average of the bias acting on the system c(t) and can be applied to different variants of metadynamics. Moreover, MFI naturally extends to aggregate information obtained from independent metadynamics simulations, allowing to converge free energy surfaces without the need to sample recrossing events in a single continuous trajectory. We validate MFI against one- and two-dimensional analytical potentials and by computing the conformational free energy landscape of ibuprofen in the bulk of its most common crystal phase.

The ageing patient with haemophilia.

Older patients with haemophilia (PWH) face many challenges related not only to haemophilia but also to general comorbidities associated with ageing. This article discusses the clinical experience published about the high prevalence of diseases in older PWH. These conditions are managed in the general population by healthcare workers with little training in haemophilia. Haemophilic arthropathy is common in elderly PWH. Prophylaxis starting at an early age in sufficient dose regimens to prevent arthropathy did not occur in patients who are now older than around 40 yr. Many PWH above this age thus have limitations in their activities of daily life. Cardiovascular diseases have become increasingly common in the growing, ageing cohort of PWH. Lifestyle issues such as sexual dysfunction may be exacerbated by the medical issues and psychological problems associated with haemophilia. Hepatitis C virus is a leading problem in PWH. Coinfection with HIV accelerates the progression to end-stage liver disease. Acute and chronic renal failure is more common in adult PWH than in general population. Other comorbidities are reviewed. The evidence is scarce, so it is imperative to report any experience regarding the diagnosis and treatment of these entities, to improve the quality of life of older PWH.

Investigating the Role of Solvent in the Formation of Vacancies on Ibuprofen Crystal Facets.

Surface defects play a crucial role in the process of crystal growth, as incorporation of growth units generally takes place on undercoordinated sites on the growing crystal facet. In this work, we use molecular simulations to obtain information on the role of the solvent in the roughening of three morphologically relevant crystal faces of form I of racemic ibuprofen. To this aim, we devise a computational strategy to evaluate the energetic cost associated with the formation of a surface vacancy for a set of ten solvents, covering a range of polarities and hydrogen bonding propensities. We find that the mechanism as well as the work of defect formation are markedly solvent and facet dependent. Based on Mean Force Integration and Well Tempered Metadynamics, the methodology developed in this work has been designed with the aim of capturing solvent effects at the atomistic scale while maintaining the computational efficiency necessary for implementation in high-throughput in-silico screenings of crystallization solvents.

Clinical characteristics, disease evolution and survival in patients with chronic myeloid leukemia, BCR-ABL1 (+) and T315I mutation.

INTRODUCTION: The T315I mutation in patients with chronic myeloid leukemia (CML) has been associated with therapeutic resistance and an unfavourable prognosis. AIM: To study the frequency of T315I mutation in patients with CML, BCR-ABL (+), their clinical characteristics, disease evolution, and median survival. PATIENTS AND METHODS: We studied 75 patients with CML and BCR-ABL1 (+). T315I mutation was detected by digital droplet PCR and BCR-ABL1 was analyzed by RT-PCR. A comparative analysis was performed by sex, age, disease phase, risk group, treatment, molecular response (MR), and median survival in T315I (+) and T315I (-) patients. RESULTS: T315I mutation was detected in 11 patients (14.7%). No significant difference was found in the phase, risk group, and first-line therapy. A significantly higher proportion of T315I (+) did not achieve MR >3.5 log: 8 (72.7%) vs. 22 (34.4%) (p=0.023). The lowest mean BCR-ABL1 levels were significantly higher in the CML T315I (+) group compared to the CML T315I (-) group: 12.1±6.0 vs. 3.77±1.28 (p=0.009). The median survival of T315I (+) patients was significantly shorter: 73 months vs. 175 months (p<0.0001, CI 95%). CONCLUSIONS: Our data confirm the world experience on the frequency of T315I mutation, including the unfavourable evolution, resistance to TKI treatment and short survival. ddPCR is a highly sensitive method for early detection of genetic mutations which gives the chance for effective treatment.

Reduction of Liver Iron Load in Adult Patients with ß-Thalassemia Major Treated with Modern Chelation Modalities.

BACKGROUND: Management of beta-thalassemia major (TM) requires life-long hemotransfusions leading to iron overload. Iron elimination is enhanced by the use of modern chelators. AIM: To assess the effect of modern chelation therapy by dynamics of serum ferritin concentration and liver MRI T2*. PATIENTS AND METHODS: Forty-six patients with TM (male to female ratio =1:1, mean age 33.2±10.9 years) were prospectively studied between 2011 and 2014. Twenty-one patients (45.7%) were treated with deferasirox, 17 (37%) - with deferiprone, and 8 (17.3%) - with deferiprone in combination with deferoxamine. Ferritin was measured by ELISA. MRI T2* was assessed by Siemens Magnetom Avanto 1.5T. The patients were allocated into 3 groups based on their initial ferritin level and liver MRI T2*. Statistical analysis was performed using SPSS v. 18 for Windows. Data were analysed by descriptive analysis, analysis of variance and correlative analysis, means were compared using t-test and one-way ANOVA. RESULTS: In 2011, 9 (19.5%) patients had normal liver MRI T2*; in 2014 they were 17 (37%). The patients with mild grade liver siderosis were 12 (26%) in 2011, and in 2014 they were 14 (30.4%). In 2011, the patients with moderate liver siderosis were 14 (30.4%), and in 2014 - 12 (26.0%). Eleven patients (23.9%) had severe liver siderosis in 2011 and only two patients (4.0%) were diagnosed with the condition in 2014. CONCLUSION: A reduction of iron overload was found in all studied groups. This positive effect is attributed to the use of modern chelators and the ease of access to accurate monitoring.

Dynamics and Thermodynamics of Ibuprofen Conformational Isomerism at the Crystal/Solution Interface.

Conformational flexibility of molecules involved in crystal growth and dissolution is rarely investigated in detail and usually considered to be negligible in the formulation of mesoscopic models of crystal growth. In this work, we set out to investigate the conformational isomerism of ibuprofen as it approaches and is incorporated in the morphologically dominant {100} crystal face, in a range of different solvents: water, 1-butanol, toluene, cyclohexanone, cyclohexane, acetonitrile, and trichloromethane. To this end, we combine extensive molecular dynamics and well-tempered metadynamics simulations to estimate the equilibrium distribution of conformers, compute conformer-conformer transition rates, and extract the characteristic relaxation time of the conformer population in solution, adsorbed at the solid/liquid interface, incorporated in the crystal in contact with the mother solution, and in the crystal bulk. We find that, while the conformational equilibrium distribution is weakly dependent on the solvent, relaxation times are instead significantly affected by it. Furthermore, differences in the relaxation dynamics are enhanced on the crystal surface, where conformational transitions become slower and specific conformational transition pathways are hindered. This leads us to observe that the dominant mechanisms of conformational transition can also change significantly moving from the bulk solution to the crystal interface, even for a small molecule with limited conformational flexibility such as ibuprofen. Our findings suggest that understanding conformational flexibility is key to provide an accurate description of the solid/liquid interface during crystal dissolution and growth, and therefore, its relevance should be systematically assessed in the formulation of mesoscopic growth models.

Mutations Associated with Imatinib Mesylate Resistance - Review.

Chronic myeloid leukemia (CML) arises from the fusion of the BCR and the ABL1 genes. The BCR gene (chromosome 22q11.2) and the ABL1 gene (chromosome 9q34) fuse together due to reciprocal chromosome translocation forming the Philadelphia chromosome (Ph). This fusion gene codes tyrosine kinase which accelerates the cell division and reduces DNA repair. Imatinib mesylate is a selective inhibitor of this tyrosine kinase. It is the first-line treatment for CML-patients. However, it became clear that Philadelphia-positive (Ph+) cells could evolve to elude inhibition due to point mutations within the BCR-ABL kinase domain. To date more than 40 mutations have been identified and their early detection is important for clinical treatment. With the development of the new tyrosine kinase inhibitors (TKIs), associated with these mutations, the resistance problem seems to diminish, as some of the new drugs are less prone to resistance. The aim of this review is to focus on the diff erent mutations leading to resistance.

Serum levels of OPG, RANKL and RANKL/OPG ratio in newly-diagnosed patients with multiple myeloma. Clinical correlations.

Serum levels of OPG and RANKL and their clinical correlations were analyzed in 66 newly-diagnosed patients with multiple myeloma (MM). RANKL and RANKL /OPG ratio were significantly increased in advanced clinical stages and high grade myeloma bone disease (MBD), while OPG showed a tendency to decrease. Renal failure modified the expression of OPG. RANKL and RANKL/OPG ratios are informative markers for myeloma tumor burden and MBD.

Bortezomib (Velcade)--a new therapeutic strategy for patients with refractory multiple myeloma.

Proteasome inhibitors are emerging as a promising class of anti-cancer therapeutic agents. The first of this new class of drugs with a clinical significance, bortezomib (PS 341, Velcade), is a modified dipeptidyl boronic acid. Bortezomib reduces the NF-kappaB translocation / transcription and blocks the drug-related signalling pathways critical to basic vital functions of myeloma cells. Bortezomib induces apoptosis by releasing cytochrome C from mitochondria and by activating caspase-9 and Jun-kinases (JNK) and the Fas-caspase-8-dependent apoptotic pathway. Bortezomib has been reported to down-regulate cytokine-induced expression of VCAM-1, a major ligand on bone marrow stromal cells for VLA-4; it inhibits the heterotypic adherence between the myeloma cells and stromal cells and blocks the signalling pathways of resistance to apoptosis. The drug has been shown experimentally to inhibit the IL-6-induced proliferation of myeloma cells; it demonstrates synergy with dexamethasone and inhibits angiogenesis. Phase II/ III clinical studies with Velcade have shown an overall therapeutic response rate of 35% in refractory, relapsed myeloma patients (Bladé criteria). These surprisingly good results, the drug's good tolerance and controllable side effects provide a solid base for further studies on bortezomib, including studies on the drug used as front line therapy.

Bone lesions in multiple myeloma--the OPG/RANK-ligand system.

Multiple myeloma has recently been found to induce considerable imbalance in the newly identified system of osteoprotegerin (OPG), receptor activator of nuclear factor KB ligand (RANKL) and RANK. The binding of RANKL to RANK on the surface of osteoclastic precursors in the presence of m-CSF activates the signalling pathways for differentiation and proliferation of an osteoclastic line. OPG is a decoy circulating receptor for RANKL which blocks its binding to RANK. There are at least three mechanisms by which myeloma cells affects the OPG/ RANKL/RANK system: 1: The adhesion between the myeloma / stromal cells and the osteoblastic precursors stimulates the system by increasing the production of RANKL. 2: Some myeloma lines produce independently membrane-bound or free RANKL. 3: The normal and mutated plasma cells bind, degrade and block the OPG production from the stromal cells. The OPG/RANKL/RANK system is the latest therapeutic target in the treatment of myeloma bone disease. The first results from the application of a synthetic analogue of OPG, as well as of RANKL antagonists or RANK inhibitors show decrease of the number of osteoclasts, osteolytic lesions and M-gradient.