Muscle thixotropy: more than just cross-bridges?

AbstractAlthough Campbell and Lakie in a Comment to the Editor in this issue of Biophysical Journal suggested that exclusive cross-bridge action is behind muscle thixotropy, recent findings and our preliminary observations suggest that additional mechanisms could also be involved

Parkinson's disease in Gaucher disease patients: What's changing in the counseling and management of patients and their relatives?

Background: How to address the counseling of lifetime risk of developing Parkinson's disease in patients with Gaucher disease and their family members carrying a single variant of the GBA1 gene is not yet clearly defined. In addition, there is no set way of managing Gaucher disease patients, taking into account the possibility that they may show features of Parkinson's disease. Methods: Starting from an overview on what has recently changed in our knowledge on this issue and grouping the experiences of healthcare providers of Gaucher disease patients, we outline a path of counseling and management of Parkinson's disease risk in Gaucher disease patients and their relatives. Conclusion: The approach proposed here will help healthcare providers to communicate Parkinson's disease risk to their patients and will reduce the possibility of patients receiving inaccurate information from inadequate sources. Furthermore, this resource will help to empower healthcare providers to identify early signs and/or symptoms of Parkinson's disease and decide when to refer these patients to the neurologist for appropriate specific therapy and follow-up

Clinical relevance of DNA ploidy and proliferative activity in childhood rhabdomyosarcoma: a retrospective analysis of patients enrolled onto the Italian Cooperative Rhabdomyosarcoma Study RMS88.

Abstract: Purpose: Evaluation of the possible clinical relevance of DNA ploidy and proliferative activity assessed as S-phase fraction (SPF) in childhood rhabdomyosarcoma (RMS). Patients and Methods: We conducted a retrospective study on 59 RMS patients enrolled onto the ICS-RMS88 protocol (seven botryoid, 35 embryonal, and 17 alveolar RMS), for which formalin-fixed paraffin-embedded (FFPE) tissue was available. Nuclear suspensions for cytometric investigation were obtained using a mechanical disaggregation, Tumors were distinguished according to their DNA index (DI) value as follows: diploid (0.9 < DI < 1.1), hyperdiploid (1.1 less than or equal to DI < 1.8 or DI greater than or equal to 2.2), and tetraploid (1.8 less than or equal to DI < 2.2); for analysis of SPF, a cutoff value of 14% was used. Results: DNA histograms were diploid in 19 (33%) cases, hyperdiploid in 29 (49%), and tetraploid in 10 (32%). One patient showed both a hyperdiploid and a tetraploid peek. The 5-year overall survival (OS) rate by ploidy status was 73% in hyperdiploid patients as compared with 33% and 25% in diploid and tetraploid patients, respectively (P = .0012), A striking difference emerged when the 5-year OS for the combined diploid and tetraploid RMS groups was compared with survival of the hyperdiploid RMS group: 30% versus 73%, respectively (P = .0006). In addition, the SPF was prognostically relevant: 5-year OS by SPF less than or greater than 14% was 70% and 36%, respectively (P = .009). Multivariate analysis confirmed the importance of DNA content (P = .0006) and SPF (P = .034) in predicting survival. Conclusion: These findings confirm that ploidy and SPF are important new prognostic factors that are able to identify selected groups of patients at high risk of treatment failure, even if the tumor's presentation is favorable according to standard criteria. (C) 1997 by American Society of Clinical Oncology

Effects of simulated microgravity In vitro on human metaphase II oocytes: an electron microscopy-based study

The Gravity Force to which living beings are subjected on Earth rules the functionality of most biological processes in many tissues. It has been reported that a situation of Microgravity (such as that occurring in space) causes negative effects on living beings. Astronauts returning from space shuttle missions or from the International Space Station have been diagnosed with various health problems, such as bone demineralization, muscle atrophy, cardiovascular deconditioning, and vestibular and sensory imbalance, including impaired visual acuity, altered metabolic and nutritional status, and immune system dysregulation. Microgravity has profound effects also on reproductive functions. Female astronauts, in fact, suppress their cycles during space travels, and effects at the cellular level in the early embryo development and on female gamete maturation have also been observed. The opportunities to use space flights to study the effects of gravity variations are limited because of the high costs and lack of repeatability of the experiments. For these reasons, the use of microgravity simulators for studying, at the cellular level, the effects, such as those, obtained during/after a spatial trip, are developed to confirm that these models can be used in the study of body responses under conditions different from those found in a unitary Gravity environment (1 g). In view of this, this study aimed to investigate in vitro the effects of simulated microgravity on the ultrastructural features of human metaphase II oocytes using a Random Positioning Machine (RPM). We demonstrated for the first time, by Transmission Electron Microscopy analysis, that microgravity might compromise oocyte quality by affecting not only the localization of mitochondria and cortical granules due to a possible alteration of the cytoskeleton but also the function of mitochondria and endoplasmic reticulum since in RPM oocytes we observed a switch in the morphology of smooth endoplasmic reticulum (SER) and associated mitochondria from mitochondria-SER aggregates to mitochondria–vesicle complexes. We concluded that microgravity might negatively affect oocyte quality by interfering in vitro with the normal sequence of morphodynamic events essential for acquiring and maintaining a proper competence to fertilization in human oocyte

FSH treatment improves sperm DNA damage in men with idiopathic infertility carriers of the FSH receptor p.N680S homozygous N genotype: an interim analysis

Study question: To assess whether in men with idiopathic infertility, the sperm DNA fragmentation (sDF) improves depending on the FSH receptor (FSHR) genotype as assessed by the non-synonymous polymorphisms (SNP) rs6166 (wild type or p.N680S). Summary answer: FSH treatment improves sDF in a subgroup of idiopathic infertile men, although 40% of these men do not show any significant improve- ment. The response of sDF, a surrogate marker of sperm quality, together with the evaluation of FSHR SNP p.N680S might be useful to predict the response to FSH treatment. What is known already: FSH is fundamental for spermatogenesis and is em- pirically used to treat male idiopathic infertility. Several studies suggest that sDF could be a candidate predictor of response to FSH treatment, in terms of probability to conceive. Furthermore, it is widely accepted that the FSHR SNP p.N680S influences ovarian response in women and testicular volume in men. Study design, size, duration: Multicenter, longitudinal, prospective, open-la- bel, two-arms clinical trial. Subjects enrolled were idiopathic infertile men and received 150 IU of recombinant FSH (Gonal f®) every other day for 12 weeks and were then followed-up for further 12 weeks after FSH-withdrawal. Patients were evaluated at baseline and at the end of the two phases. Participants/materials, setting, methods: Eighty-eight men with idiopathic male infertility carrier of the homozygous FSHR p.N680S N or S genotype, FSH 15%, were enrolled. 66 patients completed the sDF analysis. sDF was centrally evaluated by TUNEL/PI assay coupled to flow cy- tometry, resolving two different sperm populations, namely: PIbrighter and PIdimmer. Main results and the role of chance: Thirty-seven men (56%) were carriers of the p.N680S homozygous-N and 29 (44%) of the homozygous-S genotype, respectively. Total sDF (PIbrighter + PIdimmer) was significantly lower at the end of the study in patients carriers of the p.N680S-N allele than patients carri- ers of p.N680S-S allele (p = 0.008). Only in patients carriers of the p.N680S-N allele, total sDF decreased significantly from baseline to the end of the study (p = 0.021) and this decrease was entirely sustained by the sperm population containing vital sperms (i.e., PIbrighter fraction) (p = 0.008). PIdimmer frac- tion, including only non-vital sperms, was significantly higher in patients car- riers of the p.N680S-S allele than in carriers of N allele (p = 0.018). Total sDF was inversely related to total sperm number (p = 0.020) and progressive sperm motility (p = 0.014). Limitations, reason for caution: The statistical power of the results obtained so far is 86.9%, with alpha-error 0.05. This is an interim-analysis. Wider implications of the findings: The study suggests that FSH treatment induces a significant improvement of total sDF in men carriers of the p.N680S homozygous N allele. This sDF decrease awaits confirmation, since the study will be completed by June 2015. Study funding/competing interest(s): Funding by commercial/corporate company(ies) – The study was supported by unrestricted grant by Merck Serono. Trial registration number: EudraCT number 2010-020240-35. Keywords: FSH treatment, male infertility, Sperm-DNA fragmentatio

Three-dimensional stochastic model of actin–myosin binding in the sarcomere lattice

The effect of molecule tethering in three-dimensional (3-D) space on bimolecular binding kinetics is rarely addressed and only occasionally incorporated into models of cell motility. The simplest system that can quantitatively determine this effect is the 3-D sarcomere lattice of the striated muscle, where tethered myosin in thick filaments can only bind to a relatively small number of available sites on the actin filament, positioned within a limited range of thermal movement of the myosin head. Here we implement spatially explicit actomyosin interactions into the multiscale Monte Carlo platform MUSICO, specifically defining how geometrical constraints on tethered myosins can modulate state transition rates in the actomyosin cycle. The simulations provide the distribution of myosin bound to sites on actin, ensure conservation of the number of interacting myosins and actin monomers, and most importantly, the departure in behavior of tethered myosin molecules from unconstrained myosin interactions with actin. In addition, MUSICO determines the number of cross-bridges in each actomyosin cycle state, the force and number of attached cross-bridges per myosin filament, the range of cross-bridge forces and accounts for energy consumption. At the macroscopic scale, MUSICO simulations show large differences in predicted force-velocity curves and in the response during early force recovery phase after a step change in length comparing to the two simplest mass action kinetic models. The origin of these differences is rooted in the different fluxes of myosin binding and corresponding instantaneous cross-bridge distributions and quantitatively reflects a major flaw of the mathematical description in all mass action kinetic models. Consequently, this new approach shows that accurate recapitulation of experimental data requires significantly different binding rates, number of actomyosin states, and cross-bridge elasticity than typically used in mass action kinetic models to correctly describe the biochemical reactions of tethered molecules and their interaction energetics

European retrospective study of real-life haemophilia treatment

IntroductionHaemophilia treatment varies significantly between individuals, countries and regions and details of bleed rates, factor consumption and injection frequency are often not available.AimTo provide an overview of the FVIII/FIX treatment practice and outcome for patients with haemophilia A (HA) or haemophilia B (HB) across Europe.MethodsNon‐interventional, 12‐month retrospective study where anonymized data were retrieved from haemophilia centres/registers in Belgium, France, Germany, Italy, Spain, Sweden and the United Kingdom. Male patients (all ages) receiving coagulation factor treatment 24 months prior to the study, with basal FVIII/FIX levels ≤5 IU dL−1, without inhibitors, were included. Data were summarized descriptively.ResultsIn total, 1346 patients with HA and 312 with HB were included in the analysis; 75% and 57% had severe disease (FVIII/FIX < 1 IU dL−1) respectively. Prophylaxis was most common for severe haemophilia, especially for children, whereas on‐demand treatment was more common for moderate haemophilia in most countries. The mean (SD) prescribed prophylactic treatment ranged from 67.9 (30.4) to 108.4 (78.1) (HA) and 32.3 (10.2) to 97.7 (32.1) (HB) IU kg−1 per week, across countries. Most patients on prophylaxis were treated ≥3 times/week (HA) or two times/week (HB). The median annual bleeding rate (ABR) for patients on prophylaxis ranged from 1.0 to 4.0 for severe HA, and from 1.0 to 6.0 for severe HB, while those with moderate haemophilia generally had slightly higher ABRs. Median ABRs for on‐demand‐treated severe HA ranged from 4.5 to 18.0, and for HB, 1.5 to 14.0.ConclusionTreatment practice varied greatly between centres and countries and patients treated on‐demand and prophylactically both experienced bleeds, emphasizing the need for further optimization of care