11 research outputs found
Revisiting the form finding techniques of Sergio Musmeci: the Bridge over the Basento River
No full textSergio Musmeci (1926‐1981), once an apprentice to Pier Luigi Nervi (1892‐1979) and Riccardo
Morandi (1902‐1989), is noteworthy for his ability to design and construct continuous shells
with unprecedented shapes well ahead of his time. He had the design goal of minimizing area
while maximizing structural function in shells. Musmeci’s Basento Viaduct in Potenza, Italy
was built from 1972‐75, and is a historical example of this structural efficiency. What is most
intriguing about Musmeci is his understanding and manipulation of physical, numerical and
analytical methods of form finding prior to achieve his design intent. This work investigates
Sergio Musmeci’s previous experience leading to the Basento Viaduct project, analyzes his
modeling and testing techniques of the time, and revisits and discusses the shape generation of
the three dimensional structural surface structure using contemporary numerical form finding
techniques. The final shape is then validated with the support of a FE model
Assessment of Disintegration of Compostable Bioplastic Bags by Management of Electromechanical and Static Home Composters
No full textInterest in small scale composting systems is currently growing, and this in turn raises the question of whether the compostable bags are as suitable as in industrial composting facilities. In this work the physical degradation percentage of compostable lightweight bioplastic bags in two types of composter was examined. The main goal was to understand whether the mild biodegrading conditions that occur in electromechanical or static home composters are sufficient to cause effective bag degradation in times consistent with the householders’ or operators’ expectations. Bags, which complied with standard EN 13432, were composted in a number of 600 L static home composters, which were run in different ways (e.g., fed only with vegetables and yard waste, optimizing the humid/bulking agent fraction, poorly managed) and a 1 m3 electromechanical composter. Six months of residence time in static home composters resulted in 90–96 wt% degradation depending on the management approach adopted, and two months in the electromechanical composter achieved 90 wt%. In the latter case, three additional months of curing treatment of the turned heaps ensured complete physical degradation. In conclusion, in terms of the level and times of physical degradation, the use of compostable bioplastic bags appeared promising and consistent with home composting practices
Reversible Histone Acetylation During Preimplantation Embryo Development in Mammals
No full textHistone acetylation is an epigenetic modification responsible for changes in chromatin architecture, accessibility, and ultimately gene expression. At the onset of a new life, when the fully differentiated parental genomes fuse together to generate a new totipotent cell, the gametes' epigenetic program must be erased, and new ones are progressively installed. Together with other epigenetic modifications, histone acetylation participates in the early events of embryogenesis, undergoing dynamic changes that involve several amino acid residues on different histone proteins. By analyzing studies that followed these changes during the preimplantation development in different mammals, we identified critical windows of acetylation/deacetylation in relation to the oocyte-to-zygote transition, the activation of the embryonic genome, and the specification of cell lineages, all crucial events for early embryo development, the establishment of pluripotent embryonic tissue, and ultimately of a multicellular organism.Finally, this survey points out the possibility that while contributing to the necessary plasticity of the embryonic stem cells, the reversibility of histone acetylation/deacetylation patterns renders this mechanism prone to be hijacked by environmental conditions, such as maternal diet or pollutants, leading to the alterations of epigenetic marks that can be potentially transmitted to the daughter cells and up to adulthood
Effect of treatment with myo-inositol on semen parameters of patients undergoing an IVF cycle: In vivo study
No full textIntroduction: Myo-inositol (MI) is a precursor for the synthesis of phosphatidylinositol polyphosphates (PIPs). The aim of the study is to evaluate the effect of its administration on semen parameters of male patients undergoing an in vitro fertilization cycles. Methods: In vivo study. Samples were semen of 62 patients divided into three different groups: healthy fertile patients (Group A); patients with oligoasthenospermia (OA) (Group B); control group (CTR). The collected samples were analyzed by optic microscopy in order to evaluate semen’s volume, spermatozoa’s number and motility before and after density-gradient separation method. These parameters were evaluated before and after administration of 4000 mg/die of MI and 400 mg of folic acid for 2 months. The results were analyzed statistically with Student’s t-test. Results: After treatment there was a significant increase of basal and after density-gradient separation method spermatozoa concentration in Group B, and a significant increase of spermatozoa count after density-gradient separation method in Group A. The motility values were higher in healthy men than patients with OA before treatment, but there was no improvement in both groups after treatment. Conclusions: Exogenous administration of MI significantly improves semen’s parameters both in patients with OA and in normal fertile men
Resilience of preimplanta0on bovine embryos to the availability of energy substrates
No full textExposure to metabolic stress during fetal life increases the suscep0bility to metabolic diseases in adulthood. This no0on is supported by epidemiological and experimental evidences that led to the theoriza0on of the Developmental Origins of Health and Disease. The adap0ve mechanisms the embryo/fetus puts in place to cope with intra-uterine stressors is defined developmental plas0city and entails the capacity of one genotype to generate several phenotypes in response to a different environment. To capture the main molecular events of developmental plas0city, we monitored the gene expression of bovine blastocysts exposed in vitro to a mild metabolic challenge. With preliminary experiments we standardized the experimental model to remove sources of variability, such as serum, embryos of different sex, and blastocyst at different stages. Then metabolic challenges were administered by varying the content in energe0c substrates of the culture medium. Three energe0c levels, containing 0.5, 1.0, and 1.5-fold increase in energe0c substrates, were selected based on the absence of apparent changes in preimplanta0on embryo development, evaluated by blastocyst rate, distribu0on of blastocyst morphology (early, expanded, hatch-ed/ing), number of cells composing the blastocyst, and paWern of cell lineage specifica0on. Genome-wide analysis revealed minimal differences in gene expression among the three groups, likely exposing key regulatory genes whose differen0al expression allowed the adapta0on to the changing metabolic environment. Two dis0nct expression paWerns were observed for these genes: progressive upregula0on and progressive downregula0on along with the increasing energe0c availability. The lack of substan0al differences seems in line with the general observa0on that offspring born aZer a mild intra-uterine exposure to metabolic stress have normal physiological and biochemical parameters un0l later in life, while a generalized disrup0on of gene expression would probably impact embryo/fetal/early post-natal life rather than induce a late onset of the disease. Nevertheless, if metabolic stress experienced during preimplanta0on development were to commit a late phenotype, some kind of mark shall be established at this stage. A possible answer to this ques0on came from the analysis of transcript isoforms. Using a specific bioinforma0c pipeline, the presence of two or more transcript isoforms of genes related to epigene0c changes and nuclear reprogramming were detected, indica0ng that, even in absence of obvious changes in gene expression, the metabolic challenge induced biological effects that can be epigene0cally encoded in the embryo. As a proof of concept, acetyla0on of histone proteins increased when the energe0c substrates were higher.
These findings shed light on the mechanisms at the onset of developmental plas0city, whereby the ac0va0on/repression of few key genes and usage of transcript isoforms confer resilience to metabolic stressors and provide a direct link between changes in the availability of energe0c substrates and epigene0c reprogramming.
Funded by: MUR PRIN2017, No. 20172N2WL3_002; Piano di Sostegno alla Ricerca UNIMI: Linea 2 – Azione
Ciclo riproduttivo di Arbacia lixula (Linneo, 1758) (Echinodermata: echinoidea) nella AMP “Isola di Ustica”
No full textA Nuclear and Cytoplasmic Characterization of Bovine Oocytes Reveals That Cysteamine Partially Rescues the Embryo Development in a Model of Low Ovarian Reserve
No full textDecreased oocyte quality is a major determinant of age-associated fertility decline. Similarly, individuals affected by early ovarian aging carry low-quality oocytes. Using an established bovine model of early ovarian aging, we investigated key features of ‘quality’ oocyte maturation, associated with the onset of egg aneuploidy and reproductive aging, such as histone modifications, mitochondria distribution and activity, reduced glutathione (GSH) content, and gap junction functionality. Bovine ovaries were classified according to the antral follicle count (AFC), and the retrieved oocytes were processed immediately or matured in vitro. We observed alterations in several cellular processes, suggesting a multifactorial etiology of the reduced oocyte quality. Furthermore, we performed a rescue experiment for one of the parameters considered. By adding cysteamine to the maturation medium, we experimentally increased the free radical scavenger ability of the ‘low competence’ oocytes and obtained a higher embryo development. Our findings show that adopting culture conditions that counteract the free radicals has a positive impact on the quality of ‘compromised’ oocytes. Specifically, cysteamine treatment seems to be a promising option for treating aging-related deficiencies in embryo development
European compliance benchmark
No full textThe International Legal Research Group -European Compliance Benchmark is acooperation between The European Law Students' Association (ELSA) and K&L Gates. K&L Gates has provided ELSA with research questionsthat24 member and observer groups in our network successfullyinvestigatedin the framework of their respective national legislation. The topic of this LRG centered around the world of Corporate Compliance, as it is one of the hottest legal topicscurrently. What is meant by this is the degree to which companies abide by the regulations set for corporate governance and prevention of criminal measures in a commercial context. The questions of the LRG focused on outlining the relevant rules as well as assessing what the ramifications are for breaking them
Progress toward species-tailored prematuration approaches in carnivores
No full textIn the past four decades, the bovine model has been highly informative and inspiring to assisted reproductive technologies (ART) in other species. Most of the recent advances in ART have come from studies in cattle, particularly those unveiling the importance of several processes that must be recapitulated in vitro to ensure the proper development of the oocyte. The maintenance of structural and functional communications between the cumulus cells and the oocyte and a well-orchestrated chromatin remodeling with the gradual silencing of transcriptional activity represent essential processes for the progressive acquisition of oocyte developmental competence. These markers are now considered the milestones of physiological approaches to increase the efficiency of reproductive technologies. Different in vitro approaches have been proposed. In particular, the so-called "pre-IVM" or "prematuration" is a culture step performed before in vitro maturation (IVM) to support the completion of the oocyte differentiation process. Although these attempts only partially improved the embryo quality and yield, they currently represent a proof of principle that oocytes retrieved from an ovary or an ovarian batch shouldn't be treated as a whole and that tailored approaches can be developed for culturing competent oocytes in several species, including humans. An advancement in ART's efficiency would be desirable in carnivores, where the success is still limited. Since the progress in reproductive medicine has often come from comparative studies, this review highlights aspects that have been critical in other species and how they may be extended to carnivores
