Chromatin fibers are formed by heterogeneous groups of nucleosomes in vivo.

Nucleosomes help structure chromosomes by compacting DNA into fibers. To gain insight into how nucleosomes are arranged in vivo, we combined quantitative super-resolution nanoscopy with computer simulations to visualize and count nucleosomes along the chromatin fiber in single nuclei. Nucleosomes assembled in heterogeneous groups of varying sizes, here termed "clutches," and these were interspersed with nucleosome-depleted regions. The median number of nucleosomes inside clutches and their compaction defined as nucleosome density were cell-type-specific. Ground-state pluripotent stem cells had, on average, less dense clutches containing fewer nucleosomes and clutch size strongly correlated with the pluripotency potential of induced pluripotent stem cells. RNA polymerase II preferentially associated with the smallest clutches while linker histone H1 and heterochromatin were enriched in the largest ones. Our results reveal how the chromatin fiber is formed at nanoscale level and link chromatin fiber architecture to stem cell state.

Myc Regulates Chromatin Decompaction and Nuclear Architecture during B Cell Activation.

50 years ago, Vincent Allfrey and colleagues discovered that lymphocyte activation triggers massive acetylation of chromatin. However, the molecular mechanisms driving epigenetic accessibility are still unknown. We here show that stimulated lymphocytes decondense chromatin by three differentially regulated steps. First, chromatin is repositioned away from the nuclear periphery in response to global acetylation. Second, histone nanodomain clusters decompact into mononucleosome fibers through a mechanism that requires Myc and continual energy input. Single-molecule imaging shows that this step lowers transcription factor residence time and non-specific collisions during sampling for DNA targets. Third, chromatin interactions shift from long range to predominantly short range, and CTCF-mediated loops and contact domains double in numbers. This architectural change facilitates cognate promoter-enhancer contacts and also requires Myc and continual ATP production. Our results thus define the nature and transcriptional impact of chromatin decondensation and reveal an unexpected role for Myc in the establishment of nuclear topology in mammalian cells.

Double gonosomal mosaicism as an unusual hereditary mechanism in familial GRIN2A-related disorder.

We aim to describe double gonosomal mosaicism in the GRIN2A gene in a mother who passed on two different pathogenic variants at the same nucleotide to her two affected children. We studied a boy with epilepsy and intellectual disability, along with his sister and mother who exhibited language impairment and learning difficulties without epilepsy. We identified in the proband a splice-site variant in GRIN2A (c.1008-1G>A) inherited from his mother. Subsequent testing of his sister revealed a different change at the same nucleotide c.1008-1G>T, which was also present in the mother's DNA at 3.9% allele frequency. The co-occurrence of two mutational events at the same nucleotide is extremely rare. Since a chance occurrence is unlikely, we hypothesise that a base mismatch may introduce instability triggering a second event. In this family, the mother carries three alleles, of which one is at very low frequency. This complex genetic landscape poses diagnostic challenges since low-level mosaicism may escape detection via conventional methods. Applying specific technology becomes crucial, as double mosaicism might prove to be more prevalent than anticipated severely impacting diagnostic accuracy and genetic counselling.

A yeast synthetic network for in vivo assessment of reverse-engineering and modeling approaches.

Systems biology approaches are extensively used to model and reverse engineer gene regulatory networks from experimental data. Conversely, synthetic biology allows "de novo" construction of a regulatory network to seed new functions in the cell. At present, the usefulness and predictive ability of modeling and reverse engineering cannot be assessed and compared rigorously. We built in the yeast Saccharomyces cerevisiae a synthetic network, IRMA, for in vivo "benchmarking" of reverse-engineering and modeling approaches. The network is composed of five genes regulating each other through a variety of regulatory interactions; it is negligibly affected by endogenous genes, and it is responsive to small molecules. We measured time series and steady-state expression data after multiple perturbations. These data were used to assess state-of-the-art modeling and reverse-engineering techniques. A semiquantitative model was able to capture and predict the behavior of the network. Reverse engineering based on differential equations and Bayesian networks correctly inferred regulatory interactions from the experimental data.

Autism and mild epilepsy associated with a de novo missense pathogenic variant in the GTPase effector domain of DNM1.

Dynamin 1 is a GTPase protein involved in synaptic vesicle fission, which facilitates the exocytosis of neurotransmitters necessary for normal signaling. Pathogenic variants in the DNM1 gene are associated with intractable epilepsy, often manifested as infantile spasms at onset, developmental delay, and a movement disorder, and are located in the GTPase and middle domains of the protein. We describe a 36-year-old man with autism and moderate intellectual disability who experienced only a few generalized seizures between the age 16 and 30 years. Using a whole sequencing approach, we identified the c.1994T>C p.(Leu665Pro) de novo novel missense pathogenic variant in the GTPase effector domain (GED) of the DNM1 protein. Structural analyses suggest that this substitution impairs both the stalk formation and its interactions, known to be important for the dynamin-1 physiological cellular function. Our data expand the spectrum of phenotypes associated with pathogenic variants in the DNM1 gene, linking a variant in the GED domain with autism and onset in the adolescence of mild epilepsy, a phenotypic presentation remarkably different from the early infantile epileptic encephalopathy associated with pathogenic variants in the GTPase or middle domains.

The neglected role of preimplantation genetic testing for Lynch syndrome.

Preimplantation genetic testing for monogenic/single-gene disorders (PGT-M) is a procedure employed in the field of assisted reproductive technology to avoid the transmission of genetic diseases to the offspring. Hereditary cancer syndromes represent a diffuse and accepted indication for PGT-M, but take-up differs among the different disorders. Its use is markedly lower for the genes causing Lynch syndrome compared with the breast cancer type 1 or 2 susceptibility genes (BRCA1/2), despite the similar prevalence and severity of the two conditions. Reasons to explain this difference have not been explored. First, Lynch syndrome may be more frequently undiagnosed compared with hereditary breast and ovarian cancer syndrome. In addition, the different take-up may be due to different patient perceptions of the conditions and of the management options. Finally, this distinct attitude may depend on the awareness and sensibility of the professionals caring for affected patients. The authors' considerations are, however, speculative, and specific studies aimed at disentangling the causes of the different receptions of PGT-M are warranted to understand how to tackle this gap. In the meantime, we believe that empowerment regarding PGT-M of all individuals with hereditary cancer syndromes, including Lynch syndrome, is ethically due, and plead for a more active involvement of caregivers.

Unexpected enhancement of pH-stability in Au3+/Ag+ loaded H-bonded layer-by-layer thin films.

In this work, a polymeric film was synthesized through a layer-by-layer (LBL) self-assembly technique using polyacrylic acid (PAA) and polyethylene oxide (PEO), resulting in the formation of a hydrogen-bonded LBL film. The formation of these films was evaluated by PMIRRAS and QCM-D. The synergy of these techniques allowed the understanding of the mechanism of formation of the film by showing the H-bonding formation and film growth. Au and Ag metal ions were successfully incorporated into the films, as corroborated by the combination of the information obtained by XRR and PMIRRAS. The films were exposed to increasing pH, showing a pronounced improvement in stability in films loaded with Au ions, extending the stability from pH 4 to 10. This behavior allows the use of this system in a wider range of applications, including the possibility of working in biological conditions. On the other hand, films loaded with Ag disintegrated at pH above 4. At acidic pH (below 3), these films released the Ag ions, which may be useful for the preparation of antibacterial stimuli-responsive nanomaterials. In both cases, the films were adequate to produce metal nanoparticles by metal loading and in situ reduction.

Quality of life after prophylactic surgery for colorectal adenomatous polyposis.

PURPOSE: Colorectal adenomatous polyposis is characterized by the onset of tens to thousands of adenomas in the colorectal epithelium and, if not treated, leads to a lifetime increased risk of developing colorectal cancer compared to the general population. Thus, prophylactic surgery is recommended. This study aims to investigate the quality of life of colorectal adenomatous polyposis patients following prophylactic surgery and indirectly compares these findings with those of healthy adults of the normative sample. METHODS: All patients who underwent prophylactic surgery for polyposis and were in follow-up at the hereditary digestive tract tumors outpatient department of our institute were eligible for the study. The Short Form-36 questionnaire and 21 ad hoc items were used at the time of clinical evaluation. RESULTS: A total of 102 patients were enrolled. For the SF-36 domains, mean values ranged from 64.18 for vitality to 88.49 for physical functioning, with the highest variability for role-physical limitations; the minimum value of functioning was reached for role-physical limitations, role-emotional limitations, and social functioning. The maximum value of functioning was reached for role-emotional limitations (73.96%) and role-physical limitations (60.42%). In total, 48.96% and 90.63% of patients reported no fecal or urinary incontinence episodes, respectively; 69.79% of patients did not have problems in work/school resumption or the personal sexual sphere. CONCLUSION: Quality of life following prophylactic surgery for these patients seems to be good when indirectly compared to HP-normative samples'. Young adult patients appear to quickly manage and adapt to changes in bowel functioning. A minority of patients may experience social and sexual issues.

Positron Emission Tomography Molecular Imaging of the Major Neurodegenerative Disorders: Overview and Pictorial Essay, from a Nuclear Medicine Center's Perspective.

Computed tomography (CT) and magnetic resonance imaging (MRI) provide key structural information on brain pathophysiology. Positron emission tomography (PET) measures metabolism in the living brain; it plays an important role in molecular neuroimaging and is rapidly expanding its field of application to the study of neurodegenerative diseases. Different PET radiopharmaceuticals allow in vivo characterization and quantization of biological processes at the molecular and cellular levels, from which many neurodegenerative diseases develop. In addition, hybrid imaging tools such as PET/CT and PET/MRI support the utility of PET, enabling the anatomical mapping of functional data. In this overview, we describe the most commonly used PET tracers in the diagnostic work-up of patients with Alzheimer's disease, Parkinson's disease, and other neurodegenerative diseases. We also briefly discuss the pathophysiological processes of tracer uptake in the brain, detailing their specific cellular pathways in clinical cases. This overview is limited to imaging agents already applied in human subjects, with particular emphasis on those tracers used in our department.

Anionic food color tartrazine enhances antibacterial efficacy of histatin-derived peptide DHVAR4 by fine-tuning its membrane activity.

Here it is demonstrated how some anionic food additives commonly used in our diet, such as tartrazine (TZ), bind to DHVAR4, an antimicrobial peptide (AMP) derived from oral host defense peptides, resulting in significantly fostered toxic activity against both Gram-positive and Gram-negative bacteria, but not against mammalian cells. Biophysical studies on the DHVAR4-TZ interaction indicate that initially large, positively charged aggregates are formed, but in the presence of lipid bilayers, they rather associate with the membrane surface. In contrast to synergistic effects observed for mixed antibacterial compounds, this is a principally different mechanism, where TZ directly acts on the membrane-associated AMP promoting its biologically active helical conformation. Model vesicle studies show that compared to dye-free DHVAR4, peptide-TZ complexes are more prone to form H-bonds with the phosphate ester moiety of the bilayer head-group region resulting in more controlled bilayer fusion mechanism and concerted severe cell damage. AMPs are considered as promising compounds to combat formidable antibiotic-resistant bacterial infections; however, we know very little on their in vivo actions, especially on how they interact with other chemical agents. The current example illustrates how food dyes can modulate AMP activity, which is hoped to inspire improved therapies against microbial infections in the alimentary tract. Results also imply that the structure and function of natural AMPs could be manipulated by small compounds, which may also offer a new strategic concept for the future design of peptide-based antimicrobials.

Hereditary colorectal cancer syndromes and the COVID-19 pandemic: results from a survey conducted in patients enrolled in a dedicated registry.

PURPOSE: The coronavirus 2019 (COVID-19) pandemic has had profound consequences also for non-infected patients. This study aimed to evaluate the impact of the pandemic on the quality of life of a population with hereditary gastrointestinal cancer predisposition syndromes and on the surveillance/oncological care program of patients enrolled in a dedicated registry. METHODS: The study was conducted by means of an online self-report survey during the first Italian national lockdown. The survey comprised four sections: demographics; perception/knowledge of COVID-19; impact of the COVID-19 pandemic on surveillance and cancer care; health status (SF-12 questionnaire). RESULTS: 211 complete questionnaires were considered. 25.12% of respondents reported being not at all frightened by COVID-19, 63.98% felt "not at all" or "a little" more fragile than the healthy general population, and 66.82% felt the coronavirus to be no more dangerous to them than the healthy general population. 88.15% of respondents felt protected knowing they were monitored by a team of dedicated professionals. CONCLUSION: Patients with hereditary gastrointestinal cancer predisposition syndromes reported experiencing less fear related to COVID-19 than the healthy general population. The study results suggest that being enrolled in a dedicated registry can reassure patients, especially during health crises.

Novel Approaches in Molecular Imaging and Neuroimaging of Fibromyalgia.

Fibromyalgia (FM) represents a condition that is still controversial in its entity, pathophysiology, diagnosis and management. The aim of this review is to focus on imaging aspects of FM, especially on novel approaches in molecular imaging, with a special focus on neuroimaging. Novel functional and molecular imaging findings may represent, eventually, future biomarkers both in research settings and in terms of clinical practice. Several imaging techniques have already been tested in clinical trials in the FM field, including functional MRI, positron emission tomography (PET) imaging with 18F-FDG in FM, PET imaging of the dopaminergic system, PET imaging of the GABAergic system, PET imaging with neuroinflammation and neuroimmune parameters, PET imaging of the opioid system and H215O-PET activation studies. Therefore, the potential role in the FM field of fMRI and different PET tracers has been discussed in different settings, serving as a comprehensive guide of novel imaging options both in research and in the clinical field.

Legionella antibiotic susceptibility testing: is it time for international standardization and evidence-based guidance?

Legionella pneumophila, a Gram-negative bacillus, is the causative agent of Legionnaire's disease, a form of severe community-acquired pneumonia. Infection can have high morbidity, with a high proportion of patients requiring ICU admission, and up to 10% mortality, which is exacerbated by the lack of efficacy of typical empirical antibiotic therapy against Legionella spp. The fastidious nature of the entire Legionellaceae family historically required inclusion of activated charcoal in the solid medium to remove growth inhibitors, which inherently interferes with accurate antimicrobial susceptibility determination, an acknowledged methodological shortfall, now rectified by a new solid medium that gives results comparable to those of microbroth dilution. Here, as an international Legionella community (with authors representing various international reference laboratories, countries and clinical stakeholders for diagnosis and treatment of legionellosis), we set out recommendations for the standardization of antimicrobial susceptibility testing methods, guidelines and reference strains to facilitate an improved era of antibiotic resistance determination.

Medulloblastoma and familial adenomatous polyposis: Good prognosis and good quality of life in the long-term?

INTRODUCTION: Mutations of the APC (adenomatous polyposis coli) gene correlate mainly with familial adenomatous polyposis (FAP), but can occasionally be pathogenic for medulloblastoma (MBL) wingless-related integration site (WNT) subtype, the course of which has only recently been described. METHODS: We retrieved all patients with documented germline APC mutations and a diagnosis of MBL to examine their outcome, late effects of treatment, and further oncological events. RESULTS: Between 2007 and 2016, we treated six patients, all with a pathogenic APC variant mutation and all with MBL, classic histotype. None had metastatic disease. All patients were in complete remission a median 65 months after treatment with craniospinal irradiation at 23.4 Gy, plus a boost on the posterior fossa/tumor bed up to 54 Gy, followed by cisplatin/carboplatin, lomustine, and vincristine for a maximum of eight courses. Five of six diagnostic revised MRI were suggestive of the WNT molecular subgroup typical aspects. Methylation profile score (in two cases) and copy number variation analysis (chromosome 6 deletion in two cases) performed on four of six retrieved samples confirmed WNT molecular subgroup. Four out of six patients had a positive family history of FAP, while gastrointestinal symptoms prompted its identification in the other two cases. Four patients developed other tumors (desmoid, MELTUMP, melanoma, pancreatoblastoma, thyroid Tir3) from 5 to 7 years after MBL. DISCUSSION: Our data confirm a good prognosis for patients with MBL associated with FAP. Patients' secondary tumors may or may not be related to their syndrome or treatment, but warrant adequate attention when planning shared guidelines for these patients.

A community-acquired Legionnaires' disease outbreak caused by Legionella pneumophila serogroup 2: an uncommon event, Italy, August to October 2018.

In September 2018 in Brescia province, northern Italy, an outbreak of Legionnaires' disease (LD) caused by Legionella pneumophila serogroup 2 (Lp2) occurred. The 33 cases (two fatal) resided in seven municipalities along the Chiese river. All cases were negative by urinary antigen test (UAT) and most were diagnosed by real-time PCR and serology. In only three cases, respiratory sample cultures were positive, and Lp2 was identified and typed as sequence type (ST)1455. In another three cases, nested sequence-based typing was directly applied to respiratory samples, which provided allelic profiles highly similar to ST1455. An environmental investigation was undertaken immediately and water samples were collected from private homes, municipal water systems, cooling towers and the river. Overall, 533 environmental water samples were analysed and 34 were positive for Lp. Of these, only three samples, all collected from the Chiese river, were Lp2 ST1455. If and how the river water could have been aerosolised causing the LD cases remains unexplained. This outbreak, the first to our knowledge caused by Lp2, highlights the limits of UAT for LD diagnosis, underlining the importance of adopting multiple tests to ensure that serogroups other than serogroup 1, as well as other Legionella species, are identified.

Tau Biomarkers in Dementia: Positron Emission Tomography Radiopharmaceuticals in Tauopathy Assessment and Future Perspective.

Abnormal accumulation of Tau protein is closely associated with neurodegeneration and cognitive impairment and it is a biomarker of neurodegeneration in the dementia field, especially in Alzheimer's disease (AD); therefore, it is crucial to be able to assess the Tau deposits in vivo. Beyond the fluid biomarkers of tauopathy described in this review in relationship with the brain glucose metabolic patterns, this review aims to focus on tauopathy assessment by using Tau PET imaging. In recent years, several first-generation Tau PET tracers have been developed and applied in the dementia field. Common limitations of first-generation tracers include off-target binding and subcortical white-matter uptake; therefore, several institutions are working on developing second-generation Tau tracers. The increasing knowledge about the distribution of first- and second-generation Tau PET tracers in the brain may support physicians with Tau PET data interpretation, both in the research and in the clinical field, but an updated description of differences in distribution patterns among different Tau tracers, and in different clinical conditions, has not been reported yet. We provide an overview of first- and second-generation tracers used in ongoing clinical trials, also describing the differences and the properties of novel tracers, with a special focus on the distribution patterns of different Tau tracers. We also describe the distribution patterns of Tau tracers in AD, in atypical AD, and further neurodegenerative diseases in the dementia field.

Membrane Association Modes of Natural Anticancer Peptides: Mechanistic Details on Helicity, Orientation, and Surface Coverage.

Anticancer peptides (ACPs) could potentially offer many advantages over other cancer therapies. ACPs often target cell membranes, where their surface mechanism is coupled to a conformational change into helical structures. However, details on their binding are still unclear, which would be crucial to reach progress in connecting structural aspects to ACP action and to therapeutic developments. Here we investigated natural helical ACPs, Lasioglossin LL-III, Macropin 1, Temporin-La, FK-16, and LL-37, on model liposomes, and also on extracellular vesicles (EVs), with an outer leaflet composition similar to cancer cells. The combined simulations and experiments identified three distinct binding modes to the membranes. Firstly, a highly helical structure, lying mainly on the membrane surface; secondly, a similar, yet only partially helical structure with disordered regions; and thirdly, a helical monomeric form with a non-inserted perpendicular orientation relative to the membrane surface. The latter allows large swings of the helix while the N-terminal is anchored to the headgroup region. These results indicate that subtle differences in sequence and charge can result in altered binding modes. The first two modes could be part of the well-known carpet model mechanism, whereas the newly identified third mode could be an intermediate state, existing prior to membrane insertion.

Chemerin predicts carotid intima-media thickening in severe obesity.

BACKGROUND AND AIMS: Chemerin is an adipokine with an emerging role in the crosstalk between adipose tissue and immune system. It is overexpressed in severe obesity, affects adipogenesis and glucose homeostasis and it correlates with early vascular damage. The aim of this study is to investigate the correlation between circulating levels of chemerin and early vascular damage in subjects with severe obesity, before and after laparoscopic sleeve gastrectomy (LSG). METHODS: Fifty-six obese subjects eligible for LSG were enrolled in the study. The following parameters were evaluated: body mass index (BMI), glycemia, insulinemia, glycated haemoglobin, lipid profile, plasma chemerin levels and carotid intima-media thickness (cIMT). Fifty-four subjects were evaluated 1 year after the intervention. RESULTS: Univariate analysis showed a direct and significant correlation between chemerin and waist circumference, insulin resistance, glycated haemoglobin and cIMT. Chemerin was a better predictor of intima-media thickening than waist circumference and glycated haemoglobin at the ROC curve analysis, with a cut-off value for chemerin of 140 ng/mL. The reduction of chemerin is independently associated with the reduction of cIMT and the improvement of insulin sensitivity after LSG. CONCLUSION: Chemerin is involved in the development and progression of early vascular damage and insulin resistance in subjects with severe obesity, and in their healing after bariatric surgery. Chemerin could also have a role in the assessment of cardiovascular risk in subjects with severe obesity.

Early Renal Function Alterations in Renal Branches vs. Renal Fenestrations - A Dynamic Scintigraphy Based Prospective Study.

OBJECTIVE: The objective of this prospective single centre study was to assess whether branches and fenestrations have different outcomes on renal function in the early phase. METHODS: From March 2018 to June 2019, 67 patients who underwent elective fenestrated and branched endovascular aneurysm repair (F/BEVAR) procedures were enrolled in this study. The patients were divided into two groups according to the renal bridging component configuration (fenestration vs. branch). All of them underwent dynamic renal scintigraphy with 99mTc diethylenetriaminepentaacetic acid (DTPA), two weeks pre-operatively, and three months and one year post-operatively. The primary end points were peri-procedural technical success, 30 day major adverse events, differences in glomerular filtration rate (GFR) between the branch and fenestration configurations, and variations between the pre-operative and the post-operative dynamic renal scintigraphy. RESULTS: Overall, 135 kidneys were analysed: 63 in the 32 patients treated with fenestrations, and 72 in the 35 patients treated with branches; the mean GFR on baseline scintigraphy was 58.4 ± 30.9 mL/min in the fenestration group, and 65.1 ± 29.2 mL/min in the branch group. Only kidneys associated with a patent fenestration/branch were included in the split GFR final analysis. The mean total GFR at three month scintigraphy decreased by 6.0 ± 2.9 mL/min in the fenestration group and by 23.4 ± 6.4 mL/min in the branch group. The split GFR decreased by 3.5 ± 0.6 mL/min in the fenestration group, and by 15.4 ± 5.4 mL/min in the branch group. The GFR decrease remained stable at one year. CONCLUSION: In this study, the use of branches for renal arteries during F/BEVAR resulted in a greater decrease in the GFR than in those patients who were treated with fenestrations alone. The scintigraphic alterations were evident at an early phase.

Short-term and long-term outcomes after preventive surgery in adolescent patients with familial adenomatous polyposis.

BACKGROUND: APC gene pathogenic variants are characterized by a lifetime risk of nearly 100% to develop a colorectal carcinoma. International guidelines suggest a prophylactic surgery in the second decade. METHODS: A descriptive analysis was performed evaluating a surgical series of adolescent patients with familial adenomatous polyposis (FAP) enrolled in the prospectively maintained hereditary polyposis registry. RESULTS: Thirty-eight adolescent patients (median age 16 years; range, 7-19) underwent laparoscopic prophylactic surgery. APC gene pathogenic variants were detected in all patients, and six patients were proband. No patients were converted to open surgery. Median postoperative stay was five days (4-16). Early postoperative complications were one dural puncture and one anastomotic leakage. Regarding late complications, we observed one patient having small bowel obstruction 56 months after surgery. Pathological reports showed one patient with pTis adenocarcinoma in two separate sites; 33 patients with low-grade dysplasia, four with high-grade dysplasia. One patient developed a desmoid tumor 37 months after surgery. After a median follow-up of 40.5 months, no patients died or had a second abdominal surgery because of cancer in rectal stump. CONCLUSIONS: Rectal sparing surgery was the first choice in the major respect of patients' quality of life. Laparoscopic prophylactic surgery for FAP is well accepted from adolescents. It represents a safe option due to the low incidence of post-surgical desmoids and quick postoperative recovery.