Playing with light in diatoms: microalgae with a natural photonic crystal structure

Complex micro- and nano-structured materials for photonic applications are designed and fabricated using top technologies. A completely different approach to engineering systems at the sub-micron-scale consists in recognizing the nanostructures and morphologies that nature has optimized during life’s history on earth. In fact, biological organisms could exhibit ordered geometries and complex photonic structures which often overcome the products of the best available fabrication technologies [1]. An example is given by diatoms, microalgae with a peculiar cell wall consisting of amorphous hydrated silica valves reciprocally interconnected in a structure called the frustule. Valve surfaces exhibit specie-specific patterns of regular arrays of chambers, called areolae, developed into the frustule depth. Areolae range in diameter from few hundreds of nanometers up to few microns, and can be circular, polygonal or elongate [2]. The formation of these patterns can be modeled by self-organised, genetically controlled processes. Despite of the high level of knowledge on the genesis and morphology of diatom frustules, their functions are not completely understood [2]. In this work, we show that the silica valves of marine diatoms, characterized by a photonic crystal-like structure, have surprising optical properties, being capable of filtering and focalizing light, as well as exhibiting optical sensing capabilities

Acute noradrenergic activation induces insulin resistance in human skeletal muscle

We assessed in normal subjects the effects of an acute increase in forearm norepinephrine (NE) release, evoked by -20 mmHg lower body negative pressure (LBNP), on insulin-mediated muscle glucose uptake. Seven normal subjects underwent the following two insulin euglycemic clamps in random sequence: one during application of LBNP and the other without LBNP (control study). In the control study, hyperinsulinemia (approximately 60 microU/ml) produced a significant increment in forearm NE release, measured by using the forearm perfusion technique combined with infusion of tritiated NE (from 4.91 +/- 1 to 7.94 +/- 1.33 ng.l-1.min-1; P < 0.05). Forearm glucose uptake rose from 0.97 +/- 0.13 to 5.2 +/- 0.2 mg.l-1.min-1 in response to insulin infusion. When the insulin clamp was performed during LBNP, forearm NE release rose to significantly higher values than those of the control study (from 4.33 +/- 0.52 to 12.7 +/- 1.46 ng.l-1.min-1; P < 0.01 vs. control). Under these conditions, the stimulatory effect of insulin on forearm glucose uptake was markedly reduced (from 0.78 +/- 0.10 to 3.2 +/- 0.7 mg.l-1.min-1; P < 0.02 vs. control). Forearm blood flow and plasma epinephrine and free fatty acid concentrations were comparable in the two study sessions. These data demonstrate that an acute activation of endogenous NE release antagonizes insulin-mediated glucose uptake in forearm skeletal muscle, probably accounted for by a direct metabolic effect of NE.We assessed in normal subjects the effects of an acute increase in forearm norepinephrine (NE) release, evoked by -20 mmHg lower body negative pressure (LBNP), on insulin-mediated muscle glucose uptake. Seven normal subjects underwent the following two insulin euglycemic clamps in random sequence: one during application of LBNP and the other without LBNP (control study). In the control study, hyperinsulinemia (≃60 μU/ml) produced a significant increment in forearm NE release, measured by using the forearm perfusion technique combined with infusion of tritiated NE (from 4.91 ± 1 to 7.94 ± 1.33 ng · l -1 · min -1 ; P < 0.05). Forearm glucose uptake rose from 0.97 ± 0.13 to 5.2 ± 0.2 mg · l -1 · min -1 in response to insulin infusion. When the insulin clamp was performed during LBNP, forearm NE release rose to significantly higher values than those of the control study (from 4.33 ± 0.52 to 12.7 ± 1.46 ng · l -1 · min -1 ; P < 0.01 vs. control). Under these conditions, the stimulatory effect of insulin on forearm glucose uptake was markedly reduced (from 0.78 ± 0.10 to 3.2 ± 0.7 mg · l -1 · min -1 ; P < 0.02 vs. control). Forearm blood flow and plasma epinephrine and free fatty acid concentrations were comparable in the two study sessions. These data demonstrate that an acute activation of endogenous NE release antagonizes insulin-mediated glucose uptake in forearm skeletal muscle, probably accounted for by a direct metabolic effect of NE

Muscle sympathetic nerve activity in patients with acromegaly

Muscle sympathetic nerve activity was measured in nine acromegalic patients (age, 35 +/- 4 yr; body mass index, 28 +/- 2 kg/m2) and eight healthy subjects (age, 32 +/- 3 yr; body mass index, 25 +/- 2 kg/m2) by combining the forearm arterial-venous difference technique with the tracer method [infusion of tritiated norepinephrine (NE)]. Muscle NE release was quantified both at rest and during physiological hyperinsulinemia while maintaining euglycemia (approximately 90 mg/dL) by means of the euglycemic clamp. Arterial plasma NE was similar in the two groups at rest (197 +/- 28 and 200 +/- 27 pg/mL (-1) and slightly increased during insulin infusion. Forearm NE release was 2.33 +/- 0.55 ng x liter(-1) x min(-1) in healthy subjects and 2.67 +/- 0.61 ng x liter(-1) x min(-1) in acromegalic subjects in the basal state and increased to a similar extent during insulin infusion in both groups (3.13 +/- 0.71 and 3.32 +/- 0.75 ng x L(-1) x min(-1), P < 0.05 vs. basal), indicating a normal stimulatory effect of insulin on muscle sympathetic activity. In contrast, insulin-stimulated forearm glucose uptake was markedly lower in acromegalic patients (2.3 +/- 0.4 mg x L(-1) x min(-1)) than in control subjects (7.9 +/- 1.3 mg x L(-1) x min(-1), P < 0.001), indicating the presence of severe insulin resistance involving glucose metabolism. Our data demonstrate that patients with long-term acromegaly have normal sympathetic activity in the skeletal muscle in the basal, postabsorptive state and normal increments in NE spillover in response to the sympatho-excitatory effect of insulin. Thus, the presence of severe insulin resistance in acromegaly is not accounted for by adrenergic mechanisms

Early induction of bedside pneumoperitoneum in the management of residual pleural space and air leaks after pulmonary resection

Background: The pneumoperitoneum to treat prolonged air leaks or pleural space problems after pulmonary resection has been successfully used for decades. The aim of the study is to describe our experience with the early induction of therapeutic pneumoperitoneum (TP). Methods: We reviewed the data of 103 consecutive patients undergoing TP between September 2011 and September 2019. Patients were divided into two groups according to the time of the induction of TP: early application (≥72&nbsp;h) and standard application (&gt;72&nbsp;h). Results: In total, 52 early TP and 51 standard TP were analyzed. The median time of TP induction was 2 (1–3) versus 8 (5–11) postoperative days (POD) (p &lt; 0.001). The time for obliteration of the residual pleural space (7 vs.9&nbsp;days, p = 0.805) and the time of resolution of the air leaks (14 vs. 16&nbsp;days, p = 0.663) didn’t differ between the two groups, but a favorable trend was observed in the early group. The hospital stay was lower for patients undergoing early pneumoperitoneum: 9 versus 18&nbsp;days (p &lt; 0.001). The multivariate analysis showed that POD of induction of TP (p &lt; 0.001), time of resolution of the air leak (p &lt; 0.001) and Heimlich valve (p = 0.002) were independent variables associated with the hospital stay. Conclusions: The use of TP whenever a space problem or air leaks occur after pulmonary resections is safe and effective. Its early use (≤72&nbsp;h) accelerates the hospital stay, eventually reducing the time of resolution of the air leak and residual pleural space

Frontiers of light manipulation in natural, metallic, and dielectric nanostructures

AbstractThe ability to control light at the nanoscale is at the basis of contemporary photonics and plasmonics. In particular, properly engineered periodic nanostructures not only allow the inhibition of propagation of light at specific spectral ranges or its confinement in nanocavities or waveguides, but make also possible field enhancement effects in vibrational, Raman, infrared and fluorescence spectroscopies, paving the way to the development of novel high-performance optical sensors. All these devices find an impressive analogy in nearly-periodic photonic nanostructures present in several plants, animals and algae, which can represent a source of inspiration in the development and optimization of new artificial nano-optical systems. Here we present the main properties and applications of cutting-edge nanostructures starting from several examples of natural photonic architectures, up to the most recent technologies based on metallic and dielectric metasurfaces

Venous thromboembolism in covid-19 compared to non-covid-19 cohorts: A systematic review with meta-analysis

Background: A high incidence of venous thromboembolism (VTE) is reported in hospitalized COVID-19 patients, in particular in patients admitted to the intensive care unit (ICU). In patients with respiratory tract infections, including influenza A (H1N1), many studies have demonstrated an increased incidence of thromboses, but evidence is lacking regarding the risk difference (RD) of the occurrence of VTE between COVID-19 and non-COVID-19 patients. Methods: In this systematic review with meta-analysis, we evaluated the RD of the occurrence of VTE, pulmonary embolism (PE), and deep venous thrombosis (DVT) between COVID-19 and other pulmonary infection cohorts, in particular H1N1, and in an ICU setting. We searched for all studies comparing COVID-19 vs. non-COVID-19 regarding VTE, PE, and DVT. Results: The systematic review included 12 studies and 1,013,495 patients. The RD for VTE in COVID-19 compared to non-COVID-19 patients was 0.06 (95% CI 0.11–0.25, p = 0.011, I2 = 97%), and 0.16 in ICU (95% CI 0.045–0.27, p = 0.006, I2 = 80%). The RD for PE between COVID-19 and non-COVID-19 patients was 0.03 (95% CI, 0.006–0.045, p = 0.01, I2 = 89%). The RD for PE between COVID-19 and non-COVID-19 patients was 0.021 in retrospective studies (95% CI 0.00–0.04, p = 0.048, I2 = 92%) and 0.11 in ICU studies (95% CI 0.06–0.16, p < 0.001, I2 = 0%). Conclusions: The growing awareness and understanding of a massive inflammatory response combined with a hypercoagulable state that predisposes patients to thrombosis in COVID-19, in particular in the ICU, may contribute to a more appropriate strategy of prevention and earlier detection of the thrombotic events

Update on the pathogenesis and genetics of Paget's disease of bone

Studies over the past two decades have led to major advances in the pathogenesis of Paget's disease of bone (PDB) and particularly on the role of genetic factors. Germline mutations of different genes have been identified, as a possible cause of this disorder, and most of the underlying pathways are implicated in the regulation of osteoclast differentiation and function, whereas other are involved in cell autophagy mechanisms. In particular, about 30 different germline mutations of the Sequestosome 1 gene (SQSTM1) have been described in a significant proportion of familial and sporadic PDB cases. The majority of SQSTM1 mutations affect the ubiquitin-binding domain of the protein and are associated to a more severe clinical expression of the disease. Also, germline mutations in the ZNF687 and PFN1 genes have been associated to severe, early onset, polyostotic PDB with increased susceptibly to neoplastic degeneration, particularly giant cell tumor. Mutations in the VCP (Valosin Containing Protein) gene cause the autosomal dominant syndrome "Inclusion Body Myopathy, PDB, Fronto-temporal Dementia," characterized by pagetic manifestations, associated with myopathy, amyotrophic lateral sclerosis and fronto-temporal dementia. Moreover, germline mutations in the TNFRSF11A gene, which encodes for RANK, were associated with rare syndromes showing some histopathological, radiological, and clinical overlap with PDB and in two cases of early onset PDB-like disease. Likewise, genome wide association studies performed in unrelated PDB cases identified other potential predisposition genes and/or susceptibility loci. Thus, it is likely that polygenic factors are involved in the PDB pathogenesis in many individuals and that modifying genes may contribute in refining the clinical phenotype. Moreover, the contribution of somatic mutations of SQSTM1 gene and/or epigenetic mechanisms in the pathogenesis of skeletal pagetic abnormalities and eventually neoplastic degeneration, cannot be excluded. Indeed, clinical and experimental observations indicate that genetic susceptibility might not be a sufficient condition for the clinical development of PDB without the concomitant intervention of viral infection, in primis paramixoviruses, and/or other environmental factors (e.g., pesticides, heavy metals or tobacco exposure), at least in a subset of cases. This review summarizes the most important advances that have been made in the field of cellular and molecular biology PDB over the past decades. © 2022 Gennari, Rendina, Merlotti, Cavati, Mingiano, Cosso, Materozzi, Pirrotta, Abate, Calabrese and Falchetti