Radiometric Receiver for Passive Microwave Imaging System

The paper describes a new method to develop a zero-type W-band radiometric receiver. The block diagram and operating algorithm of the digital control system are presented. The main advantages of the zero method in passive radio physical investigations in comparison with classical engineering solutions are shown

Resting Potential–dependent Regulation of the Voltage Sensitivity of Sodium Channel Gating in Rat Skeletal Muscle In Vivo

Normal muscle has a resting potential of −85 mV, but in a number of situations there is depolarization of the resting potential that alters excitability. To better understand the effect of resting potential on muscle excitability we attempted to accurately simulate excitability at both normal and depolarized resting potentials. To accurately simulate excitability we found that it was necessary to include a resting potential–dependent shift in the voltage dependence of sodium channel activation and fast inactivation. We recorded sodium currents from muscle fibers in vivo and found that prolonged changes in holding potential cause shifts in the voltage dependence of both activation and fast inactivation of sodium currents. We also found that altering the amplitude of the prepulse or test pulse produced differences in the voltage dependence of activation and inactivation respectively. Since only the Nav1.4 sodium channel isoform is present in significant quantity in adult skeletal muscle, this suggests that either there are multiple states of Nav1.4 that differ in their voltage dependence of gating or there is a distribution in the voltage dependence of gating of Nav1.4. Taken together, our data suggest that changes in resting potential toward more positive potentials favor states of Nav1.4 with depolarized voltage dependence of gating and thus shift voltage dependence of the sodium current. We propose that resting potential–induced shifts in the voltage dependence of sodium channel gating are essential to properly regulate muscle excitability in vivo

Inactivation and Secondary Structure in the D4/S4-5 Region of the SkM1 Sodium Channel

The D4/S4-5 interhelical region plays a role in sodium channel fast inactivation. Examination of S4-5 primary structure in all domains suggests a possible amphipathic helical conformation in which a conserved group of small hydrophobic residues occupies one contiguous surface with a more variable complement of nonpolar and polar residues on the opposite face. We evaluated this potential structure by replacing each residue in D4/S4-5 of the rat SkM1 skeletal muscle sodium channel with substitutions having different side chain properties. Of the 63 mutations analyzed, 44 produced functional channels. P1473 was intolerant of substitutions. Nonpolar substitutions in the conserved hydrophobic region were functionally similar to wild type, while charged mutations in this region before P1473 were nonfunctional. Charged mutations at F1466, M1469, M1470, and A1474, located on the opposite surface of the predicted helix, produced functional channels with pronounced slowing of inactivation, shifted voltage dependence of steady-state inactivation, and increased rate of recovery from inactivation. The substituted-cysteine-accessibility method was used to probe accessibility at each position. Residues L1465, F1466, A1467, M1469, M1470, L1472, A1474, and F1476C were easily accessible for modification by sulfhydryl reagents; L1464, L1468, S1471, and L1475 were not accessible within the time frame of our measurements. Molecular dynamics simulations of residues A1458 to N1477 were then used to explore energetically favorable local structures. Based on mutagenesis, substituted-cysteine-accessibility method, and modeling results, we suggest a secondary structure for the D4/S4-5 region in which the peptide chain is α-helical proximal to P1473, bends at this residue, and may continue beyond this point as a random coil. In this configuration, the entire resultant loop is amphipathic; four residues on one surface could form part of the binding site for the inactivation particle

Fenfluramine increases survival and reduces markers of neurodegeneration in a mouse model of Dravet syndrome.

OBJECTIVE: In patients with Dravet syndrome (DS), fenfluramine reduced convulsive seizure frequency and provided clinical benefit in nonseizure endpoints (e.g., executive function, survival). In zebrafish mutant scn1 DS models, chronic fenfluramine treatment preserved neuronal cytoarchitecture prior to seizure onset and prevented gliosis; here, we extend these findings to a mammalian model of DS (Scn1a+/- mice) by evaluating the effects of fenfluramine on neuroinflammation (degenerated myelin, activated microglia) and survival. METHODS: Scn1a+/- DS mice were treated subcutaneously once daily with fenfluramine (15 mg/kg) or vehicle from postnatal day (PND) 7 until 35-37. Sagittal brain sections were processed for immunohistochemistry using antibodies to degraded myelin basic protein (D-MBP) for degenerated myelin, or CD11b for activated (inflammatory) microglia; sections were scored semi-quantitatively. Apoptotic nuclei were quantified by TUNEL assay. Statistical significance was evaluated by 1-way ANOVA with post-hoc Dunnetts test (D-MBP, CD11b, and TUNEL) or Logrank Mantel-Cox (survival). RESULTS: Quantitation of D-MBP immunostaining per 0.1 mm2 unit area of the parietal cortex and hippocampus CA3 yielded significantly higher spheroidal and punctate myelin debris counts in vehicle-treated DS mice than in wild-type mice. Fenfluramine treatment in DS mice significantly reduced these counts. Activated CD11b + microglia were more abundant in DS mouse corpus callosum and hippocampus than in wild-type controls. Fenfluramine treatment of DS mice resulted in significantly fewer activated CD11b + microglia than vehicle-treated DS mice in these brain regions. TUNEL staining in corpus callosum was increased in DS mice relative to wild-type controls. Fenfluramine treatment in DS mice lowered TUNEL staining relative to vehicle-treated DS mice. By PND 35-37, 55% of control DS mice had died, compared with 24% of DS mice receiving fenfluramine treatment (P = 0.0291). SIGNIFICANCE: This is the first report of anti-neuroinflammation and pro-survival after fenfluramine treatment in a mammalian DS model. These results corroborate prior data in humans and animal models and suggest important pharmacological activities for fenfluramine beyond seizure reduction. PLAIN LANGUAGE SUMMARY: Dravet syndrome is a severe epilepsy disorder that impairs learning and causes premature death. Clinical studies in patients with Dravet syndrome show that fenfluramine reduces convulsive seizures. Additional studies suggest that fenfluramine may have benefits beyond seizures, including promoting survival and improving control over emotions and behavior. Our study is the first to use a Dravet mouse model to investigate nonseizure outcomes of fenfluramine. Results showed that fenfluramine treatment of Dravet mice reduced neuroinflammation significantly more than saline treatment. Fenfluramine-treated Dravet mice also lived longer than saline-treated mice. These results support clinical observations that fenfluramine may have benefits beyond seizures

QM/MM modeling of the hydroxylation of the androstenedione substrate catalyzed by cytochrome P450 aromatase (CYP19A1)

CYP19A1 aromatase is a member of the Cytochrome P450 family of hemeproteins, and is the enzyme responsible for the final step of the androgens conversion into the corresponding estrogens, via a three-step oxidative process. For this reason, the inhibition of this enzyme plays an important role in the treatment of hormone-dependent breast cancer. The first catalytic subcycle, corresponding to the hydroxilation of androstenedione, has been proposed to occur through a first hydrogen abstraction and a subsequent oxygen rebound step. In present work, we have studied the mechanism of the first catalytic subcycle by means of hybrid quantum mechanics/molecular mechanics methods. The inclusion of the protein flexibility has been achieved by means of Free Energy Perturbation techniques, giving rise to a free energy of activation for the hydrogen abstraction step of 13.5 kcal/mol. The subsequent oxygen rebound step, characterized by a small free energy barrier (1.5 kcal/mol), leads to the hydroxylated products through a highly exergonic reaction. In addition, an analysis of the primary deuterium kinetic isotopic effects, calculated for the hydrogen abstraction step, reveals values (∼10) overpassing the semiclassical limit for the C[BOND]H, indicating the presence of a substantial tunnel effect. Finally, a decomposition analysis of the interaction energy for the substrate and cofactor in the active site is also discussed. According to our results, the role of the enzymatic environment consists of a transition state stabilization by means of dispersive and polarization effects.We acknowledge the Servei d'Informàtica of the Universitat Jaume I, GENCI-CINES, and BSC-Marenostrum for providing us with computer capabilities. The authors thank V. Moliner for valuable comments and discussion

Crystal structure of 4′-allyl-4,5,6,7,2′,7′-hexachlorofluorescein allyl ester unknown solvate

In the title compound, 4′-allyl-4,5,6,7,2′,7′-hexachlorofluorescein allyl ester {systematic name: prop-2-en-1-yl 2,3,4,5-tetrachloro-6-[2,7-dichloro-6-hydroxy-3-oxo-4-(prop-2-en-1-yl)-3H-xanthen-9-yl]benzoate}, C26H14Cl6O5, accompanied by unknown solvate molecules, the dihedral angle between the xanthene ring system (r.m.s. deviation = 0.046 Å) and the pentasubstituted benzene ring is 71.67 (9)°. Both allyl groups are disordered over two sets of sites in statistical ratios. The scattering contributions of the disordered solvent molecules (both Ph2O and CHCl3, as identified by NMR) were removed with thePLATONSQUEEZE algorithm [Spek (2015).Acta Cryst.C71, 9–18]. In the crystal, tetrameric supramolecular aggregates linked by O—H...O hydrogen bonds occur; these further interact with neighboring aggregates through C—Cl...π interactions arising from the benzene rings, forming infinite two-dimensional sheets. Each C6Cl4ring shifts in the direction perpendicular to the two-dimensional sheet, exhibiting a helical chain in which every C6Cl4ring is utilized as both a donor and an acceptor of Cl...π contacts. Thus, these two-dimensional sheets pack in a helical fashion, constructing a three-dimensional network.</jats:p

Dynamics of epileptiform activity in mouse hippocampal slices

Increase of the extracellular K +  concentration mediates seizure-like synchronized activities in vitro and was proposed to be one of the main factors underlying epileptogenesis in some types of seizures in vivo. While underlying biophysical mechanisms clearly involve cell depolarization and overall increase in excitability, it remains unknown what qualitative changes of the spatio-temporal network dynamics occur after extracellular K +  increase. In this study, we used multi-electrode recordings from mouse hippocampal slices to explore changes of the network activity during progressive increase of the extracellular K +  concentration. Our analysis revealed complex spatio-temporal evolution of epileptiform activity and demonstrated a sequence of state transitions from relatively simple network bursts into complex bursting, with multiple synchronized events within each burst. We describe these transitions as qualitative changes of the state attractors, constructed from experimental data, mediated by elevation of extracellular K +  concentration

Genomic Diversity in Two Related Plant Species with and without Sex Chromosomes - Silene latifolia and S. vulgaris

Genome size evolution is a complex process influenced by polyploidization, satellite DNA accumulation, and expansion of retroelements. How this process could be affected by different reproductive strategies is still poorly understood.We analyzed differences in the number and distribution of major repetitive DNA elements in two closely related species, Silene latifolia and S. vulgaris. Both species are diploid and possess the same chromosome number (2n = 24), but differ in their genome size and mode of reproduction. The dioecious S. latifolia (1C = 2.70 pg DNA) possesses sex chromosomes and its genome is 2.5× larger than that of the gynodioecious S. vulgaris (1C = 1.13 pg DNA), which does not possess sex chromosomes. We discovered that the genome of S. latifolia is larger mainly due to the expansion of Ogre retrotransposons. Surprisingly, the centromeric STAR-C and TR1 tandem repeats were found to be more abundant in S. vulgaris, the species with the smaller genome. We further examined the distribution of major repetitive sequences in related species in the Caryophyllaceae family. The results of FISH (fluorescence in situ hybridization) on mitotic chromosomes with the Retand element indicate that large rearrangements occurred during the evolution of the Caryophyllaceae family.Our data demonstrate that the evolution of genome size in the genus Silene is accompanied by the expansion of different repetitive elements with specific patterns in the dioecious species possessing the sex chromosomes

Measurements of the Electroweak Diboson Production Cross Sections in Proton-Proton Collisions at root s=5.02 TeV Using Leptonic Decays

The first measurements of diboson production cross sections in proton-proton interactions at a center-of-mass energy of 5.02 TeV are reported. They are based on data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 302 pb(-1). Events with two, three, or four charged light leptons (electrons or muons) in the final state are analyzed. The WW, WZ, and ZZ total cross sections are measured as sigma(WW) = 37:0(-5.2)(+5.5) (stat)(-2.6)(+2.7) (syst) pb, sigma(WZ) = 6.4(-2.1)(+2.5) (stat)(-0.3)(+0.5)(syst) pb, and sigma(ZZ) = 5.3(-2.1)(+2.5)(stat)(-0.4)(+0.5) (syst) pb. All measurements are in good agreement with theoretical calculations at combined next-to-next-to-leading order quantum chromodynamics and next-to-leading order electroweak accuracy