bluuebunny/crossref_metadata_2025 huggingface dataset:
Distinct sensitivities of OmpF and PhoE porins to charged modulators
Authors: Samartzidou Hrissi , Delcour Anne H.
Published: July 2002

The inhibition of the anion‐selective PhoE porin by ATP and of the cation‐selective OmpF porin by polyamines has been previously documented. In the present study, we have extended the comparison of the inhibitor‐porin pairs by investigating the effect of anions (ATP and aspartate) and positively charged polyamines (spermine and cadaverine) on both OmpF and PhoE with the patch‐clamp technique, and by comparing directly the gating kinetics of the channels modulated by their respective substrates. The novel findings reported here are (1) that the activity of PhoE is completely unaffected by polyamines, and (2) that the kinetic changes induced by ATP on PhoE or polyamines on OmpF suggest different mechanisms of inhibition. ATP induces a high degree of flickering in the PhoE‐mediated current and appears to behave as a blocker of ion flow during its presumed transport through PhoE. Polyamines modulate the kinetics of openings and closings of OmpF, in addition to promoting a blocker‐like flickering activity. The strong correlation between sensitivity to inhibitors and ion selectivity suggests that some common molecular determinants are involved in these two properties and is in agreement with the hypothesis that polyamines bind inside the pore of cationic porins.
Unique topology of the internal repeats in the cardiac Na+/Ca2+ exchanger
Authors: Iwamoto Takahiro , Nakamura Tomoe Y , Pan Yan , Uehara Akira , Imanaga Issei , Shigekawa Munekazu
Published: July 2002

Hydropathy analysis predicts 11 transmembrane helices in the cardiac Na+/Ca2+ exchanger. Using cysteine susceptibility analysis and epitope tagging, we here studied the membrane topology of the exchanger, in particular of the highly conserved internal α‐1 and α‐2 repeats. Unexpectedly, we found that the connecting loop in the α‐1 repeat forms a re‐entrant membrane loop with both ends facing the extracellular side and one residue (Asn‐125) being accessible from the inside and that the region containing the α‐2 repeat is mostly accessible from the cytoplasm. Together with other data, we propose that the exchanger may consist of nine transmembrane helices.
Chloroplast class I and class II aldolases are bifunctional for fructose‐1,6‐biphosphate and sedoheptulose‐1,7‐biphosphate cleavage in the Calvin cycle
Authors: Flechner Anke , Gross Wolfgang , Martin William F , Schnarrenberger Claus
Published: July 2002

Class I and class II aldolases are products of two evolutionary non‐related gene families. The cytosol and chloroplast enzymes of higher plants are of the class I type, the latter being bifunctional for fructose‐1,6‐ and sedoheptulose‐1,7‐P2 in the Calvin cycle. Recently, class II aldolases were detected for the cytosol and chloroplasts of the lower alga Cyanophora paradoxa. The respective chloroplast enzyme has been shown here to be also bifunctional for fructose‐1,6‐ and sedoheptulose‐1,7‐P2. Kinetics, also including fructose‐1‐P, were determined for all these enzymes. Apparently, aldolases are multifunctional enzymes, irrespective of their class I or class II type.
LIS1 and platelet‐activating factor acetylhydrolase (Ib) catalytic subunits, expression in the mouse oocyte and zygote
Authors: Cahana Aviv , Reiner Orly
Published: July 2002

Platelet‐activating factor is a phospholipid with several documented roles in the pre‐implantation embryo. Enzymes that belong to the platelet‐activating factor acetylhydrolases family inactivate platelet‐activating factor. Cytosolic platelet‐activating factor acetylhydrolase (Ib) is a heterotetramer composed of two catalytic subunits (α1/α2) and two regulatory LIS1 subunits. The expression of these components was monitored in the mouse oocytes and zygotes using reverse‐transcribed PCR and Western blot analysis. Interestingly, these proteins are expressed in the oocyte and zygote and their expression increases after fertilization, probably due to stabilization of maternal RNA. Lis1 mRNA transcription also increases after fertilization. However, assaying for expression of a specific paternal LIS1 isoform detected no zygotic translation in the one cell stage. These findings suggest a potential role for platelet‐activating factor acetylhydrolase (Ib) components in the early mouse embryo.
Induction of terminal differentiation and apoptosis in human colonic carcinoma cells by brefeldin A, a drug affecting ganglioside biosynthesis
Authors: Nojiri Hisao , Manya Hiroshi , Isono Hideo , Yamana Hideaki , Nojima Shoshichi
Published: July 2002

An appreciable increase in GM3 with a concomitant decrease in some neolacto‐series gangliosides was observed during differentiation of human colonic carcinoma HCT 116 cells induced by a differentiating agent. When the cells were treated with brefeldin A (BFA), a striking increase in de novo biosynthesis of GM3 and a decrease in biosynthesis of neolacto‐series gangliosides were observed after 6 h. Clear morphological changes to differentiated epithelial cells and an arrest of cells in the G0/G1 phase of the cell cycle were observed after 1 day of treatment. Then the cells were led to apoptosis. This activity was not affected by forskolin, which antagonizes the effects of BFA on protein transport and the Golgi apparatus. These results suggest that the differentiation‐inducing activity of BFA might be due to its modulatory effect on ganglioside biosynthesis, and that a specific change in ganglioside pattern is an essential prerequisite for induction of differentiation, providing a novel target for differentiation therapy of cancer.
Identification of the DNA binding surface of H‐NS protein from Escherichia coli by heteronuclear NMR spectroscopy
Authors: Shindo Heisaburo , Ohnuki Ayumi , Ginba Hiroyuki , Katoh Etsuko , Ueguchi Chiharu , Mizuno Takeshi , Yamazaki Toshimasa
Published: July 2002

The DNA binding domain of H‐NS protein was studied with various N‐terminal deletion mutant proteins and identified by gel retardation assay and heteronuclear 2D‐ and 3D‐NMR spectroscopies. It was shown from gel retardation assay that DNA binding affinity of the mutant proteins relative to that of native H‐NS falls in the range from 1/6 to 1/25 for H‐NS60–137, H‐NS70–137 and H‐NS80–137, whereas it was much weaker for H‐NS91–137. Thus, the DNA binding domain was defined to be the region from residue A80 to the C‐terminus. Sequential nuclear Overhauser effect (NOE) connectivities and those of medium ranges revealed that the region of residues Q60–R93 in mutant protein H‐NS60–137 forms a long stretch of disordered, flexible chain, and also showed that the structure of the C‐terminal region (residues A95–Q137) in mutant H‐NS60–137 was nearly identical to that of H‐NS91–137. 1H and 15N chemical shift perturbations induced by complex formation of H‐NS60–137 with an oligonucleotide duplex 14‐mer demonstrated that two loop regions, i.e. residues A80–K96 and T110–A117, play an essential role in DNA binding.
The 25 kDa protein recognizing the rat curved region upstream of the origin of the L‐strand replication is the rat homologue of the human mitochondrial transcription factor A
Authors: Pierro Pasqualina , Capaccio Lara , Gadaleta Gemma
Published: July 2002

Mass spectrometry matrix‐assisted laser desorption ionization (MALDI) analysis and N‐terminus sequencing as well as immunoblotting experiments using human and mouse antibodies have allowed us to identify the 25 kDa protein, previously isolated from rat liver using magnetic beads coated with a rat liver mitochondrial (mt) DNA region upstream of the Ori‐L, as the homologue of human mt transcription factor A (mtTFA). We can therefore identify this DNA binding protein as the rat mtTFA. Furthermore, since we previously showed that the 25 kDa protein purified from rat liver was able to bind the curved mtDNA region upstream of the Ori‐L as well as the curved mtDNA in the D‐loop region, the results here reported lead us to state, for the first time, that mtTFA binds both the curved regions of mtDNA upstream of the two replication origins.
Proteinase 3 mRNA expression is induced in monocytes but not in neutrophils of patients with cystic fibrosis
Authors: Just Jocelyne , Moog-Lutz Christel , Houzel-Charavel Anne , Canteloup Sandrine , Grimfeld Alain , Witko-Sarsat Véronique , Cayre Yvon E.
Published: July 2002

Proteinase 3 (PR3), a serine proteinase which can degrade lung tissue, is present in the cystic fibrosis (CF) sputum. In the present study, PR3 protein and mRNA expression was determined in circulating neutrophils and monocytes. CF neutrophils contained similar PR3 concentrations as healthy controls and poorly expressed PR3 mRNA. In contrast, CF monocytes showed significantly higher PR3 concentrations than controls, together with an upregulation of PR3 mRNA expression especially during pulmonary exacerbation. Interestingly, antibiotic treatment fully abrogated PR3 mRNA expression and decreased PR3 protein in monocytes. Our findings highlight a potential role of monocyte‐derived PR3 in CF‐associated airway inflammation.
Production of a recombinant chitin deacetylase in the culture medium of Escherichia coli cells
Authors: Tokuyasu Ken , Kaneko Satoshi , Hayashi Kiyoshi , Mori Yutaka
Published: July 2002

With the aid of a signal sequence of a chitinase from Streptomyces lividans, a recombinant chitin deacetylase, whose gene originated from a Deuteromycete, Colletotrichum lindemuthianum, was produced in the culture medium of Escherichia coli cells, existing as a highly active form without the signal peptide. During the production of the recombinant chitin deacetylase, both a slight increase in the value of OD600 nm in the culture medium and a drastic decrease in viable cell number were observed. When penta‐N‐acetyl‐chitopentaose was used as the substrate, the recombinant chitin deacetylase had comparable kinetic parameters to those of the original enzyme from the fungus. The addition of a C‐terminal six histidine sequence to the recombinant enzyme caused a slight decrease in the k
cat value, and the further addition of a 12 amino acid sequence at its N‐terminus caused a further decrease in the value. This production system allowed us to easily produce in the culture media the recombinant chitin deacetylases possessing as good properties as the original enzyme, without any disruption steps of the E. coli cells.
A disulfide conjugate between anti‐tetanus antibodies and HIV (37–72)Tat neutralizes tetanus toxin inside chromaffin cells
Authors: Stein Sylvia , Weiss Aryeh , Adermann Knut , Lazarovici Philip , Hochman Jacob , Wellhöner Hans
Published: July 2002

Conjugates between anti‐tetanus F(ab′)2 fragments and the (37–72) fragment of the HIV Tat protein were taken up by chromaffin cells, NG108‐15 neurohybridoma cells and Rev‐2‐T‐6 lymphoma cells. The uptake could not be inhibited by competition with (37–72)Tat, but was reduced in the presence of metabolic inhibitors or at low temperature. The disulfide as well as the thioether conjugate were translocated to the cytoplasmic space, but only the disulfide conjugate moderately restored the stimulated transmitter release inhibited by tetanus toxin. Therefore, disulfide conjugates are more promising than thioethers for the neutralization of intracellular antigens. These conjugates provide new tools to study neuroprotection against bacterial neurotoxins.
Cleavage of urokinase receptor regulates its interaction with integrins in thyroid cells
Authors: Montuori Nunzia , Rossi Guido , Ragno Pia
Published: July 2002

The urokinase‐type plasminogen activator uPA‐R can regulate integrin functions by associating with several types of β‐subunit. We have recently shown that normal thyroid TAD‐2 cells express both a native and a cleaved form of uPA‐R which lacks the binding domain for uPA. We found this cleaved form to be present in reduced amounts in papillary and follicular thyroid carcinoma cells and completely absent in cells derived from an anaplastic thyroid carcinoma (ARO). We now report that in normal thyroid cells the intact form of uPA‐R strongly associates with β‐1 integrins, whereas its cleaved form does not. uPA‐R expressed by ARO cells shows a stronger resistance to the cleavage mediated by uPA, plasmin and chymotrypsin than does uPA‐R expressed by normal thyroid cells. This resistance to cleavage correlates with the higher level of glycosylation of uPA‐R of ARO cells as compared to that of cleavable uPA‐R of normal thyroid cells. These results suggest that uPA‐R cleavage, which occurs in several cell types, represents a mechanism regulating the interactions of uPA‐R with integrins and, possibly, the subsequent integrin‐mediated cell adhesion. Moreover we hypothesize that glycosylation regulates uPA‐R cleavage and, indirectly, its interaction with integrins.
Mapping the site of interaction between annexin VI and the p120GAP C2 domain
Authors: Chow Andrew , Gawler Debra
Published: July 2002

Annexin VI is a Ca2+‐dependent membrane and phospholipid binding protein. It mediates a protein‐protein interaction with the Ras p21 regulatory protein p120GAP. In this study we have mapped the binding site of GAP within the annexin VI protein. Using Far Western overlay binding assays and cell lysate competition studies we have mapped the site of interaction to the inter‐lobe linker region; amino acids 325–363. Finally, using a GST fusion protein corresponding to this linker region we have demonstrated that cellular loading of the fusion protein into Rat‐1 fibroblasts by electroporation blocks the interaction and co‐immunoprecipitation of annexin VI and GAP.
The outer envelope protein OEP24 from pea chloroplasts can functionally replace the mitochondrial VDAC in yeast
Authors: Röhl Thomas , Motzkus Michael , Soll Jürgen
Published: July 2002

The chloroplastic outer envelope protein OEP24 from pea forms a high‐conductance low specificity solute channel as shown by in vitro studies. In order to establish its function also in an in vivo‐like system, the gene encoding OEP24 was transformed into a yeast strain which lacks the general mitochondria solute channel porin, also known as voltage‐dependent anion channel (VDAC). Transformation of the yeast VDAC(−) strain with the OEP24 gene resulted in the recovery of a phenotype indistinguishable from the wild‐type. The OEP24 polypeptide is targeted to the mitochondrial outer membrane in this heterologous system. We conclude that OEP24 forms a solute channel in pea chloroplasts in planta.
Simple ovarian cysts in premenopausal patients
Authors: Gerber B. , Müller H. , Külz T. , Krause A. , Reimer T.
Published: July 2002

Objective: To compare clinical, ultrasonographical, and cytological findings with the histopathological diagnosis of unilocular, anechoic smooth‐walled cystic ovarian tumors (‘simple ovarian cysts’). Method: In 140 premenopausal women simple ovarian cysts were removed by laparoscopy following ultrasound evaluation. In this retrospective study the histopathological diagnosis was correlated with clinical data, sonographic characteristics, macroscopic impression and with cytological findings. Results: Histopathology revealed 21 (15.0%) functional cysts, 31 (22.1%) retention cysts, 9 (6.4%) endometriomas, 3 (2.1%) cystic teratomas, 12 (8.6%) undifferentiated cysts and 64 (45.7%) cystadenomas. No mentionable differences were correlated with the patient's age or the size of the cyst as determined by ultrasound. Classically, ‘chocolate‐like’ cystic fluid characterizes endometriomas. However, in the present study cysts with different histopathological classifications exhibited similar fluid characteristics. The cytological diagnosis was correct in only 53 (37.9%) of all 140 cases. Conclusion: In premenopausal women differential diagnosis of ovarian cysts is not possible by clinical characterization, either by ultrasound or cytological evaluation. Simple ovarian cysts should be observed for at least 8 weeks or 2 menstrual cycles, respectively. If persisting over that period, the ovarian cyst should be removed by laparoscopy, but not by cyst aspiration.
Sonomorphology of endometriotic cysts
Authors: Suren A , Osmers R , Dietrich M , Kulenkampff D , Kuhn W
Published: July 2002

Objective: The aim of the study was to evaluate prospectively the sonomorphological feature of histologically verified endometriotic cysts. Methods: Transvaginal sonography was performed in 122 patients. Age distribution of the patients, and size and sonomorphology of the lesions were analyzed. Results: Eighty‐one percent of the endometriotic cysts occurred in patients between 31 and 50 years old with a peak of 29% between 31 and 35 years. Most of the cysts (81%) ranged between 30 and 59 mm in diameter. Forty‐three percent of the endometriotic cysts were observed as monolocular cysts with internal echoes. More than half of the findings were observed to be multilocular, partially without any internal echos, partially even with solid parts or purely solid. Conclusion: The so‐called ‘typically’ monolocular smooth‐walled endometriotic cyst with internal echoes was only found in 43% of the cases. However, data from the literature show that one cannot assume even this special entity to represent endometriomas. Regarding all monolocular cysts with homogeneous internal echoes, one has to be aware of a great amount of functional cysts and a non‐calculable residual risk of malignancy.
Stress analysis of the distal locking screws for femoral interlocking nailing
Authors: Lin Jinn , Lin Son‐Jyh , Chen Po‐Quang , Yang Shu‐Hua
Published: July 2002

In femoral locked nailing, the distal locking screws are vulnerable to mechanical failure. Biomechanical studies have shown that the stress on these screws is substantially affected by the fit of the nail in the medullary canal. In this study, a “closed form” mathematical model based on elastic beam‐column theory was developed to investigate how the nail‐cortical contact, which was simulated by a linear elastic foundation, affected the stress on the distal locking screws. Providing data for the model was a construct of a fractured femur with an intramedullary locked nail loaded by an eccentric vertical load. The stress on the locking screw was analyzed as a function of the distance from the fracture to the locking screw in the distal fragment under two situations: with and without nail‐cortical contact in the distal fragment. With nail‐cortical contact, the screw stress decreased as the length of nail‐cortical contact and the distance between the distal locking screw and the fracture site increased, but this stress contrarily increased when the nail reached the femoral region at which the screw length increased. The screw stress was much higher without nail‐cortical contact than with contact and continued to increase as the nail was inserted further. The mathematical model developed here can be a convenient means of rapid stress evaluation and parametric analysis for locked femoral nailing. It may be used to improve the design of interlocking nails and surgical technique. © 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Synaptophysin immunoreactivity in spinal white matter of young adult rats
Authors: Gilmore Shirley Ann , Sims Terry J.
Published: July 2002

Patterns of synaptophysin immunoreactivity were examined in the ventral and lateral funiculi of rat lumbosacral spinal cords. In normal young adults, dendrites from neurons in the spinal gray matter extended into the ventral and lateral white matter as finger‐like projections, immunopositive for synaptophysin. These projections appeared to diminish in size as they extended peripherally and, in general, did not reach the surface of the spinal cord, so that the outer one‐third to one‐fourth of the funiculi contained little or no immunoreactivity. The spinal cords of some of the animals studied were X‐irradiated on the third postnatal day. When examined 6 weeks to 5 months later, the pattern of synaptophysin immunoreactivity was found to be markedly altered in these animals. In general, the synaptophysin immunoreactivity in the white matter was less organized than in the non‐irradiated rat. As a result, the finger‐like projections, particularly into the lateral funiculi, were not as distinct, and the immunoreactivity appeared to be more diffusely distributed in the white matter. Further, the immunoreactivity was present throughout the thickness of the white matter in the irradiated animals and subpial concentrations were evident, especially along the lateral aspect of the spinal cord. Ultrastructural evaluation of the synaptic profiles revealed no differences between irradiated and non‐irradiated animals. The synapses occurred on both the shafts of the dendrites and on the spines. In general, both dendrites and axon terminals were covered by astrocyte processes except at synaptic sites, and the synaptic complexes were surrounded by astrocyte processes. Although the mechanisms underlying the altered pattern of synaptophysin immunoreactivity are not yet understood, they may be related to radiation‐induced effects on the glial populations previously reported by the investigators and/or to radiation‐induced alterations in reorganization or maturation of dendritic trees.
Effects of prenatal ionizing irradiation on the development of the ganglion cell layer of the mouse retina
Authors: Schmidt Sergio L. , Vitral Renan W.F. , Linden Rafael
Published: July 2002

Prenatal exposure to ionizing irradiation has been shown to be an effective method to eliminate selectively certain neuronal population. This investigation studied the effects on the ganglion cell layer of the retinae of adult mice exposed to a γ source (total dose=3 Gy) at 16 days gestation. There was a significant reduction in the total number of neurons (displaced amacrine+ganglion cells) in the ganglion cell layer (33%) that was mainly caused by a pronounced loss (59%) of displaced amacrine cells. The diameters of the surviving retinal ganglion cells were consistently larger than those of the controls. Prenatal irradiation is the first experimental approach that partially eliminates displaced amacrine cells. It is suggested that the morphogenesis of retinal ganglion cells may be affected by displaced amacrine cells.
School setting and teaching experience as risk factors for depressive symptoms in teachers
Authors: Jurado D , Gurpegui M , Moreno O , de Dios Luna J
Published: July 2002

A representative sample of teachers working at the primary or secondary grade level in both public and private schools answered an anonymous questionnaire on sociodemographic information and completed the Center for Epidemiologic Studies Rating Scale for Depression (CES-D). The teachers were classified as depressed when they scored ≥ 16 on the CES-D; 27.5% of the subjects were above this cut-off score. Logistic regression was used to calculate a multivariate model with the variables school ownership, grade level and teaching experience. Working in a public school, teaching at the primary level and longer teaching experience all increased the risk of depressive symptomatology.
REPRODUCTIVE HEALTH PROMOTION IN KOSOVO
Authors: Heymann Michele
Published: July 2002

Relief agencies that specialize in postwar emergency relief and then work to contribute to sustainable development as the crisis ends are increasingly recognizing the positive impact of midwifery care and training on reproductive health outcomes. Midwives are finding work and developing new roles in postwar reconstruction and refugee health care. This article describes the experiences of a nurse‐midwife who worked for Mercy Corps International in Kosovo and launched the Kosovo Women's Health Promotion Project. A short history of the conflict in Kosovo, the effects of the war on its people and the health care system, a description of women's health care, and the status of women in Kosovo are included.
Pharmacokinetic and prognostic significance of intestinal MDR1 expression in recipients of living‐donor liver transplantation
Authors: Hashida Tohru , Masuda Satohiro , Uemoto Shinji , Saito Hideyuki , Tanaka Koichi , Inui Ken‐ichi
Published: July 2002

Background

Living‐donor liver transplantation (LDLT) and subsequent immunosuppressive therapy with tacrolimus have been cornerstones in the recovery of patients from end‐stage liver failure, but there has been no critical dosage regimen for tacrolimus therapy, especially the initial dosage. In this study, we examined whether the absorptive barriers, multidrug resistance protein (MDR1), or cytochrome P450 IIIA4 (CYP3A4) are important pharmacokinetic factors for tacrolimus and are prognostic indicators for LDLT outcome.

Methods

We used competitive polymerase chain reaction to evaluate the messenger ribonucleic acid (mRNA) expression levels of MDRL And Cyp3A4 in mucosal cells of the upper jejunum from a part of the Rroux‐en‐Y limb for biliary reconstruction during LDLT of recipients (n = 48). The tacrolimus dosage was started at an oral dose of 0.075 mg/kg every 12 hours and adjusted on the basis of its whole‐blood trough level by use of a semiautomated microparticle enzyme immunoassay.

Results

The mRNA expression level of MDR1 (r = −0.776), but not CYP3A4 (r = −0.094), was inversely related to the concentration/dose ratio of tacrolimus. High levels of MDR1, but not CYP3A4, were strongly associated with reductions in survival rates after LDLT with the Kaplan‐Meier method and log‐rank statistics (P = .020 and P = .135, respectively). With use of a Cox regression procedure, high levels of MDR1 (relative risk, 12.99; 95% confidence interval, 1.64–103.23), but not CYP3A4 (relative risk, 0.93; 95% confidence interval, 0.87–1.00) appeared to be a significant prognostic indicator for poor survival.

Conclusions

Intestinal MDR1 is not only a good probe with which to predict the interindividual variation in tacrolimus pharmacokinetics after LDLT but also a powerful prognostic indicator for the outcome of LDLT.

Clinical Pharmacology & Therapeutics (2001) 69, 308–316; doi: 10.1067/mcp.2001.115142
Effects of Impedance and Dielectric Loss on the Electromagnetic Shielding Performance of an Ultrathin Carbon Nanotube Buckypaper‐Reinforced Silicon Carbide Nanocomposite
Authors: Cai Yanzhi , Ren Xuanxuan , Li Xuan , Li Yang , Cheng Laifei , Huang Shaohua , Liu Tingting , Li Yanjun , Zhou Yuan
Published: May 2021

An ultrathin carbon nanotube buckypaper‐reinforced silicon carbide (CNT/SiC) nanocomposite with a thickness of 500 μm and density of 1.78 g cm−3 is prepared by combining a CNT buckypaper preform and an in situ‐synthesized SiC matrix. A uniform CNT distribution and a high CNT content (≈35 vol%) are achieved in the nanocomposite. The SiC matrix is composed mostly of nearly spherical nanograins and submicrometer grains. No residual Si is found. The imaginary permittivity and loss tangent of the nanocomposite throughout the X‐band are 96–257 and 0.44–7.03, respectively. The normalized input impedance is 0.0012–0.0174 over the X‐band. The nanocomposite has an average total shielding effectiveness (SE) of 30 dB throughout the X‐band. The nanocomposite has a reflection coefficient of 0.9651–0.9915, an absorption coefficient of 0.0077–0.0338, and a transmission coefficient of no more than 0.0012 throughout the X‐band, indicating excellent electromagnetic SE. The nanocomposite is well suited for shielding applications, and the SE due to internal absorption (SEA) depends mostly on the impedance matching condition rather than the dielectric loss capacity. The variation with frequency of SEA is not consistent with that of the imaginary permittivity or loss tangent but approximately consistent with that of the normalized input impedance.
Temperature‐Sensitive Holograms with Switchable Memory
Authors: Irfan Muhammad , Martin Suzanne , Naydenova Izabela
Published: May 2021

Herein, the dynamics and reversibility of temperature‐induced changes in volume phase holographic gratings (VPHGs) recorded in the low‐toxicity self‐processing photopolymer poly(N‐isopropyl acrylamide) (poly‐NIPA) are reported on. Transmission and reflection gratings are exposed to temperatures ranging 8–60 °C to study the effect of temperature on their properties. First, the role of the photopolymer chemical composition is investigated by comparing layers containing NIPA with those containing acrylamide (AA) and measuring the normalized diffraction efficiency (DE) at 60 °C; higher thermal sensitivity is observed for poly‐NIPA gratings (24% drop) versus low sensitivity for AA gratings (2% increase). The impact of the physical properties of the sensing layers (e.g., thickness/protective top layer) on their thermal response is studied. The reversibility of thermally induced changes in VPHGs is studied, especially the effect of exposure to the elevated temperature of 60 °C on the subsequent low‐temperature response. The results reveal the significance of water desorption/absorption for the observed changes in poly‐NIPA upon exposure to varied temperatures and indicate a thermally controlled memory effect. This effect is observed from DE values in transmission and from the spectral characteristics of the reflection gratings. A full reversibility of the DE and spectral characteristics is achieved at 8 °C.
Recurrence of an early postzygotic rescue of an inherited unbalanced translocation resulting in mosaic segmental uniparental isodisomy of chromosome 11q in siblings
Authors: Blanluet Maud , Chantot‐Bastaraud Sandra , Chambon Pascal , Cassinari Kévin , Vera Gabriella , Goldenberg Alice , Keren Boris , Le Meur Nathalie , Hannequin Didier , Mace Bertrand , Siffroi Jean‐Pierre , Frebourg Thierry , Nicolas Gaël , Joly‐Helas Géraldine
Published: May 2021

Balanced translocations are associated with a risk of transmission of unbalanced chromosomal rearrangements in the offspring. Such inherited chromosomal abnormalities are typically non‐mosaic as they are present in the germline. We report the recurrence in two siblings of a mosaicism for a chromosomal rearrangement inherited from their asymptomatic father who carried a balanced t(2;11)(q35;q25) translocation. Both siblings exhibited a similar phenotype including intellectual disability, dysmorphic features, kyphoscoliosis, and cervical spinal stenosis. Karyotyping, fluorescence in situ hybridization and SNP array analysis of blood lymphocytes of both siblings identified two cell lines: one carrying a 2q35q37.3 duplication and a 11q25qter deletion (~90% cells), and one carrying an 11q uniparental isodisomy of maternal origin (~10% cells). We hypothesize that these mosaics were related to a postzygotic rescue mechanism which unexpectedly recurred in both siblings.
One‐Shot Intrablock Cross‐Linking of Linear Diblock Copolymer to Realize Janus‐Shaped Single‐Chain Nanoparticles
Authors: Watanabe Kodai , Kaizawa Noya , Ree Brian J. , Yamamoto Takuya , Tajima Kenji , Isono Takuya , Satoh Toshifumi
Published: May 2021

Developing an efficient and versatile process to transform a single linear polymer chain into a shape‐defined nanoobject is a major challenge in the fields of chemistry and nanotechnology to replicate sophisticated biological functions of proteins and nucleic acids in a synthetic polymer system. In this study, we performed one‐shot intrablock cross‐linking of linear block copolymers (BCPs) to realize single‐chain nanoparticles (SCNPs) with two chemically compartmentalized domains (Janus‐shaped SCNPs). Detailed structural characterizations of the Janus‐shaped SCNP composed of polystyrene‐block‐poly(glycolic acid) revealed its compactly folded conformation and compartmentalized block localization, similar to the self‐folded tertiary structures of natural proteins. Versatility of the one‐shot intrablock cross‐linking was demonstrated using several different BCP precursors. In addition, the Janus‐shaped SCNP produce miniscule microphase‐separated structures.
Cryo‐electron Microscopy Imaging of Alzheimer's Amyloid‐beta 42 Oligomer Displayed on a Functionally and Structurally Relevant Scaffold
Authors: Wu Jinming , Blum Thorsten B. , Farrell Daniel P , DiMaio Frank , Abrahams Jan Pieter , Luo Jinghui
Published: May 2021

Amyloid‐β peptide (Aβ) oligomers are pathogenic species of amyloid aggregates in Alzheimer's disease. Like certain protein toxins, Aβ oligomers permeabilize cellular membranes, presumably through a pore formation mechanism. Owing to their structural and stoichiometric heterogeneity, the structure of these pores remains to be characterized. We studied a functional Aβ42‐pore equivalent, created by fusing Aβ42 to the oligomerizing, soluble domain of the α‐hemolysin (αHL) toxin. Our data reveal Aβ42‐αHL oligomers to share major structural, functional, and biological properties with wild‐type Aβ42‐pores. Single‐particle cryo‐EM analysis of Aβ42‐αHL oligomers (with an overall 3.3 Å resolution) reveals the Aβ42‐pore region to be intrinsically flexible. The Aβ42‐αHL oligomers will allow many of the features of the wild‐type amyloid oligomers to be studied that cannot be otherwise, and may be a highly specific antigen for the development of immuno‐base diagnostics and therapies.
Generation of Diazomethyl Radicals by Hydrogen Atom Abstraction and Their Cycloaddition with Alkenes
Authors: Su Yong‐Liang , Dong Kuiyong , Zheng Haifeng , Doyle Michael P.
Published: May 2021

A general catalytic methodology for the synthesis of pyrazolines from α‐diazo compounds and conjugated alkenes is reported. The direct hydrogen atom transfer (HAT) process of α‐diazo compounds promoted by the tert‐butylperoxy radical generates electrophilic diazomethyl radicals, thereby reversing the reactivity of the carbon atom attached with the diazo group. The regiocontrolled addition of diazomethyl radicals to carbon‐carbon double bonds followed by intramolecular ring closure on the terminal diazo nitrogen and tautomerization affords a diverse set of pyrazolines in good yields with excellent regioselectivity. This strategy overcomes the limitations of electron‐deficient alkenes in traditional dipolar [3+2]‐cycloaddition of α‐diazo compounds with alkenes. Furthermore, the straightforward formation of the diazomethyl radicals provides umpolung reactivity, thus opening new opportunities for the versatile transformations of diazo compounds.
Mass Spectrometry Imaging Shows Modafinil, A Student Study Drug, Changes the Lipid Composition of the Fly Brain
Authors: Philipsen Mai H. , Ranjbari Elias , Gu Chaoyi , Ewing Andrew G.
Published: May 2021

Modafinil, a widely used psychoactive drug, has been shown to exert a positive impact on cognition and is used to treat sleep disorders and hyperactivity. Using time‐of‐flight secondary ion mass spectrometric imaging, we studied the changes of brain lipids of Drosophila melanogaster induced by modafinil to gain insight into the functional mechanism of modafinil in the brain. We found that upon modafinil treatment, the abundance of phosphatidylcholine and sphingomyelin species in the central brain of Drosophila is significantly decreased, whereas the levels of phosphatidylethanolamine and phosphatidylinositol in the brains show significant enhancement compared to the control flies. The alteration of brain lipids caused by modafinil is consistent with previous studies about cognition‐related drugs and offers a plausible mechanism regarding the action of modafinil in the brain as well as a potential target for the treatment of certain disorders.
FMRF‐NH2‐relatedneuropeptides inBiomphalariaspp., intermediate hosts for schistosomiasis: Precursor organization and immunohistochemical localization
Authors: Rolón‐Martínez Solymar , Habib Mohamed R. , Mansour Tamer A. , Díaz‐Ríos Manuel , Rosenthal Joshua J. C. , Zhou Xiao‐Nong , Croll Roger P. , Miller Mark W.
Published: May 2021

Freshwater snails of the genusBiomphalariaserve as intermediate hosts for the digenetic trematodeSchistosoma mansoni, the etiological agent for the most widespread form of intestinal schistosomiasis. As neuropeptide signaling in host snails can be altered by trematode infection, a neural transcriptomics approach was undertaken to identify peptide precursors inBiomphalaria glabrata, the major intermediate host forS.mansoniin the Western Hemisphere. Three transcripts that encode peptides belonging to the FMRF‐NH2‐related peptide (FaRP) family were identified inB.glabrata. One transcript encoded a precursor polypeptide (Bgl‐FaRP1; 292 amino acids) that included eight copies of the tetrapeptide FMRF‐NH2and single copies of FIRF‐NH2, FLRF‐NH2, and pQFYRI‐NH2. The second transcript encoded a precursor (Bgl‐FaRP2;347amino acids) that comprised 14 copies of the heptapeptide GDPFLRF‐NH2and 1 copy of SKPYMRF‐NH2. The precursor encoded by the third transcript (Bgl‐FaRP3; 287 amino acids) recapitulatedBgl‐FaRP2but lacked the full SKPYMRF‐NH2peptide. The three precursors shared a common signal peptide, suggesting a genomic organization described previously in gastropods. Immunohistochemical studies were performed on the nervous systems ofB.glabrataandB.alexandrina, a major intermediate host forS.mansoniin Egypt. FMRF‐NH2‐like immunoreactive (FMRF‐NH2‐li) neurons were located in regions of the central nervous system associated with reproduction, feeding, and cardiorespiration. Antisera raised against non‐FMRF‐NH2peptides present in the tetrapeptide and heptapeptide precursors labeled independent subsets of the FMRF‐NH2‐li neurons. This study supports the participation of FMRF‐NH2‐related neuropeptides in the regulation of vital physiological and behavioral systems that are altered by parasitism inBiomphalaria.
Effects of a Tridentate Pincer Ligand on Parahydrogen Induced Polarization
Authors: Muhammad Safiyah R. , Nugent Joseph W. , Greer Rianna B. , Lee Brian C. , Mahmoud Jumanah , Ramirez Steven B. , Goodson Boyd. M. , Fout Alison R.
Published: May 2021

The role of ligands in rhodium‐ and iridium‐catalyzed Parahydrogen Induced Polarization (PHIP) and SABRE (signal amplification by reversible exchange) chemistry has been studied in the benchmark systems, [Rh(diene)(diphos)]+ and [Ir(NHC)(sub)3(H)2]+, and shown to have a great impact on the degree of hyperpolarization observed. Here, we examine the role of the flanking moieties in the electron‐rich monoanionic bis(carbene) aryl pincer ligand, ArCCC (Ar=Dipp, 2,6‐diisopropyl or Mes, 2,4,6‐trimethylphenyl) on the cobalt‐catalyzed PHIP and PHIP‐IE (PHIP via Insertion and Elimination) chemistry that we have previously reported. The mesityl groups were exchanged for diisopropylphenyl groups to generate the (DippCCC)Co(N2) catalyst, which resulted in faster hydrogenation and up to 390‐fold 1H signal enhancements, larger than that of the (MesCCC)Co‐py (py=pyridine) catalyst. Additionally, the synthesis of the (DippCCC)Rh(N2) complex is reported and applied towards the hydrogenation of ethyl acrylate with parahydrogen to generate modest signal enhancements of both 1H and 13C nuclei. Lastly, the generation of two (MesCCC)Ir complexes is presented and applied towards SABRE and PHIP‐IE chemistry to only yield small 1H signal enhancements of the partially hydrogenated product (PHIP) with no SABRE hyperpolarization.
Direct Conversion of Carbon Dioxide to Methane over Ceria‐ and Alumina‐Supported Nickel Catalysts for Biogas Valorization
Authors: Gac Wojciech , Zawadzki Witold , Rotko Marek , Greluk Magdalena , Słowik Grzegorz , Pennemann Helmut , Neuberg Stefan , Zapf Ralf , Kolb Gunther
Published: May 2021

Direct methanation of CO2 over ceria‐ and alumina‐supported nickel catalysts in the feed stream containing methane and traces of H2S is reported. Stability tests for 20 h at 350 and 600 °C with a packed‐bed reactor showed high resistance of the catalysts to sintering processes. Higher conversion at 350 °C was observed for ceria supported nickel catalyst. Thermodynamic analysis indicated that CO2 contained in biogas can be converted to methane without carbon formation under specific reaction conditions. An introduction of CH4 to CO2−H2 feed stream led to the decrease in CO2 conversion and CH4 selectivity. An introduction of the trace amounts of H2S into the feed stream led to the fast drop of CO2 conversion and CH4 selectivity; higher durability (20 %) was observed for Al2O3 than CeO2 supported catalysts. An improved performance of catalysts coated onto high‐pressure microchannel microreactors for the direct CO2 methanation reaction applying model biogas mixture was demonstrated.
The Redox Properties of Germylenes Stabilized by N‐Donor Ligands
Authors: Kozmenkova Anna Ya. , Timofeeva Vladislava A. , Mankaev Badma N. , Lalov Andrey V. , Saverina Evgeniya A. , Egorov Mikhail P. , Karlov Sergey S. , Syroeshkin Mikhail A.
Published: May 2021

Germylenes, organic compounds of divalent germanium, are often considered as promising catalytic systems efficient in reactions of oxidative addition and reductive elimination, including SET reactions. However, the systematic studies of their redox properties, allowing for the quantitative evaluation of the levels of frontier molecular orbitals and the stability of single electron transfer products, are extremely limited in number. In this work, a series of germylenes with various types of stabilization: N−Ge−N, (N→)C−Ge−C(←N), N−Ge−N(←N), O−Ge−O(←N) и (N→)O−Ge−O(←N) (“−“ ‐a covalent bond, stabilization is achieved by p‐donation of a lone pair of electrons of N or O, “→” ‐donor‐acceptor bond) were characterized by cyclic voltammetry. The results were compared with UV/Vis spectroscopy data and DFT calculations. All germylenes studied in MeCN and THF with Bu4NPF6 as a supporting electrolyte are chemically irreversibly oxidized in the potential range of 0.5–1.4 V vs. Ag/AgCl. In all cases, as estimated by the quantum chemical calculations, the HOMO remains at the covalently unsaturated germanium center although being significantly redistributed over the molecular system. In turn, electroreduction of germylenes is possible only in the presence of a strong electron‐withdrawing substituent or a pyridine ring depleted in electron density donated to germanium. In both cases, the LUMO is localized exactly on these moieties and is absent on the germanium. Thus, the use of stabilizing groups makes it possible both to improve germylene stability and to fine‐tune their HOMO level that determines their ability to participate in oxidative addition reactions.
Electrochemical Induced Regio‐ and Stereoselective Difunctionalization of Alkynes: The Synthesis of (E)‐β‐Iodovinyl Sulfones
Authors: Zhang Xinghua , Lu Danna , Wang Zhenwei
Published: May 2021

An efficient, green, and oxidant‐free electrochemical method for alkyne difunctionalization was described. Using undivided electrochemical cell for iodosulfonylation of alkynes with commercially available iodide radical (NaI), arylsulfonyl radical (ArSO2NHNH2) sources, a variety of (E)‐β‐iodovinyl sulfones were obtained in one‐pot with wide substrate scope, excellent regio‐ and stereoselectivity under mild and ecofriendly conditions.
Ending One's Life in Advance
Authors: Battin Margaret Pabst , Kious Brent M.
Published: May 2021

If you developed Alzheimer disease, would you want to go all the way to the end of what might be a decade‐long course? Some would; some wouldn't. Options open to those who choose to die sooner are often inadequate. Do‐not‐resuscitate orders and advance directives depend on others' cooperation. Preemptive suicide may mean giving up years of life one would count as good. Do‐it‐yourself methods can fail. What we now ask of family and clinicians caring for persons with dementia, and of patients given no better option than to go on with lives they may not want, is unacceptable. To explore how one might better control one's own dying and avoid burdening others with overwhelming care and morally painful choices, we propose a thought experiment: an advance directive implant that would enable persons with early dementia, while competent, to arrange their own deaths without the subsequent intervention of anyone else.
M2 macrophage accumulation contributes to pulmonary fibrosis, vascular dilatation, and hypoxemia in rat hepatopulmonary syndrome
Authors: Chen Bing , Yang Yong , Yang Congwen , Duan Jiaxiang , Chen Lin , Lu Kaizhi , Yi Bin , Chen Yang , Xu Duo , Huang He
Published: May 2021

Hepatopulmonary syndrome (HPS) markedly increases the mortality of patients. However, its pathogenesis remains incompletely understood. Rat HPS develops in common bile duct ligation (CBDL)‐induced, but not thioacetamide (TAA)‐induced cirrhosis. We investigated the mechanisms of HPS by comparing these two models. Pulmonary histology, blood gas exchange, and the related signals regulating macrophage accumulation were assessed in CBDL and TAA rats. Anti‐polymorphonuclear leukocyte (antiPMN) and anti‐granulocyte‐macrophage colony stimulating factor (antiGM‐CSF) antibodies, clodronate liposomes (CL), and monocyte chemoattractant protein 1 (MCP1) inhibitor (bindarit) were administrated in CBDL rats, GM‐CSF, and MCP1 were administrated in bone marrow‐derived macrophages (BMDMs). Pulmonary inflammatory cell recruitment, vascular dilatation, and hypoxemia were progressively developed by 1 week after CBDL, but only occurred at 4 week after TAA. Neutrophils were the primary inflammatory cells within 3 weeks after CBDL and at 4 week after TAA. M2 macrophages were the primary inflammatory cells, meantime, pulmonary fibrosis, GM‐CSFR, and CCR2 were specifically increased from 4 week after CBDL. AntiPMN antibody treatment decreased neutrophil and macrophage accumulation, CL or the combination of antiGM‐CSF antibody and bindarit treatment decreased macrophage recruitment, resulting in pulmonary fibrosis, vascular dilatation, and hypoxemia in CBDL rats alleviated. The combination treatment of GM‐CSF and MCP1 promoted cell migration, M2 macrophage differentiation, and transforming growth factor‐β1 (TGF‐β1) production in BMDMs. Conclusively, our results highlight neutrophil recruitment mediates pulmonary vascular dilatation and hypoxemia in the early stage of rat HPS. Further, M2 macrophage accumulation induced by GM‐CSF/GM‐CSFR and MCP1/CCR2 leads to pulmonary fibrosis and promotes vascular dilatation and hypoxemia, as a result, HPS develops.
Does the COVID‐19 seroconversion in older adults resemble the young?
Authors: Bag Soytas Rabia , Cengiz Mahir , Islamoglu Mehmet Sami , Uysal Betul Borku , Ikitimur Hande , Yavuzer Hakan , Yavuzer Serap
Published: May 2021

High antibody titers have been found to correlate with the severity of coronavirus disease 2019 (COVID‐19) disease. Therefore, antibody titers may be higher in older adults, whose disease is known to have a more severe course than younger ones. This study aimed to compare the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) immunoglobulin G (IgG) antibody level in the reverse transcription‐polymerase chain reaction (RT‐PCR) to test positive older adults with young. Patients aged ≥18 with positive RT‐PCR and checked serum IgG antibodies between November 1, 2020 and January 13, 2021 were included. The IgG antibody levels and the time between RT‐PCR positivity with the antibody levels were recorded. A total of 1071 patients were divided into two groups as Group 1 <60 years old (n = 902) and Group 2 ≥60 years old (n = 169). The SARS‐CoV‐2 IgG antibody titers were higher in Group 2 (p = 0.001). This height was present in the first 3 months after positive RT‐PCR. While the antibody titers were compared by dividing Group 2 into the three groups according to age ranges (60–69, 70–79, and ≥80 years), the antibody titer was higher in ≥80 years patients (p = 0.044). High COVID‐19 IgG antibody levels may be associated with the severity of the disease. Also, the humoral immunity advantage was seen in the first 3 months in the older patients, which suggests that older adults with COVID‐19 may develop reinfection in the long term.