bluuebunny/crossref_metadata_2025 huggingface dataset:
An eikonal approximation model for two-color two-photon attosecond interferometric spectrum
Authors: Tu Qian , Chen You-Long , Liu Kai , Wang Feng , Zhang Xiao-Fan , Yang Yi , Tang Fu-Ming , Liao Qing ,   Hubei Key Laboratory of Optical Information and Pattern Recognition, Wuhan Institute of Technology, Wuhan 430205, China
Published: January 2021

The emission time of photoelectrons from atoms, molecules and solids can be accurately measured on an attosecond scale by using two-color two-photon attosecond interferometric spectroscopy, which helps us to understand the ultrafast electronic dynamics in laser-assisted single photoionization. Understanding the photoelectron emission time depends on the physical model, and the relevant theoretical model provides a better physical explanation and numerical prediction for the photoemission time delay. Although the numerical solution of the time-dependent Schrödinger equation can accurately predict the photoelectron emission time, but it cannot provide a physical explanation. Although some other current theoretical models can provide a more reasonable corresponding physical process, the quantitative prediction of the photoemission time delay has a large deviation. Therefore, we improve the exisating eikonal approximation model. Comparing with the existing eikonal approximation model, we use a more accurate final state wave function and calculate the photoelectron trajectory more accurately when calculating the phase accumulated in the photoelectron propagation process, so we can predict the photoemission time delay more accurately. By comparing our numerical simulation results, we find that when the final kinetic energy of photoelectron is low, the calculated results from the existing theoretical model are greatly different from those from the time-dependent Schrödinger equation, reaching tens of attoseconds. The resultsfrom the existing theoretical model are closer to those from the time-dependent Schrödinger equation with the increase of final kinetic energy of photoelectron. However, no matter what the final kinetic energy of the photoelectron is, the difference between the calculation result from the improved eikonal approximation model and that from the time-dependent Schrödinger equation is always very small. Therefore, our improved eikonal approximation model is closer to the results from the time-dependent Schrödinger equation than the existing theoretical model, which greatly deeps our understanding of the ultra-fast process of photoelectron emission.
Phase field simulation of grain boundary segregation and radiation-enhanced segregation in Fe-Cr alloys
Authors: Yang Zhao-Xi , Liu Wen-Bo , Zhang Cong-Yu , He Xin-Fu , Sun Zheng-Yang , Jia Li-Xia , Shi Tian-Tian , Yun Di ,   Institute of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, China,   Institute of Materials Science, Tsinghua University, Beijing 100084, China,   China Institute of Atomic Energy, Beijing 102413, China
Published: January 2021

Ferritic/martensitic steel, with Cr atomic content in a range of 7%–15%, is a promising candidate for advanced nuclear power systems, due to its swelling resistance and creep fracture resistance under irradiation. Under thermodynamic conditions, Cr segregation usually occurs at grain boundary (GB) in Fe-Cr alloys. However, irradiation can greatly accelerate this process. The enrichment of Cr at GB will enhance precipitation, resulting in embrittlement; while the depletion of Cr at GB may greatly weaken the corrosion resistance properties. In the present work, thermodynamic segregation and radiation-enhanced segregation of Cr element at GB in Fe-Cr alloy is investigated by using the Wheeler-Boettinger-McFadden (WBM) phase-field model. The simulation results show that temperature has a great influence during thermodynamic segregation of Cr at the GB without radiation: when the temperature is lower than 500 ℃ the segregation amount of Cr at the GB is relatively small; when the temperature is higher than 500 ℃ the Cr concentration at GB increases significantly. In addition, as the concentration of Cr in the matrix increases, the amount of relative increase of Cr concentration at GB decreases. However, the Cr concentration at GB under irradiation is significantly enhanced, compared with the counterpart without irradiation. With the increase of dose rate, the Cr concentration in the center of GB also increases. Moreover, with the increase of Cr concentration in the matrix, the relative increase of the Cr concentration at the GB weakens.
Modeling transfer of vaginal microbiota from mother to infant in early life
Authors: Mortensen Martin Steen , Rasmussen Morten Arendt , Stokholm Jakob , Brejnrod Asker Daniel , Balle Christina , Thorsen Jonathan , Krogfelt Karen Angeliki , Bisgaard Hans , Sørensen Søren Johannes
Published: January 2021

Early-life microbiota has been linked to the development of chronic inflammatory diseases. It has been hypothesized that maternal vaginal microbiota is an important initial seeding source and therefore might have lifelong effects on disease risk. To understand maternal vaginal microbiota’s role in seeding the child’s microbiota and the extent of delivery mode-dependent transmission, we studied 665 mother–child dyads from the COPSAC2010 cohort. The maternal vaginal microbiota was evaluated twice in the third trimester and compared with the children’s fecal (at 1 week, 1 month, and 1 year of age) and airway microbiota (at 1 week, 1 month, and 3 months). Based on the concept of weighted transfer ratios (WTRs), we have identified bacterial orders for which the WTR displays patterns indicate persistent or transient transfer from the maternal vaginal microbiome, as well as orders that are shared at later time points independent of delivery mode, indicating a common reservoir.
Identification of distinct pH- and zeaxanthin-dependent quenching in LHCSR3 from Chlamydomonas reinhardtii
Authors: Troiano Julianne M , Perozeni Federico , Moya Raymundo , Zuliani Luca , Baek Kwangyrul , Jin EonSeon , Cazzaniga Stefano , Ballottari Matteo , Schlau-Cohen Gabriela S
Published: January 2021

Under high light, oxygenic photosynthetic organisms avoid photodamage by thermally dissipating absorbed energy, which is called nonphotochemical quenching. In green algae, a chlorophyll and carotenoid-binding protein, light-harvesting complex stress-related (LHCSR3), detects excess energy via a pH drop and serves as a quenching site. Using a combined in vivo and in vitro approach, we investigated quenching within LHCSR3 from Chlamydomonas reinhardtii. In vitro two distinct quenching processes, individually controlled by pH and zeaxanthin, were identified within LHCSR3. The pH-dependent quenching was removed within a mutant LHCSR3 that lacks the residues that are protonated to sense the pH drop. Observation of quenching in zeaxanthin-enriched LHCSR3 even at neutral pH demonstrated zeaxanthin-dependent quenching, which also occurs in other light-harvesting complexes. Either pH- or zeaxanthin-dependent quenching prevented the formation of damaging reactive oxygen species, and thus the two quenching processes may together provide different induction and recovery kinetics for photoprotection in a changing environment.
Prediction of state anxiety by machine learning applied to photoplethysmography data
Authors: Perpetuini David , Chiarelli Antonio Maria , Cardone Daniela , Filippini Chiara , Rinella Sergio , Massimino Simona , Bianco Francesco , Bucciarelli Valentina , Vinciguerra Vincenzo , Fallica Piero , Perciavalle Vincenzo , Gallina Sabina , Conoci Sabrina , Merla Arcangelo
Published: January 2021

Background

As the human behavior is influenced by both cognition and emotion, affective computing plays a central role in human-machine interaction. Algorithms for emotions recognition are usually based on behavioral analysis or on physiological measurements (e.g., heart rate, blood pressure). Among these physiological signals, pulse wave propagation in the circulatory tree can be assessed through photoplethysmography (PPG), a non-invasive optical technique. Since pulse wave characteristics are influenced by the cardiovascular status, which is affected by the autonomic nervous activity and hence by the psychophysiological state, PPG might encode information about emotional conditions. The capability of a multivariate data-driven approach to estimate state anxiety (SA) of healthy participants from PPG features acquired on the brachial and radial artery was investigated.

Methods

The machine learning method was based on General Linear Model and supervised learning. PPG was measured employing a custom-made system and SA of the participants was assessed through the State-Trait Anxiety Inventory (STAI-Y) test.

Results

A leave-one-out cross-validation framework showed a good correlation between STAI-Y score and the SA predicted by the machine learning algorithm (r = 0.81; p = 1.87∙10−9). The preliminary results suggested that PPG can be a promising tool for emotions recognition, convenient for human-machine interaction applications.
Hyperglycemia in severe traumatic brain injury patients and its association with thirty-day mortality: a prospective observational cohort study in Uganda
Authors: Matovu Paul , Kirya Musa , Galukande Moses , Kiryabwire Joel , Mukisa John , Ocen William , Lowery Wilson Michael , Abio Anne , Lule Herman
Published: January 2021

Background

Traumatic brain injury (TBI) is a growing public health concern that can be complicated with an acute stress response. This response may be assessed by monitoring blood glucose levels but this is not routine in remote settings. There is a paucity of data on the prevalence of hyperglycemia and variables associated with mortality after severe TBI in Uganda.

Objective

We aimed to determine the prevalence of hyperglycemia in patients with severe TBI and variables associated with 30-day mortality at Mulago National Referral Hospital in Uganda.

Methods

We consecutively enrolled a cohort 99 patients patients with severe TBI. Serum glucose levels were measured at admission and after 24 h. Other study variables included: mechanism of injury, CT findings, location and size of hematoma, and socio-demographics. The main outcome was mortality after 30 days of management and this was compared in patients with hyperglycemia more than 11.1 mmol/L to those without.

Results

Most patients (92.9%) were male aged 18–30 years (47%). Road Traffic Collisions were the most common cause of severe TBI (64.7%) followed by assault (17.1%) and falls (8.1%). Nearly one in six patients were admitted with hyperglycemia more than 11.1 mmol/L. The mortality rate in severe TBI patients with hyperglycemia was 68.8% (OR 1.47; 95% CI [0.236–9.153]; P = 0.063) against 43.7% in those without hyperglycemia. The presence of hypothermia (OR 10.17; 95% CI [1.574–65.669]; P = 0.015) and convulsions (OR 5.64; 95% CI [1.541–19.554]; P = 0.009) were significant predictors of mortality.

Conclusion

Hypothermia and convulsions at admission were major predictors of mortality in severe TBI. Early hyperglycemia following severe TBI appears to occur with a tendency towards high mortality. These findings justify routine glucose monitoring and could form the basis for establishing a blood sugar control protocol for such patients in remote settings.
Review of the Theories of Critical Thinking. An Approach Directed to the Professional Career of Medical Technology of the National University of Jaén in Peru
Authors: Carranza José Paredes
Published: January 2021

The development of Critical Thinking is recognized as the main criterion of educational quality in international forums of Higher Education. However, there are few studies on the teaching processes, skills and methods to meet this criterion in Peruvian universities. This paper presents a review of the different approaches to critical thinking with an emphasis on students of the medical technology career at the National University of Jaén. The theoretical foundations of critical thinking are addressed, it is contextualized in the careers of health science, it is linked to scientific production and reasoning and the university environment from the various perspectives of critical thinking with an emphasis on university students. All this in order to present critical thinking in the daily dynamics of students of the medical technology career at the National University of Jaén, Peru.
RP-HPLC Method Development and Validation for the Determination of Pemigatinib using Design of Experiments Approach
Authors: Srujani C. H. , Harika K. , Nataraj K. S. , Pawar A. Krishna Manjari
Published: January 2021

Aim: To develop and validate a simple, precise, accurate and robust RP-HPLC method for the determination of Pemigatinib by using Design of Experiments (DoE) approach.

Study Design: A 23 Factorial design consisting of three factors at two levels was considered for the experimental plan initially to select the initial chromatographic conditions and optimization was done using Box-Behnken Design. The critical method parameters selected for optimization were % Organic phase composition, pH of the buffer and flow rate. The critical quality attributes investigated were retention time, theoretical plates and tailing factor.

Methodology: Chromatographic separation was achieved on Agilent Zorbax XDB C18 (250×4.6 mm, 5 µm) column maintained at ambient temperature and PDA-UV detection set at 262nm. The optimized and predicted data from the Design Expert® (12.0.12.0) modelling software (Stat-Ease Inc., Minneapolis, MN, USA) consisted of mobile phase 0.1% OPA pH 2.5 buffer (60%): Acetonitrile (40%) pumped at a flow rate of 1.06ml/min gave the highest desirability.

Results: The retention time of the drug was found to be 3.258 min. The developed method was linear over the concentration range of 25-150 µg/mL with correlation coefficient of 0.999. The optimized method was validated as per ICH Q2 (R1) guidelines.

Conclusion: Based on the ANOVA results, the selected models for the responses retention time and tailing factor were found to be significant with P=0.05. 2D Contour plots were used to visualize the effect of factors and their interactions on the responses. Design validation was done using predicted vs. actual plots for the responses. The results of the validation parameters were within the acceptable limit. The stability of the drug was examined under different stress conditions forcibly and significant degradation was found in reductive condition.
The Influence of Political Connection on Tax Avoidance
Authors: Putra Zaga Kresna Pratama , Suhardianto Novrys
Published: January 2021

The upper echelon theory and rent-seeking theory propose conflicting arguments related to the relationship between a firm’s political connection and tax avoidance. This research aims to examine the relationship between a firm’s political connection and tax avoidance. The 1,079 samples used in this research are public companies with positive income in the 2014-2018 period. By using regression analysis, this research finds that political connection has a negative relationship with tax avoidance, implying that political connection increases tax payment. This research contributes to providing supporting evidence for upper echelon theory by finding that management’s political experience or the intention to maintain a positive image of politically connected management improves tax obedience
Domination of Regional Wealth as a Determining Factor of Financial Statement Disclosure
Authors: Arifin Johan
Published: January 2021

AbstractUsing Stewardship theory, this study examines the factors that influence the level of mandatory disclosure within financial statements of provincial governments in Indonesia, including size of government, regional wealth, number of Regional Working Units (SKPD), administrative age of government and audit findings. By applying the purposive sampling method, this study uses a sample of financial statements from 27 provinces in Indonesia during 2016 to 2018, therefore the total sample is 81 financial statements. The findings reveal that there is a moderate level of compliance with key mandatory disclosures (61,33%). In addition, the regression analysis shows that from the five potential predictor variables, regional wealth is the only predictor that is significantly positive towards the level of mandatory disclosure within financial statements of Indonesian provincial governments. Given overall non-compliance rate of over 38% there is a clear need for the Indonesian government especially the Supreme Audit Board (BPK) to better enforce provincial government's compliance combined with important financial reforms and regulations.
Recherches sur les enzymes catalysant la biosynthese des acides phénoliques chez Quercus pedunculata (EHRH.): I — Formation des premiers termes des series cinnamique et benzöique
Authors: Alibert G. , Ranjeva R.
Published: July 2002

Occurence of PAL, cinnamate‐hydroxylase and p‐coumarate‐hydroxylase, is found in cell‐free extracts from Quercus pedunculata roots; moreover, an enzyme system which catalyzes benzoïc acid formation from cinnamic acid is caracterized for the first time. Role of these enzymes and their interactions within the same organ are discussed.
Interaction of cinnamyl‐tRNAPhe with Escherichia coli elongation factor Tu
Authors: Derwenskus Karl-Heinz , Sprinzl Mathias
Published: July 2002

The products of nitrous acid mediated‐deamination of Phe‐tRNAPhe from E. coli were analyzed and their capability to interact with elongation factor Tu from E. coli was investigated. Thin‐layer chromatography as well as HPLC analysis revealed the existence of at least two deamination products, 3‐phenyllactyl‐tRNAPhe and cinnamyl‐tRNAPhe. It could be shown that the aminoacyl‐tRNA analogues were active in the formation of the ternary complex with EF‐Tu·GTP, although with a lower efficiency than native Phe‐tRNAPhe. For both modified acyl‐tRNAs the dissociation constant was determined to be 3 × 10−5 M.
Control by light and oxygen of B875 and B850 pigment‐protein complexes in Rhodopseudomonas sphaeroides
Authors: Arnheim K. , Oelze J.
Published: July 2002

Control by light and oxygen of the formation of B875 and B850 pigment‐protein complexes in Rhodopseudomonas sphaeroides was evaluated by use of Hill plots. Kinetics of oxygen‐dependent control exhibited Hill coefficients of n = 1.06 and n = 0.65 for B875 and B850 complexes, respectively. Half‐maximum inhibition of B875 complexes was at 20.4% air saturation of the medium and of B850 complexes at 0.9%. Light controlled both complexes with an identical sigmoidal kinetics of n = 2.1.
Preferential utilization of endogenous arachidonate by cyclo‐oxygenase in incubations of human platelets
Authors: Sautebin L. , Caruso D. , Galli G , Paoletti R.
Published: July 2002

Thromboxane B2 (TXB2) and 12‐hydroxy‐5,8,10,14‐eicosatetraenoic acid (12‐HETE) formed from the endogenous and exogenous arachidonate during human platelet incubation, was evaluated by selected ion monitoring (SIM). TXB2 formed from endogenous substrate accounted for about one third of the total, whereas the great part of 12‐HETE derived from exogenous arachidonate. These data indicate that under the tested conditions the pool of arachidonate that acts as substrate for cyclo‐oxygenase is different from the pool that acts as substrate for lipoxygenase and that the arachidonate released from phospholipids is preferentially utilized by cyclo‐oxygenase.
The excision of AP sites by the 3'‐5' exonuclease activity of the Klenow fragment of Escherichia coli DNA polymerase I
Authors: Bailly Véronique , Verly Walter G.
Published: July 2002

The 3' AP endonucleases (class I) are said to hydrolyze the phosphodiester bond 3' to AP sites yielding 3'‐OH and 5'‐phosphate ends; on the other hand, the resulting 3' terminal AP site is not removed by the 3'‐5' exonuclease activity of the Klenow fragment [1]. We show that AP sites in DNA are easily removed by the 3'‐5' exonuclease activity of the Klenow fragment and that they are excised as deoxyribose‐5‐phosphate. It is suggested that the 3' AP endonucleases are perhaps not the hydrolases they are supposed to be.
Plasminogen activator activity in differentiating leukemia cells
Authors: Kidron M. , Nachshon I. , Mayer M. , Fibach E.
Published: July 2002

Plasminogen activator (PA) activity of human promyelocytic leukemia cell line HL‐60 was assayed by following the conversion of plasminogen to plasmin and the plasmin‐mediated hydrolysis of 14C‐labeled globin. When HL‐60 cells were induced to differentiate into macrophages by 12‐O‐tetradecanoyl‐phorbol‐13‐acetate (TPA), cell‐associated PA activity and secretion of PA into the conditioned medium increased profoundly. PA activity increased earlier and as a result of lower concentrations of TPA than the ability of the cells to adhere. Exposure to 10−6 M dexamethasone did not prevent TPA‐induced adherence and produced a slight inhibition of cellular PA activity. These findings imply that TPA‐induced differentiation of HL‐60 cells to macrophage‐like cells is associated with induction of PA activity.
Increase in temperature induces the Z to B transition of poly[d(G‐C)] in water‐ethanol solution
Authors: Karapetyan Armen T. , Minyat Elvira E. , Ivanov Valery I.
Published: July 2002

An increase in temperature from 20 to 50° C results in the complete transition from the Z to B form of poly(d(G‐C)], dissolved in a 55% ethanol‐water solution. The transition is fully reversible and displays a slow kinetics. The transition profiles for the free polynucleotide and for that in the presence of ethidium bromide, which is known to stabilize the B form, are obtained by circular dichroism. Based on these data the enthalpy value for the B‐Z transition in our conditions is estimated to be ΔH
BZ = −0.7 .
Ammonium (methylammonium) is the co‐repressor of nitrate reductase in Chlamydomonas reinhardii
Authors: Franco Antonio R. , Cárdenas Jacobo , Fernández Emilio
Published: July 2002

Methylammonium cannot be used as a nitrogen source by the green alga Chlamydomonas reinhardii and, like ammonia, caused the repression of nitrate reductase without affecting the photosynthetic activity. Glutamine synthetase catalyzed the conversion ofmethylammonium to a single product, identified as γ‐N‐methylglutamine, which accumulated in the cells. Derepression of nitrate reductase was accompanied by a decrease in the intracellular concentration of methylammonium and a concomitant accumulation of γ‐N‐methylglutamine inside the cells. These facts strongly suggest that ammonium (methylammonium) per se, and not a product of its metabolism, is the co‐repressor of nitrate reductase in C. reinhardii
Distinct effects of acetylcholine and glucose on 45calcium and 86rubidium efflux from mouse pancreatic islets
Authors: Nenquin M. , Awouters P. , Mathot F. , Henquin J.C.
Published: July 2002

The similarities between the effects of acetylcholine and glucose on phospholipid metabolism in pancreatic islet cells prompted the comparison of their effects on ionic fluxes. Acetylcholine (1 μM) consistently increased 45Ca2+ efflux from mouse islets, whereas glucose increased it in the presence, but decreased it in the absence of extracellular Ca2+. Acetylcholine consistently accelerated 86Rb+ efflux, and this effect was augmented by Ca2+ omission. On the other hand, glucose markedly inhibited 86Rb+ efflux, except when its concentration was raised from 10 to 15 mM in the presence of Ca2+. Unlike their effects on phospholipid metabolism, the ionic effects of the two insulin‐secretagogues are thus very different.
Chemiluminescent assay of lipid peroxide in plasma using cytochrome c heme peptide
Authors: Iwaoka Teiki , Tabata Fumiko
Published: July 2002

A convenient assay specific to lipid hydroperoxide in plasma is presented. Cytochrome c heme peptide obtained from Saccharomyces was found to emit a strong chemiluminescence with any hydroperoxide, but not with TBA‐reactive substances. The benefit of measuring this luminescence using photon counting is discussed with respect to in vivo lipid peroxidation.
A near infrared electronic transition associated with conversion between S‐states of the photosynthetic O2‐evolving complex
Authors: Dismukes G.Charles , Mathis Paul
Published: July 2002

A new electronic transition is observable in O2‐evolving photosynthetic membranes of spinach enriched in Photosystem II. The transition occurs predominantly in the oxidation state created after a single flash of light (S2 state). It oscillates in yield with a period of flashes when exposed to a train of short light flashes. Conditions which abolish O2 evolution and remove functional manganese destroy this effect. The spectrum and absorptivity of the oscillating component are similar to those found in synthetic manganese dimers poised in the mixed‐valent oxidation state Mn2(III,IV). A similar structural unit is thus implicated for the manganese site involved in O2 evolution.
A structural model for the ligand‐binding sites at the nicotinic acetylcholine receptor
Authors: Smart Louis , Meyers Hans-Wilhelm , Hilgenfeld Rolf , Saenger Wolfram , Maelicke Alfred
Published: July 2002

The structural properties of a selected segment of the 4 polypeptide chains of the acetylcholine receptor from Torpedo californica have been compared by model building studies. The particular segment (residues 135–142) is identical for the β, γ and δ subunits but differs in one position from the otherwise identical α‐peptide. We conclude that the exchange of a tryptophanyl by a glutaminyl residue may produce a sufficiently different folding and charge pattern to provide for the specific binding of cholinergic ligands to the α‐peptide.
Enhancement of collagen‐induced phosphoinositide turnover by thromboxane A2 analogue through Ca2+ mobilization in human platelets
Authors: Kaibuchi Kozo , Tsuda Terutaka , Kikuchi Akira , Tanimoto Tetsuji , Takai Yoshimi
Published: July 2002

In human washed platelets, collagen‐induced phosphoinositide turnover was inhibited by indomethacin, an inhibitor of thromboxane A2 (TXA2) formation, particularly at lower doses of collagen. This inhibition was counteracted by the addition of 9,11‐epithio‐11,12‐methano‐TXA2 (STA2), a stable analogue of TXA2 as well as by the Ca2+ ionophore A23187. STA2 and A23187 did not stimulate phosphoinositide turnover markedly, but significantly increased cytoplasmic free Ca2+ concentrations. The actions of STA2 were blocked by 13‐azaprostanoic acid, a TXA2 receptor antagonist. These results suggest that TXA2 is generated during the action of collagen and increases cytoplasmic free Ca2+ which then stimulates phosphoinositide turnover in cooperation with collagen.
Fusion of Sendai virions with phosphatidylcholine‐cholesterol liposomes reflects the viral activity required for fusion with biological membranes
Authors: Citovsky Vitaly , Blumenthal Robert , Loyter Abraham
Published: July 2002

Sendai virus envelopes were reconstituted after solubilization of intact virions with either Triton X‐100 or octylglucoside. Envelopes obtained from Triton X‐100, but not from octylglucoside solubilized virions, were hemolytic and promoted cell‐cell fusion. Fluorescence dequenching studies [using N‐4‐nitrobenzo‐2‐oxa‐1,3‐diazole phosphatidylethanolamine‐bearing viral envelopes] revealed that both preparations fused with negatively charged phospholipids. Fusion with phosphatidylcholine (PC)/cholesterol (chol) liposomes was promoted only by the hemolytic viral envelopes. Fluorescence dequenching studies, using intact virions bearing octadecylrhodamine B chloride, revealed that intact virions fused with PC/chol as well as with negatively charged phospholipids. Only fusion with PC/chol liposomes was inhibited by phenylmethylsulfonyl fluoride and dithiothreitol, reagents which are known to block the viral ability to fuse with biological membranes.
Mechanism of the stimulation of respiration by fatty acids in rat liver
Authors: Plomp P.J.A.M. , van Roermund C.W.T. , Groen A.K. , Meijer A.J. , Tager J.M.
Published: July 2002

The mechanism of stimulation of hepatic respiration by fatty acids was studied in isolated rat hepatocytes. Stimulation of respiration by fatty acids varied from about 35% to about 105% depending on chain length. The stimulatory effect of octanoate (1 mM) or oleate (0.5 mM) was prevented by oligomycin (2 ). With carboxyatractyloside (100 μM) and ouabain (2 mM) the stimulation of respiration was partially inhibited (by 50–70 and 50–60%, respectively). From these results it can be concluded that the increased rate of respiration after addition of fatty acids is coupled to ATP synthesis. A large part (50–60%) of this ATP is utilized by the (Na+ + K+)‐ATPase
Photosynthetic water oxidation
Authors: Webber Andrew N. , Spencer Lee , Sawyer Donald T. , Heath Robert L.
Published: July 2002

A sequential four‐step chemical model for the water oxidation process in photosystem II is presented, based on the observation that a peroxide‐linked biquinone complex can be chemically formed as a result of hydroxide ion addition to quinone. In our model, the hydroxide ion intermediate is generated in photosystem II as a result of proton abstraction from water. In the model, the first two flashes of light raise the oxidation state of the bimanganese center, while the third and fourth flashes of light sequentially generate the peroxide‐linked biquinone which is then directly oxidized by the bimanganese center to produce oxygen and regenerate quinone.
Structure of hyperacetylated chromatin: light scattering and flow linear dichroism study
Authors: Dimitrov S. , Makarov V. , Apostolova T. , Pashev I.
Published: July 2002

Cation‐induced folding of 10 nm chromatin filament to 30 nm fiber was studied with hyperacetylated chromatin using light scattering at 90° and flow linear dichroism. Acetylated chromatin folded in a way indistinguishable from that of the control chromatin: both the compactness of chromatin and the orientation of nucleosomes relative to the fiber axis were identical at a given salt concentration.
Glucagon‐stimulated respiration and intracellular Ca2+
Authors: Kraus-Friedmann Naomi
Published: July 2002

The effects of extra‐ and intracellular Ca2+ on glucagon‐stimulated respiration were examined in perfused rat liver. Glucagon increased the uptake of O2 to a significantly greater extent in Ca2+ ‐containing perfusate than in Ca2+‐free perfusate. If, however, the livers were perfused first with Ca2+‐containing perfusate for 60 min in order to load the hormone‐sensitive Ca2+ pool(s) and subsequently with Ca2+‐free perfusate, glucagon was able to stimulate O2 uptake to the same extent in Ca2+ ‐free, as in Ca2+‐containing perfusate. These experiments support previous observations of a connection between Ca2+ and the hormonal stimulation of respiration, but indicate a role for intracellular, rather than extracellular, Ca2+ in the process.
Transversal distribution of phospholipids in prothylakoid and thylakoid membranes from oat
Authors: Siegenthaler Paul-André , Giroud Christian
Published: July 2002

Prothylakoid membrane
Thylakoid membrane
Phospholipase
Phospholipid distribution
Phospholipid asymmetry (Oat)
Identification of c‐myb (chicken), c‐myb (mouse) and v‐myb (AMV) protein products by immunoprecipitation with antibodies directed against a synthetic peptide
Authors: Maly Antonín , Krchňák Viktor
Published: July 2002

A synthetic nonadecapeptide (IL 19) derived from a sequence of v‐myb was covalently bound to haemocyanin and used for immunization. Anti‐IL 19 serum immunoprecipitated a 75 kDa protein in the lysate of metabolically labelled chicken and murine thymus cells. Presaturation of the serum with IL 19 abolished this immunoprecipitation, thus indicating that the product of c‐myb in both chicken and murine thymuses is the 75 kDa protein (p75c‐myb). Anti IL 19 serum also precipitated p48c‐myb) in the lysate of nonproducer myeloblasts.
Detection of deuterium nuclei in the immediate surroundings of P700 centers of plant photosynthesis by electron spin echo modulation
Authors: Dikanov S.A. , Astashkin A.V. , Tsvetkov Yu.D. , Goldfeld M.G. , Chetverikov A.G.
Published: July 2002

A comparative analysis of the P700+ electron spin echo modulation in preparations containing normal and heavy water has permitted the detection of the deuterium resulting from isotopic substitution in the immediate surroundings of the P700 centers. The contribution to the modulation is made by a single nucleus coupled with the unpaired electron with the anisotropic hyperfine interaction T
⊥ = 0.4 MHz.
Isolation of cDNA clones of human argininosuccinate lyase and corrected amino acid sequence
Authors: Matuo Seiji , Tatsuno Michiko , Kobayashi Keiko , Saheki Takeyori , Miyata Toshiyuki , Iwanaga Sadaaki , Amaya Yoshihiro , Mori Masataka
Published: July 2002

In the present study, we isolated clones of human argininosuccinate lyase (ASL) cDNA from a liver cDNA library using a clone of rat ASL cDNA and analyzed human ASL cDNA nucleotide sequence. The results reveal that the sequence of human ASL cDNA published by O'Brien et al. in 1986 [Proc. Natl. Acad. Sci USA 83, 7211–7215] had one‐base deletions at three independent positions in the coding regions near the COOH‐terminus, which caused frame‐shift variations in the amino acid sequence. Amino acid sequencing of peptides prepared from purified human liver ASL showed our predicted amino acid sequence to be correct.
Unexpected stimulation of mitochondrial ADP‐ribosylation by cyanide
Authors: Masmoudi Ahmed , Mandel Paul , Malviya Anant N.
Published: July 2002

Cyanide, the classical inhibitor of the mitochondrial respiratory chain at site III, stimulates ADP‐ribosylation of a number of mitochondrial proteins, the major protein being the 50–55 kDa band. Sodium azide, sharing the same inhibitory site, does not have the same effect. Rotenone or antimycin A have no influence on mitochondrial ADP‐ribosylation. Data suggest that no apparent correlation exists between oxidoreductase function and protein ADP‐ribosylation. Purified nuclear poly(ADP‐ribose) polymerase activity was not affected by cyanide. The cyanide effect on mitochondrial ADP‐ribosylation seems intriguing and may be attributed to NAD+ ‐CN complex formation, since NAD reacts with cyanide at pH > 8 with N‐substituted nicotinamide which may prevent inhibition of ADP‐ribosylation.
S‐(p‐Azidophenacyl)thiocarnitine specifically binds to the γ‐butyrobetaine‐binding protein of Agrobacterium sp. and can be used as a photoaffinity label
Authors: Nobile S. , Baccino D. , Deshusses J.
Published: July 2002

The photoaffinity reagent S‐(p‐azidophenacyl)thiocarnitine (PAP‐TC) has been synthesized according to Mauro et al. [(1986) Biochem. J. 237, 533–540]. This compound, originally designed for a structure‐function study of carnitine acetyl‐transferase, was used to analyze the Agrobacterium sp. γ‐butyrobetaine transport system. PAP‐TC appears to be a reagent specific to the transport system since it showed a competitive inhibition (K
i = 70 μM) of γ‐butyrobetaine transport. UV irradiation of periplasmic proteins in the presence of [14C]PAP‐TC resulted in the irreversible labeling of the γ‐butyrobetaine‐binding protein. The addition of 1 mM γ‐butyrobetaine in the mixture significantly decreased the incorporation of the reagent, showing that this compound reacts specifically with the binding protein.
The selective role of cathepsins B and D in the lysosomal degradation of endogenous and exogenous proteins
Authors: Kominami Eiki , Ueno Takashi , Muno Daisaku , Katunuma Nobuhiko
Published: July 2002

A selective inhibitor of cathepsin B, a derivative of E‐64 (compound CA‐074), and pepstatin‐asialofetuin, a potent inhibitor of cathepsin D, were used for an in vivo study of the selective role of these proteinases in lysosomal proteolysis. Administration of compound CA‐074 or pepstatinasialofetuin to rats caused only a slight shift of the lysosomal density and no increase in sequestered enzymes in the autolysosomal fraction, although cathepsin B or D activity in the liver was markedly inhibited. These treatments also had little effect on the inhibition of the degradation of endocytosed FITC‐labeled asialofetuin. In contrast, leupeptin treatment caused marked inhibition of lysosomal degradation of endogenous and exogenous proteins. These results suggest a small contribution of cathepsins B and D to the initiation of lysosomal proteolysis.
Simultaneous synthesis of enzymatically active luciferase and biologically active β subunit of human chorionic gonadotropin in caterpillars infected with a recombinant baculovirus
Authors: Jha Prakash K. , Pal Rahul , Nakhai Bita , Sridhar Padma , Hasnain Seyed E.
Published: July 2002

The β subunit of human chorionic gonadotropin (βhCG), a secretory and extensively glycosylated hormone, and firefly luciferase, a non‐secretory enzyme, were simultaneously synthesized in Spodoptera larvae upon infection with a dual expression recombinant baculovirus, vAcβhCG‐luc. Luciferase was retained predominantly in the body tissue while βhCG was secreted into the hemolymph of infected larvae. Both the proteins were similar to their authentic counterparts in terms of immunoreactivity and bioactivity. The caterpillar‐derived recombinant hCG exhibited reduced electrophoretic mobility on SDS‐PAGE and increased biological activity as compared to the hCG expressed in insect cells in culture. The implications of using the larval system for expressing an extensively glycosylated protein are discusced.
Interleukin‐1β‐induced cytosolic phospholipase A2activity and protein synthesis is blocked by dexamethasone in rat mesangial cells
Authors: Schalkwijk Casper G. , Vervoordeldonk Margriet , Pfeilschifter J. , van den Bosch Henk
Published: July 2002

Interleukin‐1β induces gene expression and secretion of the secretory phospholipase A2(sPLA2) and prostaglandin E2(PGE2) release from rat mesangial cells. We have previousy shown that prolonged treatment of rat mesangial cells with interleukin‐1β (IL‐1β) also enhances the cytosolic phospholipase A; (cPLA2) activity. This effect of IL‐1β on the cPLA2activity is inhibited by actinomycin D and cycloheximide, indicating that both transcription and translation are involved. Here, we describe that IL‐1β increases mRNA levels and protein synthesis of cPLA2itself. In parallel with the effect of dexamethasone on the sPLA2, this glucocorticoid inhibits the IL‐1β‐enhanced cPLA2activity as a result of the suppression of IL‐1β‐induced cPLA2gene expression. This report suggests that the pro‐inflammatory action of interleukin‐1β may, in part, be mediated by its effects on cPLA2activity.
Expression of hepatic calcium‐binding protein regucalcin mRNA is mediated through Ca2+/calmodulin in rat liver
Authors: Shimokawa Noriaki , Yamaguchi Masayoshi
Published: July 2002

The effect of signal transduction‐related factors was investigated to clarify the expression mechanism for mRNA of the hepatic Ca2+‐binding protein regucalcin in the liver of rats. The change of regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin cDNA (0.6 kb). A single intraperitoneal administration of calcium chloride (15 mg Ca2+: 0.374 mmol/100 g body weight) to rats induced a remarkable increase of regucalcin mRNA in liver; the level was about 170% of controls at 30 min after administration. This increase was completely inhibited by simultaneous administration of trifluoperazine (5.0 mg/100 g), an antagonist of calmodulin. On the other hand, a single intraperitoneal administration of phorbol ester or dibutyryl cAMP (10–1,000 μg/100 g) did not cause a significant alteration of hepatic regucalcin mRNA levels. Also, administration of zinc, copper and cadmium (0.374 mmol of metal ion/100g) did not have an appreciable effect on hepatic regucalcin mRNA levels. These findings demonstrate that the expression of hepatic regucalcin mRNA is mediated through Ca2+/calmodulin.
cAMP‐dependent protein phosphorylation in mitochondria of bovine heart
Authors: Technikova-Dobrova Zuzana , Sardanelli Anna Maria , Stanca Maurizio Rosario , Papa Sergio
Published: July 2002

A study is presented of the cAMP‐dependent phosphorylation in bovine heart mitochondria of three proteins of 42, 16 and 6.5 kDa associated to the inner membrane. These proteins are also phosphorylated by the cytosolic cAMP‐dependent protein kinase and by the purified catalytic subunit of this enzyme. In the cytosol, proteins of 16 and 6.5 kDa are phosphorylated by the cAMP‐dependent kinase. It is possible that cytosolic and mitochondrial cAMP‐dependent kinases phosphorylate the same proteins in the two compartments.
Human glutathione transferase catalysis of the formation of S‐nitrosoglutathione from organic nitrites plus glutathione
Authors: Meyer David J. , Kramer Harry , Ketterer Brian
Published: July 2002

The kinetics of spontaneous and human glutathione transferase catalysed formation of S‐nitrosoglutathione(GSNO) from glutathione(GSH) and n‐butyl‐ or amyl nitrite have been studied. At physiological pH and temperature, k
2 values of 22.3 and 21.0 M−1 · min−1 were obtained for n‐butyl‐ and amyl nitrites, respectively. Rate enhancements, (kcat
/K
m × k
2) × 10−4, due to purified human GSH transferases A1−1, A2−2 and Mla−la were, respectively, 7.00, 2.94 and 10.6 for n‐butyl nitrite and 121, 3.92 and 34.5 for amyl nitrite. GSH transferase P1−1 showed no detectable catalysis of the formation of GSNO. The data suggest that the presence of GSTs A1−1, A2−2 or M1−1 contribute substantially to intracellular metabolism of alkyl nitrites to GSNO. The results may be significant with regard to the immunotoxicity of alkyl nitrites.
The ‘pterocarpan synthase” of alfalfa: Association and co‐induction of vestitone reductase and 7,2′‐dihydroxy‐4′‐methoxy‐isoflavanol (DMI) dehydratase, the two final enzymes in medicarpin biosynthesis
Authors: Guo Lining , Dixon Richard A. , Paiva Nancy L.
Published: July 2002

Vestitone reductase and 7,2′‐dihydroxy‐4′‐methoxy‐isoflavanol (DMI) dehydratase are the two final enzymes in medicarpin biosynthesis in alfalfa (Medicago sativa). Although two independent enzymes, vestitone reductase and DMI dehydratase can be loosely associated in low ionic strength buffers, presumably by a weak protein—protein interaction. The activities of vestitone reductase and DMI dehydratase increased approximately 3‐fold 6 hours after elicitor treatment in alfalfa suspension cell culture. The activities remained at maximal levels for 40 hours, correlating with a steady increase in the medicarpin content of the cells. Medicarpin produced in vitro from vestitone by the action of vestitone reductase and DMI dehydratase was found to be (−)‐medicarpin (6aR, 11aR‐medicarpin), possessing the same stereochemistry as medicarpin produced in vivo.
Phosphorylation of neurofibromatosis type 1 gene product (neurofibromin) by cAMP‐dependent protein kinase
Authors: Izawa Ichiro , Tamaki Norihiko , Saya Hideyuki
Published: July 2002

The critical function of the neurofibromatosis type 1 NF1) gene product (neurofabromin) is not well defined except that neurofibromin has homology with a family of the GTPase‐activating proteins (GAPs). In this study, we confirmed that neuofibromin is constitutively phosphorylated and detected kinase activities which specifically phosphorylated the cysteine/serine‐rich domain and the C‐terminal domain of the neurofibromin in cell lysate. In vitro and in‐gel kinase assays strongly indicated that cAMP‐dependent protein kinase (PKA) is a candidate for the neurofibromin kinase. The biological significance for the phosphorylation of neuofibromin is unclear at present, but we speculate that neurofibromin plays a crucial role in cellular function since it links the two major cellular pathways which are the GAP‐rins and PKA‐associated signals.
Tailoring echistatin to possess higher affinity for integrin αIIbβ3
Authors: Yamada Takao , Kidera Akinori
Published: July 2002

A mutant of echistatin, a disintegrin with a high affinity for the integrins, was constructed by substituting RGD for RGD in the Arg‐Gly‐Asp (RGD) region. The mutant was chemically synthesized, subjected to a folding process with air oxidation, and purified by reverse‐phase HPLC. The peptide mapping and mass spectrometric analyses revealed that the two Cys residues introduced in the mutant are linked to each other, without any effect on the mode of the four disulfide bonds present in native echistatin, as expected. The mutant strongly inhibited the binding of human fibrinogen to its receptor, integrin α
IIb
β
3, with an IC50 value of 0.12 nM. This value shows that the mutant is twice as potent as the native form (IC50 = 0.23 nM). These results indicate that the native disintegrin molecule, which has been considered to possess the optimum affinity for the integrins, can be tailored to exhibit even higher affinity by introducing the conformational constraint into the RGD region. Monte Carlo simulations of KRCRGDCMD, the RGD region in the mutant, suggested that the disulfide bond constrains the RGD region to assume a type II′ β‐turn, with Gly and Asp in positions 2 and 3 of the turn.
Functional hemisphere imbalance in patients with paranoid or disorganized schizophrenia
Authors: Spivak B , Karny N , Katz G , Radwan M , Apter A , Master R , Weizman A
Published: July 2002

We assessed hemisphere function in right-handed male chronic schizophrenic patients using dichotic listening tests. We evaluated digit, tonic and transitional tests in patients with paranoid schizophrenia (n = 8), patients with disorganized schizophrenia (n = 8) and in control subjects (n = 8). The dichotic listening analysis discriminated between paranoid and disorganized schizophrenia. In disorganized schizophrenia, functional impairment of both hemispheres was demonstrated, while in paranoid schizophrenia dysfunction was more prominent in the right hemisphere. These results indicate the possible involvement of right hemisphere dysfunction in the pathophysiology of chronic paranoid schizophrenia, in contrast to dysfunction of both hemispheres in chronic disorganized schizophrenia.
HGF/NK4 is a specific antagonist for pleiotrophic actions of hepatocyte growth factor
Authors: Date Kazuhiko , Matsumoto Kunio , Shimura Hideo , Tanaka Masao , Nakamura Toshikazu
Published: July 2002

We prepared a specific antagonist for hepatocyte growth factor (HGF) and designated it HGF/NK4. HGF/NK4 is composed of N‐terminal 447 amino acids of the α‐chain of HGF, thus contains the N‐terminal hairpin domain and subsequent four kringle domains. HGF/NK4 competitively inhibited the specific binding of HGF to the receptor. Importantly, HGF/NK4 neither stimulated DNA synthesis of primary cultured rat hepatocytes (mitogenesis) nor induced cell scattering (motogenesis) and branching tubulogenesis (morphogenesis) of MDCK renal epithelial cells, however, HGF/NK4 almost completely inhibited the mitogenic, motogenic, and morphogenic activities of HGF. HGF/NK4 also suppressed tyrosine phosphorylation of the c‐Met/HGF receptor induced by HGF. Apparently this is the first documentation of a specific antagonist which abrogates the mitogenic, motogenic, and morphogenic activities of HGF.
Unusual FTIR and EPR properties of the H2‐activating site of the cytoplasmic NAD‐reducing hydrogenase from Ralstonia eutropha
Authors: Happe Randolph P. , Roseboom Winfried , Egert Gabriele , Friedrich Cornelius G. , Massanz Christian , Friedrich Bärbel , Albracht Simon P.J.
Published: July 2002

Soluble NAD‐reducing [NiFe]‐hydrogenase (SH) from Ralstonia eutropha (formerly Alcaligenes eutrophus) has an infrared spectrum with one strong band at 1956 cm−1 and four weak bands at 2098, 2088, 2081 and 2071 cm−1 in the 2150–1850 cm−1 spectral region. Other [NiFe]‐hydrogenases only show one strong and two weak bands in this region, attributable to the NiFe(CN)2(CO) active site. The position of these three bands is highly sensitive to redox changes of the active site. In contrast, reduction of the SH resulted in a shift to lower frequencies of the 2098 cm−1 band only. These and other properties prompted us to propose the presence of a Ni(CN)Fe(CN)3(CO) active site.