bluuebunny/crossref_metadata_2025 huggingface dataset:
Staurosporine induces hydrolysis of phosphatidyl inositol 4,5‐bisphosphate in human platelets
Authors: Turkson James , Li Xue-Bin , Wong Kenneth
Published: July 2002

Staurosporine in the micromolar range raised inositol trisphosphate in intact human platelets to levels comparable to that mediated by thrombin. This response was inhibited by neomycin, a phospholipase C antagonist. Staurosporine alone induced a weak, transient rise in cytosolic free calcium levels ([Ca2+]i) from release of internal Ca2+ stores but potentiated the effect induced by thrombin. Therefore, it is unlikely that this alkaloid suppressed inositol trisphosphate mobilization of Ca2+. Additional studies show that Staurosporine, 0.5–5 μM, stimulated GTPase activity in platelet membranes while 2 μM K252a and 20 μM H7 were inactive. Present results suggest that Staurosporine may activate platelet phospholipase C at the level of G proteins or receptors.
Porcine polypyrimidine tract‐binding protein stimulates translation initiation at the internal ribosome entry site of foot‐and‐mouth‐disease virus
Authors: Niepmann Michael
Published: July 2002

The cDNA for porcine polypyrimidine tract‐binding protein (sPTB) was cloned. The sPTB amino acid sequence is highly homologous to the human PTB sequence (97% identity), and the sPTB sequence corresponds to that of the longest human PTB, PTB4. The specificity of binding in the UV‐crosslink of sPTB to the internal ribosome entry site (IRES) of foot‐and‐mouth‐disease virus (FMDV) is similar to that of human PTB. Purified recombinant sPTB efficiently stimulates internal translation initiation directed by the FMDV IRES in a rabbit reticulocyte lysate translation system from which the internal PTB had been depleted.
The active sites of cellulases are involved in chiral recognition: a comparison of cellobiohydrolase 1 and endoglucanase 1
Authors: Henriksson Hongbin , Ståhlberg Jerry , Isaksson Roland , Pettersson Göran
Published: July 2002

The cellulases cellobiohydrolase 1 (CBH 1) and endoglucanase 1 (EG 1) from the fungus Trichoderma reesei are closely related with 40% sequence identity and very similar in structure. In CBH 1 the active site is enclosed by long loops and some antiparallel β‐strands forming a 40 Å long tunnel, whereas in EG 1 part of those loops are missing so that the enzyme has a more common active site groove. Both enzymes were immobilized on silica and these materials were used as chiral stationary phases for chromatographic separation of the enantiomers of two chiral drugs, propranolol and alprenolol. The CBH 1 phase showed much better resolution than did the EG 1 phase, suggesting that the tunnel structure of the protein may play an important role in the chiral separation. The chiral compounds were found to be competitive inhibitors of both enzymes when p‐nitrophenyl lactoside (pNPL) was used as substrate. (S)‐enantiomers showed stronger inhibitory effects and also longer retention time on the stationary phases than the (R)‐enantiomers. The consistency between kinetic data and retention on the stationary phases clearly shows that the enzymatically active sites of CBH 1 and EG 1 are involved in chiral recognition.
High altitude and spontaneous preterm birth
Authors: Ali K.Z.M , Ali M.E. , Khalid M.E.M.
Published: July 2002

Objective: To study the association between high altitude and spontaneous preterm birth. Methods: Eleven placentas from cases of high altitude (3000 m) spontaneous preterm deliveries with no clinical predisposing cause were collected in Abha, a city of southern Saudi Arabia. The placentas were examined histologically using sections stained by periodic acid‐Schiff and hematoxylin‐eosin. The mean percentages of villi with syncytial knots and cytotrophoblastic cells were determined. Results: Histology of the placenta samples showed an excessive formation of syncytial knots (45.4 ±13.3%) and cytotrophoblastic cells (52.7 ±15.2%) at terminal villi. Conclusion: The enhanced formation of syncytial knots and cytotrophoblastic cells is a histological feature of placental hypoxia, which may be secondary to maternal hypoxia resulting from high altitude hypoxia. Since placental hypoxia is associated with an increased incidence of spontaneous preterm birth, we suggest that high altitude may be involved in the etiology of spontaneous preterm birth.
Prolongation of pregnancy in multiple pregnancy
Authors: Al‐Najashi S.S. , Al‐Mulhim A.A.
Published: July 2002

Objective: The purpose of the study was to determine whether the use of prophylactic oral ritodrine or hospitalization for bed rest can prolong pregnancy in multiple pregnancy. Methods: The study was conducted over a period of 8 years and included 189 cases of multiple pregnancy, all of which were delivered at the King Fahd Hospital of the University, Al‐Khobar, Saudi Arabia, between July 1986 and August 1994. The patients were divided into three groups: the first group included 64 patients who received oral ritodrine from the 25th to the end of the 37th week of gestation; the second group included 57 patients who were hospitalized from the 28th to the 32nd week of gestation; and the third group, considered the control group, included 68 patients who were managed on an outpatient basis only. Forty‐six cases of multiple pregnancy were excluded from the study for a variety of reasons. Results: The study showed an increase in gestational age at delivery, an increase in mean birth weight and a reduction in preterm delivery in the group treated with prophylactic ritodrine (P = 0.03). In the hospitalized group there was no effect on duration of gestation or reduction in preterm delivery, but there was an increase in mean birth weight (P = 0.04). Several patients experienced troublesome side effects with ritodrine. Conclusion: Our study indicates that the prophylactic use of β‐sympathomimetics is more effective, beneficial and less expensive than hospitalization for bed rest in prevention of preterm labor and delivery in multiple pregnancy.
Ultrasound appearance of a developing mole
Authors: Zaki Z.M.S. , Bahar A.M.
Published: July 2002

A 40‐year‐old primigravida at her 9th week of pregnancy presented with uterine bleeding and an ultrasound picture of a non‐embryonic pregnancy with an empty gestational sac but a thickened base of high echogenicity. A week later this thickened area showed a placenta‐like disc with a picture of early molar change. At ultrasound follow‐up, this progressed to a full hydatidiform mole filling the whole of the uterine cavity; the empty gestational sac had disappeared. The molar pregnancy was confirmed histologically following suction evacuation of the uterus. Early ultrasound diagnosis of a non‐embryonic pregnancy or a blighted ovum may not rule out the presence of abnormal trophoblast associated with hydatidiform mole. Failed early pregnancies should be evacuated immediately once diagnosed.
Role of the highly conserved Asp‐Arg‐Tyr motif in signal transduction of the CB2 cannabinoid receptor
Authors: Rhee Man-Hee , Nevo Igal , Levy Rivka , Vogel Zvi
Published: July 2002

The DRY motif, at the junction of transmembrane helix 3 and intracellular loop 2 of G protein‐coupled receptors, is highly conserved. Mutations were introduced into the CB2 cannabinoid receptor to study the role of this motif in CB2 signaling. D mutations (DRY130–132AAA and D130A) markedly reduced binding of cannabinoid agonists, while no significant reduction was observed with R131A or Y132A. Mutating R (R131A) only partially reduced, and mutating Y (Y132A) more efficiently reduced the cannabinoid‐induced inhibition of adenylyl cyclase. Thus, in CB2, D130 is involved in agonist binding, whereas Y seems to have a role in receptor downstream signaling.
A family of ubiquitin‐like proteins binds the ATPase domain of Hsp70‐like Stch
Authors: Kaye Frederic J. , Modi Sanjay , Ivanovska Irena , Koonin Eugene V. , Thress Kenneth , Kubo Akihito , Kornbluth Sally , Rose Mark D.
Published: July 2002

We have isolated two human ubiquitin‐like (UbL) proteins that bind to a short peptide within the ATPase domain of the Hsp70‐like Stch protein. Chap1 is a duplicated homologue of the yeast Dsk2 gene that is required for transit through the G2/M phase of the cell cycle and expression of the human full‐length cDNA restored viability and suppressed the G2/M arrest phenotype of dsk2Δ rad23Δ Saccharomyces cerevisiae mutants. Chap2 is a homologue for Xenopus scythe which is an essential component of reaper‐induced apoptosis in egg extracts. While the N‐terminal UbL domains were not essential for Stch binding, Chap1/Dsk2 contains a Sti1‐like repeat sequence that is required for binding to Stch and is also conserved in the Hsp70 binding proteins, Hip and p60/Sti1/Hop. These findings extend the association between Hsp70 members and genes encoding UbL sequences and suggest a broader role for the Hsp70‐like ATPase family in regulating cell cycle and cell death events.
Cloning and expression of human TRAAK, a polyunsaturated fatty acids‐activated and mechano‐sensitive K+ channel
Authors: Lesage Florian , Maingret François , Lazdunski Michel
Published: July 2002

The two P domain hTRAAK K+ channel has been cloned from human brain. hTRAAK cDNA encodes a 393 amino acid polypeptide with 88% of homology with its mouse counterpart. The hTRAAK gene has been mapped to chromosome 11q13 and the study of its organization indicates that the hTRAAK open reading frame is contained in six exons. hTRAAK is expressed abundantly in brain and placenta. In COS cells, hTRAAK currents are K+‐selective, instantaneous and non‐inactivating. These currents are insensitive to the classical K+ channels blockers 4‐aminopyridine, tetraethylammonium, barium and quinidine, but are strongly stimulated by application of arachidonic acid as well as other polyunsaturated fatty acids. hTRAAK can also be activated by a stretch of the membrane.
The APS adapter protein couples the insulin receptor to the phosphorylation of c‐Cbl and facilitates ligand‐stimulated ubiquitination of the insulin receptor
Authors: Ahmed Z , Smith B.J , Pillay T.S
Published: July 2002

The APS adapter protein is rapidly tyrosine‐phosphorylated following insulin stimulation. In insulin‐stimulated 3T3‐L1 adipocytes, APS co‐precipitated with phosphorylated c‐Cbl. In CHO.T‐APS cells overexpressing the insulin receptor and APS, APS co‐precipitated with c‐Cbl but not in CHO.T cells which do not express APS. APS‐mediated recruitment of c‐Cbl to the insulin receptor led to rapid ubiquitination of the insulin receptor β‐subunit in CHO.T‐APS but not in parental CHO.T cells. These results suggest that the function of APS is to facilitate coupling of the insulin receptor to c‐Cbl in order to catalyse the ubiquitination of the receptor and initiation of internalisation or degradation.
Differential feedback regulation of the MAPK cascade underlies the quantitative differences in EGF and NGF signalling in PC12 cells
Authors: Brightman Frances A , Fell David A
Published: July 2002

Although epidermal growth factor (EGF) induces transient activation of Ras and the mitogen‐activated protein kinase (MAPK) cascade in PC12 cells, whereas nerve growth factor (NGF) stimulates sustained activation, the basis for these contrasting responses is not known. We have developed a computer simulation of EGF‐induced MAPK cascade activation, which provides quantitative evidence that feedback inhibition of the MAPK cascade is the most important factor in determining the duration of cascade activation. Hence, we propose that the observed quantitative differences in EGF and NGF signalling can be accounted for by differential feedback regulation of the MAPK cascade.
Mutation Arg336 to Lys in Saccharomyces cerevisiae phosphoenolpyruvate carboxykinase originates an enzyme with increased oxaloacetate decarboxylase activity
Authors: Llanos Liliana , Briones René , Yévenes Alejandro , González-Nilo Fernando D , Frey Perry A , Cardemil Emilio
Published: July 2002

Saccharomyces cerevisiae phosphoenolpyruvate (PEP) carboxykinase catalyzes one of the first reactions in the biosynthesis of carbohydrates. Apart from the physiologically important reaction, the enzyme also presents low oxaloacetate decarboxylase and pyruvate kinase‐like activities. Data from the crystalline structure of homologous Escherichia coli PEP carboxykinase suggest that Arg333 may be involved in stabilization of enolpyruvate, a postulated reaction intermediate. In this work, the equivalent Arg336 from the S. cerevisiae enzyme was changed to Lys or Gln. Kinetic analyses of the varied enzymes showed that a positive charge at position 336 is critical for catalysis of the main reaction, and further suggested different rate limiting steps for the main reaction and the secondary activities. The Arg336Lys altered enzyme showed increased oxaloacetate decarboxylase activity and developed the ability to catalyze pyruvate enolization. These last results support the proposal that enolpyruvate is an intermediate in the PEP carboxykinase reaction and suggest that in the Arg336Lys PEP carboxykinase a proton donor group has appeared.
Reduction of protein disulfide bonds in an oxidizing environment
Authors: Majoul Irina , Ferrari David , Söling Hans-Dieter
Published: July 2002

Following retrograde transport to the endoplasmic reticulum (ER) the A‐subunit of cholera toxin (CTX‐A) is partially cleaved into CTX‐A1 and CTX‐A2 by reduction of a disulfide bridge [Majoul et al. (1996) J. Cell Biol. 133, 777–789], although the redox state in the ER favors disulfide formation. We show here that the disulfide bridge of CTX‐A is cleaved in vitro already at GSH/GSSG ratios between 1 and 3. Protein disulfide isomerase (PDI) exerts only a minor accelerating effect. Various mixed disulfide intermediates (CTX‐A1‐S‐S‐CTX‐A1; PDI‐S‐S‐A2; PDI‐S‐S‐A1) appear during CTX‐A reduction. These results indicate that in the ER protein disulfide formation and protein disulfide reduction can take place simultaneously.
Isolation of a mouse MT2‐MMP gene from a lung cDNA library and identification of its product
Authors: Tanaka Masaaki , Sato Hiroshi , Takino Takahisa , Iwata Kazushi , Inoue Masaki , Seiki Motoharu
Published: July 2002

We have isolated a new MT‐MMP related gene of 3.3 kb from a mouse lung cDNA library using a human MT1‐MMP cDNA as a probe. The deduced protein sequence shows 87% homology to human MT2‐MMP and 52, 50 and 29% to MT1‐MMP, MT3‐MMP and MT4‐MMP, respectively. Thus the gene is thought to be a mouse homologue of human MT2‐MMP. A monoclonal antibody raised against a synthetic peptide recognized mouse MT2‐MMP as a 70 kDa protein. Like MT1‐ and MT3‐MMPs, mouse MT2‐MMP caused activation of pro‐gelatinase A upon co‐transfection into COS‐1 cells. © 1997 Federation of European Biochemical Societies. All rights reserved
A novel, calcium‐inhibitable casein kinase in Paramecium cells
Authors: Kissmehl Roland , Treptau Tilman , Hauser Karin , Plattner Helmut
Published: July 2002

This is the first identification of a Ca2+‐inhibitable casein kinase (CPK) which we have isolated from the 100 000×g supernatant of Paramecium cell homogenates. The 1000‐fold enriched CPK activity depends on millimolar Mg2+ and is inhibited by low concentrations of heparin or by ≥100 μM Ca2+. Enzyme activity is stimulated by polylysine or polyarginine with either casein or with specific casein kinase‐2 (CK‐2) peptide substrates (RRRDDDSDDD and RREEETEEE). The enzymic properties are similar with GTP instead of ATP. CPK does not undergo autophosphorylation. In gel kinase assays, enzyme activity is associated with a 36 kDa band. Calmodulin as another characteristic substrate for mammalian CK‐2 has not been phosphorylated by this protein kinase. Besides casein, CPK phosphorylates in vitro the catalytic subunit of bovine brain calcineurin (CaN), a typical substrate of type 1 mammalian casein kinase (CK‐1) in vitro. Again this phosphorylation is significantly reduced by Ca2+. Thus, CPK combines aspects of different casein kinases, but it is clearly different from any type known by its Ca2+ inhibition. Since CPK also phosphorylates the exocytosis‐sensitive phosphoprotein, PP63, in Paramecium, which is known to be dephosphorylated by CaN, an antagonistic Ca2+‐effect during phosphorylation/dephosphorylation cycles may be relevant for exocytosis regulation.
The catalytic activity of cytochrome P450cam towards styrene oxidation is increased by site‐specific mutagenesis
Authors: Nickerson Darren P , Harford-Cross Charles F , Fulcher Sarah R , Wong Luet-Lok
Published: July 2002

© 1997 Federation of European Biochemical Societies.
A model for the [C+‐G⋅C]n triple helix derived from observation of the C+‐G⋅C base triplet in a crystal structure
Authors: Nunn Christine M , Trent John O , Neidle Stephen
Published: July 2002

A molecular modelling study on the [C+‐G⋅C]n triple helix is reported. We have observed the C+‐G⋅C base triplet in the crystal structure of an oligonucleotide‐drug complex, between the minor‐groove drug netropsin and the decanucleotide d(CGCAATTGCG)2. The complex was crystallised at pH 7.0, but the crystal structure, at a resolution of 2.4 Å, shows that a terminal cytosine has become protonated and participates in a parallel C+‐G⋅C base triplet. The structure of this triplet and its associated sugar‐phosphate backbones have been energy‐refined and then used to generate a triple helix. This has characteristics of the B‐type family of DNA structures for two strands, with the third, the C+ strand, having backbone conformations closer to the A family.
SHP‐1 is involved in neuronal differentiation of P19 embryonic carcinoma cells
Authors: Mizuno Kazuya , Katagiri Tatsuo , Maruyama Etsuko , Hasegawa Kiminori , Ogimoto Mami , Yakura Hidetaka
Published: July 2002

Accumulating evidence suggests that tyrosine phosphorylation plays an important role in the development of the central nervous system and in the differentiation of neuronal cells. To identify protein tyrosine phosphatases (PTPs) that might regulate signaling events leading to neuronal cell differentiation, we cloned PTP genes from the murine P19 embryonic carcinoma cell line and examined the change of their expression during differentiation. P19 cells are known to be pluripotent and the aggregate formation and subsequent replating in the presence of retinoic acid (RA) induce growth arrest and neuronal differentiation. The results demonstrated that among several PTP genes expressed in P19 cells, a cytosolic Src homology region 2 domain‐containing PTP, SHP‐1, is expressed highly in undifferentiated P19 cells, but is reduced to an undetectable level at day 3 after replating in the presence of RA. Further, SHP‐1 was tyrosine‐phosphorylated and activated at day 1 after replating. When ectopic SHP‐1 was constitutively expressed, P19 cells continued to proliferate and failed to differentiate upon stimulation with RA. Collectively, these results suggest that the regulated expression and activity of SHP‐1 may be involved in the neuronal differentiation of P19 cells.
Conformational independence of N‐ and C‐domains in ribosomal protein L7/L12 and in the complex with protein L10
Authors: Bocharov E.V , Gudkov A.T , Budovskaya E.V , Arseniev A.S
Published: July 2002

Isolated N‐ (1–37) and C‐terminal (47–120) fragments of L7 protein, and pentameric (L7)4L10 complex were studied by NMR spectroscopy in solution. The results indicate that the dimer state of the 1–37 fragment with a helical hairpin conformation is identical to the N‐terminal structure of the intact L7 dimer. The C‐terminal domain of the L7 protein does not participate in (L7)4L10 complex formation. The overall motions of the L7 C‐domains are essentially independent both in the L7 dimer and in the (L7)4L10 complex. Conformational motions on a millisecond time scale are detected in the (L7)4L10 complex. The possible relevance of these motions to the biological function of L7/L12 is discussed.
Proteolytic degradation of hemoglobin by endogenous lysosomal proteases gives rise to bioactive peptides: hemorphins
Authors: Fruitier Ingrid , Garreau Isabelle , Lacroix André , Cupo Anny , Piot Jean Marie
Published: July 2002

Hemorphin generation by mice peritoneal macrophages has been recently reported, nevertheless no conclusive data exist to localize clearly the macrophage proteolytic activity implicated in their generation. Because lysosomes are believed to be the main site of degradation in the endocytic pathway, we have studied their potential implication in the generation of hemorphins from hemoglobin. When this protein is submitted to purified rat liver lysosomes, an early generation of hemorphin‐7‐related peptides, detected by a radioimmunoassay, was observed. These peptides seemed to be relatively stable during the first hours of hydrolysis.
PCR random mutagenesis into Escherichia coli serine acetyltransferase: isolation of the mutant enzymes that cause overproduction of L‐cysteine and L‐cystine due to the desensitization to feedback inhibition
Authors: Takagi Hiroshi , Kobayashi Chitose , Kobayashi Shin-ichiro , Nakamori Shigeru
Published: July 2002

PCR random mutagenesis in the cysE gene encoding Escherichia coli serine acetyltransferase was employed to isolate the mutant enzymes that, due to a much less feedback inhibition by L‐cysteine, cause overproduction of L‐cysteine and L‐cystine in the recombinant strains. The L‐cysteine auxotrophic and non‐utilizing E. coli strain was transformed with plasmids having the altered cysE genes. Then, several transformants overproducing L‐cysteine were selected by detecting the halo formation of the L‐cysteine auxotroph. The production test of amino acids and analysis of the catalytic property on the mutant enzymes suggest that the carboxy‐terminal region of serine acetyltransferase plays an important role in the desensitization to feedback inhibition and the high level production of L‐cysteine and L‐cystine.
Novel tetravalent and bispecific IgG‐like antibody molecules combining single‐chain diabodies with the immunoglobulin γ1 Fc or CH3 region
Authors: Alt Margitta , Müller Rolf , Kontermann Roland E
Published: July 2002

Although bispecific IgG molecules have been successfully applied for antibody‐mediated immunotherapy of tumours, applicability is hampered by the difficulties associated with their generation. In the present study, we have used a bispecific single‐chain diabody (scDb) directed against carcinoembryonic antigen and Escherichia coli β‐galactosidase as a model to generate bispecific IgG‐like antibody molecules. We show that the fusion of this single‐chain diabody to the Fc (scDb‐Fc) or CH3 (scDb‐CH3) region of the human immunoglobulin γ1 chain results in the expression of dimeric fusion proteins exhibiting four functional antigen binding sites with increased functional affinity. This strategy represents a new and convenient way to generate IgG‐like multivalent and bispecific molecules that are efficiently secreted from mammalian cells.
Efficacy of 7‐day treatment with metronidazole+miconazole (Neo‐Penotran®) — a triple‐active pessary for the treatment of single and mixed vaginal infections
Authors: Ozyurt E. , Toykuliyeva M.B. , Danilyans I.L. , Morton O. , Baktir G.
Published: July 2002

Objective: To evaluate the efficacy of Neo‐Penotran® pessaries (metronidazole 500 mg+miconazole nitrate 100 mg) in candidal, bacterial and trichomonal vaginitis and in mixed vaginal infections. Method: Ninety‐seven patients with clinical diagnosis of vaginitis entered this open, non‐comparative study. Each patient inserted one pessary twice daily for 7 days. Gynecological and microbiological assessments were carried out before, and 8–10/21–23 days after the start of treatment. Results: Vaginitis symptoms were resolved in 91% of the 74 patients evaluated, and improved in a further 7%. Microbiological cure rates were 97.3% for trichomonal, 86.6% for bacterial and 81% for candidal vaginitis. Recurrence rates were 2.7, 3.8 and 16.1%, respectively. Overall microbiological cure rate for mixed infections was 86%, with 93% for trichomonal+bacterial, and 73% for bacterial+candidal vaginitis. In two out of three cases with trichomonal+bacterial+candidal infection, the microorganisms were eradicated completely. Conclusion: Neo‐Penotran® provides immediate and effective treatment for vaginitis, irrespective of single or multiple infection, even when the diagnosis may be uncertain.
A priori estimates for solutions of fully nonlinear special Lagrangian equations
Authors: Yuan Yu
Published: July 2002

We derive an a priori

C^{2,α}

estimate in dimension three for the equation

F(D^2u)=\arctan\, λ_1+\arctan\, λ_2+\arctan\, λ_3=c

, where

λ_1,λ_2,λ_3

are the eigenvalues of the Hessian

D^2u

. For

−π/2<c<π/2

, the c-level set of

F(D^2u)

fails the convexity condition. Note that for any solution

u

of the above equation,

(x,\nabla u(x))

is a minimizing graph in

ℝ^6

. For

c=0,±π

, the equation is equivalent to

▵u=\operatorname{det}D^2u

.

On déduit une estimation a priori

C^{2,α}

en dimension trois pour l’équation

F(D^2u)=\arctan\, λ_1+\arctan\, λ_2+\arctan\, λ_3=c

, où

λ_1,λ_2,λ_3

sont les valuers propres du hessien

D^2u

. Pour

−π/2<c<π/2

, l’ensemble de niveau c du

F(D^2u)

ne satisfait pas la condition de convexité. Remarquez que pour n’importe qu’elle solution

u

de l’équation,

(x,\nabla u(x))

est un graphe qui minimise l’aire dans

ℝ^6

. Pour

c=0,±π

, l’équation est équivalent à

▵u=\operatorname{det} D^2u

.
Global higher integrability of Jacobians on bounded domains
Authors: Li Chun , McIntosh Alan , Zhang Kewei , Hogan Jeff
Published: July 2002

We give conditions for a vector-valued function

u \in W^{1,n}(Ω, ℝ^n)

, satisfying

\operatorname{det} Du(x) ≥ 0

on a bounded domain

Ω

, which imply that

\operatorname{det} Du(x)

is globally higher integrable on

Ω

. We also give conditions for

u \in W^{1,n}(Ω, ℝ^n)

such that

\operatorname{det} Du

belongs to the Hardy space

h^1_z(Ω)

and exhibit some examples which show that our conditions are in some sense optimal. Applications to the weak convergence of Jacobians follow. Div-curl type extensions of these results to forms are also considered.

Pour une fonction à valeurs vectorielles

u \in W^{1,n}(Ω, ℝ^n)

telle que

\operatorname{det} Du(x) ≥ 0

dans un ouvert borné

Ω

, nous donnons des conditions conduisant à une amélioration de l'intégrabilité globale de

\operatorname{det} Du(x)

dans un ouvert borné

Ω

. Nous donnons aussi des conditions sur

u \in W^{1,n}(Ω, ℝ^n)

pour que

\operatorname{det} Du(x)

appartienne à l'espace de Hardy

h^1_z(Ω)

. Quelques exemples démontrent que ces conditions sont dans un certain sens optimales. Ces résultats sont appliqués à la convergence faible des jacobiens. Nous examinons aussi l'extension de ces résultats du type div-curl aux formes différentielles.
The modulational regime of three-dimensional water waves and the Davey–Stewartson system
Authors: Schanz Ulrich , Sulem Catherine , Craig Walter
Published: July 2002

Nonlinear modulation of gravity-capillary waves travelling principally in one direction at the surface of a three-dimensional fluid leads to the Davey–Stewartson system for the wave amplitude and the induced mean flow. In this paper, we present a rigorous derivation of the system and show that the resulting wavepacket satisfies the water wave equations at leading order with precise bounds for the remainder.

Key steps in the analysis are the analyticity of the Dirichlet–Neumann operator with respect to the surface elevation that defines the fluid domain, precise bounds for the Taylor remainders and the description of individual terms in the Taylor series as pseudo-differential operators and their estimates under multiple scale expansions.

La modulation nonlinéaire d’ondes se propageant principalement dans une direction à la surface d’un canal tridimensionnel conduit au système de Davey–Stewartson pour l’amplitude de l’onde et le champ moyen induit. Dans cet article, nous présentons une dérivation rigoureuse du système et nous montrons que l’approximation modulationnelle satisfait les équations des ondes de surface à l’ordre dominant.

Les étapes importantes dans l’analyse sont l’analyticité de l’opérateur de Dirichlet–Neumann par rapport à l’interface qui définit le domaine du fluide, des estimations du reste dans le développement de Taylor de l’opérateur, ainsi que la description des différents termes de la série comme opérateurs pseudo-differentiels et leurs développements multi-échelles.
The p-harmonic system with measure-valued right hand side
Authors: Dolzmann Georg , Hungerbühler Norbert , Müller Stefan
Published: July 2002

For

2 - \frac{1}{n}<p<n

we prove existence of a distributional solution

u

of the

p

-harmonic system

\begin{align*}
- \mathrm{div}\left(\left|\nabla _{u}\right|^{p - 2}\nabla u\right) &= \mu && \text{in } \Omega \\
u &= 0 && \text{on } \partial \Omega ,
\end{align*}

where

Ω

is an open subset of

ℝ^n

(bounded or unbounded),

u : Ω → ℝ^m

, and

μ

is an

ℝ^m

-valued Radon measure of finite mass. For the solution

u

we establish the Lorentz space estimate

\left\|Du\right\|_{L^{q,\infty }} + \left\|u\right\|_{L^{q*,\infty }} \leq C\left\|\mu \right\|_{\mathcal {M}}^{\frac{1}{p - 1}}

with

q = \frac{n}{n - 1}\left(p - 1\right)

and

q^* = \frac{n}{n - p}\left(p - 1\right)

. The main step in the proof is to show that for suitable approximations the gradients

Du_k

converge a.e. This is achieved by a choice of regularized test functions and a localization argument to compensate for the fact that in general

u \notin W^{1,p}

.

Soit

2 − \frac 1 n < p < n

,

Ω

un ensemble ouvert de

ℝ^n

(borné ou non borné) et μ une mesure de Radon avec masse finite. On démontre que le système

p

-harmonique

\begin{align*}
- \text{div}\left(\left|\nabla u\right|^{p - 2}\nabla u\right) &= \mu && \text{dans } \Omega , \\
u &= 0 && \text{sur } \partial \Omega ,
\end{align*}

possède une solution distributionnelle. Pour cette solution on établit des estimations dans les espaces de Lorentz.

\left\|Du\right\|_{L^{q,\infty }} + \left\|u\right\|_{L^{q*,\infty }} \leq C\left\|\mu \right\|_{\mathcal {M}}^{\frac{1}{p - 1}}.

lci,

q = \frac{n}{n - 1}\left(p - 1\right)

et

q^* = \frac{n}{n - p}\left(p - 1\right)

. Le pas le plus important est de démontrer que, pour des approximations propres, les gradients

Du_k

convergent presque partout. Celà est fait en choisissant des fonctions de test régularisées et en appliquant un argument de localisation pour compenser que, en général,

u\notin W^{1,p}

.
Periodic solutions for singular Hamiltonian systems and closed geodesics on non-compact Riemannian manifolds
Authors: Tanaka Kazunaga
Published: July 2002

We study the existence of periodic solutions of singular Hamiltonian systems as well as closed geodesics on non-compact Riemannian manifolds via variational methods.

For Hamiltonian systems, we show the existence of a periodic solution of prescribed-energy problem:

\begin{align*}
&\stackrel{••}q + \nabla V\left(q\right) = 0,\\
&\frac{1}{2}\left|\stackrel{•}q\right|^{2} + V\left(q\right) = 0
\end{align*}

under the conditions: (i)

V(q)<0

for all

q \in \mathbb{R}^{N}\backslash \left\{0\right\}

; (ii)

V(q)\sim −1/|q|^2

as

|q|∼0

and

|q|∼∞

.

For closed geodesics, we show the existence of a non-constant closed geodesic on

\left(\mathbb{R} \times S^{N - 1},g\right)

under the condition:

g_{\left(s,x\right)} \sim ds^{2} + h_{0} \quad \text{as }s \sim \pm \infty ,

where

h_0

is the standard metric on

S^{N−1}

.

Nous étudions l’existence de solutions p’eriodiques pour des systèmes Hamiltoniens singuliers, et de géodésiques fermées sur des variétes Riemanniennes non-compactes par des méthodes variationnelles.

Pour les systèmes Hamiltoniens, nouns montrons l’existence d’une solution périodique pour un probl‘eme à énergie prescrite:

\begin{align*}
&\stackrel{••}q + \nabla V\left(q\right) = 0,\\
&\frac{1}{2}\left|\stackrel{•}q\right|^{2} + V\left(q\right) = 0
\end{align*}

sous les conditions: (i)

V(q)<0

pour tout

q \in \mathbb{R}^{N}\backslash \left\{0\right\}

; (ii)

V(q)∼−1/|q|^2

quand

|q|∼0

et

|q|∼∞

.

Pour les géodésiques fermées, nouns montrons l’existence d’une géodésique fermée non-constante sur

\left(\mathbb{R} \times S^{N - 1},g\right)

sous la condition:

g_{\left(s,x\right)} \sim ds^{2} + h_{0} \quad \text{as }s \sim \pm \infty ,

où

h_0

est la métrique standard sur

S^{N−1}

.
Levels of monoamine and amino acid neurotransmitters in the developing male mouse hypothalamus and in histotypic hypothalamic cultures
Authors: Miranda‐contreras L. , Mendoza‐Briceño R.V. , Palacios‐Prü E.L.
Published: July 2002

The variation in the levels of the monoamine and amino acid neurotransmitters was studied during the period of neurogenesis in male mouse hypothalamus, from embryonic day 15 until the age of young adult. The results shown in this study demonstrate that the monoamines appear early in the fetal brain and that the maximum expression of the catecholaminergic system, particularly that of dopamine, occurs during the late neonatal period or mouse infancy, when the role played by the catecholamines on the maturation of the neurosecretory systems is more significant. In relation to the amino acid neurotransmitters, glutamate and taurine seem to be the principal transmitters of the hypothalamus since their concentrations were about five–tenfold higher than the levels of glycine and GABA. Both amino acids had the same pattern of variation during development, showing elevated values during the prenatal, late neonatal and early pubertal period. Increased concentrations of the inhibitory neurotransmitter GABA were observed on the day before birth, at the end of the neonatal period and throughout the prepubertal period, suggesting that the influence of GABA on hypothalamic neurogenesis increases by the time when the hypothalamic nuclei have reached maturity and the local circuits have been established. To determine the intrinsic neurotransmitter production, primary hypothalamic histotypic cultures prepared from mice at postnatal days 8–10 were analyzed for their content of neurotransmitters. The in vitro analysis revealed that the hypothalamic neurons intrinsically produce dopamine, glutamate, taurine and glycine in homologable amounts with those of young adult animals. The comparative analysis also showed that about 50% of the GABA content and less than 5% of the hypothalamic epinephrine level are locally produced, while serotonin comes mainly from extrinsically located neurons.
Microglia only weakly present glioma antigen to cytotoxic T cells
Authors: Flügel Alexander , Labeur Marta S. , Grasbon‐Frodl Eva‐Maria , Kreutzberg Georg W. , Graeber Manuel B.
Published: July 2002

Microglia and brain macrophages represent a substantial fraction of the cells present in astrocytic gliomas. Yet, the functional role of microglia in these tumors has remained enigmatic. We have compared rat microglial cells and thymocytes with regard to their ability to present purified CNS proteins, MBP and S100β, as well as C6 glioma cells to specific T lymphocytes. In addition, a new cytotoxicity assay based on fluorescence activated cell sorting of tumor cells carrying the green fluorescent protein was established. This assay was used to determine the influence of microglial population density and activational state on C6 glioma cell survival in vitro. Microglia were consistently found to present MBP and S100β less efficiently than thymocytes and appeared to be unable to present C6 glioma cells to cytotoxic T lymphocytes. In addition, high concentrations of microglial cells attenuated the cytotoxic effects of these T cells on C6 glioma cells whereas thymocytes significantly supported their specific killing. It is suggested that defense functions of microglial cells against C6 glioma are severely compromised and that the observed deficiency in antigen presentation may play an important role for astrocytoma growth in vivo.
Facing away from the interviewer: Evidence of little benefit to eyewitnesses' memory performance
Authors: Nash Alena , Ridout Nathan , Nash Robert A.
Published: July 2020

Averting gaze from another person's face generally improves cognitive performance, yet, little is known about how witnesses' gaze direction affects their recall during investigative interviews. Here, participants witnessed a video‐recorded incident, and were interviewed via free recall and closed questions following a short delay. In Experiment 1, participants either faced the interviewer or faced away during the interview. In Experiment 2, alongside this manipulation, the interviewer also either faced the witness or faced away. In Experiment 3, witness gaze direction was manipulated alongside rapport‐building. In Experiment 4, the effect of facing away was directly compared with that of eye‐closure. Mini meta‐analysis of all four experiments showed that the effect of witness gaze direction on memory performance was minimal. Furthermore, neither aversion of interviewer's gaze nor rapport‐building magnified this effect. Added to the cumulative literature on eyewitness gaze aversion, these findings afford better estimates of the likely size of these effects.
Measuring Demisability of Bulk Metallic Glasses for Potential Satellite Applications through Ablation Experiments
Authors: Bordeenithikasem Punnathat , Roberts Scott N. , Hofmann Douglas C. , Ratliff John Martin , Greene Benton R. , Bacon John B. , Sohn Sungwoo , Schroers Jan
Published: July 2020

Bulk metallic glasses (BMGs) exhibit attractive properties for spacecraft applications. When low Earth‐orbiting satellites reenter the atmosphere at end of mission, a measure to mitigate the generation of space debris, operators must limit the number of satellite components that reach the ground to ensure public safety. Inductively coupled plasma using an argon/air mixture to simulate reentry conditions is used to study ablation of BMG and conventional spacecraft alloys. Differential scanning calorimetry is used to determine the thermal properties of the alloys. BMGs are shown to ablate similarly to aluminum alloys (Al7075) and dramatically faster than titanium alloys (Ti‐6Al‐4V).
Addressing Crime, Violence, and Other Determinants of Health through Community‐Based Participatory Research and Implementation Science
Authors: Stalker Katie Cotter , Brown Mary Ellen , Evans Caroline B.R. , Hibdon Julie , Telep Cody
Published: July 2020

In this paper, we describe the assessment and planning phase of the Thrive community‐based initiative to reduce violence and address other determinants of health in a community in the Southwestern United States. Using community‐based participatory research (CBPR) and an implementation science framework, we engaged residents and other key stakeholders as equal partners in the assessment and planning process. The Thrive assessment and planning phase involved collaboration among researchers, residents, law enforcement, nonprofit agencies, public health, local government, and other cross‐sector partners. We used implementation science in order to examine the barriers and facilitators to addressing community health and safety, to assess the nature and scope of health and safety issues, to review existing solutions, to assess the acceptability and necessary adaptations of selected interventions, and to assess feasibility and sustainability of the initiative. Through interviews, focus groups, analysis of crime incident data, geomapping, and direct observations, our findings highlighted the presence of an open‐air drug market, the high‐stress nature of the community, concern for the lack of opportunities for youth, the lack of trust between residents and law enforcement, and a need to address the built environment to promote safety and well‐being.
Ein Methodenrepertoire für die paramagnetische NMR‐Spektroskopie zur Charakterisierung von paramagnetischen/Spin‐Crossover‐ Komplexen und Metall‐organischen Käfigverbindungen
Authors: Lehr Marc , Paschelke Tobias , Trumpf Eicke , Vogt Anna‐Marlene , Näther Christian , Sönnichsen Frank D. , McConnell Anna J.
Published: July 2020

Paramagnetische Zentren erschweren aufgrund von großen paramagnetischen Verschiebungen und kurzen Relaxationszeiten die Analytik in Lösung mittels NMR Spektroskopie. Die NMR‐Analytik von paramagnetischen Komplexen ist damit im Vergleich zu diamagnetischen Komplexen deutlich limitierter und stützt sich oftmals auf theoretische Modelle und Berechnungen. Wir präsentieren hier eine “Werkzeugkiste” für 1D (1H, Protonen‐gekoppelt 13C, 13C mit selektiver Protonen‐Entkopplung, Sättigungs‐NOE) und 2D (COSY, NOESY, HMQC) paramagnetische NMR‐Methoden, die eine bisher beispiellose Strukturaufklärung bietet und in manchen Fällen zusätzliche strukturelle Informationen liefert, welche in diamagnetischen Analoga nicht beobachtet werden könnten. Durch die Charakterisierung von mononuklearen CoII‐ und high‐spin FeII‐Komplexen und einer Co4L6‐Käfigverbindung zeigen wir, dass die Techniken vielseitig und in verschiedenen Bereichen einsetzbar sind, beispielsweise in der Koordinationschemie, für Spin‐Crossover‐Komplexe und in der supramolekularen Chemie.
Selective Loading of Atomic Platinum on a RuCeOx Support Enables Stable Hydrogen Evolution at High Current Densities
Authors: Liu Tongtong , Gao Wenbin , Wang Qiqi , Dou Meiling , Zhang Zhengping , Wang Feng
Published: July 2020

High‐performance electrocatalysts for the hydrogen evolution reaction (HER) have an important role to play in the development of renewable energy. Platinum remains the most efficient known HER electrocatalyst. Therefore, it is necessary to find ways to maximize Pt utilization in actual practical applications. Herein we demonstrate a facile strategy for synthesizing RuCeOx‐supported, selectively loaded, atomic Pt (0.49 wt. %) (denoted Pt/RuCeOx‐PA) by photoactivation at ambient temperature and pressure. Through the photoelectron transfer at the Mott‐Schottky heterojunction in RuCeOx, Pt atoms became embedded into the RuO2 lattice. The resulting selectively loaded Pt‐O‐Ru moieties in Pt/RuCeOx‐PA give a stronger hydrogen spillover effect than Pt complexes randomly loaded by either chemical activation or thermal activation. As a result, Pt/RuCeOx‐PA shows superior HER performance to the materials prepared by random loading and is even better than a commercial Pt/C catalyst with much higher Pt loading (20 wt. %) at high current densities (from 50–600 mA cm−2).
From Glucose to Polymers: A Continuous Chemoenzymatic Process
Authors: Maiti Sampa , Manna Saikat , Banahene Nicholas , Pham Lucynda , Liang Zhijie , Wang Jun , Xu Yi , Bettinger Reuben , Zientko John , Esser‐Kahn Aaron P. , Du Wenjun
Published: July 2020

Efforts to synthesize degradable polymers from renewable resources are deterred by technical and economic challenges; especially, the conversion of natural building blocks into polymerizable monomers is inefficient, requiring multistep synthesis and chromatographic purification. Herein we report a chemoenzymatic process to address these challenges. An enzymatic reaction system was designed that allows for regioselective functional group transformation, efficiently converting glucose into a polymerizable monomer in quantitative yield, thus removing the need for chromatographic purification. With this key success, we further designed a continuous, three‐step process, which enabled the synthesis of a sugar polymer, sugar poly(orthoester), directly from glucose in high yield (73 % from glucose). This work may provide a proof‐of‐concept in developing technically and economically viable approaches to address the many issues associated with current petroleum‐based polymers.
Synthesis of Amides and Esters by Palladium(0)‐Catalyzed Carbonylative C(sp3)−H Activation
Authors: Čarný Tomáš , Rocaboy Ronan , Clemenceau Antonin , Baudoin Olivier
Published: July 2020

The 1,4‐palladium shift strategy allows the functionalization of remote C−H bonds that are difficult to reach directly. Reported here is a domino reaction proceeding by C(sp3)−H activation, 1,4‐palladium shift, and amino‐ or alkoxycarbonylation, which generates a variety of amides and esters bearing a quaternary β‐carbon atom. Mechanistic studies showed that the aminocarbonylation of the σ‐alkylpalladium intermediate arising from the palladium shift is fast using PPh3as the ligand, and leads to the amide rather than the previously reported indanone product.
NHC‐Pd complex heterogenized on graphene oxide for cross‐coupling reactions and supercapacitor applications
Authors: Kandathil Vishal , Siddiqa Aisha , Patra Abhinandan , Kulkarni Bhakti , Kempasiddaiah Manjunatha , Sasidhar B.S. , Patil Shivaputra A. , Rout Chandra Sekhar , Patil Siddappa A.
Published: July 2020

N‐heterocyclic carbene (NHC)‐palladium(II) complex (GO@NHC‐Pd) was synthesized on graphene oxide (GO) support via a simple and cost‐effective multistep approach. The spectroscopic, microscopic, thermal, and surface analyses of GO@NHC‐Pd confirmed the successful formation of the catalyst. The investigation of catalytic activity showed that GO@NHC‐Pd was very effective in Suzuki–Miyaura as well as Hiyama cross‐coupling. Being heterogeneous in nature, GO@NHC‐Pd was recovered after each reaction cycle easily and reused for up to nine and six cycles in Suzuki–Miyaura and Hiyama cross‐coupling, respectively, without significant loss of activity. Further exploration of the supercapacitor performance of GO@NHC‐Pd catalyst assembled in a two‐electrode cell configuration shown a maximum attained capacitance of 105.26 F/g at a current density of 0.1 A/g with good cycling stability of 96.89% over 2,500 cycles.
Extension of cell membrane boosting squalene production in the engineered Escherichia coli
Authors: Meng Yunhe , Shao Xixi , Wang Yan , Li Yumei , Zheng Xiaojian , Wei Gongyuan , Kim Seon‐Won , Wang Chonglong
Published: July 2020

Squalene is a lipophilic and non‐volatile triterpene with many industrial applications for food, pharmaceuticals, and cosmetics. Metabolic engineering focused on optimization of the production pathway suffer from little success in improving titers because of a limited space of the cell membrane accommodating the lipophilic product. Extension of cell membrane would be a promising approach to overcome the storage limitation for successful production of squalene. In this study, Escherichia coli was engineered for squalene production by overexpression of some membrane proteins. The highest production of 612 mg/L was observed in the engineered E. coli with overexpression of Tsr, a serine chemoreceptor protein, which induced invagination of inner membrane to form multilayered structure. It was also observed an increase in unsaturated fatty acid in membrane lipids composition, suggesting cellular response to maintain membrane fluidity against squalene accumulation in the engineered strain. This study potentiates the capability of E. coli for squalene production and provides an effective strategy for the enhanced production of such compounds.
The interrelationships between wheat quality, composition, and dough rheology for a range of Western Canadian wheat cultivars
Authors: Tozatti Patricia , Güldiken Burcu , Fleitas María C. , Chibbar Ravindra N. , Hucl Pierre , Nickerson Michael T.
Published: July 2020

Background and objectives

The overall goal of this research was to understand the interrelationships between wheat quality, grain and flour composition, and dough rheology for a range of commercially grown Canadian wheat (Triticum aestivum L.) cultivars (×25) within different wheat market classes.

Findings

Cultivar type varied in proximate analyses, which directly impacted dough handling parameters. Micro‐doughLAB absorption was positively correlated with protein content, grain hardness, wet gluten, and dry gluten content, and was negatively correlated with the gluten performance index. Strong and significant correlation was found between gluten properties, flour composition, and dough strength measurements.

Conclusions

Protein and gluten properties, in particular, significantly impacted dough strength measurements. Cultivars displaying stronger gluten strengths may result in dough with better dough handling properties.

Significance and novelty

The study provides useful information about 25 commercially grown Western Canadian wheat cultivars with a range of gluten strength, and their relation to their glutenin and gliadin subunit composition, and dough handling properties.