bluuebunny/crossref_metadata_2025_split huggingface dataset:
Population-Based Genetic and Evolutionary Analysis ofChlamydia trachomatisUrogenital Strain Variation in the United States
Authors: Millman Kim , Black Carolyn M. , Johnson Robert E. , Stamm Walter E. , Jones Robert B. , Hook Edward W. , Martin David H. , Bolan Gail , Tavaré Simon , Dean Deborah 
Published: April 2004

ABSTRACTChlamydia trachomatisis a major cause of ocular and sexually transmitted diseases worldwide. While much of our knowledge about its genetic diversity comes from serotyping orompAgenotyping, no quantitative assessment of genetic diversity within serotypes has been performed. To accomplish this, 507 urogenital samples from a multicenter U.S. study were analyzed by phylogenetic and statistical modeling. No B, Da, or I serotypes were represented. Based on our analyses, all but one previous urogenital B serotype was identified as Ba. This, coupled with the lack of B serotypes in our population, suggests that B has specific tropism for ocular mucosa. We identified a Ba/D recombinant (putative crossover nucleotide 477;P< 0.0001) similar to a B/D mosaic we described previously from an African trachoma patient. Computational analyses of the Ba/D recombinant indicated that upstream changes were less important for tissue tropism than downstream incorporation of the D sequence. Since most serotypes had nonsynonymous/synonymous ratios of <1.0, the major outer membrane protein, encoded byompA, has many functional constraints and is under purifying selection. Surprisingly, all serotype groups except for J had a unimodal population structure indicating rapid clonal expansion. Of the groups with a unimodal structure, E and Ia and, to a lesser extent, G and K were prevalent, had infrequent incorporation of mutations, and, compared to other groups, had a relatively greater degree of diversifying selection, consistent with a selective sweep of mutations within these groups. Collectively, these data suggest a diverse evolutionary strategy for different serogroups of the organism.
Unraveling the Function of the
Rhodospirillum rubrum
Activator of Polyhydroxybutyrate (PHB) Degradation: the Activator Is a PHB-Granule-Bound Protein (Phasin)
Authors: Handrick Rene , Reinhardt Simone , Schultheiss Daniel , Reichart Thomas , Schüler Dirk , Jendrossek Verena , Jendrossek Dieter 
Published: April 2004

ABSTRACT

Efficient hydrolysis of native poly(3-hydroxybutyrate) (nPHB) granules in vitro by soluble PHB depolymerase of
Rhodospirillum rubrum
requires pretreatment of nPHB with an activator compound present in
R. rubrum
cells (J. M. Merrick and M. Doudoroff, J. Bacteriol.
88:
60-71, 1964). Edman sequencing of the purified activator (17.4 kDa; matrix-assisted laser desorption ionization—time of flight mass spectrometry) revealed identity to a hypothetical protein deduced from a partially sequenced
R. rubrum
genome. The complete activator gene,
apdA
(activator of polymer degradation), was cloned from genomic DNA, expressed as a six-His-tagged protein in recombinant
Escherichia coli
(
M
r
, 18.3 × 10
3
), and purified. The effect of ApdA on PHB metabolism was studied in vitro and in vivo. In vitro, the activity of the activator could be replaced by trypsin, but recombinant ApdA itself had no protease activity. Comparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the protein patterns of trypsin- and ApdA-treated nPHB granules isolated from different PHB-accumulating bacteria showed that trypsin activated nPHB by removing proteins of the surface layer of nPHB regardless of the origin of nPHB, but ApdA bound to and interacted with the surface layer of nPHB in a nonproteolytic manner, thereby transforming nPHB into an activated form that was accessible to the depolymerase. In vivo, expression of ApdA in
E. coli
harboring the PHB biosynthetic genes,
phaCBA
, resulted in significant increases in the number and surface/volume ratio of accumulated PHB granules, which was comparable to the effect of phasin proteins, such as PhaP in
Ralstonia eutropha
. The amino acid sequence of ApdA was 55% identical to the amino acid sequence of Mms16, a magnetosome-associated protein in magnetotactic
Magnetospirillum
species. Mms16 was previously reported to be a GTPase with an essential function in magnetosome formation (Y. Okamura, H. Takeyama, and T. Matsunaga, J. Biol. Chem.
276:
48183-48188, 2001). However, no GTPase activity of ApdA could be demonstrated. We obtained evidence that Mms16 of
Magnetospirillum gryphiswaldense
can functionally replace ApdA in
R. rubrum
. Fusions of
apdA
and
mms16
to
gfp
or
yfp
were functionally expressed, and both fusions colocalized with PHB granules after conjugative transfer to
R. rubrum
. In conclusion, ApdA in vivo is a PHB-bound, phasin-like protein in
R. rubrum.
The function of Mms16 in magnetotactic bacteria requires further clarification.
PhoP Can Activate Its Target Genes in a PhoQ-Independent Manner
Authors: Lejona Sergio , Castelli María Eugenia , Cabeza María Laura , Kenney Linda J. , García Véscovi Eleonora , Soncini Fernando C. 
Published: April 2004

ABSTRACT

The PhoP/PhoQ two-component system controls the extracellular magnesium depletion response in
Salmonella enterica
. Previous studies have shown that PhoP is unable to up-regulate its target genes in the absence of PhoQ function. In this work, we demonstrate that PhoP overexpression can substitute for PhoQ- and phosphorylation-dependent activation. Either a high concentration of PhoP or activation via phosphorylation stimulates PhoP self-association.
Novel
rpoB
Mutations Conferring Rifampin Resistance on
Bacillus subtilis
: Global Effects on Growth, Competence, Sporulation, and Germination
Authors: Maughan Heather , Galeano Belinda , Nicholson Wayne L. 
Published: April 2004

ABSTRACT

Previously, spontaneous rifampin resistance mutations were isolated in cluster I of the
rpoB
gene, resulting in amino acid replacements (Q469R, H482R, H482Y, or S487L) in the
Bacillus subtilis
RNA polymerase β subunit (W. L. Nicholson and H. Maughan, J. Bacteriol.
184:
4936-4940, 2002). In this study, each amino acid change in the β subunit was observed to result in its own unique spectrum of effects on growth and various developmental events, including sporulation, germination, and competence for transformation. The results thus establish the important role played by the RNA polymerase β subunit, not only in the catalytic aspect of transcription, but also in the regulation of major developmental events in
B. subtilis
.
Analysis of an Engineered
Salmonella
Flagellar Fusion Protein, FliR-FlhB
Authors: Van Arnam John S. , McMurry Jonathan L. , Kihara May , Macnab Robert M. 
Published: April 2004

ABSTRACT

Salmonella
FliR and FlhB are membrane proteins necessary for flagellar export. In
Clostridium
a
fliR-flhB
fusion gene exists. We constructed a similar
Salmonella
fusion gene which is able to complement
fliR
,
flhB
, and
fliR flhB
null strains. Western blotting revealed that the FliR-FlhB fusion protein retains the FlhB protein's cleavage properties. We conclude that the FliR and FlhB proteins are physically associated in the wild-type
Salmonella
basal body, probably in a 1:1 ratio.
Interplay between Plasmid Partition and Postsegregational Killing Systems
Authors: Brendler Therese , Reaves Lucretia , Austin Stuart 
Published: April 2004

ABSTRACT

Active partition systems and postsegregational killing (PSK) systems are present together in naturally occurring low-copy-number plasmids. Theory suggests that PSK may act as the ultimate determinant of plasmid retention, whereas the partition system may minimize the growth penalty to the host, resulting in a near-ideal symbiosis when the systems combine. Here, we prove the validity of this principle for a specific case involving the P1
par
system and the
mvp
PSK system.
Control of Expression of the Arginine Deiminase Operon ofStreptococcus gordoniiby CcpA and Flp
Authors: Dong Yiqian , Chen Yi-Ywan M. , Burne R. A. 
Published: April 2004

ABSTRACTInStreptococcus gordoniiDL1, inactivation of theccpAgene and a gene encoding an Fnr-like protein (Flp) demonstrated that CcpA was essential for carbohydrate catabolite repression and that Flp was required for optimal expression and anaerobic induction of the arginine deiminase system.
Clinical Evaluation of the Risk of Twin-to-Twin Transfusion Syndrome Using the Relative Power Contribution of Fetal Heart Rate Fluctuations
Authors: Kimura Yoshitaka , Suzuki Nobuaki , Sugawara Jun-Ichi , Murakami Takashi , Terada Yukihiro , Chisaka Hiroshi , Okamura Kunihiro 
Published: April 2004

<i>Objectives:</i> In twin pregnancies, it has been suggested that fluctuations of the two fetal heart rates should be considered as two variates that affect each other. We therefore investigated whether the relative power contribution (RPC) of heart rate fluctuation between twins reflects the clinical severity of twin-to-twin transfusion syndrome. <i>Study Design: </i>Sixty-three cases of twin pregnancy including 43 monochorionic twins and 20 dichorionic twins were studied. Thirteen monochorionic twins with polyhydramnios in one twin were regarded as twin-to-twin transfusion syndrome (TTTS). Of the 13 TTTS cases, 8 cases with polyhydramnios in one twin and oligohydramnios in the other were deemed to be a ‘stuck’ twin. The RPC of the very low frequency domain (VL; 0.0125–0.0625 Hz) of fetal heart rate fluctuation in the twin fetuses of monochorionic and dichorionic pregnancies was obtained within a week of delivery. The relationship between the value of the RPC and the outcome of these twins was examined. <i>Results:</i> For both monochorionic and dichorionic twins the RPC of twin fetuses was significantly higher in TTTS twins than in twins without TTTS. In particular, in pregnancies that resulted in fetal death, early neonatal death, or hydrops of one of the twins, this twin had a higher RPC than the other twin. No significant difference was observed in the RPC value between twins of either monochorionic or dichorionic pregnancies that did not develop TTTS. Serial changes in RPC values were followed in 7 cases of TTTS. The RPC value rose rapidly just before delivery in three cases with resultant poor outcome. <i>Conclusion:</i> A rapid change in the RPC of twin fetuses measured using the VL frequency domain of fetal heart rate fluctuations may predict poor outcome in twin pregnancies.
The Recurrence Risk of Ischemic Stroke in Childhood
Authors: Brankovic-Sreckovic Vesna , Milic-Rasic Vedrana , Jovic Nebojsa , Milic Natasa , Todorovic Slobodanka 
Published: April 2004

<i>Objective:</i> To determine the risk of recurrence of ischemic stroke in children and to evaluate the influence of etiological factors and underlying mechanisms on recurrence rate. <i>Subjects and Methods:</i> Thirty-six children (21 boys and 15 girls) with clinically and radiographically proven ischemic cerebral infarction were prospectively followed up over a period of 1–9 years (median 5 years 5 months). The median age of onset of stroke was 8.4 years (1–16 years). Patients with hemorrhagic stroke, neonatal infarction and sinovenous thrombosis were not included. The patients were analyzed according to the mechanisms and etiology of the initial and recurrent stroke event. <i>Results:</i> For the initial stroke, cardioembolic (33.3%) and arteriopathic processes (36.1%) were identified as the most probable mechanisms of arterial ischemic stroke. Prothrombotic abnormalities were found in 4 children (11.1%). Underlying pathology in the remaining 7 (19.4%) was not known. Recurrent ischemic infarction was diagnosed in 5 children (13.9%) within 5 days to 18 months (median 6 months) after the first stroke manifestation. In 3 of them stroke recurrence was due to cardiac or transcardiac embolism. Cardiac abnormality prior to the first stroke was detected in 1 child. Clinically silent multiple cerebral infarcts disclosed by MRI preceded the overt stroke episode in 2 patients. <i>Conclusion:</i> Congenital and acquired heart diseases were the most common cause of repeated stroke in our study. The risk of recurrence appeared to be fivefold higher in children with cardiac disease irrespective of the coexistence of other risk factors. The risk factors of stroke in children were multiple and overlapping. Consequently, recognition of the major one and its underlying mechanism is crucial for both effective therapeutic approach and the prevention of recurrence.
The Development of a Non-Fluorocarbon-Based Extruded Polystyrene Foam Which Contains a Halogen-Free Blowing Agent
Authors: Ohara Youichi , Tanaka Kenkichi , Hayashi Takahiro , Tomita Haruo , Motani Shigeru 
Published: April 2004

Abstract
This technology is concerned with a new type of extruded polystyrene foam (XPS), which gives high performance of thermal insulation without containing any fluorocarbons as a blowing agent. Avoiding such typically harmful materials will help solve global environmental problems like ozone layer depletion and global warming. Kaneka Corporation developed this technology for the first time in the world. As a blowing agent of this new XPS in place of fluorocarbons we adopted isobutane, an excellent green gas that helps prevent ozone layer depletion and global warming. However, there is a problem: it is difficult to secure high performance of thermal insulation and flame retardation when isobutane is used. This originates from the fact that isobutane has a higher thermal conductivity than fluorocarbons, and is highly flammable. To overcome the former problem, we found a novel cell structure to secure high performance of thermal insulation, and we developed new technologies to control it. To solve the latter problem, namely securing flame retardation, we clarified the mechanism to suppress combustion of isobutane, and developed a new flame retardation technology by the addition of specific compounds. As a result of a combination of these technologies, we were able to develop and commercialize a new XPS with high performance of thermal insulation. These technologies directly contribute to prevent adverse effects on the global environment such as ozone layer depletion and global warming, by not using fluorocarbons. And, in addition, these technologies indirectly but more greatly contribute to global warming prevention by the reduction in carbon dioxide emissions through a high effect of energy conservation as a thermal insulator. Therefore, the thermal insulator with these technologies is valuable for environmental protection. And as the needs for a material for better energy conservation will increase, the contribution of this technology will expand much more in the future.
Correlation of the Mutual Viscosity and the NMR Spin-Lattice Relaxation Time in Several Substituted Benzoic Acids
Authors: Singh Anupam , Singh Ajay Kumar , Mehrotra Nand Kumar 
Published: April 2004

Abstract
The present communication reports on the experimental values of the mutual viscosity (η12) and NMR spin-lattice time (T1) of o-nitrobenzoic acid, m-nitrobenzoic acid, p-nitrobenzoic acid, o-hydroxybenzoic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, and m-chlorobenzoic acid. The small difference between the values of η12 and η1 suggests that the basic model of the dielectric relaxation process does not suffer any major changes even when η12 is used instead of η1. The experimental values of the NMR spin-lattice relaxation time (T1) have been correlated with the calculated values of T1 obtained using various equations of the dielectric relaxation time (τ). It has been concluded that the equations of Writz and Murty are better representations of the dielectric relaxation phenomenon.
Secondary Organic Aerosol Formation during the Photo-Oxidation of Toluene: Dependence on Initial Hydrocarbon Concentration
Authors: Sato Kei , Klotz Björn , Hatakeyama Shiro , Imamura Takashi , Washizu Yuuki , Matsumi Yutaka , Washida Nobuaki 
Published: April 2004

Abstract
Aerosol formation in toluene–NOx–air–photoirradiation systems was examined in a 6-m3 photochemical reaction chamber. The initial toluene concentration was varied between 2 and 16 ppmv, whereas the initial NOx concentration was kept constant. The aerosol mass concentrations were plotted as a function of the concentration of toluene reacted. The aerosol profiles showed a curved feature at low toluene consumptions, and merged into a single line at longer reaction times. The observed characteristics were explained by assuming condensable products were formed through reactions of ozone with primary toluene photo-oxidation products.
Effects of Na+ on Dynamics of p-Nitroaniline Molecules in Zeolite ZSM-5 Studied by Solid-State NMR
Authors: Komori Yoshihiko , Hayashi Shigenobu 
Published: April 2004

Abstract
The dynamics of deuterated p-nitroaniline (pNA-d) molecules in zeolite ZSM-5 including Na+ (NaZSM-5) were investigated by means of 2H and 13C solid-state NMR to clarify the effects of Na+ and hydrated Na+. The adsorbed amount of pNA-d was four molecules per unit cell of NaZSM-5. 2H NMR spectra of a dehydrated sample indicated that the motion of pNA-d in the micropore is a 180°flip-flop around the C2 axis of the molecule. Another species with a faster flip-flop motion was distinguishable and assigned to pNA-d on the outer surface. When the sample adsorbed water molecules, 2H spectra showed that the flip-flop motion of pNA-d was largely suppressed in the micropore and that pNA-d on the outer surface underwent an isotropic motion. These results indicated that the dynamics of pNA-d in NaZSM-5 depended on the interactions with Na+ and hydrated Na+ as well as on the location.
Charge-Transfer Molecular Complexes of Guanazole and Some 1,2,4-Triazoles with σ- and π-Acceptors Involving a New Acceptor: Resulting In Situ; DDQH2
Authors: Rabie Usama Mohamed , Salman Hasan Mahmoud Ali , Abou-El-Wafa Moustafa Hassan Mohamed 
Published: April 2004

Abstract
Charge-transfer complexes of 1,2,4-triazole (1T), 3-amino-1,2,4-triazole (2T), 4-amino-4H-1,2,4-triazole (3T), and guanazole (3,5-diamino-1,2,4-triazole) (4T) with iodine as a typical σ-type acceptor and with typical π-type acceptors (tetracyanoethene (TCNE) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)) have been synthesized and characterized. The spectral characteristics and thermodynamic properties of such CT complexes were investigated. The system triazoles/iodine is characterized by the formation of triiodide ions (I3−), which is proposed to occur via the initial formation of outer-sphere charge-transfer complexes. The systems (1T–4T)/TCNE and (1T–4T)/DDQ produced the corresponding anion radicals, TCNE•− and DDQ•−, respectively. The time dependency of the spectral bands due to the 4T/TCNE system is discussed in terms of the scope of transformation from outer-sphere CT complexes to inner-sphere ones. Meanwhile, for the system 4T/DDQ the time dependency is accounted for by the stepwise reduction of DDQ to its anion radicals, and then to the corresponding hydroquinone (2,3-dichloro-5,6-dicyanohydroquinone), DDQH2. However, because the resulting in situ (DDQH2) was an unconventional new acceptor, it formed a CT complex with the donor (4T). The results show that the formed complexes are strong kinds of n–σ and n–π types in a 1:2 and 1:1 stoichiometry for the complexes of triazoles donors with iodine and DDQ, respectively.
The Hydrogen Bond of the One-Dimensional Assembled Complex [Ni(2,2′-biimidazole)2]: The Effect of Transition Metals on the Hydrogen Bond
Authors: Mori Hirotoshi , Miyoshi Eisaku 
Published: April 2004

Abstract
The topologies of hydrogen-bond potential energy surfaces of one-dimensional assembled 2,2′-biimidazole (H2bim) and its deprotonated Ni complex ([NiII(Hbim)2]) were investigated by density functional theory calculations at the B3LYP/CEP-31G(d,p) level. It was revealed that the formation of coordination bonds between Hbim and Ni makes the N–H···N hydrogen bond between Hbim units linear and strong.
Hot Water Induces an Acid-Catalyzed Reaction in Its Undissociated Form
Authors: Nagai Yasuharu , Matubayasi Nobuyuki , Nakahara Masaru 
Published: April 2004

Abstract
Hot water in its undissociated form has been kinetically proven to induce a chemical reaction that does not undergo under ambient conditions in the absence of a strong acid. The water-induced and acid-catalyzed rate constants were separately determined for the dehydration of 1,4-butanediol by varying the oxonium ion (H+) concentration. It was found on the kinetic level over a wide range of temperature from moderate to supercritical that the undissociated form of water promotes the reaction at an effective acid concentration of 10−4–10−6 M. A strong density dependence of the reaction rate constant was further observed under supercritical condition, and is related to the anomalous temperature dependence of the rate constant near the critical point.
Immobilization of a Metal Complex in Y-Zeolite Matrix: Synthesis, X-ray Single-Crystal, and Catalytic Activities of a Copper (Schiff-Base)–Y Zeolite Based Hybrid Catalyst
Authors: Saha Pratap Kumar , Banerjee Surajit , Saha Sandip , Mukherjee Alok Kumar , Sivasanker Subramanian , Koner Subratanath 
Published: April 2004

Abstract
A new zeolite-immobilized copper(II) complex catalyst has been prepared by entrapping [CuL] [LH2 = N,N′-(1,1-dimethylethylene)bis(salicylaldiimine)] on NaY zeolite matrix. The reaction of Cu–NaY and molten LH2 affords a green mass of crude catalyst that upon a treatment with CH3CN gives a gray-colored hybrid catalyst (CuL–NaY). The prepared catalyst has been characterized by IR and UV–vis spectroscopic and EPR spectrometric measurements, TG–DTA analysis, powder X-ray diffraction, and surface-area measurements. To ascertain the structure of the immobilized complex, a single-crystal X-ray diffraction analysis of [CuL] was performed. Spectroscopic measurements showed that the green crude of CuL–NaY contains a penta- or hexa-coordinated copper(II) moiety, while the CuL–NaY catalyst contains a distorted square-planar [CuL] complex moiety. A remarkable catalytic activity of the prepared hybrid catalyst has been observed in oxidation reactions of 1-naphthol and norbornene.
Structure and Physical Properties of Molecule-Based Magnets Including Transition Metal Complexes of Crown Thioethers
Authors: Nishijo Junichi , Miyazaki Akira , Enoki Toshiaki 
Published: April 2004

Abstract
A new series of molecule-based magnets, including crown thioether (9S3 = 1,4,7-trithiacyclononane) complexes of transition metals (Ni, Co, Cu), are presented. TCNQ salts [M(9S3)2](TCNQ)2 (M = Ni, Co) are one-dimensional (1D), antiferromagnetic (AF) complexes with an intra-chain interaction J = −3.9 K and −1.3 K for M = Ni and Co, respectively, despite its long intermolecular distance, for which the large spin density on the sulfur atom in the magnetic [M(9S3)2]2+ cation is responsible. The mixed valence salt [M(9S3)2](TCNQ)3 (M = Ni, Co) is a paramagnetic semiconductor. 1D AF magnet [Cu(9S3)Br2] does not undergo any magnetic transition because of the weak inter-chain interaction. Substituting a very small amount (∼5%) of Cu with Ni causes a structural change. The change decreases the distances of inter-chain S–S contacts, resulting in the generation of an AF transition at TN = 4.5 K. [M(9S3)2][Ni(bdt)2]2 (M = Ni, Co; bdt = 1,2-benzenedithiolato) are weak-ferromagnets with TN = 6.2 K and 2.6 K for M = Ni and Co, respectively. In the crystals, [M(9S3)2]2+–[Ni(bdt)2]− alternate chains and [Ni(bdt)2]− uniform chains coexist. The appearance of weak-ferromagnetism is associated with a competition between two kinds of inter-chain AF interactions between [M(9S3)2]2+–[Ni(bdt)2]− alternate chains, where the stronger one is an indirect inter-chain interaction through [Ni(bdt)2]− uniform chains, while the weaker is a direct inter-chain interaction.