bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Cytosolic ADP-Glucose Pyrophosphorylase Is a Feature of Graminaceous Endosperms, But Not of Other Starch-Storing Organs
Authors: Beckles Diane M. , Smith Alison M. , ap Rees Tom 
Published: July 2002

Abstract
The occurrence of an extra-plastidial isoform of ADP-glucose (Glc) pyrophosphorylase (AGPase) among starch-storing organs was investigated in two ways. First, the possibility that an extra-plastidial isoform arose during the domestication of cereals was studied by comparing the intracellular distribution of enzyme activity and protein in developing endosperm of noncultivated Hordeum species with that previously reported for cultivated barley (Hordeum vulgare). As in cultivated barley, the AGPase of H. vulgare subsp. spontaneum and Hordeum murinum endosperm is accounted for by a major extra-plastidial and a minor plastidial isoform. Second, the ratio of ADP-Glc to UDP-Glc was used as an indication of the intracellular location of the AGPase activity in a wide range of starch-synthesizing organs. The ratio is expected to be high in organs in which UDP-Glc and ADP-Glc are synthesized primarily in the cytosol, because the reactions catalyzed by AGPase and UDP-Glc pyrophosphorylase will be coupled and close to equilibrium. This study revealed that ADP-Glc contents and the ratio of ADP-Glc to UDP-Glc were higher in developing graminaceous endosperms than in any other starch-storing organs. Taken as a whole the results indicate that an extra-plastidial AGPase is important in ADP-Glc synthesis in graminaceous endosperms, but not in other starch-storing organs.
Phytochelatins Are Involved in Differential Arsenate Tolerance inHolcus lanatus
Authors: Hartley-Whitaker Jeanette , Ainsworth Gillian , Vooijs Riet , Bookum Wilma Ten , Schat Henk , Meharg Andrew A. 
Published: July 2002

Abstract
Arsenate tolerance is conferred by suppression of the high-affinity phosphate/arsenate uptake system, which greatly reduces arsenate influx in a number of higher plant species. Despite this suppressed uptake, arsenate-tolerant plants can still accumulate high levels of As over their lifetime, suggesting that constitutive detoxification mechanisms may be required. Phytochelatins are thiol-rich peptides, whose production is induced by a range of metals and metalloids including arsenate. This study provides evidence for the role of phytochelatins in the detoxification of arsenate in arsenate-tolerant Holcus lanatus. Elevated levels of phytochelatin were measured in plants with a range of tolerance to arsenate at equivalent levels of arsenate stress, measured as inhibition of root growth. The results suggest that arsenate tolerance in H. lanatus requires both adaptive suppression of the high-affinity phosphate uptake system and constitutive phytochelatin production.
Alteration of Auxin Polar Transport in the Arabidopsisifl1 Mutants
Authors: Zhong Ruiqin , Ye Zheng-Hua 
Published: July 2002

Abstract
The INTERFASCICULAR FIBERLESS/REVOLUTA(IFL1/REV) gene is essential for the normal differentiation of interfascicular fibers and secondary xylem in the inflorescence stems of Arabidopsis. It has been proposed thatIFL1/REV influences auxin polar flow or the transduction of auxin signal, which is required for fiber and vascular differentiation. Assay of auxin polar transport showed that the ifl1 mutations dramatically reduced auxin polar flow along the inflorescence stems and in the hypocotyls. The null mutant allele ifl1-2was accompanied by a significant decrease in the expression level of two putative auxin efflux carriers. The ifl1 mutants remained sensitive to auxin and an auxin transport inhibitor. Theifl1-2 mutant exhibited visible phenotypes associated with defects in auxin polar transport such as pin-like inflorescence, reduced numbers of cauline branches, reduced numbers of secondary rosette inflorescence, and dark green leaves with delayed senescence. The visible phenotypes displayed by the ifl1 mutants could be mimicked by treatment of wild-type plants with an auxin polar transport inhibitor. In addition, the auxin polar transport inhibitor altered the normal differentiation of interfascicular fibers in the inflorescence stems of wild-type Arabidopsis. Taken together, these results suggest a correlation between the reduced auxin polar transport and the alteration of cell differentiation and morphology in theifl1 mutants.
The Three-Dimensional Structure of Cystathionine β-Lyase from Arabidopsis and Its Substrate Specificity
Authors: Breitinger Ulrike , Clausen Tim , Ehlert Stephan , Huber Robert , Laber Bernd , Schmidt Frank , Pohl Ehmke , Messerschmidt Albrecht 
Published: July 2002

AbstractThe pyridoxal 5′-phosphate-dependent enzyme cystathionine β-lyase (CBL) catalyzes the penultimate step in the de novo biosynthesis of Met in microbes and plants. Absence of CBL in higher organisms makes it an important target for the development of antibiotics and herbicides. The three-dimensional structure of cystathionine β-lyase from Arabidopsis was determined by Patterson search techniques, using the structure of tobacco (Nicotiana tabacum) cystathionine γ-synthase as starting point. At a resolution of 2.3 Å, the model was refined to a final crystallographic R-factor of 24.9%. The overall structure is very similar to other pyridoxal 5′-phosphate-dependent enzymes of the γ-family. Exchange of a few critical residues within the active site causes the different substrate preferences betweenEscherichia coli and Arabidopsis CBL. Loss of interactions at the α-carboxyl site is the reason for the poorer substrate binding of Arabidopsis CBL. In addition, the binding pocket of Arabidopsis CBL is larger than that of E. coli CBL, explaining the similar binding of l-cystathionine andl-djenkolate in Arabidopsis CBL in contrast to E. coli CBL, where the substrate binding site is optimized for the natural substrate cystathionine.
Preliminary crystallographic studies of a protease-resistant botulinum neurotoxin associated protein Hn-33
Authors: Hadfield Andrea T. , Petsko Greg , Lindo Paul , Singh Bal-Ram 
Published: July 2002

Botulinum neurotoxin (BoNT) is one of the most potent toxins known. BoNT is also a food poison, which means that the toxin must survive the protease action and acidity of the gut. A group of neurotoxin-associated proteins which are only beginning to be identified and characterized are believed to be responsible for this protection. Hn-33 is a 33 kDa polypeptide which is a major component of the type A botulinum neurotoxin complex. Crystals of Hn-33 have been grown by vapour-diffusion techniques. They belong to a primitive orthorhombic space group and diffract to a resolution of 2.6 Å, with unit-cell parameters a = 130.3, b = 122.2, c = 37.2 Å.
Crystallization and preliminary diffraction data analysis of both single and pseudo-merohedrally twinned crystals of rubredoxin oxygen oxidoreductase from Desulfovibrio gigas
Authors: Frazão C. , Sieker L. , Coelho R. , Morais J. , Pacheco I. , Chen L. , LeGall J. , Dauter Z. , Wilson K. , Carrondo M. A. 
Published: July 2002

Crystals of rubredoxin oxygen oxidoreductase have been obtained and characterized. They belong to space group P21212, with unit-cell dimensions a = 88.24 (15), b = 101.25 (7), c = 90.80 (3) Å. The homodimer (86 kDa) in the asymmetric unit is related by a non-crystallographic twofold rotation axis parallel to the ab `diagonal' direction, as shown by the self-rotation maximum in the section with χ = 180°. This pseudo-crystallographic symmetry element was also found to be the twinning axis of pseudo-merohedrally twinned crystals, leading to apparent pseudo-tetragonal P4212 crystal symmetry.
Some thermodynamic implications for the thermostability of proteins
Authors: Rees Douglas C. , Robertson Andrew D. 
Published: July 2002

AbstractAn analysis of the thermodynamics of protein stability reveals a general tendency for proteins that denature at higher temperatures to have greater free energies of maximal stability. To a reasonable approximation, the temperature of maximal stability for the set of globular, water‐soluble proteins surveyed by Robertson and Murphy occurs at T* ∼283K, independent of the heat denaturation temperature, Tm. This observation indicates, at least for these proteins, that thermostability tends to be achieved through elevation of the stability curve rather than by broadening or through a horizontal shift to higher temperatures. The relationship between the free energy of maximal stability and the temperature of heat denaturation is such that an increase in maximal stability of ∼0.008 kJ/mole/residue is, on average, associated with a 1°C increase in Tm. An estimate of the energetic consequences of thermal expansion suggests that these effects may contribute significantly to the destabilization of the native state of proteins with increasing temperature.
The Spherical Surface Symmetrical Equal Dividing Angular Quadrature
Scheme for Discrete Ordinates Method
Authors: Li Ben-Wen , Chen Hai-Geng , Zhou Jun-Hu , Cao Xin-Yu , Cen Ke-Fa 
Published: July 2002

Abstract
A new angular quadrature scheme named Spherical surface Symmetrical equal Dividing (abbreviated to SSDN) is presented. The evaluations of double moments by SSDN and other traditional quadrature sets show that the new SSDN is able to provide good accuracy and compete well with others (as for example the SN and LSN method). Radiative predictions in a black-walled rectangular enclosure containing absorbing-emitting medium indicate that, compared with SN,LSN,TN, and SRAPN, the SSDN can give higher accuracy than SN under some order numbers N. Numerical experiments demonstrate the computational economy of SSDN for some cases.
Activities of Clinafloxacin, Gatifloxacin, Gemifloxacin, and Trovafloxacin against Recent Clinical Isolates of Levofloxacin-Resistant
Streptococcus pneumoniae
Authors: Jorgensen J. H. , Weigel L. M. , Swenson J. M. , Whitney C. G. , Ferraro M. J. , Tenover F. C. 
Published: July 2002

ABSTRACT

The activities of two investigational fluoroquinolones and three fluoroquinolones that are currently marketed were determined for 182 clinical isolates of
Streptococcus pneumoniae
. The collection included 57 pneumococcal isolates resistant to levofloxacin (MIC ≥ 8 μg/ml) recovered from patients in North America and Europe. All isolates were tested with clinafloxacin, gatifloxacin, gemifloxacin, levofloxacin, and trovafloxacin by the National Committee for Clinical Laboratory Standards broth microdilution and disk diffusion susceptibility test methods. Gemifloxacin demonstrated the greatest activity on a per gram basis, followed by clinafloxacin, trovafloxacin, gatifloxacin, and levofloxacin. Scatterplots of the MICs and disk diffusion zone sizes revealed a well-defined separation of levofloxacin-resistant and -susceptible strains when the isolates were tested against clinafloxacin and gatifloxacin. DNA sequence analyses of the quinolone resistance-determining regions of
gyrA
,
gyrB
,
parC
, and
parE
from 21 of the levofloxacin-resistant strains identified eight different patterns of amino acid changes. Mutations among the four loci had the least effect on the MICs of gemifloxacin and clinafloxacin, while the MICs of gatifloxacin and trovafloxacin increased by up to six doubling dilutions. These data indicate that the newer fluoroquinolones have greater activities than levofloxacin against pneumococci with mutations in the DNA gyrase or topoisomerase IV genes. Depending upon pharmacokinetics and safety, the greater potency of these agents could provide improved clinical efficacy against levofloxacin-resistant pneumococcal strains.
In Vitro Antimicrobial Susceptibility Testing of Bacterial Enteropathogens Causing Traveler's Diarrhea in Four Geographic Regions
Authors: Gomi Harumi , Jiang Zhi-Dong , Adachi Javier A. , Ashley David , Lowe Brett , Verenkar Mangala P. , Steffen Robert , DuPont Herbert L. 
Published: July 2002

ABSTRACT

The emergence of resistant enteropathogens has been reported worldwide. Few data are available on the contemporary in vitro activities of commonly used antimicrobial agents against enteropathogens causing traveler's diarrhea (TD). The susceptibility patterns of antimicrobial agents currently available or under evaluation against pathogens causing TD in four different areas of the world were evaluated. Pathogens were identified in stool samples from U.S., Canadian, or European adults (18 years of age or older) with TD during 1997, visiting India, Mexico, Jamaica, or Kenya. MICs of 11different antimicrobials were determined against 284 bacterial enteropathogens by the agar dilution method. Ciprofloxacin, levofloxacin, ceftriaxone, and azithromycin were highly active in vitro against the enteropathogens, while traditional antimicrobials such as ampicillin, trimethoprim, and trimethoprim/sulfamethoxazole showed high levels and high frequencies of resistance. Rifaximin, a promising and poorly absorbable drug, had an MIC at which 90% of the strains tested were inhibited of 32 μg/ml, 250 times lower than the concentration of this drug in the stools. Amdinocillin, nalidixic acid, and doxycycline showed moderate activity. Fluoroquinolones are still the drugs of choice for TD in most regions of the world, although our study has a limitation due to the lack of
Escherichia coli
samples from Kenya and possible bias in selection of the patients for evaluation. Azithromycin and rifaximin should be considered as promising new agents. The widespread in vitro resistance of the traditional antimicrobial agents reported since the 1980s and the new finding of resistance to fluoroquinolones in Southeast Asia are the main reasons for monitoring carefully the antimicrobial susceptibility patterns worldwide and for developing and evaluating new antimicrobial agents for the treatment of TD.
Effect of Endotoxin on P-Glycoprotein-Mediated Biliary and Renal Excretion of Rhodamine-123 in Rats
Authors: Ando Hideyuki , Nishio Yuki , Ito Katsuki , Nakao Akimasa , Wang Li , Zhao Ying Lan , Kitaichi Kiyoyuki , Takagi Kenzo , Hasegawa Takaaki 
Published: July 2002

ABSTRACT

The effects of
Klebsiella pneumoniae
endotoxin on the biliary excretion and renal handling of rhodamine-123 were investigated in rats at different times after intraperitoneal injection (1 mg/kg of body weight). The typical substrates for P glycoprotein, i.e., cyclosporine, colchicine, and erythromycin, inhibited the biliary clearance of rhodamine-123, whereas a substrate for organic cation transporter, cimetidine, did not inhibit clearance, suggesting that rhodamine-123 is transported mainly by P glycoprotein. The biliary, renal, and tubular secretory clearances of rhodamine-123 and the glomerular filtration rate significantly decreased 6 h after injection of endotoxin but returned to control levels by 24 h. These results suggest that endotoxin-induced decreases in P-glycoprotein-mediated biliary excretion and renal handling of rhodamine-123 were probably due to impairment of P-glycoprotein-mediated transport ability. Pretreatment with pentoxifylline (50 mg/kg) significantly inhibited endotoxin-induced increases in tumor necrosis factor alpha (TNF-α) levels in plasma, which ameliorated the endotoxin-induced reduction of the biliary excretion of rhodamine-123. It is likely that endotoxin-induced impairment of the transport of rhodamine-123 is caused, in part, by overproduction of TNF-α. The effect of endotoxin on the expression of P-glycoprotein mRNA in liver and kidneys of rats was investigated by using a reverse transcriptase PCR. The expression of Mdr1a mRNA in both liver and kidney decreased 6 h after endotoxin injection and returned to control levels after 24 h, whereas the expression of Mdr1b mRNA in liver increased at both times and that in kidney decreased at 24 h. These findings suggest that
K. pneumoniae
endotoxin dramatically decreases P-glycoprotein-mediated biliary and renal excretion of rhodamine-123 probably by decreasing the expression of Mdr1a, which is likely due to increased plasma TNF-α levels.
Effects of Renal Function on Pharmacokinetics of Recombinant Human Granulocyte Colony-Stimulating Factor in Lung Cancer Patients
Authors: Fukuda Masaaki , Oka Mikio , Ishida Yoshimasa , Kinoshita Haruki , Terashi Kenji , Fukuda Minoru , Kawabata Shigeru , Kinoshita Akitoshi , Soda Hiroshi , Kohno Shigeru 
Published: July 2002

ABSTRACTAnimal studies suggest that the kidney is involved in the elimination of recombinant human granulocyte colony-stimulating factor (rhG-CSF), which is used for patients with neutropenia during cancer chemotherapy. Since anticancer drugs induce nephrotoxicity, it is important to clarify the role of the kidney in the pharmacokinetics of rhG-CSF in cancer patients. Our study was designed to evaluate the relationship between the pharmacokinetics of rhG-CSF and renal function in lung cancer patients compared to the absolute neutrophil count (ANC). The pharmacokinetic studies were conducted with 25 lung cancer patients. Following chemotherapy using platinum-based compounds, a bolus 5 μg of rhG-CSF/kg of body weight was intravenously injected from the first day of leukopenia or neutropenia. Pharmacokinetic parameters were estimated by fitting the concentration in serum-time data to a two-compartment model according to the population pharmacokinetics and the Bayesian method. Creatinine clearance (CLCR) was predicted by the Cockcroft-Gault formula. rhG-CSF clearance (CLG-CSF) correlated significantly with the ANC (r= 0.613;P< 0.001) and CLCR(r= 0.632;P< 0.001). Multiple linear regression analysis showed that the combination of the ANC and CLCRaccounted for 57.4% of the variation of CLG-CSF. In patients with an ANC of <1,000/μl, CLCRaccounted for 72.9% of the variation of CLG-CSF(P< 0.001). Our findings suggest that renal function and neutrophil counts correlate with CLG-CSFand that the role of renal function in eliminating rhG-CSF is important in lung cancer patients with neutropenia.
Genes Encoding TEM-4, SHV-2, and CTX-M-10 Extended-Spectrum β-Lactamases Are Carried by MultipleKlebsiella pneumoniaeClones in a Single Hospital (Madrid, 1989 to 2000)
Authors: Coque Teresa M. , Oliver Antonio , Pérez-Díaz José Claudio , Baquero Fernando , Cantón Rafael 
Published: July 2002

ABSTRACTOver a 12-year period (1989 to 2000), 159Klebsiella pneumoniaeisolates harboring extended-spectrum β-lactamases (ESBLs) (4.8% of the total number ofK. pneumoniaeisolates obtained) were recovered from 58 patients, who were mainly hospitalized in intensive care and surgery units. For 62 representative isolates from 58 patients, 31 clonal types harboring TEM-4 (n= 5), SHV-2 (n= 7), SHV2a (n= 4), SHV-5 (n= 1), CTX-M-10 (n= 13), or CTX-M-9 (n= 1) β-lactamases were identified by pulsed-field gel electrophoresis. This is the first report to document the presence of the CTX-M-10 or the CTX-M-9 β-lactamase inK. pneumoniae. These β-lactamases were previously identified inEscherichia coliisolates from Spain. Only two of fiveK. pneumoniaeTEM-4 clones caused more than a single case of infection, with one of them spreading for 9 months. A single plasmid was detected among these TEM-4 clones. Only two of sevenK. pneumoniaeclones containing SHV-2 and three of four strains harboring SHV-2a were detected in more than one case of infection. Plasmids encoding SHV-2 or SHV-2a were unrelated. Four of 13K. pneumoniaeCTX-M-10 clones were found in more than one patient, with two of them recovered 2 and 5 years apart. As in the case of the SHV-2 isolates, we were unable to document a common transmissible genetic element that could explain the polyclonal structure of our isolates. Nevertheless, the spread of a single gene may be suggested by the presence of a conserved set of noncoding polymorphisms in the sequences. Most ESBL-producingK. pneumoniaeclones were ephemeral, being poorly selected and maintained in the hospital setting, but the genes encoding ESBL persisted successfully over the years that the strains were recovered, probably as a minority gene population in the hospital metagenome.
Epigallocatechin Gallate Synergistically Enhances the Activity of Carbapenems against Methicillin-Resistant
Staphylococcus aureus
Authors: Hu Zhi-Qing , Zhao Wei-Hua , Asano Nozomi , Yoda Yoshiyuki , Hara Yukihiko , Shimamura Tadakatsu 
Published: July 2002

ABSTRACT

Combinations of carbapenems and epigallocatechin gallate (EGCg; a main constituent of tea catechins) showed potent synergy against 24 clinical isolates of methicillin-resistant
Staphylococcus aureus
(MRSA). MICs of imipenem in the presence of EGCg at 3.125, 6.25, 12.5, and 25 μg/ml, were restored to the susceptible breakpoint (≤4 μg/ml) for 8, 38, 46, and 75% of the MRSA isolates, respectively. Similar results were also observed for combinations of panipenem or meropenem and EGCg. Therefore, the combinations may be worthy of further evaluation in vivo against MRSA infection.
Dose Range Study of Pharmacokinetics, Safety, and Preliminary Antiviral Activity of Emtricitabine in Adults with Hepatitis B Virus Infection
Authors: Gish R. G. , Leung N. W. Y. , Wright T. L. , Trinh Huy , Lang W. , Kessler H. A. , Fang L. , Wang L. H. , Delehanty J. , Rigney A. , Mondou E. , Snow A. , Rousseau F. 
Published: July 2002

ABSTRACT

A multicenter, open-label study was performed to evaluate the safety, anti-hepatitis B virus (anti-HBV) activity, and pharmacokinetics of emtricitabine therapy administered once daily for 8 weeks to patients infected with HBV. Clinical and virologic evaluations were completed at the baseline; at 7, 14, 28, 42, and 56 days during treatment; and at 24, 48, and 28 days posttreatment. Forty-nine patients were enrolled in five dose cohorts (doses of 25, 50, 100, 200, and 300 mg, all of which were administered once daily [q.d.]). Peak plasma emtricitabine concentrations occurred within 1.5 h following dosing. Plasma emtricitabine concentrations (maximum concentrations of drug in plasma and areas under the concentration-time curves) increased nearly dose proportionally over the 25- to 300-mg dose range, with relatively small intersubject variabilities. The plasma half-life of emtricitabine ranged from 6 to 9 h. HBV DNA levels were measured by the Digene HBV Hybrid Capture II assay. Viral suppression (reduction in log
10
serum HBV DNA levels) occurred in all dose cohorts. All doses demonstrated potent and rapid antiviral activities, with a trend toward a greater suppression with daily doses of 100 mg or greater. At 2 months, the median change in the serum HBV DNA level from the baseline level ranged from −1.7 log
10
for the 25-mg dose administered q.d. to −3.3 log
10
for the 300 mg dose administered q.d. Emtricitabine was well tolerated over the 2-month dosing period. These results support further clinical development of emtricitabine for the treatment of chronic hepatitis B infection.
Correlations between Morphological, Molecular Biological, and Physiological Characteristics in Clinical and Nonclinical Isolates of
Acanthamoeba
spp
Authors: Walochnik Julia , Obwaller Andreas , Aspöck Horst 
Published: July 2002

ABSTRACT

Eleven
Acanthamoeba
isolates, obtained from
Acanthamoeba
keratitis patients, from contact lens cases of non-
Acanthamoeba
keratitis patients, from asymptomatic individuals, from necrotic tissue, and from tap water and two reference strains were investigated by morphological, molecular biological, and physiological means in order to discriminate clinically relevant and nonrelevant isolates. All clinically relevant isolates showed
Acanthamoeba
sp. group II morphology. 18S ribosomal DNA sequencing revealed sequence type T4 to be the most prevalent group among the isolates and also the group recruiting most of the pathogenic strains. Interestingly, within T4 the strains of no clinical relevance clustered together. Moreover, physiological properties appeared to be highly consistent with initial pathogenicity and with sequence clustering. Altogether, the results of our study indicate a correlation between the phylogenetic relationship and pathogenicity.