bluuebunny/crossref_metadata_2025 huggingface dataset:
Mutation of a Gene Encoding a Protein with Extracellular Matrix Motifs in Usher Syndrome Type IIa
Authors: Eudy James D. , Weston Michael D. , Yao SuFang , Hoover Denise M. , Rehm Heidi L. , Ma-Edmonds Manling , Yan Denise , Ahmad Iqbal , Cheng Jason J. , Ayuso Carmen , Cremers Cor , Davenport Sandra , Moller Claes , Talmadge Catherine B. , Beisel Kirk W. , Tamayo Marta , Morton Cynthia C. , Swaroop Anand , Kimberling William J. , Sumegi Janos
Published: July 2002

Usher syndrome type IIa (OMIM 276901), an autosomal recessive disorder characterized by moderate to severe sensorineural hearing loss and progressive retinitis pigmentosa, maps to the long arm of human chromosome 1q41 between markers AFM268ZD1 and AFM144XF2. Three biologically important mutations in Usher syndrome type IIa patients were identified in a gene (
USH2A
) isolated from this critical region. The
USH2A
gene encodes a protein with a predicted size of 171.5 kilodaltons that has laminin epidermal growth factor and fibronectin type III motifs; these motifs are most commonly observed in proteins comprising components of the basal lamina and extracellular matrixes and in cell adhesion molecules.
Biotic Transitions in Global Marine Diversity
Authors: Miller Arnold I.
Published: July 2002

Long-term transitions in the composition of Earth's marine biota during the Phanerozoic have historically been explained in two different ways. One view is that they were mediated through biotic interactions among organisms played out over geologic time. The other is that mass extinctions transcended any such interactions and governed diversity over the long term by resetting the relative diversities of higher taxa. However, a growing body of evidence suggests that macroevolutionary processes effecting biotic transitions during background times were not fundamentally different from those operating during mass extinctions. Physical perturbations at many geographic scales combined to produce the long-term trajectory of Phanerozoic diversity.
Characterization of an Ammonium Transport Protein from the Peribacteroid Membrane of Soybean Nodules
Authors: Kaiser Brent N. , Finnegan Patrick M. , Tyerman Stephen D. , Whitehead Lynne F. , Bergersen Fraser J. , Day David A. , Udvardi Michael K.
Published: July 2002

Nitrogen-fixing bacteroids in legume root nodules are surrounded by the plant-derived peribacteroid membrane, which controls nutrient transfer between the symbionts. A nodule complementary DNA (
GmSAT1
) encoding an ammonium transporter has been isolated from soybean.
GmSAT1
is preferentially transcribed in nodules and immunoblotting indicates that GmSAT1 is located on the peribacteroid membrane. [
14
C]methylammonium uptake and patch-clamp analysis of yeast expressing GmSAT1 demonstrated that it shares properties with a soybean peribacteroid membrane NH
4
+
channel described elsewhere. GmSAT1 is likely to be involved in the transfer of fixed nitrogen from the bacteroid to the host.
Controlling Charge States of Large Ions
Authors: Scalf Mark , Westphall Michael S. , Krause Joern , Kaufman Stanley L. , Smith Lloyd M.
Published: July 2002

The charge state of ions produced in electrospray ionization (ESI) was reduced in a controlled manner to yield predominantly singly charged species by exposure of the aerosol to a bipolar ionizing gas. Analysis of the resulting ions on an orthogonal time-of-flight mass spectrometer yielded mass spectra greatly simplified compared with conventional ESI spectra. The decreased spectral complexity afforded by the charge reduction facilitates the analysis of mixtures by ESI mass spectrometry.
Hunting Behavior of a Marine Mammal Beneath the Antarctic Fast Ice
Authors: Davis R. W. , Fuiman L. A. , Williams T. M. , Collier S. O. , Hagey W. P. , Kanatous S. B. , Kohin S. , Horning M.
Published: July 2002

The hunting behavior of a marine mammal was studied beneath the Antarctic fast ice with an animal-borne video system and data recorder. Weddell seals stalked large Antarctic cod and the smaller subice fish
Pagothenia borchgrevinki
, often with the under-ice surface for backlighting, which implies that vision is important for hunting. They approached to within centimeters of cod without startling the fish. Seals flushed
P. borchgrevinki
by blowing air into subice crevices or pursued them into the platelet ice. These observations highlight the broad range of insights that are possible with simultaneous recordings of video, audio, three-dimensional dive paths, and locomotor effort.
UV Irradiation of Polycyclic Aromatic Hydrocarbons in Ices: Production of Alcohols, Quinones, and Ethers
Authors: Bernstein Max P. , Sandford Scott A. , Allamandola Louis J. , Gillette J. Seb , Clemett Simon J. , Zare Richard N.
Published: July 2002

Polycyclic aromatic hydrocarbons (PAHs) in water ice were exposed to ultraviolet (UV) radiation under astrophysical conditions, and the products were analyzed by infrared spectroscopy and mass spectrometry. Peripheral carbon atoms were oxidized, producing aromatic alcohols, ketones, and ethers, and reduced, producing partially hydrogenated aromatic hydrocarbons, molecules that account for the interstellar 3.4-micrometer emission feature. These classes of compounds are all present in carbonaceous meteorites. Hydrogen and deuterium atoms exchange readily between the PAHs and the ice, which may explain the deuterium enrichments found in certain meteoritic molecules. This work has important implications for extraterrestrial organics in biogenesis.
Century-Scale Shifts in Early Holocene Atmospheric CO
2
Concentration
Authors: Wagner Friederike , Bohncke Sjoerd J. P. , Dilcher David L. , Kürschner Wolfram M. , Geel Bas van , Visscher Henk
Published: July 2002

The inverse relation between atmospheric carbon dioxide concentration and stomatal frequency in tree leaves provides an accurate method for detecting and quantifying century-scale carbon dioxide fluctuations. Stomatal frequency signatures of fossil birch leaves reflect an abrupt carbon dioxide increase at the beginning of the Holocene. A succeeding carbon dioxide decline matches the Preboreal Oscillation, a 150-year cooling pulse that occurred about 300 years after the onset of the Holocene. In contrast to conventional ice core estimates of 270 to 280 parts per million by volume (ppmv), the stomatal frequency signal suggests that early Holocene carbon dioxide concentrations were well above 300 ppmv.
Genetic Selection of Peptide Inhibitors of Biological Pathways
Authors: Norman Thea C. , Smith Dana L. , Sorger Peter K. , Drees Becky L. , O'Rourke Sean M. , Hughes Timothy R. , Roberts Christopher J. , Friend Stephen H. , Fields Stan , Murray Andrew W.
Published: July 2002

Genetic selections were used to find peptides that inhibit biological pathways in budding yeast. The peptides were presented inside cells as peptamers, surface loops on a highly expressed and biologically inert carrier protein, a catalytically inactive derivative of staphylococcal nuclease. Peptamers that inhibited the pheromone signaling pathway, transcriptional silencing, and the spindle checkpoint were isolated. Putative targets for the inhibitors were identified by a combination of two-hybrid analysis and genetic dissection of the target pathways. This analysis identified Ydr517w as a component of the spindle checkpoint and reinforced earlier indications that Ste50 has both positive and negative roles in pheromone signaling. Analysis of transcript arrays showed that the peptamers were highly specific in their effects, which suggests that they may be useful reagents in organisms that lack sophisticated genetics as well as for identifying components of existing biological pathways that are potential targets for drug discovery.
Inhibition of the Mitogen-Activated Protein Kinase Kinase Superfamily by a
Yersinia
Effector
Authors: Orth Kim , Palmer Lance E. , Bao Zhao Qin , Stewart Scott , Rudolph Amy E. , Bliska James B. , Dixon Jack E.
Published: July 2002

The bacterial pathogen
Yersinia
uses a type III secretion system to inject several virulence factors into target cells. One of the
Yersinia
virulence factors, YopJ, was shown to bind directly to the superfamily of MAPK (mitogen-activated protein kinase) kinases (MKKs) blocking both phosphorylation and subsequent activation of the MKKs. These results explain the diverse activities of YopJ in inhibiting the extracellular signal–regulated kinase, c-Jun amino-terminal kinase, p38, and nuclear factor kappa B signaling pathways, preventing cytokine synthesis and promoting apoptosis. YopJ-related proteins that are found in a number of bacterial pathogens of animals and plants may function to block MKKs so that host signaling responses can be modulated upon infection.
Dissociation of CH
4
at High Pressures and Temperatures: Diamond Formation in Giant Planet Interiors?
Authors: Benedetti Laura Robin , Nguyen Jeffrey H. , Caldwell Wendell A. , Liu Hongjian , Kruger Michael , Jeanloz Raymond
Published: July 2002

Experiments using laser-heated diamond anvil cells show that methane (CH
4
) breaks down to form diamond at pressures between 10 and 50 gigapascals and temperatures of about 2000 to 3000 kelvin. Infrared absorption and Raman spectroscopy, along with x-ray diffraction, indicate the presence of polymeric hydrocarbons in addition to the diamond, which is in agreement with theoretical predictions. Dissociation of CH
4
at high pressures and temperatures can influence the energy budgets of planets containing substantial amounts of CH
4
, water, and ammonia, such as Uranus and Neptune.
Subtropical North Atlantic Temperatures 60,000 to 30,000 Years Ago
Authors: Sachs Julian P. , Lehman Scott J.
Published: July 2002

A reconstruction of sea surface temperature based on alkenone unsaturation ratios in sediments of the Bermuda Rise provides a detailed record of subtropical climate from 60,000 to 30,000 years ago. Northern Sargasso Sea temperatures changed repeatedly by 2° to 5°C, covarying with high-latitude temperatures that were previously inferred from Greenland ice cores. The largest temperature increases were comparable in magnitude to the full glacial-Holocene warming at the site. Abrupt cold reversals of 3° to 5°C, lasting less than 250 years, occurred during the onset of two such events (Greenland interstadials 8 and 12), suggesting that the largest, most rapid warmings were especially unstable.
A Triassic Fauna from Madagascar, Including Early Dinosaurs
Authors: Flynn John J. , Parrish J. Michael , Rakotosamimanana Berthe , Simpson William F. , Whatley Robin L. , Wyss André R.
Published: July 2002

The discovery of a Middle to Late Triassic (∼225 to 230 million years old) terrestrial vertebrate fauna from Madagascar is reported. This fauna documents a temporal interval not well represented by continental vertebrate assemblages elsewhere in the world. It contains two new prosauropod dinosaurs, representing some of the earliest dinosaur occurrences known globally. This assemblage provides information about the poorly understood transition to the dinosaur-dominated faunas of the latest Triassic.
Possible Ancient Oceans on Mars: Evidence from Mars Orbiter Laser Altimeter Data
Authors: Head James W. , Hiesinger Harald , Ivanov Mikhail A. , Kreslavsky Mikhail A. , Pratt Stephen , Thomson Bradley J.
Published: July 2002

High-resolution altimetric data define the detailed topography of the northern lowlands of Mars, and a range of data is consistent with the hypothesis that a lowland-encircling geologic contact represents the ancient shoreline of a large standing body of water present in middle Mars history. The contact altitude is close to an equipotential line, the topography is smoother at all scales below the contact than above it, the volume enclosed by this contact is within the range of estimates of available water on Mars, and a series of extensive terraces parallel the contact in many places.
Crystal Structure of a γδ T Cell Receptor Ligand T22: A Truncated MHC-Like Fold
Authors: Wingren Christer , Crowley Michael P. , Degano † Massimo , Chien Yueh-hsiu , Wilson Ian A.
Published: July 2002

Murine T10 and T22 are highly related nonclassical major histocompatibility complex (MHC) class Ib proteins that bind to certain γδ T cell receptors (TCRs) in the absence of other components. The crystal structure of T22
b
at 3.1 angstroms reveals similarities to MHC class I molecules, but one side of the normal peptide-binding groove is severely truncated, which allows direct access to the β-sheet floor. Potential γδ TCR-binding sites can be inferred from functional mapping of T10 and T22 point mutants and allelic variants. Thus, T22 represents an unusual variant of the MHC-like fold and indicates that γδ and αβ TCRs interact differently with their respective MHC ligands.
Patients' Voices: The Powerful Sound in the Stem Cell Debate
Authors: Perry Daniel
Published: July 2002

Millions of patients may benefit from the applications of stem cell research, although there is disagreement about whether public funds should be used to develop the science. Patients have been key to winning political support. Acting as advocates, they have contended that public investment will speed the research and bring accountability to biomedical technology. A political dispute about the new research, which holds the potential for cures to devastating diseases and to foster healthy aging, shows the need to respect public sensibilities and to court public approval, as well as the importance of involving patients in debates where the methods of biomedical discoveries and ethical beliefs collide.
Virus-Induced Neuronal Apoptosis Blocked by the Herpes Simplex Virus Latency-Associated Transcript
Authors: Perng Guey-Chuen , Jones Clinton , Ciacci-Zanella Janice , Stone Melissa , Henderson Gail , Yukht Ada , Slanina Susan M. , Hofman Florence M. , Ghiasi Homayon , Nesburn Anthony B. , Wechsler Steven L.
Published: July 2002

Latent infections with periodic reactivation are a common outcome after acute infection with many viruses. The latency-associated transcript (
LAT
) gene is required for wild-type reactivation of herpes simplex virus (HSV). However, the underlying mechanisms remain unclear. In rabbit trigeminal ganglia, extensive apoptosis occurred with
LAT
−
virus but not with
LAT

+

viruses. In addition, a plasmid expressing
LAT
blocked apoptosis in cultured cells. Thus,
LAT
promotes neuronal survival after HSV-1 infection by reducing apoptosis.
Harnessing the Power of the Genome in the Search for New Antibiotics
Authors: Rosamond John , Allsop Aileen
Published: July 2002

Over the past 40 years, the search for new antibiotics has been largely restricted to well-known compound classes active against a standard set of drug targets. Although many effective compounds have been discovered, insufficient chemical variability has been generated to prevent a serious escalation in clinical resistance. Recent advances in genomics have provided an opportunity to expand the range of potential drug targets and have facilitated a fundamental shift from direct antimicrobial screening programs toward rational target-based strategies. The application of genome-based technologies such as expression profiling and proteomics will lead to further changes in the drug discovery paradigm by combining the strengths and advantages of both screening strategies in a single program.
A Fossil Snake with Limbs
Authors: Tchernov Eitan , Rieppel Olivier , Zaher Hussam , Polcyn Michael J. , Jacobs Louis L.
Published: July 2002

A 95-million-year-old fossil snake from the Middle East documents the most extreme hindlimb development of any known member of that group, as it preserves the tibia, fibula, tarsals, metatarsals, and phalanges. It is more complete than
Pachyrhachis
, a second fossil snake with hindlimbs that was recently portrayed to be basal to all other snakes. Phylogenetic analysis of the relationships of the new taxon, as well as reanalysis of
Pachyrhachis
, shows both to be related to macrostomatans, a group that includes relatively advanced snakes such as pythons, boas, and colubroids to the exclusion of more primitive snakes such as blindsnakes and pipesnakes.
New Observational Constraints for Atmospheric Hydroxyl on Global and Hemispheric Scales
Authors: Montzka S. A. , Spivakovsky C. M. , Butler J. H. , Elkins J. W. , Lock L. T. , Mondeel D. J.
Published: July 2002

Dramatic declines in emissions of methyl chloroform (1,1,1-trichloroethane) resulting from the Montreal Protocol provide an unprecedented opportunity to improve our understanding of the oxidizing power of Earth's atmosphere. Atmospheric observations of this industrial gas during the late 1990s yield new insights into the global burden and distribution of the hydroxyl radical. Our results set firm upper limits on the global and Southern Hemispheric lifetimes of methyl chloroform and confirm the predominance of hydroxyl in the tropics. Our analysis suggests a global lifetime for methyl chloroform of 5.2 (+0.2, −0.3) years, a Southern Hemispheric lifetime of 4.9 (+0.2, −0.3) years, and mean annual concentrations of OH that are 15 ± 10% higher south of the intertropical convergence zone than those north of this natural mixing boundary between the hemispheres.
Prometheus: Io's Wandering Plume
Authors: Kieffer Susan W. , Lopes-Gautier Rosaly , McEwen Alfred , Smythe William , Keszthelyi Laszlo , Carlson Robert
Published: July 2002

Unlike any volcanic behavior ever observed on Earth, the plume from Prometheus on Io has wandered 75 to 95 kilometers west over the last 20 years since it was first discovered by Voyager and more recently observed by Galileo. Despite the source motion, the geometric and optical properties of the plume have remained constant. We propose that this can be explained by vaporization of a sulfur dioxide and/or sulfur “snowfield” over which a lava flow is moving. Eruption of a boundary-layer slurry through a rootless conduit with sonic conditions at the intake of the melted snow can account for the constancy of plume properties.
The Spin Excitation Spectrum in Superconducting YBa
2
Cu
3
O
6.85
Authors: Bourges P. , Sidis Y. , Fong H. F. , Regnault L. P. , Bossy J. , Ivanov A. , Keimer B.
Published: July 2002

A comprehensive inelastic neutron scattering study of magnetic excitations in the near optimally doped high-temperature superconductor YBa
2
Cu
3
O
6.85
is presented. The spin correlations in the normal state are commensurate with the crystal lattice, and the intensity is peaked around the wave vector characterizing the antiferromagnetic state of the insulating precursor, YBa
2
Cu
3
O
6
. Profound modifications of the spin excitation spectrum appear abruptly below the superconducting transition temperature
T
c
, where a commensurate resonant mode and a set of weaker incommensurate peaks develop. The data are consistent with models that are based on an underlying two-dimensional Fermi surface, predicting a continuous, downward dispersion relation connecting the resonant mode and the incommensurate excitations. The magnetic incommensurability in the YBa
2
Cu
3
O
6+

x

system is thus not simply related to that of another high-temperature superconductor, La
2–

x

Sr

x

CuO
4
, where incommensurate peaks persist well above
T
c
. The temperature-dependent incommensurability is difficult to reconcile with interpretations based on charge stripe formation in YBa
2
Cu
3
O
6+

x

near optimum doping.
Vibrational Promotion of Electron Transfer
Authors: Huang Yuhui , Rettner Charles T. , Auerbach Daniel J. , Wodtke Alec M.
Published: July 2002

By using laser methods to prepare specific quantum states of gas-phase nitric oxide molecules, we examined the role of vibrational motion in electron transfer to a molecule from a metal surface free from the complicating influence of solvation effects. The signature of the electron transfer process is a highly efficient multiquantum vibrational relaxation event, where the nitrogen oxide loses hundreds of kilojoules per mole of energy on a subpicosecond time scale. These results cannot be explained simply on the basis of Franck-Condon factors. The large-amplitude vibrational motion associated with molecules in high vibrational states strongly modulates the energetic driving force of the electron transfer reaction. These results show the importance of molecular vibration in promoting electron transfer reactions, a class of chemistry important to molecular electronics devices, solar energy conversion, and many biological processes.
Two-Amino Acid Molecular Switch in an Epithelial Morphogen That Regulates Binding to Two Distinct Receptors
Authors: Yan Minhong , Wang Li-Chong , Hymowitz Sarah G. , Schilbach Sarah , Lee James , Goddard Audrey , de Vos Abraham M. , Gao Wei-Qiang , Dixit Vishva M.
Published: July 2002

Ectodysplasin, a member of the tumor necrosis factor family, is encoded by the anhidrotic ectodermal dysplasia (EDA) gene. Mutations in EDA give rise to a clinical syndrome characterized by loss of hair, sweat glands, and teeth. EDA-A1 and EDA-A2 are two isoforms of ectodysplasin that differ only by an insertion of two amino acids. This insertion functions to determine receptor binding specificity, such that EDA-A1 binds only the receptor EDAR, whereas EDA-A2 binds only the related, but distinct, X-linked ectodysplasin-A2 receptor (XEDAR). In situ binding and organ culture studies indicate that EDA-A1 and EDA-A2 are differentially expressed and play a role in epidermal morphogenesis.
The CIDA-QUEST Large-Scale Survey of Orion OB1: Evidence for Rapid Disk Dissipation in a Dispersed Stellar Population
Authors: Briceño César , Vivas A. Katherina , Calvet Nuria , Hartmann Lee , Pacheco Ricardo , Herrera David , Romero Lysett , Berlind Perry , Sánchez Gerardo , Snyder Jeffrey A. , Andrews Peter
Published: July 2002

We are conducting a large-scale, multiepoch, optical photometric survey [Centro de Investigaciones de Astronomı́a–Quasar Equatorial Survey Team (CIDA-QUEST)] covering about 120 square degrees to identify the young low-mass stars in the Orion OB1 association. We present results for an area of 34 square degrees. Using photometric variability as our main selection criterion, as well as follow-up spectroscopy, we confirmed 168 previously unidentified pre–main sequence stars that are about 0.6 to 0.9 times the mass of the sun (
M
⊙
), with ages of about 1 million to 3 million years (Ori OB1b) and about 3 million to 10 million years (Ori OB1a). The low-mass stars are spatially coincident with the high-mass (at least 3
M
⊙
) members of the associations. Indicators of disk accretion such as Hα emission and near-infrared emission from dusty disks fall sharply from Ori OB1b to Ori OB1a, indicating that the time scale for disk dissipation and possibly the onset of planet formation is a few million years.
Establishment of Transcriptional Silencing in the Absence of DNA Replication
Authors: Li Yao-Cheng , Cheng Tzu-Hao , Gartenberg Marc R.
Published: July 2002

Transcriptional repression of the silent mating-type loci in
Saccharomyces cerevisiae
requires a cell cycle–dependent establishment step that is commonly assumed to involve DNA replication. Using site-specific recombination, we created a nonreplicating DNA ring in vivo to test directly the role of replication in establishment of silencing. Sir1 was tethered to the ring following excision from the chromosome to activate a dormant silencer. We show here that silencing can be established in DNA that does not replicate. The silenced ring adopted structural features characteristic of bona fide silent chromatin, including an altered level of DNA supercoiling and reduced histone acetylation. In addition, the process required silencing factors Sir2, Sir3, and Sir4 and progression between early S and M phases of the cell cycle. The results indicate that passage of a replication fork is not the cell-cycle event required for establishment of silencing in yeast.
Antibody-Targeted Lethal Photosensitization ofPorphyromonas gingivalis
Authors: Bhatti M. , MacRobert A. , Henderson B. , Shepherd P. , Cridland J. , Wilson M.
Published: July 2002

We have previously demonstrated thatPorphyromonas gingivalisis susceptible to killing by toluidine blue O (TBO) when irradiated with light from a helium-neon (HeNe) laser. The aim of this study was to determine whether a TBO-antibody conjugate (Ab-TBO) could be used to specifically targetP. gingivalisto lethal photosensitization in the presence ofStreptococcus sanguisor human gingival fibroblasts (HGFs). When a mixture ofP. gingivalisandS. sanguiswas exposed to 4 μg of TBO/ml and irradiated with HeNe laser light, there were 1.5- and 4.0-log10-unit reductions in the viable counts, respectively. In contrast, when TBO was conjugated with a murine monoclonal antibody againstP. gingivalislipopolysaccharide, the reductions in viable counts ofP. gingivalisandS. sanguisamounted to 5.0 and 0.1 log10units, respectively. Lethal photosensitization ofP. gingivalisin the presence of HGFs using unconjugated TBO resulted in a 0.7-log10-unit reduction inP. gingivalisviable counts and a 99% reduction in the incorporation of tritiated thymidine ([3H]Tdr) by the HGFs. In contrast, when the Ab-TBO conjugate was used, there was a 100% reduction inP. gingivalisviable counts but no significant reduction in the incorporation of [3H]Tdr by HGFs. These results demonstrate that specific targeting ofP. gingivaliscan be achieved using TBO conjugated to a monoclonal antibody raised against a cell surface component of this organism.
Activities of Trovafloxacin, Gatifloxacin, Clinafloxacin, Sparfloxacin, Levofloxacin, and Ciprofloxacin against Penicillin-Resistant
Streptococcus pneumoniae
in an In Vitro Infection Model
Authors: Hershberger Ellie , Rybak Michael J.
Published: July 2002

We adapted an in vitro pharmacodynamic model of infection to incorporate infected fibrin clots. The bactericidal activities of various fluoroquinolones against two strains of penicillin-resistant
Streptococcus pneumoniae
were studied over a 48-h period. Bacteria were prepared in Muller-Hinton broth by using colonies from a 24-h tryptic soy agar plus 5% sheep blood plate and were added to a mixture of cryoprecipitate (80%) and thrombin (10%) to achieve approximately 10
6
CFU of organism per fibrin clot. The fibrin clots were suspended into the models and removed, in triplicate, at various time points over 48 h. Control models were also conducted to characterize the growth of
S. pneumoniae
in the growth medium without antibiotic. Trovafloxacin, gatifloxacin, clinafloxacin, sparfloxacin, levofloxacin, and ciprofloxacin were administered to simulate their pharmacokinetic profiles in humans. Fibrin clot samples were also plated onto antibiotic-containing tryptic soy agar plus 5% lysed horse blood to detect resistance. The newer fluoroquinolones demonstrated better activity than ciprofloxacin against both isolates. In conclusion, the newer quinolones demonstrated significant activity against penicillin-resistant
S. pneumoniae
, with standard dosing resulting in area under the concentration-time curve/MIC ratios and peak concentration/MIC ratios that resulted in 99.9% killing against these isolates.
Pulsed Ultrasound Enhances the Killing of
Escherichia coli
Biofilms by Aminoglycoside Antibiotics In Vivo
Authors: Rediske Andrea M. , Roeder Beverly L. , Nelson Jared L. , Robison Rachel L. , Schaalje G. Bruce , Robison Richard A. , Pitt William G.
Published: July 2002

Escherichia coli
biofilms on two polyethylene disks were implanted subcutaneously into rabbits receiving systemic gentamicin. Ultrasound was applied for 24 h to one disk. Both disks were removed, and viable bacteria were counted. Pulsed ultrasound significantly reduced bacterial viability below that of nontreated biofilms without damage to the skin.
In Vitro Activity of ABT 773, a New Ketolide Antibiotic, against
Chlamydia pneumoniae
Authors: Strigl Sebastian , Roblin Patricia M. , Reznik Tamara , Hammerschlag Margaret R.
Published: July 2002

The in vitro activities of ABT 773, telithromycin (HMR 3647), azithromycin, clarithromycin, erythromycin, and levofloxacin were tested against 20 strains of
Chlamydia pneumoniae
. The MIC at which 90% of the isolates were inhibited and the minimal bactericidal concentration at which 90% of the isolates were killed by ABT 773 were 0.015 μg/ml (range, 0.008 to 0.015 μg/ml). ABT 773 was the most active antibiotic tested in this study.
In Vitro Pharmacodynamic Parameters of Sordarin Derivatives in Comparison with Those of Marketed Compounds against
Pneumocystis carinii
Isolated from Rats
Authors: Aviles Pablo , Aliouat El-Moukhtar , Martinez Antonio , Dei-Cas Eduardo , Herreros Esperanza , Dujardin Lucien , Gargallo-Viola Domingo
Published: July 2002

Pneumocystis carinii
pneumonia remains one of the most serious complications of immunosuppressed patients. In this study, the in vitro pharmacodynamic parameters of four sordarin derivatives (GM 191519, GM 237354, GM 193663, and GM 219771) have been evaluated by a new quantitative approach and compared with the commercially available drugs pentamidine, atovaquone, and trimethoprim-sulfamethoxazole (TMP-SMX). In vitro activities and in vivo therapeutic efficacies of sordarin derivatives against
P. carinii
were also evaluated. In vitro activity was determined by the broth microdilution technique, comparing the total number of microorganisms in treated and drug-free cultures by using Giemsa staining. The in vitro maximum effect (
E
max
), the drug concentrations to reach 50% of
E
max
(EC
50
), and the slope of the dose-response curve were then estimated by the Hill equation (
E
max
sigmoid model). Sordarin derivatives were the most potent agents against
P. carinii
, with EC
50
s of 0.00025, 0.0007, 0.0043, and 0.025 μg/ml for GM 191519, GM 237354, GM 193663, and GM 219771, respectively. The EC
50
s of pentamidine, atovaquone, and TMP-SMX were 0.025, 0.16, and 26.7/133.5 μg/ml, respectively. The results obtained with this approach showed GM 237354 and GM 191519 to be approximately 35- and 100-fold more active in vitro than pentamidine, the most active marketed compound. All sordarin derivatives tested were at least 5,000-fold more active in vitro than TMP-SMX. The three sordarin derivatives tested in vivo—GM 191519, GM 237354, and GM 219771—showed a marked therapeutic efficacy, defined as reduction of cyst forms per gram of lung. GM 191519 was the most potent (daily dose reducing 50% of the
P. carinii
burden in the lungs [ED
50
], 0.05 mg/kg/day) followed by GM 237354 and GM 219771 (ED
50
s, 0.30 and 0.49 mg/kg/day, respectively). Good agreement between in vitro parameters and in vivo outcome was obtained when
P. carinii
pneumonia in rats was treated with sordarin derivatives.
Prevalence of SHV-12 among Clinical Isolates of
Klebsiella pneumoniae
Producing Extended-Spectrum β-Lactamases and Identification of a Novel AmpC Enzyme (CMY-8) in Southern Taiwan
Authors: Yan Jing-Jou , Wu Shiou-Mei , Tsai Shu-Huei , Wu Jiunn-Jong , Su Ih-Jen
Published: July 2002

Twenty (8.5%) of 234 nonrepetitive clinical isolates of
Klebsiella pneumoniae
from southern Taiwan were found to produce extended-spectrum β-lactamases (ESBLs): 10 strains produced SHV-12, 4 produced SHV-5, 2 produced a non-TEM non-SHV ESBL with a pI of 8.3, 3 produced a novel AmpC β-lactamase designated CMY-8 with a pI of 8.25, and 1 produced SHV-12 and an unidentified AmpC enzyme with a pI of 8.2. The CMY-8 enzyme confers a resistance phenotype similar to CMY-1 and MOX-1, and sequence comparisons showed high homologies (>95%) of nucleotide and amino acid sequences among these three enzymes. Plasmid and pulse-field gel electrophoresis analyses revealed that all isolates harboring an SHV-derived ESBL were genetically unrelated, indicating that dissemination of resistance plasmids is responsible for the spread of SHV ESBLs among
K. pneumoniae
in this area. All three isolates carrying CMY-8 had identical genotypic patterns, suggesting the presence of an epidemic strain.
Increasing Bacterial Resistance in Pediatric Acute Conjunctivitis (1997–1998)
Authors: Block Stan L. , Hedrick James , Tyler Ron , Smith Alan , Findlay Rebecca , Keegan Eileen , Stroman Dave W.
Published: July 2002

We sought to determine the current level of resistance in
Haemophilus influenzae
and
Streptococcus pneumoniae
, the primary pathogens of pediatric conjunctivitis. Between January 1997 and March 1998, we prospectively cultured acute conjunctivitis in 250 ambulatory pediatric patients from rural Kentucky whose average age was 24.3 months. In those 250 cases, 106
H. influenzae
(42% of the total) and 75
S. pneumoniae
(30% of the total) pathogens were isolated, with no growth or no pathogen resulting in 79 cases (32% of the total). Beta-lactamase was detected in 60 (69%) of 87 tested strains of
H. influenzae
. Among 65 isolates of
S. pneumoniae
tested for penicillin susceptibility, 44 (68%) were susceptible, 17 (26%) were resistant, and 4 (6%) were intermediate. Conjunctivitis with acute otitis media was observed in 97 patients (39%), and
H. influenzae
was recovered in 57% of these 97 cases. As for in vitro activity, ciprofloxacin, ofloxacin, and tetracycline were the most active; and gentamicin, tobramycin, polymyxin B-trimethoprim, and polymyxin B-neomycin were intermediately active. Sulfamethoxazole possessed no activity against either pathogen. Beta-lactamase production was detected in 69% of
H. influenzae
strains, which still remains the primary causative pathogen of both conjunctivitis and conjunctivitis-otitis syndrome. Penicillin-nonsusceptible
S. pneumoniae
was observed in 32% of 65 patients with
S. pneumoniae
conjunctivitis, with most strains being penicillin resistant.
Postantibiotic Suppression of Growth of Erythromycin A-Susceptible and -Resistant Gram-Positive Bacteria by the Ketolides Telithromycin (HMR 3647) and HMR 3004
Authors: Munckhof Wendy J. , Borlace Glenn , Turnidge John D.
Published: July 2002

We investigated the in vitro postantibiotic effects (PAEs) of the ketolides telithromycin (HMR 3647) and HMR 3004 and analyzed the results using the sigmoid
E
max
model. Mean maximum telithromycin PAEs against erythromycin A-susceptible strains of
Staphylococcus aureus
,
Streptococcus pyogenes
, and
Streptococcus pneumoniae
were 3.7, 8.9, and 9.7 h, respectively, while maximum PAEs for erythromycin A-resistant strains were much shorter. Mean maximum HMR 3004 PAEs were 3.2 to 4.4 h for all species.
Rapid Discriminatory Detection of Genes Coding for SHV β-Lactamases by Ligase Chain Reaction
Authors: Kim Jungmin , Lee Hoan-Jong
Published: July 2002

Ligase chain reaction (LCR) is a recently developed technique that employs a thermostable ligase and allows for the discrimination of DNA sequences differing in only a single base pair. The method has been adapted and applied to differentiation of
bla
SHV
genes. We have developed an LCR typing method to characterize point mutations in genes for SHV-derived extended-spectrum β-lactamases with four different sets of biotinylated LCR primers. To evaluate the applicability of the current technique, we tested seven
Escherichia coli
strains producing SHV-1, SHV-2, SHV-2a, SHV-3, SHV-4, SHV-5, and SHV-12. With the LCR typing, seven SHV genes can be distinguished according to their incorporating point mutations. In an attempt to characterize SHV β-lactamases by LCR typing in clinical isolates, 46 strains carrying
bla
SHV
genes (32
Klebsiella pneumoniae
, 10
Enterobacter cloacae
, and 4
E. coli
) were subjected to antibiotic susceptibility testing, isoelectric focusing, and LCR typing. LCR typing allowed the characterization of β-lactamases, and genotypes obtained by LCR typing were in accordance with phenotypes such as antibiotic resistance profile and pI value of β-lactamase. Therefore, we concluded that LCR typing may permit defining the SHV families with simplicity and reliability and can be applied to the detailed characterization and molecular epidemiology of SHV-type β-lactamases.
Genetic Organization of the Downstream Region of the
mecA
Element in Methicillin-Resistant
Staphylococcus aureus
Isolates Carrying Different Polymorphisms of This Region
Authors: Oliveira Duarte C. , Wu Shang W. , de Lencastre Hermínia
Published: July 2002

We describe here the genetic organization of the
mec
element downstream of the
mecA
gene in 34 different methicillin-resistant
Staphylococcus aureus
(MRSA) clinical isolates carrying 13 of the most frequent polymorphisms of
mecA
and representing the major epidemic clones of MRSA. All polymorphisms carried three common genetic elements: the hypervariable region, a copy of IS
431
, and a unique 2-kb sequence (downstream constant segment, or
dcs
) for which no homologous sequences are found in data banks. Polymorphisms of the downstream region were shown to be caused by the presence of linearized plasmids flanked by insertion sequences (pUB110, pT181, and pI258) and the autonomous insertion sequence IS
256
.
A Novel CTX-M β-Lactamase (CTX-M-8) in Cefotaxime-Resistant
Enterobacteriaceae
Isolated in Brazil
Authors: Bonnet R. , Sampaio J. L. M. , Labia R. , De Champs C. , Sirot D. , Chanal C. , Sirot J.
Published: July 2002

To estimate the diversity of extended-spectrum β-lactamases in Brazil, 18 strains from different species of the family
Enterobacteriaceae
exhibiting a positive double-disk synergy test were collected by a clinical laboratory from several hospitals in Rio de Janeiro, Brazil, in 1996 and 1997. Four strains (
Proteus mirabilis
,
Enterobacter cloacae
,
Enterobacter aerogenes
, and
Citrobacter amalonaticus
) hybridized with a 550-bp CTX-M probe. The
P. mirabilis
strain produced a CTX-M-2 enzyme. The
E. cloacae
,
E. aerogenes
, and
C. amalonaticus
isolates harbored a
bla
gene which was identified by cloning and sequencing as a
bla
CTX-M
gene.
E. coli
HB101 transconjugants and the
E. coli
DH5α transformant harboring a recombinant plasmid produced a CTX-M β-lactamase with an isoelectric point of 7.6 conferring a resistance phenotype characterized by a higher level of resistance to cefotaxime than to ceftazidime, as observed with the other CTX-M enzymes. The deduced protein sequence showed a novel Ambler class A CTX-M enzyme, named CTX-M-8, which had 83 to 88% identity with the previously described CTX-M enzymes. The phylogenic study of the CTX-M family including CTX-M-8 revealed four CTX-M types, CTX-M-8 being the first member of a new phylum of CTX-M enzymes. The evolutionary distances between the four types of CTX-M were large, suggesting that the four clusters branched off early from a distant unknown enzyme and that intermediate enzymes probably existed.
In Vitro Activities of Linezolid Alone and in Combination with Amoxicillin, Clarithromycin, and Metronidazole againstHelicobacter pylori
Authors: Hirschl Alexander M. , Apfalter Petra , Makristathis Athanasios , Rotter Manfred L. , Wimmer Margit
Published: July 2002

Linezolid was tested against 70 strains ofHelicobacter pyloriby the agar dilution method. The MIC range and MICs at which 50 and 90% of strains were inhibited were 8 to 64, 16, and 32 μg/ml, respectively. With minimum and maximum fractional inhibitory concentration summation values of 0.31 and 2.50, respectively, the combination of linezolid with amoxicillin, clarithromycin, or metronidazole showed either partial synergy or indifference for the majority of strains.
Comparative Activities of Telithromycin (HMR 3647), Levofloxacin, and Other Antimicrobial Agents against Human Mycoplasmas
Authors: Bebear C. M. , Renaudin H. , Bryskier A. , Bebear C.
Published: July 2002

The activities of telithromycin and levofloxacin against 99 mycoplasma strains were compared to those of several macrolides, ofloxacin, and doxycycline. Telithromycin MICs of ≤0.25 μg/ml were found for all isolates, except for
Mycoplasma hominis
, while levofloxacin was active at concentrations of ≤1 μg/ml against all species studied.
Multiple-Dose Pharmacokinetics and Pharmacodynamics of Abacavir Alone and in Combination with Zidovudine in Human Immunodeficiency Virus-Infected Adults
Authors: McDowell James A. , Lou Yu , Symonds William S. , Stein Daniel S.
Published: July 2002

Abacavir (1592U89) is a nucleoside reverse transcriptase inhibitor with potent activity against human immunodeficiency virus type 1 (HIV-1) when used alone or in combination with other antiretroviral agents. The present study was conducted to determine the multiple-dose pharmacokinetics and pharmacodynamics of abacavir in HIV-1-infected subjects following oral administration of daily doses that ranged from 600 to 1,800 mg, with and without zidovudine. Seventy-nine subjects received abacavir monotherapy for 4 weeks (200, 400, or 600 mg every 8 hours [TID] and 300 mg every 12 h [BID]) and thereafter received either zidovudine (200 mg TID or 300 mg BID) or matching placebo with abacavir for 8 additional weeks. Pharmacokinetic parameters were calculated for abacavir after administration of the first dose and at week 4 and for abacavir, zidovudine, and its glucuronide metabolite at week 12. The concentrations of abacavir in cerebrospinal fluid were determined in a subset of subjects. Steady-state plasma abacavir concentrations were achieved by week 4 of monotherapy and persisted to week 12. At steady state, abacavir pharmacokinetic parameters (area under the plasma concentration-time curve for a dosing interval [AUC
tau
] and peak concentration [
C
max
]) were generally proportional to dose over the range of a 600- to 1,200-mg total daily dose. Coadministration of zidovudine with abacavir produced a small and inconsistent effect on abacavir pharmacokinetic parameters across the different doses. At the clinical abacavir dose (300 mg BID) zidovudine coadministration had no effect on the abacavir AUC
tau
, which is most closely associated with efficacy. Zidovudine pharmacokinetics appeared to be unaffected by abacavir. Statistically significant but weak relationships were found for the change in the log
10
HIV-1 RNA load from the baseline to week 4 versus total daily AUC
tau
and
C
tau
(
P
< 0.05). The incidence of nausea was significantly associated with total daily AUC
tau
and
C
max
. In conclusion, abacavir has predictable pharmacokinetic characteristics following the administration of multiple doses.
Urinary Excretion and Bactericidal Activities of Gemifloxacin and Ofloxacin after a Single Oral Dose in Healthy Volunteers
Authors: Naber Christoph K. , Hammer Michaela , Kinzig-Schippers Martina , Sauber Christian , Sörgel Fritz , Bygate Elizabeth A. , Fairless Amanda J. , Machka Konstanze , Naber Kurt G.
Published: July 2002

In a randomized crossover study, 16 volunteers (8 men, 8 women) received single oral doses of 320 mg of gemifloxacin and 400 mg of ofloxacin on two separate occasions in the fasting state to assess the urinary excretion and urinary bactericidal titers (UBTs) at intervals for up to 144 h. Ofloxacin showed higher concentrations in urine compared with those of gemifloxacin. The median (range) cumulative excretion of gemifloxacin was 29.7% (8.4 to 48.7%) of the parent drug administered, and median (range) cumulative excretion of ofloxacin was 84.3% (46.5 to 95.2%) of the parent drug administered. The UBTs, i.e., the highest twofold dilutions (with antibiotic-free urine as the diluent) of urine that were still bactericidal, were determined for a reference strain and nine uropathogens for which the MICs of gemifloxacin and ofloxacin were as follows:
Escherichia coli
ATCC 25922, 0.016 and 0.06 μg/ml, respectively;
Klebsiella pneumoniae
, 0.03 and 0.06 μg/ml, respectively;
Proteus mirabilis
, 0.125 and 0.125 μg/ml, respectively;
Escherichia coli
, 0.06 and 0.5 μg/ml, respectively;
Pseudomonas aeruginosa
, 1 and 4 μg/ml, respectively;
Staphylococcus aureus
, 0.008 and 0.25 μg/ml, respectively;
Enterococcus faecalis
, 0.06 and 2 μg/ml, respectively;
Staphylococcus aureus
, 0.25 and 4 μg/ml, respectively;
Enterococcus faecalis
, 0.5 and 32 μg/ml, respectively; and
Staphylococcus aureus
, 2 and 32 μg/ml, respectively. Generally, the UBTs for gram-positive uropathogens were higher for gemifloxacin than for ofloxacin and the UBTs for gram-negative uropathogens were higher for ofloxacin than for gemifloxacin. According to the UBTs, ofloxacin-resistant uropathogens (MICs, ≥4 mg/liter) should also be considered gemifloxacin resistant. Although clinical trials have shown that gemifloxacin is effective for the treatment of uncomplicated urinary tract infections, whether an oral dosage of 320 mg of gemifloxacin once daily is also adequate for the treatment of complicated urinary tract infections has yet to be confirmed.
Safety and Pharmacokinetics of Single Doses of (+)-Calanolide A, a Novel, Naturally Occurring Nonnucleoside Reverse Transcriptase Inhibitor, in Healthy, Human Immunodeficiency Virus-Negative Human Subjects
Authors: Creagh Terri , Ruckle Jon L. , Tolbert Dwain T. , Giltner Jeremy , Eiznhamer David A. , Dutta Bipul , Flavin Michael T. , Xu Ze-Qi
Published: July 2002

(+)-Calanolide A is a novel, naturally occurring, nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase first isolated from a tropical tree (Calophyllum lanigerum) in the Malaysian rain forest. Previous studies have demonstrated that (+)-calanolide A has specific activity against the reverse transcriptase of HIV-1 and a favorable safety profile in animals. In addition, (+)-calanolide A exhibits a unique HIV-1 resistance profile in vitro. The safety and pharmacokinetics of (+)-calanolide A was examined in four successive single-dose cohorts (200, 400, 600, and 800 mg) in healthy, HIV-negative volunteers. In this initial phase I study, the toxicity of (+)-calanolide A was minimal in the 47 subjects treated. Dizziness, taste perversion, headache, eructation, and nausea were the most frequently reported adverse events. These events were not all judged to be related to study medication nor were they dose related. While 51% of subjects reported mild and transient dizziness, in many cases this appeared to be temporally related to phlebotomy. Calculation of the terminal-phase half-life (t1/2) was precluded by intrasubject variability in the 200-, 400-, and 600-mg dose cohorts but was approximately 20 h for the 800-mg dose group. (+)-Calanolide A was rapidly absorbed following administration, with time to maximum concentration of drug in plasma (Tmax) values occurring between 2.4 and 5.2 h postdosing depending on the dose. Plasma levels of (+)-calanolide A at all dosing levels were quite variable; however, both the mean concentration in plasma (Cmax), and the area under the plasma concentration-time curve increased proportionately in relation to the dose. Although raw plasma drug levels were higher in women than in men, when doses were normalized for body mass, the pharmacokinetic profiles were virtually identical with those observed for males. In general, levels of (+)-calanolide A in human plasma were higher than would have been predicted from animal studies, yet the safety profile remained benign. In conclusion, this study demonstrated the safety and favorable pharmacokinetic profile of single doses of (+)-calanolide A in healthy, HIV-negative individuals.
Proinflammatory Activity of a Cecropin-Like Antibacterial Peptide fromHelicobacter pylori
Authors: Bylund Johan , Christophe Thierry , Boulay Francois , Nyström Thomas , Karlsson Anna , Dahlgren Claes
Published: July 2002

Helicobacter pylori, the bacterial pathogen associated with gastritis and peptic ulcers, is highly successful in establishing infection in the human gastric mucosa, a process typically associated with massive infiltration of inflammatory cells. Colonization of the mucosa is suggested to be facilitated byH. pylori-produced cecropin-like peptides with antibacterial properties, giving the microbe a competitive advantage over other bacteria. We show that a cecropin-like antibacterial peptide fromH. pylori, Hp(2-20), not only has a potent bactericidal effect but also induces proinflammatory activities in human neutrophils, e.g., upregulation of integrins (Mac-1), induction of chemotaxis, and activation of the oxygen radical producing NADPH-oxidase. Furthermore, we show that these effects are mediated through binding of Hp(2-20) to the promiscuous, G-protein-linked lipoxin A4receptor–formyl peptide-like receptor 1.