bluuebunny/crossref_metadata_2025 huggingface dataset:
Early Neocortical Regionalization in the Absence of Thalamic Innervation
Authors: Miyashita-Lin Emily M. , Hevner Robert , Wassarman Karen Montzka , Martinez Salvador , Rubenstein John L. R.
Published: July 2002

There is a long-standing controversy regarding the mechanisms that generate the functional subdivisions of the cerebral neocortex. One model proposes that thalamic axonal input specifies these subdivisions; the competing model postulates that patterning mechanisms intrinsic to the dorsal telencephalon generate neocortical regions.
Gbx-2
mutant mice, whose thalamic differentiation is disrupted, were investigated. Despite the lack of cortical innervation by thalamic axons, neocortical region–specific gene expression (
Cadherin-6
,
EphA-7
,
Id-2
, and
RZR-beta
) developed normally. This provides evidence that patterning mechanisms intrinsic to the neocortex specify the basic organization of its functional subdivisions.
Control of the Terminal Step of Intracellular Membrane Fusion by Protein Phosphatase 1
Authors: Peters C. , Andrews P. D. , Stark M. J. R. , Tadic S. Cesaro- , Glatz A. , Podtelejnikov A. , Mann M. , Mayer A.
Published: July 2002

Intracellular membrane fusion is crucial for the biogenesis and maintenance of cellular compartments, for vesicular traffic between them, and for exo- and endocytosis. Parts of the molecular machinery underlying this process have been identified, but most of these components operate in mutual recognition of the membranes. Here it is shown that protein phosphatase 1 (PP1) is essential for bilayer mixing, the last step of membrane fusion. PP1 was also identified in a complex that contained calmodulin, the second known factor implicated in the regulation of bilayer mixing. The PP1-calmodulin complex was required at multiple sites of intracellular trafficking; hence, PP1 may be a general factor controlling membrane bilayer mixing.
Improved Weather and Seasonal Climate Forecasts from Multimodel Superensemble
Authors: Krishnamurti T. N. , Kishtawal C. M. , LaRow Timothy E. , Bachiochi David R. , Zhang Zhan , Williford C. Eric , Gadgil Sulochana , Surendran Sajani
Published: July 2002

A method for improving weather and climate forecast skill has been developed. It is called a superensemble, and it arose from a study of the statistical properties of a low-order spectral model. Multiple regression was used to determine coefficients from multimodel forecasts and observations. The coefficients were then used in the superensemble technique. The superensemble was shown to outperform all model forecasts for multiseasonal, medium-range weather and hurricane forecasts. In addition, the superensemble was shown to have higher skill than forecasts based solely on ensemble averaging.
A Nonpeptidyl Mimic of Superoxide Dismutase with Therapeutic Activity in Rats
Authors: Salvemini Daniela , Wang Zhi-Qiang , Zweier Jay L. , Samouilov Alexandre , Macarthur Heather , Misko Thomas P. , Currie Mark G. , Cuzzocrea Salvatore , Sikorski James A. , Riley Dennis P.
Published: July 2002

Many human diseases are associated with the overproduction of oxygen free radicals that inflict cell damage. A manganese(II) complex with a bis(cyclohexylpyridine)-substituted macrocyclic ligand (M40403) was designed to be a functional mimic of the superoxide dismutase (SOD) enzymes that normally remove these radicals. M40403 had high catalytic SOD activity and was chemically and biologically stable in vivo. Injection of M40403 into rat models of inflammation and ischemia-reperfusion injury protected the animals against tissue damage. Such mimics may result in better clinical therapies for diseases mediated by superoxide radicals.
Gas-Rich Galaxy Pair Unveiled in the Lensed Quasar 0957+561
Authors: Planesas P. , Martı́n-Pintado J. , Neri R. , Colina L.
Published: July 2002

Molecular gas in the host galaxy of the lensed quasar 0957+561 (QSO 0957+561) at the redshift of 1.41 has been detected in the carbon monoxide (CO) line. This detection shows the extended nature of the molecular gas distribution in the host galaxy and the pronounced lensing effects due to the differentially magnified CO luminosity at different velocities. The estimated mass of molecular gas is about 4 × 10
9
solar masses, a molecular gas mass typical of a spiral galaxy like the Milky Way. A second, weaker component of CO is interpreted as arising from a close companion galaxy that is rich in molecular gas and has remained undetected so far. Its estimated molecular gas mass is 1.4 × 10
9
solar masses, and its velocity relative to the main galaxy is 660 kilometers per second. The ability to probe the molecular gas distribution and kinematics of galaxies associated with high-redshift lensed quasars can be used to improve the determination of the Hubble constant
H
0
.
A Critical Role for Murine Complement Regulator Crry in Fetomaternal Tolerance
Authors: Xu Chenguang , Mao Dailing , Holers V. Michael , Palanca Ben , Cheng Alec M. , Molina Hector
Published: July 2002

Complement is a component of natural immunity. Its regulation is needed to protect tissues from inflammation, but mice with a disrupted gene for the complement regulator decay accelerating factor were normal. Mice that were deficient in another murine complement regulator, Crry, were generated to investigate its role in vivo. Survival of
Crry
−/−
embryos was compromised because of complement deposition and concomitant placenta inflammation. Complement activation at the fetomaternal interface caused the fetal loss because breeding to
C3
−/−
mice rescued
Crry
−/−
mice from lethality. Thus, the regulation of complement is critical in fetal control of maternal processes that mediate tissue damage.
The Role of the Southern Ocean in Uptake and Storage of Anthropogenic Carbon Dioxide
Authors: Caldeira Ken , Duffy Philip B.
Published: July 2002

An ocean-climate model that shows high fluxes of anthropogenic carbon dioxide into the Southern Ocean, but very low storage of anthropogenic carbon there, agrees with observation-based estimates of ocean storage of anthropogenic carbon dioxide. This low simulated storage indicates a subordinate role for deep convection in the present-day Southern Ocean. The primary mechanism transporting anthropogenic carbon out of the Southern Ocean is isopycnal transport. These results imply that if global climate change reduces the density of surface waters in the Southern Ocean, isopycnal surfaces that now outcrop may become isolated from the atmosphere, tending to diminish Southern Ocean carbon uptake.
Out of Eden: Stem Cells and Their Niches
Authors: Watt Fiona M. , Hogan and Brigid L. M.
Published: July 2002

Stem cells are currently in the news for two reasons: the successful cultivation of human embryonic stem cell lines and reports that adult stem cells can differentiate into developmentally unrelated cell types, such as nerve cells into blood cells. Both intrinsic and extrinsic signals regulate stem cell fate and some of these signals have now been identified. Certain aspects of the stem cell microenvironment, or niche, are conserved between tissues, and this can be exploited in the application of stem cells to tissue replacement therapy.
Translocation of
Helicobacter pylori
CagA into Gastric Epithelial Cells by Type IV Secretion
Authors: Odenbreit Stefan , Püls Jürgen , Sedlmaier Bettina , Gerland Elke , Fischer Wolfgang , Haas Rainer
Published: July 2002

The Gram-negative bacterium
Helicobacter pylori
is a causative agent of gastritis and peptic ulcer disease in humans. Strains producing the CagA antigen (
cagA
+
) induce strong gastric inflammation and are strongly associated with gastric adenocarcinoma and MALT lymphoma. We show here that such strains translocate the bacterial protein CagA into gastric epithelial cells by a type IV secretion system, encoded by the
cag
pathogenicity island. CagA is tyrosine-phosphorylated and induces changes in the tyrosine phosphorylation state of distinct cellular proteins. Modulation of host cells by bacterial protein translocation adds a new dimension to the chronic
Helicobacter
infection with yet unknown consequences.
Prostaglandin D
2
as a Mediator of Allergic Asthma
Authors: Matsuoka Toshiyuki , Hirata Masakazu , Tanaka Hiroyuki , Takahashi Yoshimasa , Murata Takahiko , Kabashima Kenji , Sugimoto Yukihiko , Kobayashi Takuya , Ushikubi Fumitaka , Aze Yoshiya , Eguchi Naomi , Urade Yoshihiro , Yoshida Nobuaki , Kimura Kazushi , Mizoguchi Akira , Honda Yoshihito , Nagai Hiroichi , Narumiya Shuh
Published: July 2002

Allergic asthma is caused by the aberrant expansion in the lung of T helper cells that produce type 2 (T
H
2) cytokines and is characterized by infiltration of eosinophils and bronchial hyperreactivity. This disease is often triggered by mast cells activated by immunoglobulin E (IgE)–mediated allergic challenge. Activated mast cells release various chemical mediators, including prostaglandin D
2
(PGD
2
), whose role in allergic asthma has now been investigated by the generation of mice deficient in the PGD receptor (DP). Sensitization and aerosol challenge of the homozygous mutant (DP
−/−
) mice with ovalbumin (OVA) induced increases in the serum concentration of IgE similar to those in wild-type mice subjected to this model of asthma. However, the concentrations of T
H
2 cytokines and the extent of lymphocyte accumulation in the lung of OVA-challenged DP
−/−
mice were greatly reduced compared with those in wild-type animals. Moreover, DP
−/−
mice showed only marginal infiltration of eosinophils and failed to develop airway hyperreactivity. Thus, PGD
2
functions as a mast cell–derived mediator to trigger asthmatic responses.
Bacterial Rhodopsin: Evidence for a New Type of Phototrophy in the Sea
Authors: Béjà Oded , Aravind L. , Koonin Eugene V. , Suzuki Marcelino T. , Hadd Andrew , Nguyen Linh P. , Jovanovich Stevan B. , Gates Christian M. , Feldman Robert A. , Spudich John L. , Spudich Elena N. , DeLong Edward F.
Published: July 2002

Extremely halophilic archaea contain retinal-binding integral membrane proteins called bacteriorhodopsins that function as light-driven proton pumps. So far, bacteriorhodopsins capable of generating a chemiosmotic membrane potential in response to light have been demonstrated only in halophilic archaea. We describe here a type of rhodopsin derived from bacteria that was discovered through genomic analyses of naturally occuring marine bacterioplankton. The bacterial rhodopsin was encoded in the genome of an uncultivated γ-proteobacterium and shared highest amino acid sequence similarity with archaeal rhodopsins. The protein was functionally expressed in
Escherichia coli
and bound retinal to form an active, light-driven proton pump. The new rhodopsin exhibited a photochemical reaction cycle with intermediates and kinetics characteristic of archaeal proton-pumping rhodopsins. Our results demonstrate that archaeal-like rhodopsins are broadly distributed among different taxa, including members of the domain
Bacteria
. Our data also indicate that a previously unsuspected mode of bacterially mediated light-driven energy generation may commonly occur in oceanic surface waters worldwide.
Dating of Pore Waters with
129
I: Relevance for the Origin of Marine Gas Hydrates
Authors: Fehn Udo , Snyder Glen , Egeberg Per K.
Published: July 2002

Pore waters associated with gas hydrates at Blake Ridge in the Atlantic Ocean were dated by measuring their iodine-129/iodine ratios. Samples collected from sediments with ages between 1.8 and 6 million years ago consistently yield ages around 55 million years ago. These ages, together with the strong iodine enrichment observed in the pore waters, suggest that the origin of iodine is related to organic material of early Tertiary age, which probably is also the source of the methane in the gas hydrates at this location.
Regulation of STAT3 by Direct Binding to the Rac1 GTPase
Authors: Simon Amy R. , Vikis Haris G. , Stewart Scott , Fanburg Barry L. , Cochran Brent H. , Guan Kun-Liang
Published: July 2002

The signal transducers and activators of transcription (STAT) transcription factors become phosphorylated on tyrosine and translocate to the nucleus after stimulation of cells with growth factors or cytokines. We show that the Rac1 guanosine triphosphatase can bind to and regulate STAT3 activity. Dominant negative Rac1 inhibited STAT3 activation by growth factors, whereas activated Rac1 stimulated STAT3 phosphorylation on both tyrosine and serine residues. Moreover, activated Rac1 formed a complex with STAT3 in mammalian cells. Yeast two-hybrid analysis indicated that STAT3 binds directly to active but not inactive Rac1 and that the interaction occurs via the effector domain. Rac1 may serve as an alternate mechanism for targeting STAT3 to tyrosine kinase signaling complexes.
Natural Selection and the Reinforcement of Mate Recognition
Authors: Higgie Megan , Chenoweth Steve , Blows Mark W.
Published: July 2002

Natural selection on mate recognition may often contribute to speciation, resulting in reproductive character displacement. Field populations of
Drosophila serrata
display reproductive character displacement in cuticular hydrocarbons when sympatric with
Drosophila birchii
. We exposed field sympatric and allopatric populations of
D. serrata
to experimental sympatry with
D. birchii
for nine generations. Cuticular hydrocarbons of field allopatric
D. serrata
populations evolved to resemble the field sympatric populations, whereas field sympatric
D. serrata
populations remained unchanged. Our experiment indicates that natural selection on mate recognition resulted in the field pattern of reproductive character displacement.
Response to RAG-Mediated V(D)J Cleavage by NBS1 and γ-H2AX
Authors: Chen Hua Tang , Bhandoola Avinash , Difilippantonio Michael J. , Zhu Jie , Brown Martin J. , Tai Xuguang , Rogakou Emmy P. , Brotz Tilmann M. , Bonner William M. , Ried Thomas , Nussenzweig André
Published: July 2002

Genetic disorders affecting cellular responses to DNA damage are characterized by high rates of translocations involving antigen receptor loci and increased susceptibility to lymphoid malignancies. We report that the Nijmegen breakage syndrome protein (NBS1) and histone γ-H2AX, which associate with irradiation-induced DNA double-strand breaks (DSBs), are also found at sites of V(D)J (variable, diversity, joining) recombination–induced DSBs. In developing thymocytes, NBS1 and γ-H2AX form nuclear foci that colocalize with the T cell receptor α locus in response to recombination activating gene (RAG) protein–mediated V(D)J cleavage. Our results suggest that surveillance of T cell receptor recombination intermediates by NBS1 and γ-H2AX may be important for preventing oncogenic translocations.
Entrainment of the Circadian Clock in the Liver by Feeding
Authors: Stokkan Karl-Arne , Yamazaki Shin , Tei Hajime , Sakaki Yoshiyuki , Menaker Michael
Published: July 2002

Circadian rhythms of behavior are driven by oscillators in the brain that are coupled to the environmental light cycle. Circadian rhythms of gene expression occur widely in peripheral organs. It is unclear how these multiple rhythms are coupled together to form a coherent system. To study such coupling, we investigated the effects of cycles of food availability (which exert powerful entraining effects on behavior) on the rhythms of gene expression in the liver, lung, and suprachiasmatic nucleus (SCN). We used a transgenic rat model whose tissues express luciferase in vitro. Although rhythmicity in the SCN remained phase-locked to the light-dark cycle, restricted feeding rapidly entrained the liver, shifting its rhythm by 10 hours within 2 days. Our results demonstrate that feeding cycles can entrain the liver independently of the SCN and the light cycle, and they suggest the need to reexamine the mammalian circadian hierarchy. They also raise the possibility that peripheral circadian oscillators like those in the liver may be coupled to the SCN primarily through rhythmic behavior, such as feeding.
Control of Synapse Number by Glia
Authors: Ullian Erik M. , Sapperstein Stephanie K. , Christopherson Karen S. , Barres Ben A.
Published: July 2002

Although astrocytes constitute nearly half of the cells in our brain, their function is a long-standing neurobiological mystery. Here we show by quantal analyses, FM1-43 imaging, immunostaining, and electron microscopy that few synapses form in the absence of glial cells and that the few synapses that do form are functionally immature. Astrocytes increase the number of mature, functional synapses on central nervous system (CNS) neurons by sevenfold and are required for synaptic maintenance in vitro. We also show that most synapses are generated concurrently with the development of glia in vivo. These data demonstrate a previously unknown function for glia in inducing and stabilizing CNS synapses, show that CNS synapse number can be profoundly regulated by nonneuronal signals, and raise the possibility that glia may actively participate in synaptic plasticity.
Breeding Together: Kin Selection and Mutualism in Cooperative Vertebrates
Authors: Clutton-Brock Tim
Published: July 2002

In cooperatively breeding vertebrates, nonbreeding helpers raise young produced by dominant breeders. Although the evolution of cooperative breeding has often been attributed primarily to kin selection (whereby individuals gain “indirect” benefits to their fitness by assisting collateral relatives), there is increasing evidence that helpers can be unrelated to the young they are raising. Recent studies also suggest that the indirect benefits of cooperative behavior may often have been overestimated while the direct benefits of helping to the helper's own fitness have probably been underestimated. It now seems likely that the evolutionary mechanisms maintaining cooperative breeding are diverse and that, in some species, the direct benefits of helping may be sufficient to maintain cooperative societies. The benefits of cooperation in vertebrate societies may consequently show parallels with those in human societies, where cooperation between unrelated individuals is frequent and social institutions are often maintained by generalized reciprocity.
Nucleotide Sequence of the Chromosomal
ampC
Gene of
Enterobacter aerogenes
Authors: Preston Karen E. , Radomski Christopher C. A. , Venezia Richard A.
Published: July 2002

The AmpC β-lactamase gene and a small portion of the regulatory
ampR
sequence of
Enterobacter aerogenes
97B were cloned and sequenced. The β-lactamase had an isoelectric point of 8 and conferred cephalosporin and cephamycin resistance on the host. The sequence of the cloned gene is most closely related to those of the
ampC
genes of
E. cloacae
and
C. freundii
.
A Standardized Plaque Reduction Assay for Determination of Drug Susceptibilities of Cytomegalovirus Clinical Isolates
Authors: Landry Marie L. , Stanat Sylvia , Biron Karen , Brambilla Donald , Britt William , Jokela Janet , Chou Sunwen , Drew W. Lawrence , Erice Alejo , Gilliam Bruce , Lurain Nell , Manischewitz Jody , Miner Richard , Nokta Mostafa , Reichelderfer Patricia , Spector Stephen , Weinberg Adriana , Yen-Lieberman Belinda , Crumpacker Clyde ,   the AIDS Clinical Trials Group CMV Resistance Working Group
Published: July 2002

Twelve laboratories collaborated in formulating and testing a standardized plaque reduction assay for cytomegalovirus (CMV) cell-associated clinical isolates. Four characterized and plaque-purified CMV strains, as well as six coded clinical isolates obtained after antiviral therapy, were distributed and tested. Good agreement was obtained for four of the clinical isolates, but a broad distribution of results was obtained for two isolates. Analysis of these results indicates the problems associated with clinical isolates, including the large genetic variability and the highly cell-associated phenotype. This collaborative effort, by addressing these problems, represents a significant step toward the development of a standardized assay.
Effects of Atovaquone and Diospyrin-Based Drugs on the Cellular ATP of
Pneumocystis carinii
f. sp.
carinii
Authors: Cushion Melanie T. , Collins Margaret , Hazra Banasri , Kaneshiro Edna S.
Published: July 2002

Atovaquone (also called Mepron, or 566C80) is a napthoquinone used for the treatment of infections caused by pathogens such as
Plasmodium
spp. and
Pneumocystis carinii
. The mechanism of action against the malarial parasite is the inhibition of dihydroorotate dehydrogenase (DHOD), a consequence of blocking electron transport by the drug. As an analog of ubiquinone (coenzyme Q [CoQ]), atovaquone irreversibly binds to the mitochondrial cytochrome
bc
1
complex; thus, electrons are not able to pass from dehydrogenase enzymes via CoQ to cytochrome
c
. Since DHOD is a critical enzyme in pyrimidine biosynthesis, and because the parasite cannot scavenge host pyrimidines, the drug is lethal to the organism. Oxygen consumption in
P. carinii
is inhibited by the drug; thus, electron transport has also been identified as the drug target in
P. carinii
. However, unlike
Plasmodium
DHOD,
P. carinii
DHOD is inhibited only at high atovaquone concentrations, suggesting that the organism may salvage host pyrimidines and that atovaquone exerts its primary effects on ATP biosynthesis. In the present study, the effect of atovaquone on ATP levels in
P. carinii
was measured directly from 1 to 6 h and then after 24, 48, and 72 h of exposure. The average 50% inhibitory concentration after 24 to 72 h of exposure was 1.5 μg/ml (4.2 μM). The kinetics of ATP depletion were in contrast to those of another family of naphthoquinone compounds, diospyrin and two of its derivatives. Whereas atovaquone reduced ATP levels within 1 h of exposure, the diospyrins required at least 48 h. After 72 h, the diospyrins were able to decrease ATP levels of
P. carinii
at nanomolar concentrations. These data indicate that although naphthoquinones inhibit the electron transport chain, the molecular targets in a given organism are likely to be distinct among members of this class of compounds.
SCH 56592, Amphotericin B, or Itraconazole Therapy of Experimental Murine Cerebral Phaeohyphomycosis Due to
Ramichloridium obovoideum
(“
Ramichloridium mackenziei
”)
Authors: Al-Abdely Hail M. , Najvar Laura , Bocanegra Rosie , Fothergill Annette , Loebenberg David , Rinaldi Michael G. , Graybill John R.
Published: July 2002

Ramichloridium obovoideum
(“
Ramichloridium makenziei
”) is a rare cause of lethal cerebral phaeohyphomycosis. It has been, so far, geographically restricted to the Middle East. BALB/c mice were inoculated with two strains of
R. obovoideum
intracranially. Therapy with amphotericin B, itraconazole, or the investigational triazole SCH 56592 was conducted for 10 days. Half the mice were monitored for survival and half were killed for determination of the fungal load in brain tissue. Recipients of SCH 56592 had significantly prolonged survival and lower brain fungal burden, and this result was found for mice infected with both of the fungal strains tested. Itraconazole reduced the brain fungal load in mice infected with one strain but not the other, while amphotericin B had no effect on brain fungal concentrations. This study indicates a possible role of SCH 56592 in the treatment of the serious cerebral phaeohyphomycosis due to
R. obovoideum.
A Simple Screen for Murein Transglycosylase Inhibitors
Authors: Vollmer Waldemar , Höltje Joachim-Volker
Published: July 2002

A simple assay for detection of compounds that bind to the active site in the transglycosylation domain of the essential bifunctional transglycosylase and transpeptidase penicillin-binding proteins (PBPs) is reported. The method is based on a competition with the specific transglycosylase inhibitor moenomycin. With moenomycin coupled to Affi-Gel beads, a simple filtration procedure allows the amount of labeled PBPs that bind to moenomycin beads in the presence of test substances to be determined. The PBPs can easily be labeled by the covalent binding of penicillin derivatives. Crude membrane extracts can be used as a source for the PBPs, and different kinds of labels for the penicillin-PBP complexes can be used. The assay can be adapted to high-throughput screens.
Comparison of High-Performance Liquid Chromatographic and Microbiological Methods for Determination of Voriconazole Levels in Plasma
Authors: Perea Sofia , Pennick Gennethel J. , Modak Asha , Fothergill Annette W. , Sutton Deanna A. , Sheehan Daniel J. , Rinaldi Michael G.
Published: July 2002

A new selective high-performance liquid chromatography (HPLC) method with UV detection for the determination of the investigational triazole voriconazole in human plasma by using acetonitrile precipitation followed by reverse-phase HPLC on a C18column was compared with a simple agar well diffusion bioassay method withCandida kefyrATCC 46764 as the assay organism. Pooled plasma was used to prepare standard and control samples for both methods. The results of analyses with spiked serum samples (run as unknowns) were concordant by the bioassay and HPLC methods, with expected values being obtained. HPLC demonstrated an improved precision (3.47 versus 12.12%) and accuracy (0.81 versus 1.28%) compared to those of the bioassay method. The range of linearity obtained by both methods (from 0.2 to 10 μg/ml for HPLC and from 0.25 to 20 μg/ml for the bioassay) includes the range of concentrations of voriconazole (from 1.2 to 4.7 μg/ml) which are considered clinically relevant. Although either methodology could be used for the monitoring of patient therapy, the smaller variability observed with HPLC compared to that observed with the bioassay favors the use of HPLC for pharmacokinetic studies.
A Population Pharmacokinetic Analysis of the Penetration of the Prostate by Levofloxacin
Authors: Drusano G. L. , Preston S. L. , Van Guilder M. , North D. , Gombert M. , Oefelein M. , Boccumini L. , Weisinger B. , Corrado M. , Kahn J.
Published: July 2002

Prostatitis has remained a pathological entity that is difficult to treat. Part of the difficulty revolves about the putative offending pathogens. For acute prostatitis, members of the
Enterobacteriaceae
, particularly
Escherichia coli
, play a central role, while intracellular pathogens such as
Chlamydia
are more frequently seen in chronic prostatitis. Consequently, a drug needs to be able to penetrate to this specialized site in both the acute and chronic infection forms of the disease and also have potent activity against the most common causative pathogens, both intracellular and extracellular. Levofloxacin has such an activity profile. We wished to document its ability to penetrate to the site of infection. Patients undergoing prostatectomies were administered 500 mg of levofloxacin orally every 24 h for 2 days prior to surgery, and then on the day of surgery, 500 mg was administered as an hour-long, constant-rate intravenous (i.v.) infusion. A set of blood samples was obtained as guided by stochastic optimal design theory. Prostate biopsy times were determined by randomizing subjects into one of four groups, based on the interval after the i.v. dose. All plasma and prostate drug concentrations were comodeled by a population modeling program, BigNPEM, implemented on the Cray T3E Supercomputer housed at the Supercomputer Center at the University of California at San Diego. Penetration was determined as the ratio of the area under the concentration-time curve (AUC) of levofloxacin in the prostate to the plasma levofloxacin AUC. When calculated from the mean population parameters, this penetration ratio was 2.96. We also performed a 1,000-subject Monte Carlo simulation from the mean parameter vector and covariance matrix. The mean penetration ratio here was 4.14 with a 95% confidence interval of 0.20 to 19.6. Over 70% of the population had a penetration ratio in excess of 1.0. Levofloxacin adequately penetrates a noninflamed prostate and should be evaluated for the therapy of prostatitis.
Effects of Fluconazole and Clarithromycin on Rifabutin and 25-
O
-Desacetylrifabutin Pharmacokinetics
Authors: Jordan M. Kelli , Polis Michael A. , Kelly Grace , Narang Prem K. , Masur Henry , Piscitelli Stephen C.
Published: July 2002

Ten human immunodeficiency virus-infected patients were given rifabutin in addition to fluconazole and clarithromycin. There was a 76% increase in the area under the concentration-time curve of rifabutin when either fluconazole or clarithromycin was given alone and a 152% increase when both drugs were given together with rifabutin. Patients should be monitored for adverse effects of rifabutin administered concomitantly with clarithromycin and/or fluconazole.
Functional Analysis of the Active Site of a Metallo-β-Lactamase Proliferating in Japan
Authors: Haruta Shin , Yamaguchi Hitomi , Yamamoto Elise Tie , Eriguchi Yoshiro , Nukaga Michiyoshi , O'Hara Koji , Sawai Tetsuo
Published: July 2002

An R-plasmid-mediated metallo-β-lactamase was found in
Klebsiella pneumoniae
DK4 isolated in Japan in 1991. The nucleotide sequence of its structural gene revealed that the β-lactamase termed DK4 was identical to the IMP-1 metallo-β-lactamase which was mediated by a chromosomal gene of
Serratia marcescens
TN9106 isolated in Japan in 1991 (E. Osano et al., Antimicrob. Agents Chemother. 38:71–78, 1994). The dose effect of DK4 β-lactamase production on the resistance levels indicated a significant contribution of the enzyme to bacterial resistance to all the β-lactams except monobactams. The enzymatic characteristics of the DK4 β-lactamase and its kinetic parameters for nine β-lactams were examined. The DK4 β-lactamase was confirmed to contain 2 mol of zinc per mol of enzyme protein. The apoenzyme that lacked the two zincs was structurally unstable, and the activities of only 30% of the apoenzyme molecules could be restored by the addition of 1 mM zinc sulfate. The substitution of five conserved histidines (His28, His86, His88, His149, His210) and a cysteine (Cys168) for an alanine indicated that His86, His88, and His149 served as ligands to one of the zincs and that Cys168 played a role as a ligand to the second zinc. Both zinc molecules contribute to the enzymatic process. Mutant enzymes that lack only one of these retained some activity. Additionally, a conserved aspartic acid at position 90 was replaced by asparagine. This mutant enzyme showed an approximately 1,000 times lower
k
cat
value for cephalothin than that of the wild-type enzyme but retained the two zincs even after dialysis against zinc-free buffer. The observed effect of pH on the activity suggested that Asp90 functions as a general base in the enzymatic process.
In Vitro Resistance Profile of the Human Immunodeficiency Virus Type 1 Protease Inhibitor BMS-232632
Authors: Gong Yi-Fei , Robinson Brett S. , Rose Ronald E. , Deminie Carol , Spicer Timothy P. , Stock David , Colonno Richard J. , Lin Pin-fang
Published: July 2002

BMS-232632 is an azapeptide human immunodeficiency virus (HIV) type 1 (HIV-1) protease inhibitor that displays potent anti-HIV-1 activity (50% effective concentration [EC
50
], 2.6 to 5.3 nM; EC
90
, 9 to 15 nM). In vitro passage of HIV-1 RF in the presence of inhibitors showed that BMS-232632 selected for resistant variants more slowly than nelfinavir or ritonavir did. Genotypic and phenotypic analysis of three different HIV strains resistant to BMS-232632 indicated that an N88S substitution in the viral protease appeared first during the selection process in two of the three strains. An I84V change appeared to be an important substitution in the third strain used. Mutations were also observed at the protease cleavage sites following drug selection. The evolution to resistance seemed distinct for each of the three strains used, suggesting multiple pathways to resistance and the importance of the viral genetic background. A cross-resistance study involving five other protease inhibitors indicated that BMS-232632-resistant virus remained sensitive to saquinavir, while it showed various levels (0.1- to 71-fold decrease in sensitivity)-of cross-resistance to nelfinavir, indinavir, ritonavir, and amprenavir. In reciprocal experiments, the BMS-232632 susceptibility of HIV-1 variants selected in the presence of each of the other HIV-1 protease inhibitors showed that the nelfinavir-, saquinavir-, and amprenavir-resistant strains of HIV-1 remained sensitive to BMS-232632, while indinavir- and ritonavir-resistant viruses displayed six- to ninefold changes in BMS-232632 sensitivity. Taken together, our data suggest that BMS-232632 may be a valuable protease inhibitor for use in combination therapy.
Effect of Dosing Schedule on Pharmacokinetics of Alpha Interferon and Anti-Alpha Interferon Neutralizing Antibody in Mice
Authors: Wang De-sheng , Ohdo Shigehiro , Koyanagi Satoru , Takane Hiroshi , Aramaki Hironori , Yukawa Eiji , Higuchi Shun
Published: July 2002

The influences of dosing time and dosing schedule on the plasma alpha interferon (IFN-α) concentration and the production of anti-IFN-α neutralizing antibodies were investigated in ICR male mice adapted to cycles of 12 h of light and 12 h of dark. In mice pretreated with IFN-α for 21 days, the plasma IFN-α concentrations were significantly lower than those in control mice (P< 0.01). The clearance of IFN-α and its volume of distribution obtained at steady state were significantly higher in the animals with IFN-α pretreatment than in the mice without IFN-α pretreatment. The area under the concentration-time curve and the mean residence time of IFN-α were significantly smaller in IFN-α-pretreated animals than in control animals. The plasma IFN-α levels (measured 2 h after dosing) were significantly lower in mice treated daily with IFN-α, while the anti-IFN-α neutralizing antibody levels (measured 24 h after dosing) were significantly increased on days 15 and 21 of treatment. Plasma IFN-α levels were significantly decreased in association with the production of anti-IFN-α neutralizing antibodies in mice treated with IFN-α daily at either 0900 or 2100 h. By contrast, the plasma IFN-α levels (measured 2 h after dosing) remained stable in mice treated with IFN-α at 0900 h on alternate days, while they were significantly lower after 21 days of treatment in mice treated with IFN-α at 2100 h on alternate days. These changes were associated with a significant increase in the levels of anti-IFN-α neutralizing antibodies in the latter group. The present findings suggest that an appropriate dosing schedule and/or dosing time for IFN-α may reduce the level of production of anti-IFN-α neutralizing antibodies in experimental and clinical situations.
Genomic Rearrangement of the
mec
Regulator Region Mediated by Insertion of IS
431
in Methicillin-Resistant Staphylococci
Authors: Kobayashi Nobumichi , Alam Mohammed Mahbub , Urasawa Shozo
Published: July 2002

Genomic diversification of the
mec
regulator region mediated by IS
431
was investigated for clinical isolates of methicillin-resistant staphylococci. A single rearranged form of the
mecR1
gene due to IS
431
insertion was detected in the three staphylococcal species, while another type of
mecR1
truncation with IS
431
and an IS
431
located downstream of
mecI
were found only in
Staphylococcus haemolyticus
. Genetic differentiation of IS
431
and staphylococcal isolates suggested transmission of
mec
DNA with IS
431
-mediated rearrangement among different staphylococcal species.
Prevalence and Mechanisms of Macrolide Resistance in
Streptococcus pyogenes
in Santiago, Chile
Authors: Palavecino E. L. , Riedel I. , Berrios X. , Bajaksouzian S. , Johnson D. , Kaplan E. , Jacobs M. R.
Published: July 2002

Thirty-two macrolide-resistant
Streptococcus pyogenes
isolates were found among 594 clinical isolates collected from 1990 to 1998 in Santiago, Chile, for an overall prevalence of 7.2%. Among the 32 resistant isolates, 28 (87.5%) presented the M phenotype and 4 (12.5%) presented the MLS
B
phenotype. Serotyping and pulsed-field gel electrophoresis analysis showed genetic diversity among the resistant isolates.
Effects of AIDS and Gender on Steady-State Plasma and Intrapulmonary Ethambutol Concentrations
Authors: Conte John E. , Golden Jeffrey A. , Kipps Juliana , Lin Emil T. , Zurlinden Elisabeth
Published: July 2002

Our objective was to study the steady-state plasma and intrapulmonary orally administered ethambutol concentrations in healthy volunteers and subjects with AIDS. Ethambutol (15 mg/kg of body weight) was administered orally once daily to 10 men with AIDS, 10 healthy men, 10 women with AIDS, and 10 healthy women. The mean (±standard deviation [SD]) CD4 cell count for the 20 subjects with AIDS was (350 ± 169) × 106cells per liter. Blood was obtained for drug assay 2 h after the last dose and at the completion of bronchoalveolar lavage, performed 4 h after the last dose. Standardized bronchoscopy was performed without systemic sedation. The volume of epithelial lining fluid (ELF) was calculated by the urea dilution method. The total number of alveolar cells (AC) was counted in a hemocytometer, and differential cell counting was performed after cytocentrifugation. Ethambutol was measured by a new, sensitive and specific liquid chromotography-mass spectrometry method. The presence of AIDS, as defined in this study, or gender was without significant effect on the concentrations of ethambutol in plasma at 2 or 4 h or in ELF at 4 h following the last dose. Plasma drug concentrations (mean ± SD) at 2 and 4 h were 2.1 ± 1.2 and 2.1 ± 0.8 μg/ml, respectively, and both values were not significantly different from the concentration of ethambutol in ELF at 4 h (2.2 ± 1.1 μg/ml). The concentration of ethambutol was significantly greater in AC in all four groups (range, 44.5 ± 15.6 to 82.0 ± 39.4 μg/ml) than in ELF or plasma and was approximately 30 to 240 times the reported MIC for ethambutol-susceptible strains ofMycobacterium tuberculosis. The AC ethambutol concentration (mean ± SD) in the smoking women (97.2 ± 32.1 μg/ml) was more than twice the concentration in all other nonsmoking subjects (45.2 ± 16.8 μg/ml) combined (P< 0.05). Two- and 4-h concentrations of ethambutol in plasma were not affected by AIDS status or gender. The high AC/plasma and AC/ELF concentration ratios suggest that substantial antimycobacterial activity resides in these cells. The data confirm earlier observations of active transport ex vivo of ethambutol into pulmonary macrophages.
Marked Potentiation of Activity of β-Lactams against Methicillin-Resistant
Staphylococcus aureus
by Corilagin
Authors: Shimizu Masato , Shiota Sumiko , Mizushima Tohru , Ito Hideyuki , Hatano Tsutomu , Yoshida Takashi , Tsuchiya Tomofusa
Published: July 2002

We found that an extract of
Arctostaphylos uva-ursi
markedly reduced the MICs of β-lactam antibiotics, such as oxacillin and cefmetazole, against methicillin-resistant
Staphylococcus aureus
. We isolated the effective compound and identified it as corilagin. Corilagin reduced the MICs of various β-lactams by 100- to 2,000-fold but not the MICs of other antimicrobial agents tested. The effect of corilagin and oxacillin was synergistic. Corilagin showed a bactericidal action when added to the growth medium in combination with oxacillin.
Inhibitory Effects of Small-Molecule CCR5 Antagonists on Human Immunodeficiency Virus Type 1 Envelope-Mediated Membrane Fusion and Viral Replication
Authors: Takashima Katsunori , Miyake Hiroshi , Furuta Rika A. , Fujisawa Jun-Ichi , Iizawa Yuji , Kanzaki Naoyuki , Shiraishi Mitsuru , Okonogi Kenji , Baba Masanori
Published: July 2002

We established a human immunodeficiency virus type 1 (HIV-1) envelope (Env)-mediated membrane fusion assay and examined the small-molecule CCR5 antagonist TAK-779 and its derivatives for their inhibitory effects on HIV-1 Env-mediated membrane fusion and viral replication. The membrane fusion assay is based on HIV-1 long terminal repeat-directed β-
d
-galactosidase reporter gene expression in CD4- and CCR5-expressed HeLa (MAGI-CCR5) cells after cocultivation with effector 293T cells expressing HIV-1 Env. Inhibition of HIV-1 replication was also determined in MAGI-CCR5 cells infected with the corresponding cell-free HIV-1. TAK-779 effectively suppressed R5 HIV-1 (strain JR-FL) Env-mediated membrane fusion as well as viral replication. Its 50% inhibitory concentrations (IC
50
s) for membrane fusion and viral replication were 0.87 ± 0.11 and 1.4 ± 0.1 nM, respectively. These values corresponded well to the IC
50
for
125
I-RANTES (regulated on activation, T cell expressed, and secreted) binding to CCR5 (1.4 nM). The inhibitory effects of 18 TAK-779 derivatives on membrane fusion differed from one compound to another. However, there was a close correlation among their inhibitory effects on membrane fusion, viral replication, and RANTES binding. The correlation coefficient between their IC
50
s for membrane fusion and viral replication was 0.881. Furthermore, since this assay depends on Env expressed in the effector cells, it is also applicable to the evaluation of CXCR4 antagonists. These results indicate that the HIV-1 Env-mediated membrane fusion assay is a useful tool for the evaluation of entry inhibitors.
GeneyerP, Involved in Surfactin Self-Resistance inBacillus subtilis
Authors: Tsuge Kenji , Ohata Yuichiro , Shoda Makoto
Published: July 2002

Surfactin is a cyclic lipopeptide biosurfactant. Transposon mutagenesis was performed inBacillus subtilisstrain 168, and a surfactin-susceptible mutant, strain 801, was isolated. Analysis of the region of insertion revealed thatyerPwas the determinant of surfactin self-resistance. YerP had homology with the resistance, nodulation, and cell division (RND) family proton motive force-dependent efflux pumps only characterized in gram-negative strains. TheyerP-deficient strain 802, in which the internal region of theyerPgene ofB.subtilisstrain 168 was deleted, showed susceptibility to acriflavine and ethidium bromide. When strain 802 was converted to a surfactin producer by introducing a functionalsfpwhich encodes a 4′-phosphopantetheinyl transferase and is mutated inB.subtilisstrain 168, thisyerP-deficient strain produced surfactin, although surfactin production was significantly reduced. The expression ofyerPwas at its maximum at the end of the logarithmic growth phase and was not induced by surfactin.yerPis the first RND-like gene characterized in gram-positive strains and is supposed to be involved in the efflux of surfactin.
Characterization of a Chromosomally Encoded Extended-Spectrum Class A β-Lactamase from
Kluyvera cryocrescens
Authors: Decousser Jean W. , Poirel Laurent , Nordmann Patrice
Published: July 2002

A chromosomally located β-lactamase gene, cloned and expressed in
Escherichia coli
from a reference strain of the enterobacterial species
Kluyvera cryocrescens
, encoded a clavulanic acid-inhibited Ambler class A enzyme, KLUC-1, with a pI value of 7.4. KLUC-1 shared 86% amino acid identity with a subgroup of plasmid-mediated CTX-M-type extended-spectrum β-lactamases (CTX-M-1, -3, -10, -11, and -12), the most closely related enzymes, and 77% amino acid identity with KLUA-1 from
Kluyvera ascorbata.
The substrate profile of KLUC-1 corresponded to that of CTX-M-type enzymes.
In Vitro Activities of Fluoroquinolones against the SpirocheteBorrelia burgdorferi
Authors: Kraiczy Peter , Weigand Judith , Wichelhaus Thomas A. , Heisig Peter , Backes Herbert , Schäfer Volker , Acker Georg , Brade Volker , Hunfeld Klaus-Peter
Published: July 2002

Little is known to date about the in vitro activity of fluoroquinolones againstBorreliaspecies. Our study aimed at determining the in vitro activities of 15 quinolones against nine isolates of theBorrelia burgdorferisensu lato complex in addition to oneBorrelia valaisianaand oneBorrelia bissettiitick isolate. For the determination of MICs, a standardized colorimetric microdilution method was applied. Determination of minimal borreliacidal concentrations providing 100% killing of the final inoculum (MBCs) after 72 h and time-kill experiments were performed by conventional culture in Barbour-Stoenner-Kelly medium in combination with dark-field microscopy. The rank order of potency on a microgram-per-milliliter basis for the substances with in vitro activity againstB. burgdorferiwas gemifloxacin (MIC at which 90% of the isolates tested are inhibited [MIC90], 0.12 μg/ml) > sitafloxacin (MIC90, 0.5 μg/ml), grepafloxacin (MIC90, 0.5 μg/ml) > gatifloxacin (MIC90, 1 μg/ml), sparfloxacin (MIC90, 1 μg/ml), trovafloxacin (MIC90, 1 μg/ml) > moxifloxacin (MIC90, 2 μg/ml), ciprofloxacin (MIC90, 2 μg/ml) > levofloxacin (MIC90, 4 μg/ml) > ofloxacin (MIC90, 8 μg/ml), norfloxacin (MIC90, 8 μg/ml) > fleroxacin (MIC90, >16 μg/ml), and pefloxacin (MIC90, 32 μg/ml) > nalidixic acid (MIC90, 256 μg/ml). After 72 h of exposure, gemifloxacin was borreliacidal (100% killing) against the isolates investigated at a median MBC of 4 μg/ml. In the other compounds tested, median MBCs were higher (≥8 μg/ml). Results of electron microscopy and time-kill studies clearly support an in vitro activity of some fluoroquinolones against borreliae. Our study demonstrates for the first time the enhanced in vitro effectiveness of some of the recently introduced 4-quinolones againstB. burgdorferi.
Postneurosurgical Meningitis Due to
Proteus penneri
with Selection of a Ceftriaxone-Resistant Isolate: Analysis of Chromosomal Class A β-Lactamase HugA and its LysR-Type Regulatory Protein HugR
Authors: Liassine Nadia , Madec Stéphanie , Ninet Béatrice , Metral Catherine , Fouchereau-Peron Martine , Labia Roger , Auckenthaler Raymond
Published: July 2002

We report on a case of a postneurosurgical meningitis due to ceftriaxone-susceptible
Proteus penneri
, with selection of a ceftriaxone-resistant isolate following treatment with ceftriaxone. The isolates presented identical patterns by pulsed-field gel electrophoresis and produced a single β-lactamase named HugA with an isoelectric point of 6.7. The ceftriaxone-resistant isolate hyperproduced the β-lactamase (increase in the level of production, about 90-fold). The sequences of the
hugA
β-lactamase gene and its regulator,
hugR
, were identical in both
P. penneri
strains and had 85.96% homology with those of
Proteus vulgaris
. The HugA β-lactamase belongs to molecular class A, and the transcriptional regulator HugR belongs to the LysR family.
Genetic Determinants of Tetracycline Resistance in
Vibrio harveyi
Authors: Teo Jeanette W. P. , Tan Theresa M. C. , Poh Chit Laa
Published: July 2002

Isolates of
Vibrio harveyi
, a prawn pathogen, have demonstrated multiple antibiotic resistance to commonly used antimicrobial agents, such as oxytetracycline. In this paper, we describe the cloning and characterization of two tetracycline resistance determinants from
V. harveyi
strain M3.4L. The first resistance determinant, cloned as a 4,590-bp fragment, was identical to
tetA
and flanking sequences encoded on transposon Tn
10
from
Shigella flexneri.
The second determinant, cloned as a 3,358-bp fragment in pATJ1, contains two open reading frames, designated
tet35
and
txr
.
tet35
encodes a 369-amino-acid protein that was predicted to have nine transmembrane regions. It is a novel protein which has no homology to any other drug resistance protein but has low levels of homology (28%) to Na
+
/H
+
antiporters. Transposon mutagenesis showed that
tet35
and
txr
were required for tetracycline resistance in a heterologous
Escherichia coli
host. Tetracycline accumulation studies indicate that
E. coli
carrying
tet35
and
txr
can function as an energy-dependent tetracycline efflux pump but is less efficient than TetA.