bluuebunny/crossref_metadata_2025_split huggingface dataset:
Robust incremental compensation of the light attenuation with depth in 3D fluorescence microscopy
Authors: KERVRANN C. , LEGLAND D. , PARDINI L. 
Published: May 2004

SummaryFluorescent signal intensities from confocal laser scanning microscopes (CLSM) suffer from several distortions inherent to the method. Namely, layers which lie deeper within the specimen are relatively dark due to absorption and scattering of both excitation and fluorescent light, photobleaching and/or other factors. Because of these effects, a quantitative analysis of images is not always possible without correction. Under certain assumptions, the decay of intensities can be estimated and used for a partial depth intensity correction. In this paper we propose an original robust incremental method for compensating the attenuation of intensity signals. Most previous correction methods are more or less empirical and based on fitting a decreasing parametric function to the section mean intensity curve computed by summing all pixel values in each section. The fitted curve is then used for the calculation of correction factors for each section and a new compensated sections series is computed. However, these methods do not perfectly correct the images. Hence, the algorithm we propose for the automatic correction of intensities relies on robust estimation, which automatically ignores pixels where measurements deviate from the decay model. It is based on techniques adopted from the computer vision literature for image motion estimation. The resulting algorithm is used to correct volumes acquired in CLSM. An implementation of such a restoration filter is discussed and examples of successful restorations are given.
Using microscopic techniques to reveal the mechanism of anion exchange in crystalline co‐ordination polymers
Authors: THOMPSON C. , CHAMPNESS N. R. , KHLOBYSTOV A. N. , ROBERTS C. J. , SCHRÖDER M. , TENDLER S. J. B. , WILKINSON M. J. 
Published: May 2004

SummaryCo‐ordination polymers are currently attracting extensive interest due to their potential applications as supramolecular hosts, vessels, and frameworks for storage and separations. Many applications rely on the ion exchange capabilities of these compounds, and considerable debate surrounds the mechanism by which ion exchange occurs in co‐ordination polymers. Here AFM and SEM were applied, for the first time, to investigate this class of materials. In situ AFM studies revealed the mechanism by which anion exchange and the subsequent structural transformations of the crystalline co‐ordination polymers {[Ag(4,4′‐bipy)]BF4}∞ and {[Ag(4,4′‐bipy)]NO3}∞ occur. The process is initiated by the dissolution of the metastable crystalline polymer, followed by the subsequent crystallization of the new stable phase on the surface of the original crystal. The formation of deep clefts in the metastable polymer crystal during the transformation allows the solution to access the successive crystalline layers. Thus, the entire process can be viewed as a self‐perpetuating cascade of dissolution and recrystallization throughout the macroscopic crystal. SEM data consolidate the findings of AFM. These techniques collectively illustrate that the anion exchange, and subsequent structural transformation, proceeds via a solvent‐mediated mechanism, rather than a purely solid‐state one.
Trends in Labor Induction in the United States: Is It True That What Goes Up Must Come Down?
Authors: Kirby Russell S. 
Published: May 2004

Commentary on: Zhang J, Yancey MK, Henderson CE. U.S. national trends in labor induction, 1989–1998. J Reprod Med 2002;47:120–124.

MacDorman MF, Mathews TJ, Martin JA, Malloy MH. Trends and characteristics of induced labour in the United States, 1989–98. Paediatr Perinat Epidemiol 2002;16:263–273.

Kozak LJ, Weeks JD. U.S. trends in obstetric procedures, 1990–2000. Birth 2002;29:157–161.Abstract:  Three recent studies examined the national trend in labor induction in the United States. All show a doubling in the rate of induction during the 1990s, although vital statistics data show a consistently higher trend than that obtained from national hospital discharge data. Neither data source adequately documents the full range of indications for induction, its timing, hospital staffing considerations, and other factors that may play a role. Although rates of induction of labor may be leveling off, despite a lack of scientific evidence for its widespread use, rates are likely to remain at current levels for the next few years.
Carbonic anhydrase and C4 photosynthesis: a transgenic analysis
Authors: VON CAEMMERER S. , QUINN V. , HANCOCK N. C. , PRICE G. D. , FURBANK R. T. , LUDWIG M. 
Published: May 2004

ABSTRACTCarbonic anhydrase (CA, EC 4.2.1.1) catalyses the first reaction in the C4 photosynthetic pathway, the conversion of atmospheric CO2 to bicarbonate in the mesophyll cytosol. To examine the importance of the enzyme to the functioning of the C4 photosynthetic pathway, Flaveria bidentis (L.) Kuntze, a C4 dicot, was genetically transformed with an antisense construct in which the cDNA encoding a putative cytosolic CA (CA3) was placed under the control of a constitutive promoter. Some of the primary transformants had impaired CO2 assimilation rates and required high CO2 for growth. The T1 progeny of four primary transformants were used to examine the quantitative relationship between leaf CA activity and CO2 assimilation rate. CA activity was determined in leaf extracts with a mass spectrometric technique that measured the rate of 18O exchange from doubly labelled 13C18O2. Steady‐state CO2 assimilation rates were unaffected by a decrease in CA activity until CA activity was less than 20% of wild type when they decreased steeply. Transformants with less than 10% of wild‐type CA activity had very low CO2 assimilation rates and grew poorly at ambient CO2 partial pressure. Reduction in CA activity also increased the CO2 partial pressure required to saturate CO2 assimilation rates. The present data show that CA activity is essential for the functioning of the C4 photosynthetic pathway.
Vegetation‐induced sedimentary structures from fossil forests in the Pennsylvanian Joggins Formation, Nova Scotia
Authors: Rygel Michael C. , Gibling Martin R. , Calder John H. 
Published: May 2004

AbstractVegetation‐induced sedimentary structures (VISS) are primary structures formed by the interaction of detrital sediment within situplants. VISS provide physical evidence of vegetation's fundamental role in mediating sediment accumulation and erosion in clastic depositional systems. Despite the abundance of modern VISS, descriptions from the ancient record are surprisingly rare. Analysis of fossil forests in floodplain strata of the Pennsylvanian Joggins Formation has identified seven types of VISS. Five hydrodynamic types comprise simple forms developed around a single plant (centroclinal cross‐strata, scratch circles, upturned beds) and complex forms where structures have amalgamated between several plants (coalesced scour fills, scour‐and‐mound beds). Two types (mudstone‐filled hollows, downturned beds) form by the decay of an entombed plant and represent infilling of an empty hollow and/or soft‐sediment deformation. Hydrodynamic types are present in both dryland and wetland settings, whereas decay‐related types occur only in dryland settings where the water table was perennially or periodically low. VISS represent significant accumulations of sediment and are present in a high proportion of Joggins Formation strata. The paucity of descriptions from the ancient record suggests that these structures have been overlooked or misinterpreted as strictly hydrodynamic. Recognition of VISS in early to middle Palaeozoic strata may provide an important insight into the distribution of early land plants in oxidizing environments where organic material was not preserved.
Changes in clay mineral content of tidal flat sediments resulting from dike construction along the Lower Saxony coast of the North Sea, Germany
Authors: Brockamp Olaf , Zuther Michael 
Published: May 2004

AbstractThe clay mineral content of the < 2 µm fraction in tidal flat sediments in the former Harle Bay on the Lower Saxony coast has changed considerably since the thirteenth century up to the present time. The proportion of smectite has decreased from 29 to 11 wt%, whereas the proportion of illite has increased by about 10 wt% and those of chlorite and kaolinite by about 3 wt% each. The chemical composition of the major clay mineral illite has also changed: Al2O3 has decreased by about 2 wt%, K2O by about 1·5 wt% and SiO2 by about 3 wt%. It can be concluded that the changes in the clay mineral content are mainly influenced by dike construction and sea level rise, modifying flow pattern, submarine morphology, sedimentation and tidal range. These processes cause smectite to settle less rapidly because of its small grain size and low density resulting from interlayer water, so that the sediment becomes impoverished in this mineral.
Tectonic controls on drainage evolution and development of terminal alluvial fans, southern Pyrenees, Spain
Authors: Jones Stuart J. 
Published: May 2004

AbstractAn understanding of how drainage patterns respond to tectonics can provide an insight into past deformational events within mountain belts and where sediment flux is supplied to depositional basins. The transverse rivers draining the Spanish Pyrenees show sudden diversions to axial courses and the capture of lateral systems producing large trunk rivers that break through the thrust front at structurally controlled points. The drainage reorganization from the initial regularly spaced pattern in the Late Eocene caused by the growth of thrust‐controlled topography influenced the location of outlets into the Ebro basin. The headward capture and merger of rivers as a result of structural diversion formed two large terminal fan systems during the Oligo‐Miocene along the Pyrenean thrust front. The early structural topographic controls on drainage evolution will have long‐term effects on sedimentation and stratigraphic architecture of foreland basins. This will only be maintained as long as there is tectonic uplift and the river systems strive to re‐attain a regular drainage spacing across the orogenic belt as partly achieved in the Pyrenees.
Intergranular diamonds derived from partial melting of crustal rocks at ultrahigh‐pressure metamorphic conditions
Authors: Korsakov Andrey V. , Theunissen Karel , Smirnova Larissa V. 
Published: May 2004

AbstractBy reporting for the first time intergranular diamond in quartz–feldspar (Qtz–Kfs) aggregates, the processes of metamorphic diamond formation have to be reconsidered. Based on their Kfs/Qtz ratio, the texture of these aggregates are proposed to result from ‘granitic’ melt with a calculated composition that corresponds well with that of experimental data for the pelitic system. Taking into account experiments on CO2 solubility in silicate melt under ultrahigh‐pressure conditions, a granitic melt is further suggested to act as a crystallization medium as well as a transport medium for producing metamorphic diamond.
tcaA
Inactivation Increases Glycopeptide Resistance in
Staphylococcus aureus
Authors: Maki Hideki , McCallum Nadine , Bischoff Markus , Wada Akihito , Berger-Bächi Brigitte 
Published: May 2004

ABSTRACT

The experimental deletion of the
tcaRAB
region has been shown to increase teicoplanin resistance in
Staphylococcus aureus
. By sequential genetic complementation of a
tcaRAB
mutant, we identified
tcaA
as the key gene within
tcaRAB
that is responsible for changes in glycopeptide resistance levels. Northern blot analysis of the
tcaRAB
region showed that the
tcaA
gene is expressed only weakly over the growth cycle and is strongly inducible by teicoplanin. Among some clinical isolates tested, glycopeptide-intermediate-resistant (GISA) strains Michigan and SA137/93G were found to have truncated
tcaA
genes. While the former carries a nucleotide insertion that creates a premature stop codon, the latter was found to harbor an IS
256
insertion. Complementation of these two GISA strains with a functional
tcaA
allele reduced their levels of teicoplanin and vancomycin resistance five- to eightfold and twofold, respectively. The data presented here indicate that inactivation of
tcaA
contributes to and plays a relevant role in glycopeptide resistance in
S. aureus
clinical isolates.
Antimicrobial Activities of Garenoxacin (BMS 284756) against Asia-Pacific Region Clinical Isolates from the SENTRY Program, 1999 to 2001
Authors: Christiansen K. J. , Bell J. M. , Turnidge J. D. , Jones R. N. 
Published: May 2004

ABSTRACT

Between 1999 and 2001, 16,731 isolates from the Asia-Pacific Region were tested in the SENTRY Program for susceptibility to six fluoroquinolones including garenoxacin. Garenoxacin was four- to eightfold less active against
Enterobacteriaceae
than ciprofloxacin, although both drugs inhibited similar percentages at 1 μg/ml. Garenoxacin was more active against gram-positive species than all other fluoroquinolones except gemifloxacin. For
Staphylococcus aureus
, oxacillin resistance was high in many participating countries (Japan, 67%; Taiwan, 60%; Hong Kong, 55%; Singapore, 52%), with corresponding high levels of ciprofloxacin resistance (57 to 99%) in oxacillin-resistant
S. aureus
(ORSA). Of the ciprofloxacin-resistant ORSA isolates, the garenoxacin MIC was >4 μg/ml for only 9% of them. For
Streptococcus pneumoniae
, penicillin nonsusceptibility and macrolide resistance were high in many countries. No relationship was seen between penicillin and garenoxacin susceptibility, with all isolates being susceptible at <2 μg/ml. There was, however, a partial correlation between ciprofloxacin and garenoxacin MICs. For ciprofloxacin-resistant isolates for which garenoxacin MICs were 0.25 to 1 μg/liter, mutations in both the ParC and GyrA regions of the quinolone resistance-determining region could be demonstrated. No mutations conferring high-level resistance were detected. Garenoxacin shows useful activity against a wide range of organisms from the Asia-Pacific region. In particular, it has good activity against
S. aureus
and
S. pneumoniae
, although there is evidence that low-level resistance is present in those organisms with ciprofloxacin resistance.
Comparative Activities of the Triterpene Saponin Maesabalide III and Liposomal Amphotericin B (AmBisome) againstLeishmania donovaniin Hamsters
Authors: Maes Louis , Germonprez Nils , Quirijnen Ludo , Van Puyvelde Luc , Cos Paul , Vanden Berghe Dirk 
Published: May 2004

ABSTRACTMaesabalide III (MB-III), an oleane triterpene saponin isolated from the Vietnamese plantMaesa balansae, is a new antileishmanial lead compound whose activity againstLeishmania donovani(MHOM/ET/67/L82) in groups of five golden hamsters was evaluated after administration of a single subcutaneous dose on either day 1 (prophylactic treatment) or day 28 (curative treatment) after infection. Liposomal amphotericin B (AmBisome), administered intravenously at 5 mg/kg of body weight, was used as the reference drug. Amastigote burdens in liver, spleen, and bone marrow were determined either 7 days (early effects) or 56 days (late effects) after treatment. Prophylactic administration of MB-III at 0.2 mg/kg reduced liver amastigote burdens by 99.8 and 83% within 7 and 56 days after treatment, respectively. In the latter group, however, all animals became ill and some died. Both MB-III at 0.8 mg/kg and liposomal amphotericin B were 100% effective against liver stages, but clearance from the spleen and bone marrow was not achieved. Curative administration of MB-III at 0.2 and 0.4 mg/kg was not protective, as no survivors were left at the termination of the experiment on day 84. Despite the high level of reduction of the liver amastigote burden after treatment with MB-III at 0.8 mg/kg (94.2%) or liposomal amphotericin B (99.4%), clinical protection could not be obtained in either group, with two deaths occurring and the residual liver burdens persisting. It is concluded that administration of a single dose of MB-III at 0.8 mg/kg has efficacy potential comparable to that of a single dose of liposomal amphotericin B at 5 mg/kg and is therefore considered a promising new antileishmanial lead compound. However, multiple-dose pharmacological, toxicological, and pharmacokinetic studies are still needed before it can become a valid drug candidate for development.
Spread of Novel Aminoglycoside Resistance Gene
aac
(
6
′)-
Iad
among
Acinetobacter
Clinical Isolates in Japan
Authors: Doi Yohei , Wachino Jun-ichi , Yamane Kunikazu , Shibata Naohiro , Yagi Tetsuya , Shibayama Keigo , Kato Haru , Arakawa Yoshichika 
Published: May 2004

ABSTRACT

A novel aminoglycoside resistance gene,
aac
(
6
′)-
Iad
, encoding aminoglycoside 6′-
N
-acetyltransferase, was identified in
Acinetobacter
genospecies 3 strain A-51. The gene encoded a 144-amino-acid protein, which shared modest identity (up to 36.7%) with some of the aminoglycoside 6′-
N
-acetyltransferases. The results of high-pressure liquid chromatography assays confirmed that the protein is a functional aminoglycoside 6′-
N
-acetyltransferase. The enzyme conferred resistance to amikacin, tobramycin, sisomicin, and isepamicin but not to gentamicin. The prevalence of this gene among
Acinetobacter
clinical isolates in Japan was then investigated. Of 264
Acinetobacter
sp. strains isolated from geographically diverse areas in Japan in 2002, 16 were not susceptible to amikacin, and
aac
(
6
′)
-Iad
was detected in 7. Five of the producers of aminoglycoside 6′-
N
-acetyltransferase type Iad were identified as
Acinetobacter baumannii
, and two were identified as
Acinetobacter
genospecies 3. These results suggest that
aac
(
6
′)-
Iad
plays a substantial role in amikacin resistance among
Acinetobacter
spp. in Japan.
Antibacterial Activities of the Cathelicidins Prophenin (Residues 62 to 79) and LL-37 in the Presence of a Lung Surfactant Preparation
Authors: Wang Yuqin , Walter Gabi , Herting Egbert , Agerberth Birgitta , Johansson Jan 
Published: May 2004

ABSTRACT
The antibacterial activities of the cathelicidin peptides LL-37 and an 18-residue C-terminal fragment of prophenin, corresponding to positions 62 to 79 of native prophenin (PF-18), were analyzed in the presence of a modified surfactant preparation isolated from minced porcine lungs. At low micromolar concentrations, both LL-37 and PF-18 showed significant activities against different serotypes of group B streptococci, with LL-37 being more active on a molar basis. The surfactant preparation at a concentration of 10 mg/ml partly blocked the antibacterial activity of 9 μM LL-37 and completely blocked the antibacterial activity of 9 μM PF-18. However, 10 mg of the surfactant preparation per ml had only minor inhibitory effects on LL-37 and PF-18 at 90 μM. Addition of up to 900 μM PF-18 did not affect the surface properties of the surfactant preparation. These data suggest that surfactant preparations containing antimicrobial peptides could be useful for the local treatment of pulmonary infections.
Efficacies of Amphotericin B (AMB) Lipid Complex, AMB Colloidal Dispersion, Liposomal AMB, and Conventional AMB in Treatment of Murine Coccidioidomycosis
Authors: González Gloria M. , Tijerina Rolando , Najvar Laura K. , Bocanegra Rosie , Rinaldi Michael G. , Graybill John R. 
Published: May 2004

ABSTRACT

The therapeutic efficacy of three lipid formulations of amphotericin B was compared with that of conventional amphotericin B in treatment of murine coccidioidomycosis. All treatments prolonged survival compared with the no-treatment group (
P
< 0.0001). Although conventional amphotericin B was more active than lipid formulations on reducing quantitative fungal load on a milligram-per-kilogram basis (
P
< 0.003 to 0.0002), the lipid preparations could be administered at higher doses, sterilizing liver and spleen tissues. The efficacies of the lipid preparations were similar in this murine model of coccidioidomycosis.
In Vitro Activities of the New Semisynthetic Glycopeptide Telavancin (TD-6424), Vancomycin, Daptomycin, Linezolid, and Four Comparator Agents against Anaerobic Gram-Positive Species and
Corynebacterium
spp
Authors: Goldstein Ellie J. C. , Citron Diane M. , Merriam C. Vreni , Warren Yumi A. , Tyrrell Kerin L. , Fernandez Helen T. 
Published: May 2004

ABSTRACT

Telavancin
is a new semisynthetic glycopeptide anti-infective with multiple
mechanisms of action, including inhibition of bacterial membrane
phospholipid synthesis and inhibition of bacterial cell wall synthesis.
We determined the in vitro activities of telavancin, vancomycin,
daptomycin, linezolid, quinupristin-dalfopristin, imipenem,
piperacillin-tazobactam, and ampicillin against 268 clinical isolates
of anaerobic gram-positive organisms and 31
Corynebacterium
strains using agar dilution methods according to National Committee for
Clinical Laboratory Standards procedures. Plates with daptomycin were
supplemented with Ca
2+
to 50 mg/liter. The MICs at
which 90% of isolates tested were inhibited (MIC
90
s)
for telavancin and vancomycin were as follows:
Actinomyces
spp. (
n
= 45), 0.25 and 1 μg/ml, respectively;
Clostridium difficile
(
n
= 14), 0.25 and 1μ
g/ml, respectively;
Clostridium ramosum
(
n
=
16), 1 and 4 μg/ml, respectively;
Clostridium
innocuum
(
n
= 15), 4 and 16 μg/ml,
respectively;
Clostridium clostridioforme
(
n
=
15), 8 and 1 μg/ml, respectively;
Eubacterium
group (
n
= 33), 0.25 and 2μ
g/ml, respectively;
Lactobacillus
spp. (
n
=
26), 0.5 and 4 μg/ml, respectively;
Propionibacterium
spp. (
n
= 34), 0.125 and
0.5 μg/ml, respectively;
Peptostreptococcus
spp.
(
n
= 52), 0.125 and 0.5 μg/ml, respectively;
and
Corynebacterium
spp. (
n
= 31), 0.03 and
0.5 μg/ml, respectively. The activity of TD-6424 was similar to
that of quinupristin-dalfopristin for most strains except
C.
clostridioforme
and
Lactobacillus casei
, where
quinupristin-dalfopristin was three- to fivefold more active.
Daptomycin had decreased activity (MIC > 4 μg/ml)
against 14 strains of
Actinomyces
spp. and all
C.
ramosum
,
Eubacterium lentum
, and
Lactobacillus plantarum
strains. Linezolid showed decreased
activity (MIC > 4 μg/ml) against
C. ramosum
,
two strains of
C. difficile
, and 15 strains of
Lactobacillus
spp. Imipenem and piperacillin-tazobactam were
active against >98% of strains. The MICs of ampicillin
for eight
Clostridium
spp. and three strains of
L.
casei
were >1 μg/ml. The MIC
90
of
TD-6424 for all strains tested was ≤2 μg/ml. TD-6424
has potential for use against infections with gram-positive anaerobes
and deserves further clinical
evaluation.