bluuebunny/crossref_metadata_2025_split huggingface dataset:
Just do it? impact of a science apprenticeship program on high school students' understandings of the nature of science and scientific inquiry
Authors: Bell Randy L. , Blair Lesley M. , Crawford Barbara A. , Lederman Norman G. 
Published: April 2003

AbstractThe purpose of this study was to explicate the impact of an 8‐week science apprenticeship program on a group of high‐ability secondary students' understandings of the nature of science and scientific inquiry. Ten volunteers (Grades 10–11) completed a modified version of the Views of Nature of Science, Form B both before and after their apprenticeship to assess their conceptions of key aspects of the nature of science and scientific inquiry. Semistructured exit interviews provided an opportunity for students to describe the nature of their apprenticeship experiences and elaborate on their written questionnaire responses. Semistructured exit interviews were also conducted with the scientists who served as mentors for each of the science apprentices. For the most part, students held conceptions about the nature of science and scientific inquiry that were inconsistent with those described in current reforms. Participating science mentors held strong convictions that their apprentices had learned much about the scientific enterprise in the course of doing the science in their apprenticeship. Although most students did appear to gain knowledge about the processes of scientific inquiry, their conceptions about key aspects of the nature of science remained virtually unchanged. Epistemic demand and reflection appeared to be crucial components in the single case where a participant experienced substantial gains in her understandings of the nature of science and inquiry. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 487–509, 2003
Intentions and beliefs in students' understanding and acceptance of biological evolution
Authors: Sinatra Gale M. , Southerland Sherry A. , McConaughy Frances , Demastes James W. 
Published: April 2003

AbstractWe examined the intersection of students' understanding and acceptance of evolution and their epistemological beliefs and cognitive dispositions. Based on previous research, we hypothesized there would be a relation between understanding and acceptance. We also hypothesized that students who viewed knowledge as changing and who have a disposition toward open‐minded thinking would be more likely to accept the scientific explanation of human evolution, and that beliefs and dispositions would not be related to acceptance of a topic that is generally perceived as noncontroversial. Ninety‐three undergraduate students enrolled in a nonmajors biology class completed measures of their (a) content knowledge of evolution and photosynthesis and respiration; (b) acceptance of theories of animal evolution, human evolution, and photosynthesis; and (c) epistemological beliefs and cognitive dispositions. Although our findings did reveal a significant relation between knowledge and reported acceptance for photosynthesis, there was no relation between knowledge and acceptance of animal or human evolution. Epistemological beliefs were related to acceptance, but only to the acceptance of human evolution. There was no relation between students' epistemological beliefs and their general acceptance of animal evolution or photosynthesis. Three subscales, Ambiguous Information, Actively Open‐Minded Thinking, and Belief Identification, were significantly correlated with understanding evolutionary theory. We argue these findings underscore the importance of intentional level constructs, such as epistemological beliefs and cognitive dispositions, in the learning of potentially controversial topics. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 510–528, 2003
Small- and wide-angle elastic light scattering study of fibrin structure
Authors: De Spirito M. , Arcòvito G. , Papi M. , Rocco M. , Ferri F. 
Published: April 2003

We show how small- and wide-angle elastic light scattering (q ~ 0.03-30 μm-1) can be used to quantitatively characterize the structure of polymeric gels made of semi-flexible entangled fibers. We applied the technique to the study of fibrin gels grown from the polymerization of fibrinogen (FG) macromolecular monomers following activation by the enzyme thrombin (TH), at different concentrations and under different physical-chemical conditions of the gelling solution. Our findings show that the gel can be imagined as a random network of fibers of size d and density ρ, entangled together to form densely packed blobs of mass fractal dimension Dm and average size ξ, which may overlap by a factor η and exhibit a long-range order. Provided that d ≥ 50-100 nm, all of the above parameters can be recovered by the use of a global fitting function developed by us on the basis on the proposed gel model. When the fibers are thinner (d < ~50 nm), only the fiber mass/length ratio μ ~ ρ d
2 can be retrieved instead of d and ρ. Our data confirm and quantify the major changes in the gel structure that can be obtained by varying either the salt concentration of the solution and/or the molar ratio TH/FG. Gels formed in Tris-HCl 50 mM/NaCl 150 mM, pH 7.4 and TH/FG = 0.01 are characterized by relatively small, fairly branched (D
m ~ 1.4-2.0) fibers with a mass/length ratio independent of concentration. On reducing the TH/FG ratio, the fibers become increasingly thicker, with d ~ 90 nm at TH/FG = 10-5. When the salt concentration is reduced to NaCl 100 mM (TH/FG = 0.01) the fibers are less branched (D
m ~ 1.2-1.4), but much thicker, with μ increasing by an order of magnitude. These effects are quantitatively analyzed and discussed.
Role of 16S rRNA Helix 44 in Ribosomal Resistance to Hygromycin B
Authors: Pfister P. , Risch M. , Brodersen D. E. , Böttger E. C. 
Published: April 2003

ABSTRACT

Hygromycin B is an aminoglycoside antibiotic active against prokaryotic and eukaryotic ribosomes. Ribosomal alterations in bacteria conferring resistance to hygromycin B have not been described, prompting us to use a single rRNA allelic derivative of the gram-positive bacterium
Mycobacterium smegmatis
for investigation of the molecular mechanisms involved in ribosomal resistance to hygromycin B in eubacteria. Resistance mutations were found to localize exclusively in 16S rRNA. The mutations observed, i.e., 16S rRNA U1406C, C1496U, and U1498C (
E. coli
numbering), are in close proximity to the hygromycin B binding site located in conserved helix 44 of 16S rRNA. The 16S rRNA positions involved in hygromycin B resistance are highly conserved in all three domains of life, explaining the lack of specificity and general toxicity of hygromycin B.
Prevention of Human Rhinovirus Infection by Multivalent Fab Molecules Directed against ICAM-1
Authors: Charles Catherine H. , Luo Guang X. , Kohlstaedt Lori A. , Morantte Ianessa G. , Gorfain Elliott , Cao Linguang , Williams Jimmy H. , Fang Fang 
Published: April 2003

ABSTRACT
We have developed a technology for improving avidity by making bivalent, trivalent, or tetravalent recombinant polypeptides. We designed tripartite proteins consisting of the Fab fragment of an antibody fused with a hinge derived from human immunoglobulin D that was further linked to polymerization domains derived from human coiled-coil proteins. We report here on the application of this method with a Fab domain directed against the major human rhinovirus receptor, intercellular adhesion molecule 1 (ICAM-1). Multivalent anti-ICAM-1 molecules were produced in bacteria and purified as soluble preassembled homogeneous proteins at high yield. These proteins successfully blocked rhinovirus infection in vitro, with the efficiency increasing from monomer to dimer, trimer, and tetramer. The diminished dissociation rate of these multivalent antibodies and their improved efficacy in preventing rhinovirus infection provide a foundation for producing prophylactic and therapeutic molecules against human rhinovirus, the causative agent of the majority of common colds.
Adverse Effect of Rifampin on Quinine Efficacy in Uncomplicated Falciparum Malaria
Authors: Pukrittayakamee S. , Prakongpan S. , Wanwimolruk S. , Clemens R. , Looareesuwan S. , White N. J. 
Published: April 2003

ABSTRACT

The effects of adding rifampin to quinine were assessed in adults with uncomplicated falciparum malaria. Patients were randomized to receive oral quinine either alone (
n
= 30) or in combination with rifampin (
n
= 29). Although parasite clearance times were shorter in the quinine-rifampin-treated patients (mean ± standard deviation, 70 ± 21 versus 82 ± 18 h;
P
= 0.023), recrudescence rates were five times higher (
n
= 15 of 23; 65%) than those obtained with quinine alone (
n
= 3 of 25; 12%),
P
< 0.001. Patients receiving rifampin had significantly greater conversion of quinine to 3-hydroxyquinine and consequently considerably lower concentrations of quinine in their plasma after the second day of treatment (median area under the plasma drug concentration-time curve from day zero to day 7 = 11.7 versus 47.5 μg/ml · day,
P
< 0.001). Rifampin significantly increases the metabolic clearance of quinine and thereby reduces cure rates. Rifampin should not be combined with quinine for the treatment of malaria, and the doses of quinine should probably be increased in patients who are already receiving rifampin treatment.
Novel Point Mutations in the Dihydrofolate Reductase Gene of
Plasmodium vivax
: Evidence for Sequential Selection by Drug Pressure
Authors: Imwong Mallika , Pukrittayakamee Sasithon , Rénia Laurent , Letourneur Franck , Charlieu Jean-Paul , Leartsakulpanich Ubolsree , Looareesuwan Sornchai , White Nicholas J. , Snounou Georges 
Published: April 2003

ABSTRACT

Mutations in the dihydrofolate reductase (
dhfr
) genes of
Plasmodium falciparum
and
P. vivax
are associated with resistance to the antifolate antimalarial drugs.
P. vivax
dhfr
sequences were obtained from 55
P. vivax
isolates (isolates Belem and Sal 1, which are established lines originating from Latin America, and isolates from patient samples from Thailand [
n
= 44], India [
n
= 5], Iran [
n
= 2], and Madagascar [
n
= 2]) by direct sequencing of both strands of the purified PCR product and were compared to the
P. vivax dhfr
sequence from a
P. vivax
parasite isolated in Pakistan (isolate ARI/Pakistan), considered to represent the wild-type sequence. In total, 144
P. vivax dhfr
mutations were found at only 12 positions, of which 4 have not been described previously. An F→L mutation at residue 57 had been observed previously, but a novel codon (TTA) resulted in a mutation in seven of the nine mutated variant sequences. A new mutation at residue 117 resulted in S→T (S→N has been described previously). These two variants are the same as those observed in the
P. falciparum dhfr
gene at residue 108, where they are associated with different levels of antifolate resistance. Two novel mutations, I→L at residue 13 and T→M at residue 61, appear to be unique to
P. vivax.
The clinical, epidemiological, and sequence data suggest a sequential pathway for the acquisition of the
P. vivax dhfr
mutations. Mutations at residues 117 and 58 arise first when drug pressure is applied. Highly mutated genes carry the S→T rather than the S→N mutation at residue 117. Mutations at residues 57 and 61 then occur, followed by a fifth mutation at residue 13.
IMP-12, a New Plasmid-Encoded Metallo-β-Lactamase from a
Pseudomonas putida
Clinical Isolate
Authors: Docquier Jean-Denis , Riccio Maria Letizia , Mugnaioli Claudia , Luzzaro Francesco , Endimiani Andrea , Toniolo Antonio , Amicosante Gianfranco , Rossolini Gian Maria 
Published: April 2003

ABSTRACT

A
Pseudomonas putida
strain showing broad-spectrum resistance to β-lactams, including expanded-spectrum cephalosporins and carbapenems, was isolated from a patient with a urinary tract infection at the University Hospital of Varese in northern Italy. The isolate was found to produce metallo-β-lactamase activity and to harbor a 50-kb plasmid, named pVA758, carrying a new
bla
IMP
determinant, named
bla
IMP-12
. Plasmid pVA758 was not self-transferable by conjugation to either
Escherichia coli
or
Pseudomonas aeruginosa
but could be introduced by electroporation and maintained in the latter host, where it conferred resistance or decreased susceptibility to various β-lactams. The IMP-12 enzyme is quite divergent from other IMP variants: its closest relatives are IMP-8 and IMP-2 (89 and 88% sequence identity, respectively), and IMP-1 is 85% identical to IMP-12. The
bla
IMP-12
determinant is carried on an integron-borne gene cassette whose
attC
recombination site is related to those present in cassettes containing
bla
IMP-1
,
bla
IMP-6
,
bla
IMP-7
,
bla
IMP-10
, and
bla
IMP-11
and unrelated to that present in cassettes containing
bla
IMP-2
and
bla
IMP-8
. IMP-12 was overproduced in
E. coli
by using a T7-based expression system and was purified by cation-exchange chromatography followed by gel filtration. Kinetic analysis revealed that, like other IMP variants, IMP-12 exhibits an overall preference for cephalosporins and carbapenems rather than for penicillins and does not hydrolyze temocillin and aztreonam. However, IMP-12 also exhibits some notable functional differences from other IMP variants, including uniformly poor activity toward penicillins (
k
cat
/

K
m

values, around 10
4
M
−1
· s
−1
) and a remarkably high

K
m

(around 900 μM) for imipenem.
The In Vivo Susceptibility of
Leishmania donovani
to Sodium Stibogluconate Is Drug Specific and Can Be Reversed by Inhibiting Glutathione Biosynthesis
Authors: Carter K. C. , Sundar S. , Spickett C. , Pereira O. C. , Mullen A. B. 
Published: April 2003

ABSTRACT

Resistance to pentavalent antimonial (Sb
v
) agents such as sodium stibogluconate (SSG) is creating a major problem in the treatment of visceral leishmaniasis. In the present study the in vivo susceptibilities of
Leishmania donovani
strains, typed as SSG resistant (strain 200011) or SSG sensitive (strain 200016) on the basis of their responses to a single SSG dose of 300 mg of Sb
v
/kg of body weight, to other antileishmanial drugs were determined. In addition, the role of glutathione in SSG resistance was investigated by determining the influence on SSG treatment of concomitant treatment with a nonionic surfactant vesicle formulation of buthionine sulfoximine (BSO), a specific inhibitor of the enzyme γ-glutamylcysteine synthetase which is involved in glutathione biosynthesis, and SSG, on the efficacy of SSG treatment.
L. donovani
strains that were SSG resistant (strain 200011) and SSG sensitive (strain 200016) were equally susceptible to in vivo treatment with miltefosine, paromomycin and amphotericin B (Fungizone and AmBisome) formulations. Combined treatment with SSG and vesicular BSO significantly increased the in vivo efficacy of SSG against both the 200011 and the 200016
L. donovani
strains. However, joint treatment that included high SSG doses was unexpectedly associated with toxicity. Measurement of glutathione levels in the spleens and livers of treated mice showed that the ability of the combined therapy to inhibit glutathione levels was also dependent on the SSG dose used and that the combined treatment exhibited organ-dependent effects. The SSG resistance exhibited by the
L. donovani
strains was not associated with cross-resistance to other classes of compounds and could be reversed by treatment with an inhibitor of glutathione biosynthesis, indicating that clinical resistance to antimonial drugs should not affect the antileishmanial efficacies of alternative drugs. In addition, it should be possible to identify a treatment regimen that could reverse antimony resistance.
Chromosomal Integration of a Cephalosporinase Gene from
Acinetobacter baumannii
into
Oligella urethralis
as a Source of Acquired Resistance to β-Lactams
Authors: Mammeri Hedi , Poirel Laurent , Mangeney Nicole , Nordmann Patrice 
Published: April 2003

ABSTRACT

Clinical
Oligella urethralis
isolate COH-1, which was uncommonly resistant to penicillins and narrow-spectrum cephalosporins, was recovered from a 55-year-old patient with a urinary tract infection. Shotgun cloning into
Escherichia coli
and expression experiments gave recombinant clones expressing either an AmpC β-lactamase-type phenotype of resistance or a carbenicillin-hydrolyzing β-lactamase-type phenotype of resistance. The AmpC β-lactamase identified (ABA-1), which had a pI value of 8.2, had 98% amino acid identity with a chromosomally encoded cephalosporinase of
Acinetobacter baumannii
. A 820-bp insertion sequence element, IS
Our1
, belonging to the IS
6
family of insertion sequence elements, was identified immediately upstream of
bla
ABA-1
, providing a −35 promoter sequence and likely giving rise to a hybrid promoter region. The carbenicillin-hydrolyzing β-lactamase identified (CARB-8), which had a pI value of 6.4, differed from CARB-5 by two amino acid substitutions. Hybridization of
Ceu
I fragment I-restricted DNA fragments of
O. urethralis
COH-1 with
bla
ABA-1
-,
bla
CARB-8
-, and 16S rRNA-specific probes indicated the chromosomal integration of the β-lactamase genes. PCR and hybridization experiments failed to detect
bla
CARB-8
- and
bla
ABA-1
-like genes in three
O. urethralis
reference strains, indicating that the β-lactamase genes identified were the source of acquired resistance in
O. urethralis
COH-1. This is one of the few examples of the interspecies transfer and the chromosomal integration of a gene encoding a naturally occurring β-lactamase.
Functional Similarities and Differences between
Candida albicans
Cdr1p and Cdr2p Transporters
Authors: Gauthier Christian , Weber Sandra , Alarco Anne-Marie , Alqawi Omar , Daoud Roni , Georges Elias , Raymond Martine 
Published: April 2003

ABSTRACT

The
Candida albicans CDR1
and
CDR2
genes code for highly homologous ATP-binding cassette (ABC) transporters which are overexpressed in azole-resistant clinical isolates and which confer resistance to multiple drugs by actively transporting their substrates out of the cells. These transporters are formed by two homologous halves, each with an intracellular domain containing an ATP-binding site followed by a membrane-associated domain. We have expressed Cdr1p and Cdr2p in
Saccharomyces cerevisiae
to investigate their functions. The two proteins were properly expressed and functional, as determined by Western blotting, drug susceptibility assays, and rhodamine efflux. Using total membrane proteins from these transformants, we showed that Cdr1p and Cdr2p bind to the photoreactive analogue of rhodamine 123, [
125
I]iodoaryl azido-rhodamine 123 (IAARh123). IAARh123 photoaffinity labeling of membranes prepared from cells expressing either the N half or the C half of Cdr2p, or both, demonstrated that both halves contribute to rhodamine binding and can bind to rhodamine independently. Interestingly, Cdr1p was found to confer hypersusceptibility to FK520, an immunosuppressant and antifungal agent, whereas Cdr2p conferred resistance to this compound, uncovering a major functional difference between the two transporters. Furthermore, when administered in combination with azoles, FK520 sensitized cells expressing
CDR1
but not those expressing
CDR2
. Finally, we showed that Cdr2p confers hypersusceptibility to hydrogen peroxide and resistance to diamide, while Cdr1p has no effect against these oxidative agents. Taken together, our results demonstrate that, despite a high level of structural conservation, Cdr1p and Cdr2p exhibit major functional differences, suggesting distinct biological functions.
Modification of Outer Membrane Protein Profile and Evidence Suggesting an Active Drug Pump in
Enterobacter aerogenes
Clinical Strains
Authors: Gayet Stéphane , Chollet Renaud , Molle Gérard , Pagès Jean-Marie , Chevalier Jacqueline 
Published: April 2003

ABSTRACT

Two clinical strains of
Enterobacter aerogenes
that exhibited phenotypes of multiresistance to β-lactam antibiotics, fluoroquinolones, chloramphenicol, tetracycline, and kanamycin were investigated. Both strains showed a porin pattern different from that of a susceptible strain, with a drastic reduction in the amount of the major porin but with an apparently conserved normal structure (size and immunogenicity), together with overproduction of two known outer membrane proteins, OmpX and LamB. In addition, the full-length O-polysaccharide phenotype was replaced by a semirough Ra phenotype. Moreover, in one isolate the intracellular accumulation of chloramphenicol was increased in the presence of the energy uncoupler carbonyl cyanide
m
-chlorophenylhydrazone, suggesting an energy-dependent efflux of chloramphenicol in this strain. The resistance strategies used by these isolates appear to be similar to that induced by stress in
Escherichia coli
cells.
Impact of Elements Containing Glycopeptide Resistance Genes on Expression of Virulence in
Enterococcus faecalis
Peritonitis: a Pilot Study with Rats
Authors: Plantefeve G. , Dupont H. , Hubert V. , Garry L. , Poüs C. , Carbon C. , Montravers P. 
Published: April 2003

ABSTRACT

The relationship between virulence and chromosomal elements containing glycopeptide resistance genes was experimentally assessed for two transconjugant strains of
Enterococcus faecalis
(VanA and VanB phenotypes) and compared to that for a susceptible wild-type strain. Microbiologic and inflammatory effects were assessed in a polymicrobial rat model of peritonitis. Mean peritoneal enterococcus concentrations ± standard deviations at day 1 were 2.1 ± 1.9, 1.3 ± 1.1, and 1.7 ± 2.0 log
10
CFU/ml for susceptible, VanA, and VanB strains, respectively (
P
< 0.05). At day 3 also there were lower concentrations of glycopeptide-resistant enterococcal strains in peritoneal fluid (3.2 ± 3.4, 1.8 ± 1.8, and 2.1 ± 2.4 log
10
CFU/ml for susceptible, VanA, and VanB strains, respectively [
P
< 0.05]). Transconjugant glycopeptide-resistant strains were associated with increased peritoneal cell counts at the different evaluation times of the experiment (
P
< 0.001). Plasma α1-acid glycoprotein concentrations were lower in the presence of the susceptible strain (667 ± 189 mg/liter) than in the presence of the VanA or VanB strain (1,193 ± 419 or 1,210 ± 404 mg/liter, respectively [
P
< 0.05]), while concentrations of tumor necrosis factor alpha and interleukin-6 in peritoneal fluid remained similar for the strains. These results suggest a trend toward variation of virulence of transconjugant strains compared to the wild-type strain in this peritonitis model.