bluuebunny/crossref_metadata_2025 huggingface dataset:
Uniaxial to unidirectional transition of perpendicular interlayer coupling in IrMn∕CoFe∕NiFeO∕CoFe quadrilayers
Authors: Wang Yu-Jen , Lai Chih-Huang , Huang Po-Hsiang , Shen Chih-Ta , Yang S. Y. , Chin T. S. , Lin Hsiu-Hau , Hong Tzay-Ming , Lin H. J. , Chen C. T.
Published: March 2006

We studied the interlayer coupling in the quadrilayer consisting of IrMn∕CoFe (bottom layer)/NiFeOx∕CoFe (top layer). An in-plane perpendicular interlayer coupling is observed between CoFe layers at room temperature. An anisotropy transition from uniaxial to unidirectional in a perpendicular direction is observed around Tt=55K. The nano-oxide layer NiFeOx shows no distinguishable ferromagnetic signal in the high-temperature (uniaxial) phase, while a strong signal appeared in the low-temperature (unidirectional) phase. A possible two-component scenario, in which the nano-oxide layer may contain both amorphous short-range antiferromagnetic domains and superparamagneitc clusters, is proposed to explain the phase transition.
External-cavity quantum-dot laser tunable through 1.55μm
Authors: Allen C. Nì. , Ortner G. , Dion C. , Poole P. J. , Barrios P. , Lapointe J. , Pakulski G. , Render W. , Fafard S. , Raymond S.
Published: March 2006

The optical performance of external-cavity lasers based on InAs∕InGaAsP quantum dot laser diodes is investigated. The broad electroluminescence reveals a gain spectrum with full width at half maximum of at least 175nm. By fabricating as-cleaved ridge lasers of different length and width, tuning ranges as high as 110nm have been achieved at wavelengths encompassing 1.55μm. The tuning ranges and efficiencies obtained are limited by internal losses and competition between the external-cavity lasing modes and the laser diode natural lasing modes. The laser diode length is found to affect both the wavelength tuning range and the threshold current density, which is consistent with a quantum-dot type density of states.
Alignment of nanoparticles formed on the surface of 6H-SiC crystals irradiated by two collinear femtosecond laser beams
Authors: Jia T. Q. , Zhao F. L. , Huang M. , Chen H. X. , Qiu J. R. , Li R. X. , Xu Z. Z. , Kuroda H.
Published: March 2006

Nanoripples with periods of 150 and 80nm are formed on the surface of 6H-SiC crystals irradiated by the p-polarized 800nm and the s-polarized 400nm femtosecond lasers, respectively. When both of the two collinear laser beams focus simultaneously on the sample surface, nanoparticles are formed on the whole ablation area, and they array in parallel lines. We propose and confirm that the second harmonics in the sample surface excited by the incident lasers plays an important role in the formation of nanostructures.
Finite-size effects in BaTiO3 nanowires
Authors: Geneste Grégory , Bousquet Eric , Junquera Javier , Ghosez Philippe
Published: March 2006

The size dependence of the ferroelectric properties of BaTiO3 nanowires is studied from first principles. We show that the ferroelectric distortion along the wire axis disappears below a critical diameter of about 1.2nm. This disappearance is related to a global contraction of the unit cell resulting from low atomic coordinations at the wire surface. It is shown that a ferroelectric distortion can be recovered under appropriate tensile strain conditions.
Characterization of ultrasmall all-Nb tunnel junctions with ion gun oxidized barriers
Authors: Im Hyunsik , Pashkin Yu. A. , Yamamoto T. , Astafiev O. , Nakamura Y. , Tsai J. S.
Published: March 2006

We have fabricated ultrasmall all-Nb tunnel junctions and single electron transistors using shadow evaporation combined with in situ ion gun oxidation. Basic parameters of the Nb/Nb-oxide/Nb junctions, namely, the barrier height, width, and specific junction capacitance, are estimated from the transport characteristics.
Extracellular respiration of dimethyl sulfoxide by
Shewanella oneidensis
strain MR-1
Authors: Gralnick Jeffrey A. , Vali Hojatollah , Lies Douglas P. , Newman Dianne K.
Published: March 2006

Shewanella
species are renowned for their
respiratory versatility, including their ability to respire poorly
soluble substrates by using enzymatic machinery that is localized to
the outside of the cell. The ability to engage in “extracellular respiration” to date has focused primarily on
respiration of minerals. Here, we identify two gene clusters in
Shewanella oneidensis
strain MR-1 that each
contain homologs of genes required for metal reduction and genes that
are predicted to encode dimethyl sulfoxide (DMSO) reductase subunits.
Molecular and genetic analyses of these clusters indicate that one
(SO1427–SO1432) is required for anaerobic respiration of DMSO.
We show that DMSO respiration is an extracellular respiratory process
through the analysis of mutants defective in type II secretion, which
is required for transporting proteins to the outer membrane in
Shewanella
. Moreover, immunogold labeling of DMSO
reductase subunits reveals that they reside on the outer leaflet of
the outer membrane under anaerobic conditions. The extracellular
localization of the DMSO reductase in
S.
oneidensis
suggests these organisms may perceive DMSO in the
environment as an insoluble compound.
Somatic gene transfer of cAMP response element-binding protein attenuates memory impairment in aging rats
Authors: Mouravlev Alexandre , Dunning Jane , Young Deborah , During Matthew J.
Published: March 2006

cAMP response element-binding protein (CREB) is important for the formation and facilitation of long-term memory in diverse models. However, to our knowledge, involvement of CREB in age-associated memory impairment has not been reported. Here, we use a recombinant adeno-associated virus vector to obtain stable transgenic expression of CREB as well as the inducible cAMP early repressor (ICER) in the hippocampus of adult rats. In a longitudinal study, we show that somatic gene transfer of both CREB and ICER does not alter long-term memory in young (3-month-old) rats. However, at 15 months of age, the same CREB-transduced rats show significantly better long-term memory in spatial-navigation and passive-avoidance tasks compared with their equally aged control littermates, and a threshold effect is evident. In contrast, the aged ICER-transduced rats demonstrate significantly reduced memory in comparison with the same control group. Hippocampal CREB gene transfer prevented the aging-related decrease in long-term memory found in the control rats. These data suggest that elevation of CREB protein levels in a subset of hippocampal neurons as achieved by somatic cell gene transfer might compensate for general deficits in molecular mechanisms underlying age-related memory loss in rats and, therefore, attenuate long-term-memory impairment during normal aging.
Wiring optimization can relate neuronal structure and function
Authors: Chen Beth L. , Hall David H. , Chklovskii Dmitri B.
Published: March 2006

We pursue the hypothesis that neuronal placement in animals minimizes wiring costs for given functional constraints, as specified by synaptic connectivity. Using a newly compiled version of theCaenorhabditis eleganswiring diagram, we solve for the optimal layout of 279 nonpharyngeal neurons. In the optimal layout, most neurons are located close to their actual positions, suggesting that wiring minimization is an important factor. Yet some neurons exhibit strong deviations from “optimal” position. We propose that biological factors relating to axonal guidance and command neuron functions contribute to these deviations. We capture these factors by proposing a modified wiring cost function.
Infection of human cancer cells with myxoma virus requires Akt activation via interaction with a viral ankyrin-repeat host range factor
Authors: Wang Gen , Barrett John W. , Stanford Marianne , Werden Steven J. , Johnston James B. , Gao Xiujuan , Sun Mei , Cheng Jin Q. , McFadden Grant
Published: March 2006

We demonstrate that the susceptibility of human cancer cells to be infected and killed by an oncolytic poxvirus, myxoma virus (MV), is related to the basal level of endogenous phosphorylated Akt. We further demonstrate that nonpermissive tumor cells will switch from resistant to susceptible for MV infection after expression of ectopically active Akt (Myr-Akt) and that permissive cancer cells can be rendered nonpermissive by blocking Akt activation with a dominant-negative inhibitor of Akt. Finally, the activation of Akt by MV involves the formation of a complex between the viral host range ankyrin-repeat protein, M-T5, and Akt. We conclude that the Akt pathway is a key restriction determinant for permissiveness of human cancer cells by MV.
Reverse genetics system for introduction of site-specific mutations into the double-stranded RNA genome of infectious rotavirus
Authors: Komoto Satoshi , Sasaki Jun , Taniguchi Koki
Published: March 2006

We describe here the successful establishment of a reverse genetics system for rotavirus (RV), a member of the
Reoviridae
family whose genome consists of 10–12 segmented dsRNA. The system is based on the recombinant vaccinia virus T7 RNA polymerase-driven procedure for supplying artificial viral mRNA in the cytoplasm. With the aid of helper virus (human RV strain KU) infection, intracellularly transcribed full-length VP4 mRNA of simian RV strain SA11 resulted in the rescue of the KU-based transfectant virus carrying the SA11 VP4 RNA segment derived from cDNA. In addition to the rescued transfectant virus with the authentic SA11 VP4 gene, three more infectious RV transfectants, into which silent mutation(s) were introduced to destroy both or one of the two restriction enzyme sites as gene markers in the SA11 VP4 genome, were also rescued with this method. The ability to artificially manipulate the RV genome will greatly increase the understanding of the replication and the pathogenicity of RV and will provide a tool for the design of attenuated vaccine vectors.
Suppressing Brownian motion of individual biomolecules in solution
Authors: Cohen Adam E. , Moerner W. E.
Published: March 2006

Single biomolecules in free solution have long been of interest for detailed study by optical methods, but Brownian motion prevents the observation of one single molecule for extended periods. We have used an anti-Brownian electrokinetic (ABEL) trap to trap individual protein molecules in free solution, under ambient conditions, without requiring any attachment to beads or surfaces. We also demonstrate trapping and manipulation of single virus particles, lipid vesicles, and fluorescent semiconductor nanocrystals.
Targeted disruption of genes in the
Bombyx mori
sex pheromone biosynthetic pathway
Authors: Ohnishi Atsushi , Hull J. Joe , Matsumoto Shogo
Published: March 2006

The sex pheromone biosynthetic pathways of lepidopterans require the concerted actions of multiple gene products. A number of pheromone gland (PG)-specific genes have been cloned in recent years and, whereas
in vitro
characterizations have indicated functions consistent with roles in pheromone production, there have been no clear demonstrations
in vivo
. Using an RNA interference-mediated loss-of-function approach, we injected newly formed
Bombyx mori
pupae with dsRNAs corresponding to genes of interest [i.e., PG fatty acyl reductase (
pgFAR
),
B. mori
PG Z11/Δ10,12 desaturase (
Bmpgdesat1
), PG acyl-CoA-binding protein (
pgACBP
), midgut ACBP, and pheromone biosynthesis activating neuropeptide receptor (
PBANR
)] to assess their specific roles during pheromonogenesis. In all cases, the introduced dsRNAs induced a dose-dependent reduction in sex pheromone production with the corresponding decrease in transcript levels. No effects on pupal development or adult emergence were observed. Disrupting the PBANR gene resulted in a loss of the lipase activity that liberates pheromone precursors, whereas knockout of the pgACBP gene prevented the daily accumulation and fluctuation of the triacylglycerols that function as the cellular deposits for the pheromone precursors. Taken together, our results provide unequivocal evidence that the pgACBP, Bmpgdesat1, pgFAR, and PBANR gene products are essential during pheromonogenesis and demonstrate the power of this methodology for dissecting the molecular interactions that comprise biosynthetic pathways.
High-resolution mapping of DNA copy alterations in human chromosome 22 using high-density tiling oligonucleotide arrays
Authors: Urban Alexander Eckehart , Korbel Jan O. , Selzer Rebecca , Richmond Todd , Hacker April , Popescu George V. , Cubells Joseph F. , Green Roland , Emanuel Beverly S. , Gerstein Mark B. , Weissman Sherman M. , Snyder Michael
Published: March 2006

Deletions and amplifications of the human genomic sequence (copy number polymorphisms) are the cause of numerous diseases and a potential cause of phenotypic variation in the normal population. Comparative genomic hybridization (CGH) has been developed as a useful tool for detecting alterations in DNA copy number that involve blocks of DNA several kilobases or larger in size. We have developed high-resolution CGH (HR-CGH) to detect accurately and with relatively little bias the presence and extent of chromosomal aberrations in human DNA. Maskless array synthesis was used to construct arrays containing 385,000 oligonucleotides with isothermal probes of 45–85 bp in length; arrays tiling the β-globin locus and chromosome 22q were prepared. Arrays with a 9-bp tiling path were used to map a 622-bp heterozygous deletion in the β-globin locus. Arrays with an 85-bp tiling path were used to analyze DNA from patients with copy number changes in the pericentromeric region of chromosome 22q. Heterozygous deletions and duplications as well as partial triploidies and partial tetraploidies of portions of chromosome 22q were mapped with high resolution (typically up to 200 bp) in each patient, and the precise breakpoints of two deletions were confirmed by DNA sequencing. Additional peaks potentially corresponding to known and novel additional CNPs were also observed. Our results demonstrate that HR-CGH allows the detection of copy number changes in the human genome at an unprecedented level of resolution.
Lipopeptide antagonists of growth hormone-releasing hormone with improved antitumor activities
Authors: Zarandi Marta , Varga Jozsef L. , Schally Andrew V. , Horvath Judit E. , Toller Gabor L. , Kovacs Magdolna , Letsch Markus , Groot Kate , Armatis Patricia , Halmos Gabor
Published: March 2006

Antagonists of growth hormone-releasing hormone (GHRH) synthesized previously inhibit proliferation of various human cancers, but derivatisation with fatty acids could enhance their clinical efficacy. We synthesized a series of antagonists of GHRH(1-29)NH
2
acylated at the N terminus with monocarboxylic or α,ω-dicarboxylic acids containing six to sixteen carbon atoms. These peptides are analogs of prior potent antagonists JV-1-36, JV-1-38, and JV-1-65 with phenylacetyl group at their N terminus. Several new analogs, including MZ-J-7-46 and MZ-J-7-30, more effectively inhibited GHRH-induced GH release
in vitro
in a superfused rat pituitary system than their parent compound JV-1-36 and had increased binding affinities to rat pituitary GHRH receptors, but they showed weaker inhibition of GH release
in vivo
than JV-1-36. All antagonists acylated with fatty acids containing 8–14 carbon atoms inhibited the proliferation of MiaPaCa-2 human pancreatic cancer cells
in vitro
better than JV-1-36 or JV-1-65. GHRH antagonist MZ-J-7-114 (5 μg/day) significantly suppressed the growth of PC-3 human androgen-independent prostate cancers xenografted into nude mice and reduced serum IGF-I levels, whereas antagonist JV-1-38 had no effect at the dose of 10 μg/day. GHRH antagonists including MZ-J-7-46 and MZ-J-7-114 acylated with octanoic acid and MZ-J-7-30 and MZ-J-7-110 acylated with 1,12-dodecanedicarboxylic acid represent relevant improvements over earlier antagonists. These and previous results suggest that this class of GHRH antagonists might be effective in the treatment of various cancers.
Microtubule-associated protein 2 (MAP2) is a neurosteroid receptor
Authors: Fontaine-Lenoir Virginie , Chambraud Béatrice , Fellous Arlette , David Sébastien , Duchossoy Yann , Baulieu Etienne-Emile , Robel Paul
Published: March 2006

The neurosteroid pregnenolone (PREG) and its chemically synthesized analog 3β-methoxypregnenolone (MePREG) bind to microtubule-associated protein 2 (MAP2) and stimulate the polymerization of microtubules. PREG, MePREG, and progesterone (PROG; the physiological immediate metabolite of PREG) significantly enhance neurite outgrowth of nerve growth factor-pretreated PC12 cells. However, PROG, although it binds to MAP2, does not increase the immunostaining of MAP2, contrary to PREG and MePREG. Nocodazole, a microtubule-disrupting agent, induces a major retraction of neurites in control cultures, but pretreatment with PREG/MePREG is protective. Decreasing MAP2 expression by RNA interference does not modify PROG action, but it prevents the stimulatory effects of PREG and MePREG on neurite extension, showing that MAP2 is their specific receptor.
Residues in substrate proteins that interact with GroEL in the capture process are buried in the native state
Authors: Stan George , Brooks Bernard R. , Lorimer George H. , Thirumalai D.
Published: March 2006

We have used a bioinformatic approach to predict the natural substrate proteins for the
Escherichia coli
chaperonin GroEL based on two simple criteria. Natural substrate proteins should contain binding motifs similar in sequence to the mobile loop peptide of GroES that displaces the binding motif during the chaperonin cycle. Secondly, each substrate protein should contain multiple copies of the binding motif so that the chaperonin can perform “work” on the substrate protein. To validate these criteria, we have used a database of 252 proteins that have been experimentally shown to interact with the chaperonin machinery
in vivo
. More than 80% are identified by these criteria. The binding motifs of all 79 proteins in the database with a known three-dimensional structure are buried (<50% solvent-accessible surface area) in the native state. Our results show that the binding motifs are inaccessible in the native state but become solvent-exposed in unfolded state, thus enabling GroEL to distinguish between unfolded and native states. The structures of the binding motif in the native states of the substrate proteins include α-helices, β-strands, and random coils. The diversity of secondary structures implies that there are large and varied conformational transitions in the recognition motifs after their displacement by the mobile loops of GroES.
Surprising contribution to aminoacylation and translation of non-Watson–Crick pairs in tRNA
Authors: McClain William H.
Published: March 2006

Molecules of transfer RNA (tRNA) typically contain four stems composed of Watson–Crick (W-C) base pairs and infrequent mispairs such as G-U and A-C. The latter mispairs are fundamental units of RNA secondary structure found in nearly every class of RNA and are nearly isomorphic to W-C pairs. Therefore, they often substitute for G-C or A-U base pairs. The mispairs also have unique chemical, structural, and dynamic conformational properties, which can only be partially mimicked by W-C base pairs. Here, I characterize the identities and tasks of six mutant G-U and A-C mispairs in
Escherichia coli
tRNA
Gly
using genetic and bioinformatic tools and show that mispairs are significantly more important for aminoacylation and translation than previously realized. Mispairs boost aminoacylation and translation primarily because they activate tRNA by means of their conformational flexibility. The statistical preservation of the six mutant mispair sites across tRNA
Gly
in many organisms points to a fundamental structure–function signature within tRNA
Gly
with possible analogous missions in other RNAs.
The role of phospholipase D and phosphatidic acid in the mechanical activation of mTOR signaling in skeletal muscle
Authors: Hornberger T. A. , Chu W. K. , Mak Y. W. , Hsiung J. W. , Huang S. A. , Chien S.
Published: March 2006

Signaling by the mammalian target of rapamycin (mTOR) has been reported to be necessary for mechanical load-induced growth of skeletal muscle. The mechanisms involved in the mechanical activation of mTOR signaling are not known, but several studies indicate that a unique [phosphotidylinositol-3-kinase (PI3K)- and nutrient-independent] mechanism is involved. In this study, we have demonstrated that a regulatory pathway for mTOR signaling that involves phospholipase D (PLD) and the lipid second messenger phosphatidic acid (PA) plays a critical role in the mechanical activation of mTOR signaling. First, an elevation in PA concentration was sufficient for the activation of mTOR signaling. Second, the isozymes of PLD (PLD1 and PLD2) are localized to the z-band in skeletal muscle (a critical site of mechanical force transmission). Third, mechanical stimulation of skeletal muscle with intermittent passive stretch
ex vivo
induced PLD activation, PA accumulation, and mTOR signaling. Finally, pharmacological inhibition of PLD blocked the mechanically induced increase in PA and the activation of mTOR signaling. Combined, these results indicate that mechanical stimuli activate mTOR signaling through a PLD-dependent increase in PA. Furthermore, we showed that mTOR signaling was partially resistant to rapamycin in muscles subjected to mechanical stimulation. Because rapamycin and PA compete for binding to the FRB domain on mTOR, these results suggest that mechanical stimuli activate mTOR signaling through an enhanced binding of PA to the FRB domain on mTOR.
Aurora B is required for mitotic chromatin-induced phosphorylation of Op18/Stathmin
Authors: Gadea Bedrick B. , Ruderman Joan V.
Published: March 2006

Oncoprotein 18/Stathmin (Op18) is a microtubule-destabilizing protein that is inhibited by phosphorylation in response to many types of signals. During mitosis, phosphorylation of Op18 by cdc2 is necessary but not sufficient for Op18 inhibition. The presence of mitotic chromosomes is additionally required and involves phosphorylation of Ser-16 in
Xenopus
Op18 (and/or Ser-63 in human). Given that Ser-16 is an excellent Aurora A (Aur-A) kinase consensus phosphorylation site and the Aurora kinase inhibitor ZM447439 (ZM) blocks phosphorylation in the activation loop of Aur-A, we asked whether either Aur-A or Aurora B (Aur-B) might regulate Op18. We find that ZM blocks the ability of mitotic chromatin to induce Op18 hyperphosphorylation in
Xenopus
egg extracts. Depletion of Aur-B, but not Aur-A, blocks hyperphosphorylation of Op18, and chromatin assembled in the absence of Aur-B fails to induce hyperphosphorylation. These results suggest that Aur-B, which concentrates at centromeres of metaphase chromosomes, contributes to localized regulation of Op18 during the process of spindle assembly.
Antiretroviral Drug Resistance in Human Immunodeficiency Virus–Infected Source Patients for Occupational Exposures to Healthcare Workers
Authors: Beltrami Elise M. , Cheingsong Rachanee , Heneine Walid M. , Respess Richard A. , Orelien Jean G. , Mendelson Meryl H. , Stewart Mari A. , Koll Brian S. , Sulis Carol A. , Cardo Denise M. ,   Occupational HIV Exposure Study Group
Published: March 2006

Objective:

To assess the prevalence of HIV antiretroviral resistance among source patients for occupational HIV exposures.

Design:

Blood and data (eg, stage of HIV, previous antiretroviral drug therapy, and HIV RNA viral load) were collected from HIV-infected patients who were source patients for occupational exposures.

Setting:

Seven tertiary-care medical centers in five U.S. cities (San Diego, California; Miami, Florida; Boston, Massachusetts; Albany, New York; and New York, New York [three sites]) during 1998 to 1999.

Participants:

Sixty-four HIV-infected patients who were source patients for occupational exposures.

Results:

Virus from 50 patients was sequenced; virus from 14 patients with an undetectable (ie, < 400 RNA copies/mL) viral load could not be sequenced. Overall, 19 (38%) of the 50 patients had primary eenotypic mutations associated with resistance to reverse transcriptase or protease inhibitors. Eighteen of the 19 viruses with primary mutations and 13 wild type viruses were phenotyped by recombinant assays; 19 had phenotypic resistance to at least one antiretroviral agent. Of the 50 source patients studied, 26 had taken antiretroviral agents in the 3 months before the occupational exposure incident. Sixteen (62%) of the 26 drug-treated patients had virus that was phenotypically resistant to at least one drug. Four (17%) of 23 untreated patients had phenotypically resistant virus. No episodes of HIV transmission were observed among the exposed HCWs.

Conclusions:

There was a high prevalence of drug-resistant HIV among source patients for occupational HIV exposures. Healthcare providers should use the drug treatment information of source patients when making decisions about postexposure prophylaxis.
Differences in Percutaneous Injury Patterns in A Multi-Hospital System
Authors: Babcock Hilary M. , Fraser Victoria
Published: March 2006

Objective:

Determine differences in patterns of percutaneous injuries (PIs) in different types of hospitals.

Design:

Case series of injuries occurring from 1997 to 2001.

Setting:

Large midwestern healthcare system with a consolidated occupational health database from 9 hospitals, including rural and urban, community and teaching (1 pediatric, 1 adult) facilities, ranging from 113 to 1,400 beds.

Participants:

Healthcare workers injured between 1997 and 2001.

Results:

Annual injury rates for all hospitals decreased during the study period from 21 to 16.5/100 beds (chi-square for trend = 22.7; P = .0001). Average annual injury rates were higher at larger hospitals (22.5 vs 9.5 Pis/100 beds; P = .0001). Among small hospitals, rural hospitals had higher rates than did urban hospitals (14.87 vs 8.02 PIs/100 beds; P = .0143). At small hospitals, an increased proportion of injuries occurred in the emergency department (13.7% vs 8.6%; P = .0004), operating room (32.3% vs 25.4%; P = .0002), and ICU (12.3% vs 9.4%; P = .0225), compared with large hospitals. Rural hospitals had higher injury rates in the radiology department (7.7% vs 2%; P = .0015) versus urban hospitals. Injuries at the teaching hospitals occurred more commonly on the wards (28.8% vs 24%; P = .0021) and in ICUs (11.4% vs 7.8%; P = .0006) than at community hospitals. Injuries involving butterfly needles were more common at pediatric versus adult hospitals (15.8% vs 6.5%; P = .0001). The prevalence of source patients infected with HIV and hepatitis C was higher at large hospitals.

Conclusions:

Significant differences exist in injury rates and patterns among different types of hospitals. These data can be used to target intervention strategies.
Prolonged Candidemia in Infants Following Surgery for Congenital Heart Disease
Authors: Chakrabarti Chandrama , Sood Sunil K. , Parnell Vincent , Rubin Lorry G.
Published: March 2006

Objectives:

To describe a group of infants with complex congenital heart disease (CCHD) who had candidemia postoperatively and to perform a case–control study of risk factors.

Design:

Descriptive and case–control study.

Setting:

Tertiary-care medical centers.

Patients:

Infants with CCHD who underwent cardiac surgery and developed candidemia. Controls were matched for congenital heart disease lesions, age, and postoperative hospital stay.

Results:

Of 95 infants younger than 6 months with CCHD who underwent cardiac surgery between January 1999 and April 2001, 6 (6.3%) developed candidemia with 5 different species. The candidemia was prolonged (range, 12 to 32 days; median, 17 days). The interval between cardiac surgery and onset of candidemia was 12 to 57 days (median, 24 days). All had a central venous catheter inserted 8 to 50 days prior to the onset of candidemia. The mortality rate was 83%, compared with 13% for the group without candidemia. A univariate analysis of the potential risk factors revealed that duration of total parenteral nutrition (TPN), duration of antibiotics, intraoperative cardiopulmonary bypass time, and documentation of an intravascular thrombus were associated with candidemia. In multivariate analysis, long duration of TPN and documentation of a thrombus were associated with candidemia.

Conclusions:

Candidemia following cardiac surgery for infants with CCHD was persistent and associated with high mortality. The variety of species indicates that this was not a common-source outbreak. Risk factors associated with candidemia were duration of TPN and documentation of an intravascular thrombus.
Nonmagical Tools
Authors: Lee James T.
Published: March 2006

At a recent luncheon meeting hosted by the Oklahoma Foundation for Medical Quality, a speaker preceding me at the podium began his performance by reminding audience members of the quality improvement jingle, “all of us together are smarter than any one of us alone.” This may be a major rallying slogan for quality improvers now busy at just about every hospital. Awaiting my turn in the proceedings, I found myself remembering Charles Mackay's famous warning1 that “… men think in herds and it will be seen that they go mad in herds, while they only recover their senses slowly, and one by one.” Whether agreeing to join local quality improvement sorties or choosing to say “thanks, but I'm already on too many committees,” each of us must individually recover our senses about the atmosphere in which evidence is being marshaled and massaged by earnest quality improvers choosing their “action opportunities.” There is no shortage of raw material, and surgical care continues to be a popular target.
Biocides Currently Used for Bronchoscope Decontamination Are Poorly Effective Against Free-Living Amoebae
Authors: Greub Gilbert , Raoult Didier
Published: March 2006

Free-living amoebae may be pathogenic and harbor several agents of pneumonia. We tested the susceptibility of amoebal cysts and trophozoites to currently used biocides for bronchoscope decontamination. We showed that two particular biocides are inadequate for disinfecting bronchoscopes, asAcanthamoeba polyphagasurvived 3 hours of exposure to these undiluted agents.
Utility of Dual Skin Tests to Evaluate Tuberculin Skin Test Reactions of 10 to 14 mm in Healthcare Workers
Authors: Marsh Bryan J. , Vicente Joshua San , von Reyn C. Fordham
Published: March 2006

Objective:

To define the utility of 10- to 14-mm reactions to a Mycobacterium tuberculosis purified protein derivative (PPD) skin test for healthcare workers (HCWs).

Design:

Blinded dual skin testing, using PPD and M. avium sensitin, of HCWs at a single medical center who had a 10-to 14-mm reaction to PPD when tested by personnel from the Occupational Health Department as part of routine annual screening.

Setting:

A single tertiary-care academic medical center.

Participants:

Employees of the medical center who underwent routine annual PPD screening and were identified by the Occupational Health Department as having a reaction of 10 to 14 mm to PPD.

Results:

Nineteen employees were identified as candidates and 11 underwent dual skin testing. Only 4 (36%) had repeat results for PPD in the 10- to 14-mm range, whether read by Occupational Health Department personnel or study investigators. For only 5 (45%) of the subjects did the Occupational Health Department personnel and study investigators concur (± 3 mm) on the size of the PPD reaction. Two of the 4 subjects with reactions of 10 to 14 mm as measured by the study investigators were M. avium sensitin dominant, 1 was PPD dominant, and 1 was nondominant.

Conclusion:

A reaction of 10 to 14 mm to PPD should not be used as an indication for the treatment of latent tuberculosis (TB) infection in healthy HCWs born in the United States with no known exposure to TB.
Impact of a Program of Intensive Surveillance and Interventions Targeting Ventilated Patients in the Reduction of Ventilator-Associated Pneumonia and Its Cost-Effectiveness
Authors: Lai Kwan Kew , Baker Stephen P. , Fontecchio Sally A.
Published: March 2006

Objective:

We hypothesized that a program of prospective intensive surveillance for ventilator-associated pneumonia (VAP) and concomitant implementations of multimodal, multidisciplinary preventive and intervention strategies would result in a reduction in the incidence of VAP and would be cost-effective.

Setting:

Medical and surgical intensive care units (ICUs) in a university teaching hospital.

Interventions:

All ventilated patients in the medical and surgical ICUs were monitored for VAP from January 1997 through December 1998. Interventions including elevation of the head of the bed, use of sterile water and replacement of stopcocks with enteral valves for nasogastric feeding tubes, and prolongation of changing of in-line suction catheters from 24 hours to as needed were implemented.

Results:

The rates of VAP decreased by 10.8/1,000 ventilator-days in the medical ICU (CI95, 4.65-16.91) and by 17.2/1,000 ventilator-days in the surgical ICU (CI95> 2.85-31.56) when they were compared for 1997 and 1998. With the use of the estimated cost of a VAP of $4,947 from the literature, the reduction resulted in cost savings of $178,092 and $148,410 in the medical and surgical ICUs, respectively, for a total of $326,482. In addition, $25,497 was saved due to the lengthening of the time for the change of in-line suction catheters, resulting in a cost savings of $351,979. This total cost savings of $351,979 minus the cost of enteral valves of $2,100 resulted in total net savings of $349,899.

Conclusion:

Intensive surveillance and interventions targeted at ventilated patients resulted in reduction of VAP and appeared to be cost-effective.
Ventilator-Associated Pneumonia at a Tertiary-Care Center in a Developing Country: Incidence, Microbiology, and Susceptibility Patterns of Isolated Microorganisms
Authors: Kanafani Zeina A. , Kara Layla , Hayek Shady , Kanj Souha S.
Published: March 2006

Objective:

Ventilator-associated pneumonia (VAP) complicates the course of up to 24% of intubated patients. Data from the Middle East are scarce. The objective of this study was to evaluate the incidence, microbiology, and antimicrobial susceptibility patterns of isolated microorganisms in VAP in a developing country.

Design:

Prospective observational cohort study.

Setting:

The American University of Beirut Medical Center, a tertiary-care center that serves as a major referral center for Lebanon and neighboring countries.

Patients:

All patients admitted to the intensive care and respiratory care units from March to September 2001, and who had been receiving mechanical ventilation for at least 48 hours, were included in the study. Results of samples submitted for culture were recorded and antimicrobial susceptibility testing of isolated pathogens was performed.

Results:

Seventy patients were entered into the study. The incidence of VAP was 47%. Gram-negative bacilli accounted for 83% of all isolates. The most commonly identified organism was Acinetobacter anitratus, followed by Pseudomonas aeruginosa. Fifty percent of all gram-negative bacterial isolates were classified as antibiotic resistant. Compared with patients without VAP, patients with VAP remained intubated for a longer period and stayed in the intensive care unit longer. VAP was not associated with an increased mortality rate.

Conclusion:

Compared with other studies, the results from this referral center in Lebanon indicate a higher incidence of VAP and a high prevalence of resistant organisms. These data are relevant because they direct the choice of empiric antibiotic therapy for VAP.
Risk of Acquiring Influenza A in a Nursing Home From a Culture-Positive Roommate
Authors: Drinka Paul J. , Krause Peggy , Nest Lori , Goodman Brian M. , Gravenstein Stefan
Published: March 2006

Influenza A was cultured in 62 double rooms. The roommate was infected in 12 (19.4%). During 3,294 resident-seasons, influenza was cultured in 208 single rooms (6.3%). Those who lived in double rooms with a culture-positive roommate had a 3.07 relative risk (CI95, 1.61-5.78) of acquiring influenza.
Absence of Excess Mortality in Critically Ill Patients With Nosocomial Escherichia coli Bacteremia
Authors: Blot Stijn , Vandewoude Koenraad , Hoste Eric , Waele Jan De , Kint Kathleen , Rosiers Fanny , Vogelaers Dirk , Colardyn Francis
Published: March 2006

Objective:

To evaluate excess mortality in critically ill patients with Escherichia coli bacteremia after adjustment for severity of illness.

Design:

Retrospective (1992-2000), pairwise-matched (1:2), risk-adjusted cohort study.

Setting:

Fifty-four-bed ICU in a university hospital including a medical and surgical ICU, a unit for care after cardiac surgery, and a burns unit.

Patients:

ICU patients with nosocomial E. coli bacteremia (defined as cases; n = 64) and control-patients without nosocomial bloodstream infection (n = 128).

Methods:

Case-patients were matched with control-patients on the basis of the Acute Physiology and Chronic Health Evaluation (APACHE) II system: an equal APACHE II score (± 2 points) and diagnostic category. In addition, control-patients were required to have an ICU stay at least as long as that of the respective case-patients prior to onset of the bacteremia.

Results:

The overall rate of appropriate antibiotic therapy in patients with E. coli bacteremia was high (93%) and such therapy was initiated soon after onset of the bacteremia (0.6 ± 1.0 day). ICU patients with E. coli bacteremia had more acute renal failure. No differences were noted between case-patients and control-patients in incidence of acute respiratory failure, hemodynamic instability, or age. No differences were observed in length of mechanical ventilation or length of ICU stay. In-hospital mortality rates for cases and controls were not different (43.8% and 45.3%, respectively; P = .959).

Conclusion:

After adjustment for disease severity and acute illness and in the presence of adequate antibiotic therapy, no excess mortality was found in ICU patients with E. coli bacteremia.
Effect of Nurse Staffing and Antimicrobial-Impregnated Central Venous Catheters on the Risk for Bloodstream Infections in Intensive Care Units
Authors: Alonso-Echanove Juan , Edwards Jonathan R. , Richards Michael J. , Brennan Patrick , Venezia Richard A. , Keen Janet , Ashline Vivian , Kirkland Kathy , Chou Ellen , Hupert Mark , Veeder Abigail V. , Speas Janice , Kaye Judy , Sharma Kailash , Martin Aliki , Moroz V. Dianne , Gaynes Robert P.
Published: March 2006

Background:

Defining risk factors for central venous catheter (CVC)-associated bloodstream infections (BSIs) is critical to establishing prevention measures, especially for factors such as nurse staffing and antimicrobial-impregnated CVCs.

Methods:

We prospectively monitored CVCs, nurse staffing, and patient-related variables for CVC-associated BSIs among adults admitted to eight ICUs during 2 years.

Results:

A total of 240 CVC-associated BSIs (2.8%) were identified among 4,535 patients, representing 8,593 CVCs. Antimicrobial-impregnated CVCs reduced the risk for CVC-associated BSI only among patients whose CVC was used to administer total parenteral nutrition (TPN, 2.6 CVC-associated BSIs per 1,000 CVC-days vs no TPN, 7.5 CVC-associated BSIs per 1,000 CVC-days;P= .006). Among patients not receiving TPN, there was an increase in the risk of CVC-associated BSI in patients cared for by “float” nurses for more than 60% of the duration of the CVC. In multivariable analysis, risk factors for CVC-associated BSIs were the use of TPN in non-antimicrobial-impregnated CVCs (P= .0001), patient cared for by a float nurse for more than 60% of CVC-days (P= .0019), no antibiotics administered to the patient within 48 hours of insertion (P= .0001), and patient unarousable for 70% or more of the duration of the CVC (P= .0001). Peripherally inserted central catheters (PICCs) were associated with a lower risk for CVC-associated BSI (P= .0001).

Conclusions:

Antimicrobial-impregnated CVCs reduced the risk of CVC-associated BSI by 66% in patients receiving TPN. Limiting the use of float nurses for ICU patients with CVCs and the use of PICCs may also reduce the risk of CVC-associated BSI.
Improving Water Quality Can Reduce Pyrogenic Reactions Associated With Reuse of Cardiac Catheters
Authors: Duffy Rosemary E. , Couto Braulio , Pessoa Jussara M. , Starling Carlos , Pinheiro Silma , Pearson Michele L. , Arduino Matthew J. , Mattson Barbara J. , Jarvis William R.
Published: March 2006

Objective:

To report the results of our preintervention investigation and subsequent 19-month three-phase intervention study designed to reduce pyrogenic reactions among patients undergoing cardiac catheterization using reprocessed catheters.

Design:

A case-control study for the preintervention period and a prospective cohort study for the intervention period.

Setting:

A 400-bed hospital in Belo Horizonte, Brazil.

Participants:

Any patient undergoing cardiac catheterization in the hospital.

Interventions:

Three intervention phases were implemented to improve the quality of the water supplied to the cardiac catheter reprocessing laboratory. Standard operating procedures for reprocessing cardiac catheters were established and reprocessing staff were trained and educated.

Results:

The rate of pyrogenic reactions decreased significantly during the intervention phases, from 12.8% (159 of 1,239) in phase 1 to 5.3% (38 of 712) in phase 2 to 0.5% (4 of 769) in phase 3 (chi-square test for linear trend, 97.5;P< .001).

Conclusion:

Improving water quality and using standard operating procedures for reprocessing catheters can prevent pyrogenic reactions in hospitalized patients.
Clinical Experience With Minocycline and Rifampin-Impregnated Central Venous Catheters in Bone Marrow Transplantation Recipients: Efficacy and Low Risk of Developing Staphylococcal Resistance
Authors: Chatzinikolaou Ioannis , Hanna Hend , Graviss Linda , Chaiban Gassan , Perego Cheryl , Arbuckle Rebecca , Champlin Richard , Darouiche Rabih , Samonis George , Raad Issam
Published: March 2006

In this retrospective evaluation of the 4-year clinical use of minocycline and rifampin-impregnated catheters in bone marrow transplantation (BMT) patients, we report low risk of development of staphylococcal resistance to the antibiotics coating the catheters and efficacy in preventing primary staphylococcal bloodstream infections.
RoseomonasInfection Associated With a Left Ventricular Assist Device
Authors: Singal Amit , Malani Preeti N. , Day Larry J. , Pagani Francis D. , Clark Nina M.
Published: March 2006

Roseomonasspecies have been increasingly noted as causes of human infection. We present what we believe is the first case of left ventricular assist device (LVAD) infection secondary toRoseomonas. The clinical characteristics ofRoseomonasinfection and the pertinent features of LVAD infection are reviewed.
Zinc Supplementation in Acute Diarrhea is Acceptable, Does Not Interfere with Oral Rehydration, and Reduces the Use of Other Medications
Authors:   INCLEN Childnet Zinc Effectiveness for Diarrhea (IC‐ZED) Group
Published: March 2006

Objective:

Assess the impact of zinc supplementation with locally developed culturally specific educational statements (messages) on oral rehydration solution (ORS) and antibiotics or antidiarrheal use in children with acute watery diarrhea as well as to assess adherence and side effects of zinc.

Methods:

This was a randomized effectiveness trial conducted in outpatient health facilities of six sites in five countries, namely, Fortaleza (Brazil), Addis Adaba (Ethiopia), Cairo (Egypt), Lucknow and Nagpur (India), and Manila (Philippines). Participants were 2,002 children aged 2 to 59 months. Intervention was zinc (20 mg orally, once daily for 14 days) with ORS (zinc group) compared with ORS alone (control group). Primary outcomes were ORS use on day 3 to 5; adherence to zinc; and any use of an antibacterial/antidiarrheal up to day 14.

Results:

One thousand ten and 992 children enrolled in zinc and control groups, respectively. Loss to follow‐up on days 3 to 5 and 15 to 17 was 1.2% and 2.8% in the zinc group and 0.8% and 1.7% in the control group. In five of six sites, ORS use in cases with continued diarrhea on days 3 to 5 was the same in the two groups or higher in zinc group. Overall adherence to zinc supplementation was 83.8% (95% confidence interval [CI] 81‐86). There was no difference in vomiting by group. In consideration of the six countries overall, less antibiotic/antidiarrheal use occurred in the zinc group (absolute difference, 3.8% [95% CI 1.7‐5.9]).

Conclusions:

In the management of acute watery diarrhea, zinc plus ORS along with culturally appropriate, site‐specific messages in local language does not affect overall ORS use generally and decreases antibiotic/antidiarrheal use; children had good adherence without side effects.
Double‐Blind, Placebo‐Controlled Trial Comparing Effects of Supplementation with Two Different Combinations of Micronutrients Delivered as Sprinkles on Growth, Anemia, and Iron Deficiency in Cambodian Infants
Authors: Giovannini Marcello , Sala Debora , Usuelli Michele , Livio Luca , Francescato Gaia , Braga Marta , Radaelli Giovanni , Riva Enrica
Published: March 2006

Objectives:

To assess and compare efficacy of two micronutrient sprinkle supplementation on growth, anemia, and iron deficiency in Cambodian infants.

Methods:

A total of 204 infants aged 6 months and living in Kompong Chhnang Province, Cambodia were randomly assigned to receive daily supplements of either iron (12.5 mg) plus folic acid (150 μg) plus zinc (5 mg) (MMN, n = 68), or iron (12.5 mg) plus folic acid (150 μg) alone (FFA, n = 68), or placebo (n = 68) for a 12 month period in powder form as sprinkles. Anthropometrics was evaluated bimonthly. Biochemical assessment was performed at baseline and at the end of intervention period.

Results:

At baseline, the overall mean (SD) of hemoglobin concentration was 101 g/L. No difference among groups was found for growth pattern. Significant decline was observed for weight‐for‐age and height‐for‐age z‐scores in any group (P < 0.0001). The rate of recovery from anemia was significant (P < 0.001) and comparable between MMN (54%) and FFA (53%) groups and higher than in the placebo group (22%, P < 0.0001). Through the study period, no significant change in the rate of iron deficiency was found in MMN and FFA groups, whereas it increased in the placebo group (31%, baseline vs. 52%, end of study; P < 0.0001).

Conclusion:

Both MMN and FFA supplements were effective for preventing or treating anemia in Cambodian infants and stabilizing plasma levels of ferritin. Use of micronutrients in a controlled home setting, as sprinkled daily supplements, may be promising in preventing and treating anemia in developing countries.