bluuebunny/crossref_metadata_2025 huggingface dataset:
Venomous protease of aphid soldier for colony defense
Authors: Kutsukake Mayako , Shibao Harunobu , Nikoh Naruo , Morioka Mizue , Tamura Tomohiro , Hoshino Tamotsu , Ohgiya Satoru , Fukatsu Takema
Published: July 2004

In social aphids, morphological, behavioral, and physiological differences between soldiers and normal insects are attributed to differences in gene expression between them, because they are clonal offspring parthenogenetically produced by the same mothers. By using cDNA subtraction, we identified a soldier-specific cysteine protease of the family cathepsin B in a social aphid,
Tuberaphis styraci
, with a second-instar soldier caste. The cathepsin B gene was specifically expressed in soldiers and first-instar nymphs destined to be soldiers. The cathepsin B protein was preferentially produced in soldiers and showed a protease activity typical of cathepsin B. The cathepsin B mRNA and protein were localized in the midgut of soldiers. For colony defense, soldiers attack enemies with their stylet, which causes paralysis and death of the victims. Notably, after soldiers attacked moth larvae, the cathepsin B protein was detected from the paralyzed larvae. Injection of purified recombinant cathepsin B protein certainly killed the recipient moth larvae. From these results, we concluded that the cathepsin B protein is a major component of the aphid venom produced by soldiers of
T
.
styraci
. Soldier-specific expression of the cathepsin B gene was found in other social aphids of the genus
Tuberaphis
. The soldier-specific cathepsin B gene showed an accelerated molecular evolution probably caused by the action of positive selection, which had been also known from venomous proteins of other animals.
Bioreactor-based bone tissue engineering: The influence of dynamic flow on osteoblast phenotypic expression and matrix mineralization
Authors: Yu Xiaojun , Botchwey Edward A. , Levine Elliot M. , Pollack Solomon R. , Laurencin Cato T.
Published: July 2004

An important issue in tissue engineering concerns the possibility of limited tissue ingrowth in tissue-engineered constructs because of insufficient nutrient transport. We report a dynamic flow culture system using high-aspect-ratio vessel rotating bioreactors and 3D scaffolds for culturing rat calvarial osteoblast cells. 3D scaffolds were designed by mixing lighter-than-water (density, <1g/ml) and heavier-than-water (density, >1g/ml) microspheres of 85:15 poly(lactide-
co
-glycolide). We quantified the rate of 3D flow through the scaffolds by using a particle-tracking system, and the results suggest that motion trajectories and, therefore, the flow velocity around and through scaffolds in rotating bioreactors can be manipulated by varying the ratio of heavier-than-water to lighter-than-water microspheres. When rat primary calvarial cells were cultured on the scaffolds in bioreactors for 7 days, the 3D dynamic flow environment affected bone cell distribution and enhanced cell phenotypic expression and mineralized matrix synthesis within tissue-engineered constructs compared with static conditions. These studies provide a foundation for exploring the effects of dynamic flow on osteoblast function and provide important insight into the design and optimization of 3D scaffolds suitable in bioreactors for
in vitro
tissue engineering of bone.
The ion channel of F-ATP synthase is the target of toxic organotin compounds
Authors: von Ballmoos Christoph , Brunner Josef , Dimroth Peter
Published: July 2004

ATP is the universal energy currency of living cells, and the majority of it is synthesized by the F
1
F
0
ATP synthase. Inhibitors of this enzyme are therefore potentially detrimental for all life forms. Tributyltin chloride (TBT-Cl) inhibits ATP hydrolysis by the Na
+
-translocating ATP synthase of
Ilyobacter tartaricus
or the H
+
-translocating counterpart of
Escherichia coli
with apparent
K
i
of 200 nM. To target the site of this inhibition, we synthesized a tritium-labeled derivative of TBT-Cl in which one of the butyl groups was replaced by a photoactivatable aryldiazirine residue. Upon illumination, subunit a of the ATP synthase becomes specifically modified, and this labeling is suppressed in the presence of the original inhibitor. In case of the Na
+
ATP synthase, labeling is also suppressed in the presence of Na
+
ions, suggesting an interference in Na
+
or TBT-Cl binding to subunit a. This interference is corroborated by the protection of ATP hydrolysis from TBT-Cl inhibition by 105 mM Na
+
. TBT-Cl strongly inhibits Na
+
exchange by the reconstituted
I. tartaricus
ATP synthase. Taken together these results indicate that the subunit a ion channel is the target site for ATPase inhibition by toxic organotin compounds. An inhibitor interacting specifically with this site has not been reported previously.
Venezuelan equine encephalitis emergence: Enhanced vector infection from a single amino acid substitution in the envelope glycoprotein
Authors: Brault Aaron C. , Powers Ann M. , Ortiz Diana , Estrada-Franco Jose G. , Navarro-Lopez Roberto , Weaver Scott C.
Published: July 2004

In 1993 and 1996, subtype IE Venezuelan equine encephalitis (VEE) virus caused epizootics in the Mexican states of Chiapas and Oaxaca. Previously, only subtype IAB and IC VEE virus strains had been associated with major outbreaks of equine and human disease. The IAB and IC epizootics are believed to emerge via adaptation of enzootic (sylvatic, equine-avirulent) strains for high titer equine viremia that results in efficient infection of mosquito vectors. However, experimental equine infections with subtype IE equine isolates from the Mexican outbreaks demonstrated neuro-virulence but little viremia, inconsistent with typical VEE emergence mechanisms. Therefore, we hypothesized that changes in the mosquito vector host range might have contributed to the Mexican emergence. To test this hypothesis, we evaluated the susceptibility of the most abundant mosquito in the deforested Pacific coastal locations of the VEE outbreaks and a proven epizootic vector,
Ochlerotatus taeniorhynchus
. The Mexican epizootic equine isolates exhibited significantly greater infectivity compared with closely related enzootic strains, supporting the hypothesis that adaptation to an efficient epizootic vector contributed to disease emergence. Reverse genetic studies implicated a Ser → Asn substitution in the E2 envelope glycoprotein as the major determinant of the increased vector infectivity phenotype. Our findings underscore the capacity of RNA viruses to alter their vector host range through minor genetic changes, resulting in the potential for disease emergence.
Cardioprotective effects of thioredoxin in myocardial ischemia and the reperfusion role of S-nitrosation
Authors: Tao Ling , Gao Erhe , Bryan Nathan S. , Qu Yan , Liu Hui-Rong , Hu Aihua , Christopher Theodore A. , Lopez Bernard L. , Yodoi Junji , Koch Walter J. , Feelisch Martin , Ma Xin L.
Published: July 2004

Apoptosis contributes to myocardial ischemia/reperfusion (MI/R) injury, and both thioredoxin (Trx) and nitric oxide have been shown to exert antiapoptotic effectsin vitro. Recent evidence suggests that this particular action of Trx requires S-nitrosation at Cys-69. The present study sought to investigate whether or not exogenously applied Trx reduces MI/R injuryin vivoand to which extent this effect depends on S-nitrosation. Adult mice were subjected to 30 min of MI and treated with either vehicle or human Trx (hTrx, 2 mg/kg, i.p.) 10 min before reperfusion. Native hTrx was incorporated into myocardial tissue as shown by immunostaining, and reduced MI/R injury as evidenced by decreased terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) staining, DNA fragmentation, caspase-3 activity, and infarct size. When hTrx was partially S-nitrosated by preincubation withS-nitrosoglutathione, its cardioprotective effect was markedly enhanced. Treatment with hTrx significantly reduced p38 mitogen-activated protein kinase (MAPK) activity, and this effect was also potentiated by S-nitrosation. To further address the role of S-nitrosation for the overall antiapoptotic effect to Trx, the action ofEscherichia coliTrx (eTrx) was investigated in the same model. Whereas eTrx inhibited MI/R-induced apoptosis to a degree similar to hTrx, S-nitrosation of this protein, which lacks Cys-69, failed to further enhance its antiapoptotic action. Collectively, our results demonstrate that systemically applied Trx is taken up by the myocardium to exert potent cardioprotective effectsin vivo, offering interesting therapeutic avenues. In the case of hTrx, these effects are further potentiated by S-nitrosation, but this posttranslational modification is not essential for protection.
Transcriptional repression of target genes by LEUNIG and SEUSS, two interacting regulatory proteins for
Arabidopsis
flower development
Authors: Sridhar Vaniyambadi V. , Surendrarao Anandkumar , Gonzalez Deyarina , Conlan R. Steven , Liu Zhongchi
Published: July 2004

Transcription repression plays important roles in preventing crucial regulatory proteins from being expressed in inappropriate temporal or spatial domains.
LEUNIG
(
LUG
) and
SEUSS
(
SEU
) normally act to prevent ectopic expression of the floral homeotic gene
AGAMOUS
in flowers.
LUG
encodes a protein with sequence similarities to the yeast Tup1 corepressor.
SEU
encodes a plant-specific regulatory protein with sequence similarity in a conserved dimerization domain to the LIM-domain binding 1/Chip proteins in mouse and
Drosophila
. Despite the molecular isolation of
LUG
and
SEU
, the biochemical function of these two proteins remains uncharacterized, and the mechanism of
AGAMOUS
repression remains unknown. Here, we report that LUG and SEU interact directly
in vitro
and
in vivo
. Furthermore, LUG exhibits a strong repressor activity on several heterologous promoters in yeast and plant cells. SEU, in contrast, does not exhibit any direct repressor activity, but can repress reporter gene expression only in the presence of LUG, indicating a possible role of SEU as an adaptor protein for LUG. Our results demonstrate that LUG encodes a functional homologue of Tup1 and that SEU may function similarly to Ssn6, an adaptor protein of Tup1. We have defined the LUG/LUH, Flo8, single-strand DNA-binding protein domain of LUG as both necessary and sufficient for the interaction with SEU and two domains of LUG as important for its repressor function. Our work provides functional insights into plant transcriptional corepressors and reveals both conservation and distinctions between plant corepressors and those of yeast and animals.
Reproductive ground plan may mediate colony-level selection effects on individual foraging behavior in honey bees
Authors: Amdam Gro V. , Norberg Kari , Fondrk M. Kim , Page Robert E.
Published: July 2004

The colony-level phenotype of an insect society emerges from interactions between large numbers of individuals that may differ considerably in their morphology, physiology, and behavior. The proximate and ultimate mechanisms that allow this complex integrated system to form are not fully known, and understanding the evolution of social life strategies is a major topic in systems biology. In solitary insects, behavior, sensory tuning, and reproductive physiology are linked. These associations are controlled in part by pleiotropic networks that organize the sequential expression of phases in the reproductive cycle. Here we explore whether similar associations give rise to different behavioral phenotypes in a eusocial worker caste. We document that the pleiotropic genetic network that controls foraging behavior in functionally sterile honey bee workers (
Apis mellifera
) has a reproductive component. Associations between behavior, physiology, and sensory tuning in workers with different foraging strategies indicate that the underlying genetic architectures were designed to control a reproductive cycle. Genetic circuits that make up the regulatory “ground plan” of a reproductive strategy may provide powerful building blocks for social life. We suggest that exploitation of this ground plan plays a fundamental role in the evolution of social insect societies.
Rpe65 Leu450Met variant is associated with reduced levels of the retinal pigment epithelium lipofuscin fluorophores A2E and iso-A2E
Authors: Kim So Ra , Fishkin Nathan , Kong Jian , Nakanishi Koji , Allikmets Rando , Sparrow Janet R.
Published: July 2004

There is a growing body of evidence that the nondegradable fluorophores that accumulate as the lipofuscin of retinal pigment epithelium (RPE) are involved in mechanisms leading to the degeneration of RPE in macular degeneration. Most of the constituents of RPE lipofuscin are inadvertent products of the retinoid visual cycle, the enzymatic pathway by which the 11-
cis
-retinal chromophore of rhodopsin is generated. Indeed, a major constituent of RPE lipofuscin, the pyridinium bisretinoid A2E, is a diretinal conjugate that forms in photoreceptor cells and is deposited in RPE cells as a consequence of the phagocytosis of the outer segment membrane by RPE cells. Given the adverse effects of A2E, there is considerable interest in combating its deposition so as to protect against vision loss. These efforts, however, necessitate an understanding of factors that modulate its formation. Here we show that an amino acid variant in murine Rpe65, a visual-cycle protein required for the regeneration of 11-
cis
-retinal, is associated with reduced A2E accumulation.
Pheromone anosmia in a scarab beetle induced by
in vivo
inhibition of a pheromone-degrading enzyme
Authors: Maïbèche-Coisne Martine , Nikonov Alexander A. , Ishida Yuko , Jacquin-Joly Emmanuelle , Leal Walter S.
Published: July 2004

Previous biochemical evidence suggests that a cytochrome P450 specific to male antennae of the pale-brown chafer,
Phyllopertha diversa
, has evolved as a pheromone-degrading enzyme. By using a bioinformatics approach, we have now cloned three P450 cDNAs: CYP4AW1, CYP4AW2, and CYP6AT1. RT-PCR indicated that CYP4AW2 is expressed in all tissues examined, that CYP6AT1 is antennae-rich, and that CYP4AW1 is antennae-specific. Both tissue specificity and electrophysiological studies strongly support that CYP4AW1 in
P. diversa
is a pheromone-degrading enzyme involved in pheromone inactivation. Highly sensitive, pheromone-specific olfactory receptor neurons in male antennae were completely desensitized by direct application of metyrapone into the sensillar lymph. When tested in the same or different individuals, the metyrapone treatment had no effect on olfactory receptor neurons tuned to the plant volatile (
Z
)-3-hexenyl acetate, which might be inactivated by an esterase. Metyrapone treatment did not affect pheromone reception in the Japanese beetle,
Popillia japonica
, in the scarab beetle,
Anomala octiescostata
, or in the Oriental beetle,
Exomala orientalis
. Metyrapone-induced anosmia was restricted to the pheromone detectors in
P. diversa
, which became insensitive to physiological concentrations of pheromones for a few minutes. As opposed to previous trials, the specificity of the inhibitor and pheromone system led to unambiguous evidence for the role of pheromone-degrading enzymes in the fast inactivation of pheromones.
Tissue remodeling of rat pulmonary arteries in recovery from hypoxic hypertension
Authors: Li Zhuangjie , Huang Wei , Jiang Zong Lai , Gregersen Hans , Fung Yuan-Cheng
Published: July 2004

The reversibility of tissue remodeling is of general interest to medicine. Pulmonary arterial tissue remodeling during hypertension induced by hypoxic breathing is well known, but little has been said about the recovery of the arterial wall when the blood pressure is lowered again. We hypothesize that tissue recovery is a function of the oxygen concentration, blood pressure, location on the vascular tree, and time. We measured the changes of blood pressure, vessel lumen, vessel wall thicknesses, and opening angle of each segment of the blood vessel at its zero-stress state after step changes of the oxygen concentration in the breathing gas. The zero-stress state of each vessel is emphasized because it is important to the analysis of stress and strain and in morphometry. Experimental results are presented as histories of tissue parameters after step changes of the oxygen level. Tissue characteristics are examined under the hypothesis that they are linearly related to changes in the local blood pressure. Under this linearity hypothesis, each aspect of the tissue change can be expressed as a convolution integral of the blood pressure history with a kernel called the indicial response function. It is shown the indicial response function for rising blood pressure is different from that for falling blood pressure. This difference represents a major nonlinearity of the tissue remodeling process of the blood vessels.
The SapB morphogen is a lantibiotic-like peptide derived from the product of the developmental gene
ramS
in
Streptomyces coelicolor
Authors: Kodani Shinya , Hudson Michael E. , Durrant Marcus C. , Buttner Mark J. , Nodwell Justin R. , Willey Joanne M.
Published: July 2004

SapB is a morphogenetic peptide that is important for aerial mycelium formation by the filamentous bacterium
Streptomyces coelicolor
. Production of SapB commences during aerial mycelium formation and depends on most of the genes known to be required for the morphogenesis of aerial hyphae. Furthermore, the application of purified SapB to mutants blocked in morphogenesis restores their capacity to form aerial hyphae. Here, we present evidence that SapB is a lantibiotic-like peptide that is derived by posttranslational modification from the product of a gene (
ramS
) in the four-gene
ram
operon, which is under the control of the regulatory gene
ramR
. We show that the product of another gene in the operon (
ramC
) contains a region that is similar to enzymes involved in the biosynthesis of lantibiotics, suggesting that it might be involved in the posttranslational processing of RamS. We conclude that SapB is derived from RamS through proteolytic cleavage and the introduction of four dehydroalanine residues and two lanthionine bridges. We provide an example of a morphogenetic role for an antibiotic-like molecule.
Mapping glycoside hydrolase substrate subsites by isothermal titration calorimetry
Authors: Zolotnitsky Gennady , Cogan Uri , Adir Noam , Solomon Vered , Shoham Gil , Shoham Yuval
Published: July 2004

Relating thermodynamic parameters to structural and biochemical data allows a better understanding of substrate binding and its contribution to catalysis. The analysis of the binding of carbohydrates to proteins or enzymes is a special challenge because of the multiple interactions and forces involved. Isothermal titration calorimetry (ITC) provides a direct measure of binding enthalpy (Δ
H
a
) and allows the determination of the binding constant (free energy), entropy, and stoichiometry. In this study, we used ITC to elucidate the binding thermodynamics of xylosaccharides for two xylanases of family 10 isolated from
Geobacillus stearothermophilus
T-6. The change in the heat capacity of binding (Δ
C
p
= Δ
H
/Δ
T
) for xylosaccharides differing in one sugar unit was determined by using ITC measurements at different temperatures. Because hydrophobic stacking interactions are associated with negative Δ
C
p
, the data allow us to predict the substrate binding preference in the binding subsites based on the crystal structure of the enzyme. The proposed positional binding preference was consistent with mutants lacking aromatic binding residues at different subsites and was also supported by tryptophan fluorescence analysis.
Subfertility and defective folliculogenesis in female mice lacking androgen receptor
Authors: Hu Yueh-Chiang , Wang Peng-Hui , Yeh Shuyuan , Wang Ruey-Sheng , Xie Chao , Xu Qingquan , Zhou Xinchang , Chao Hsiang-Tai , Tsai Meng-Yin , Chang Chawnshang
Published: July 2004

The roles of the androgen receptor (AR) in female fertility and ovarian function remain largely unknown. Here we report on the generation of female mice lacking AR (
AR
–/–
) and the resulting influences on the reproductive system. Female
AR
–/–
mice appear normal but show longer estrous cycles and reduced fertility. The ovaries from sexually mature
AR
–/–
females exhibited a marked reduction in the number of corpora lutea. After superovulation treatment, the
AR
–/–
ovaries produced fewer oocytes and also showed fewer corpora lutea. During the periovulatory period, an intensive granulosa apoptosis event occurs in the
AR
–/–
preovulatory follicles, concurrent with the down-regulation of p21 and progesterone receptor expression. Furthermore, the defective conformation of the cumulus cell–oocyte complex from the
AR
–/–
females implies a lower fertilization capability of the
AR
–/–
oocytes. In addition to insufficient progesterone production, the diminished endometrial growth in uteri in response to exogenous gonadotropins indicates that
AR
–/–
females exhibit a luteal phase defect. Taken together, these data provide
in vivo
evidence showing that AR plays an important role in female reproduction.
In vivopositron-emission tomography imaging of progression and transformation in a mouse model of mammary neoplasia
Authors: Abbey Craig K. , Borowsky Alexander D. , McGoldrick Erik T. , Gregg Jeffrey P. , Maglione Jeannie E. , Cardiff Robert D. , Cherry Simon R.
Published: July 2004

Imaging mouse models of human cancer promises more effective analysis of tumor progression and reduction of the number of animals needed for statistical power in preclinical therapeutic intervention trials. This study utilizes positron emission tomography imaging of 2-[18F]-fluoro-deoxy-d-glucose to monitor longitudinal development of mammary intraepithelial neoplasia outgrowths in immunocompetent FVB/NJ mice. The mammary intraepithelial neoplasia outgrowth tissues mimic the progression of breast cancer from premalignant ductal carcinomain situto invasive carcinoma. Progression of disease is clearly evident in the positron emission tomography images, and tracer uptake correlates with histological evaluation. Furthermore, quantitative markers of disease extracted from the images can be used to track proliferation and progressionin vivoover multiple time points.
Specific and differential inhibition of very-long-chain fatty acid elongases from
Arabidopsis thaliana
by different herbicides
Authors: Trenkamp Sandra , Martin William , Tietjen Klaus
Published: July 2004

In higher plants, very-long-chain fatty acids (VLCFAs) are the main constituents of hydrophobic polymers that prevent dessication at the leaf surface and provide stability to pollen grains. Of the 21 genes encoding VLCFA elongases (VLCFAEs) from
Arabidopsis thaliana
, 17 were expressed heterologously in
Saccharomyces cerevisiae
. Six VLCFAEs, including three known elongases (FAE1, KCS1, and KCS2) and three previously uncharacterized gene products (encoded by At5g43760, At1g04220, and At1g25450) were found to be enzymatically active with endogenous yeast fatty acid substrates and to some extent with externally supplied unsaturated substrates. The spectrum of VLCFAs accumulated in expressing yeast strains was determined by gas chromatography/mass spectrometry. Marked specificity was found among elongases tested with respect to their elongation products, which encompassed saturated and monounsaturated fatty acids 20–30 carbon atoms in length. The active VLCFAEs revealed highly distinct patterns of differential sensitivity to oxyacetamides, chloroacetanilides, and other compounds tested, whereas yeast endogenous VLCFA production, which involves its unrelated elongase (ELO) in sphingolipid synthesis, was unaffected. Several compounds inhibited more than one VLCFAE, and some inhibited all six active enzymes. These findings pinpoint VLCFAEs as the target of the widely used K
3
class herbicides, which have been in commercial use for 50 years, provide important clues as to why spontaneous resistance to this class is rare, and point to complex patterns of substrate specificity and product spectrum among members of the
Arabidopsis
VLCFAE family.
MR imaging of displaced meniscal tears of the knee: Importance of a “disproportional posterior horn sign”
Authors: Chen H.C. , Hsu C.Y. , Shih T.T.F. , Huang K.M. , Li Y.W.
Published: July 2004

Purpose: Meniscal tears associated with displaced fragments are clinically significant. We propose the "disproportional posterior horn sign" as a supportive criterion to identify a posterocentrally displaced meniscal fragment on MR imaging studies. If the meniscal posterior horn in the central portion appears larger than that in the peripheral section, it is considered positive for "disproportional posterior horn sign".

Material and Methods: MR images obtained in 42 patients with 43 lesions, confirmed to have displaced meniscal tears, were included in this study. The MR images were retrospectively evaluated for the presence of the "disproportional posterior horn sign", as well as the other known signs.

Results: The "disproportional posterior horn sign" was seen in 9 (20.9%) of 43 lesions, including 1 lateral discoid meniscal tear, 5 lateral meniscal tears and 3 medial meniscal tears. Five of them also had other signs of a displaced meniscal fragment. However, the remaining 4 cases only exhibited the "disproportional posterior horn sign". For the other MR signs, the "absent bow tie sign" was detected in 40 (93%) of 43 lesions, the "flipped meniscus sign" in 27 (62.8%) of 43 lesions, the "double posterior cruciate ligament sign" in 17 (39.5%) of 43 lesions and the "notch fragment sign" in 22 (51.2%) of 43 lesions.

Conclusion: The "disproportional posterior horn sign" is helpful in demonstrating a posterocentrally displaced meniscal fragment, especially when other characteristic signs are unremarkable or absent.
Long-term results of combined surgical and radiological intervention in complicated aortic dissection type-a: A case report
Authors: Cwikiel W. , Harnek J. , Dobre M.
Published: July 2004

We report the long-term results of combined surgical and radiological intervention in a patient with complicated aortic dissection, type-A. Following surgical graft-repair of a dissected part of the ascending aorta, embolization of the splenic artery, and stenting of the major abdominal arteries and of the left renal artery, was performed. The patient was able to return to normal active life, and all stented arteries remained patent after 32 months. A stent that was mispositioned across the aortic lumen did not cause any symptoms.
Relationship Between Fractional Separation Curves and Quantitative Optimization Criteria in the Separation of Pourable Materials
Authors: Barsky E. , Barsky M.
Published: July 2004

For more than 60 years, the accepted wisdom has been that the methods of optimizing separation processes based on quantitative criteria are fundamentally different from those based on separation curves. The present article demonstrates a functional relation between these two approaches. Reposing upon this relation, we propose a new method for the optimization of separation processes, which combines the advantages of both approaches, namely the availability of a quantitative evaluation and invariance of the evaluation with respect to the grain‐size distribution of the starting material.
Analysis of the Influence of the Neighbouring Elements in an HGMS Matrix on the Magnetic Field Distribution in the Vicinity of One Element
Authors: Mostyka Yu. S. , Shutov V. Yu. , Grebenyuk L. Z.
Published: July 2004

This article theoretically researches the magnetic field distribution within HGMS matrix free space – a stack of orderly placed cylinder bars. It is shown that, in near vicinity of any matrix bar, the distribution of the magnetic field practically coincides with the field distribution around a single cylinder. Relative differences of force distribution characteristic f(x, y) = H|gradH| are calculated for the bar stack and single cylinders depending upon the relative distance between a given field point and the axis of the bar.
Muscle satellite cells adopt divergent fates
Authors: Zammit Peter S. , Golding Jon P. , Nagata Yosuke , Hudon Valérie , Partridge Terence A. , Beauchamp Jonathan R.
Published: July 2004

Growth, repair, and regeneration of adult skeletal muscle depends on the persistence of satellite cells: muscle stem cells resident beneath the basal lamina that surrounds each myofiber. However, how the satellite cell compartment is maintained is unclear. Here, we use cultured myofibers to model muscle regeneration and show that satellite cells adopt divergent fates. Quiescent satellite cells are synchronously activated to coexpress the transcription factors Pax7 and MyoD. Most then proliferate, down-regulate Pax7, and differentiate. In contrast, other proliferating cells maintain Pax7 but lose MyoD and withdraw from immediate differentiation. These cells are typically located in clusters, together with Pax7−ve progeny destined for differentiation. Some of the Pax7+ve/MyoD−ve cells then leave the cell cycle, thus regaining the quiescent satellite cell phenotype. Significantly, noncycling cells contained within a cluster can be stimulated to proliferate again. These observations suggest that satellite cells either differentiate or switch from terminal myogenesis to maintain the satellite cell pool.
Zinc and the Msc2 zinc transporter protein are required for endoplasmic reticulum function
Authors: Ellis Charissa D. , Wang Fudi , MacDiarmid Colin W. , Clark Suzanne , Lyons Thomas , Eide David J.
Published: July 2004

In this report, we show that zinc is required for endoplasmic reticulum function in Saccharomyces cerevisiae. Zinc deficiency in this yeast induces the unfolded protein response (UPR), a system normally activated by unfolded ER proteins. Msc2, a member of the cation diffusion facilitator (CDF) family of metal ion transporters, was previously implicated in zinc homeostasis. Our results indicate that Msc2 is one route of zinc entry into the ER. Msc2 localizes to the ER when expressed at normal levels. UPR induction in low zinc is exacerbated in an msc2 mutant. Genetic and biochemical evidence indicates that this UPR induction is due to genuine ER dysfunction. Notably, we found that ER-associated protein degradation is defective in zinc-limited msc2 mutants. We also show that the vacuolar CDF proteins Zrc1 and Cot1 are other pathways of ER zinc acquisition. Finally, zinc deficiency up-regulates the mammalian ER stress response indicating a conserved requirement for zinc in ER function among eukaryotes.
Monitoring disulfide bond formation in the eukaryotic cytosol
Authors: Østergaard Henrik , Tachibana Christine , Winther Jakob R.
Published: July 2004

Glutathione is the most abundant low molecular weight thiol in the eukaryotic cytosol. The compartment-specific ratio and absolute concentrations of reduced and oxidized glutathione (GSH and GSSG, respectively) are, however, not easily determined. Here, we present a glutathione-specific green fluorescent protein–based redox probe termed redox sensitive YFP (rxYFP). Using yeast with genetically manipulated GSSG levels, we find that rxYFP equilibrates with the cytosolic glutathione redox buffer. Furthermore, in vivo and in vitro data show the equilibration to be catalyzed by glutaredoxins and that conditions of high intracellular GSSG confer to these a new role as dithiol oxidases. For the first time a genetically encoded probe is used to determine the redox potential specifically of cytosolic glutathione. We find it to be −289 mV, indicating that the glutathione redox status is highly reducing and corresponds to a cytosolic GSSG level in the low micromolar range. Even under these conditions a significant fraction of rxYFP is oxidized.
Deletion of the Nucleotide Excision Repair Gene Ercc1 Reduces Immunoglobulin Class Switching and Alters Mutations Near Switch Recombination Junctions
Authors: Schrader Carol E. , Vardo Joycelyn , Linehan Erin , Twarog Michael Z. , Niedernhofer Laura J. , Hoeijmakers Jan H.J. , Stavnezer Janet
Published: July 2004

The structure-specific endonuclease ERCC1-XPF is an essential component of the nucleotide excision DNA repair pathway. ERCC1-XPF nicks double-stranded DNA immediately adjacent to 3′ single-strand regions. Substrates include DNA bubbles and flaps. Furthermore, ERCC1 interacts with Msh2, a mismatch repair (MMR) protein involved in class switch recombination (CSR). Therefore, ERCC1-XPF has abilities that might be useful for antibody CSR. We tested whether ERCC1 is involved in CSR and found that Ercc1−/− splenic B cells show moderately reduced CSR in vitro, demonstrating that ERCC1-XPF participates in, but is not required for, CSR. To investigate the role of ERCC1 in CSR, the nucleotide sequences of switch (S) regions were determined. The mutation frequency in germline Sμ segments and recombined Sμ-Sγ3 segments cloned from Ercc1−/− splenic B cells induced to switch in culture was identical to that of wild-type (WT) littermates. However, Ercc1−/− cells show increased targeting of the mutations to G:C bp in RGYW/WRCY hotspots and mutations occur at sites more distant from the S–S junctions compared with WT mice. The results indicate that ERCC1 is not epistatic with MMR and suggest that ERCC1 might be involved in processing or repair of DNA lesions in S regions during CSR.
Classification and Consequences of Errors in Otolaryngology
Authors: Shah Rahul K. , Kentala Erna , Healy Gerald B. , Roberson David W.
Published: July 2004

Objective: To develop a preliminary classification system for errors in otolaryngology.

Methods: A retrospective, anonymous survey was distributed to 2,500 members of the American Academy of Otolaryngology–Head and Neck Surgery (AAO‐HNS). Respondents were asked whether an error had occurred in their practice in the last 6 months, and if so, to describe the error, its consequences, and any corrective action taken.

Results: There were 466 (18.6%) responses. Two hundred ten (45% of respondents) otolaryngologists reported 216 errors. A classification system for errors in otolaryngology was developed. Errors were classified as related to history and physical (1.4%), differential or final diagnosis (1.4%), testing (10.4%), surgical planning (9.9%), wrong‐site surgery (6.1%), anesthesia‐related (3.3%), wrong drug/dilution on the surgical field (3.8%), technical (19.3%), retained foreign body (0.9%), equipment‐related (9.4%), postoperative care (8.5%), medical management (13.7%), nursing/ancillary (0.5%), administrative (6.6%), communication (3.8%), and miscellaneous (0.9%). There were 78 cases of major morbidity and 9 deaths. If these data are representative, there may be more than 2,600 episodes of major morbidity and more than 165 deaths related to medical error in otolaryngology patients annually.

Conclusions: Human error in otolaryngology occurs in all practice components, including diagnostic, treatment, surgical, communication, and administrative. Types of errors reported by otolaryngologists differ from those reported by other specialists. Error classification systems may need to reflect each specialty's realm of practice. Errors in otolaryngology cause appreciable morbidity and mortality. Quantitative study of errors and the development of targeted prevention and amelioration strategies should be a high priority.
Diagnosis and Surgical Management of Nasopalatine Duct Cysts
Authors: Elliott Kimberly A. , Franzese Christine B. , Pitman Karen T.
Published: July 2004

Objectives/Hypothesis: Nasopalatine duct cysts are the most common cystic lesion of nonodontogenic origin of the maxilla. The purposes of the study were to review the epidemiology and clinical presentation, to describe the radiographic and pathological findings, and to discuss surgical management of this entity.

Study Design: Case presentations of two patients with nasopalatine duct cysts at a tertiary care institution with a review of the English medical literature from January 1960 to the present.

Methods: A 69‐year‐old man presented with an asymptomatic swelling of the premaxilla, and a 17‐year‐old woman presented with a painful swelling of the hard palate. A computed tomography scan, fine‐needle aspiration, and preoperative workup were obtained in both cases. Literature was reviewed with respect to epidemiology, etiology, presentation, diagnostic studies, operative management, and recurrence rates.

Results: Computed tomography scan demonstrated midline ovoid cystic lesions in both cases. Fine‐needle aspiration of both lesions revealed no evidence of malignancy. Surgical treatment consisted of enucleation in the first case and marsupialization in the second case. Both patients did well with no evidence of recurrence. Nasopalatine duct cyst presents in the fourth to sixth decades of life with a male predilection. Recurrence rates range from 0% to 11%.

Conclusion: Nasopalatine duct cyst occurs in approximately 1% of the population. Presentation may be asymptomatic or include swelling, pain, and drainage from the hard palate. A well‐circumscribed, round, ovoid, or heart‐shaped radiolucency is seen on computed tomography. Pathological findings reveal squamous or respiratory cell types, or a combination of these, infiltrated by inflammatory cells. Enucleation is the preferred treatment with low recurrence rates.
Respiratory Retraining of Refractory Cough and Laryngopharyngeal Reflux in Patients With Paradoxical Vocal Fold Movement Disorder
Authors: Murry Thomas , Tabaee Abtin , Aviv Jonathan E.
Published: July 2004

Objectives/Hypothesis: The objective was to describe a case series of patients with refractory cough and paradoxical vocal fold movement disorder treated with respiratory retraining therapy.

Study Design: Retrospective review of a case series in a tertiary medical care center.

Methods: Five patients with laryngopharyngeal reflux were identified with refractory cough and paradoxical fold movement disorder on transnasal fiberoptic laryngoscopy by a greater than 50% reduction in airway during inspiration. The were four women and one man (age range, 42–67 y). All patients had normal forced vital capacity and forced expiratory flow but decreased ratio of forced inspiratory volume at 0.5 seconds (FIV0.5) to forced inspiratory vital capacity (FIVC) before starting therapy. All patients were treated with more than 6 months of twice‐daily proton pump inhibitor therapy with improvement in reflux symptoms but persistent and severe daytime cough. They were subsequently treated with respiratory retraining therapy. Patients were asked to rate subjectively the severity of cough at the onset and conclusion of therapy. All patients underwent pulmonary function testing before and after therapy. Long‐term follow‐up ranged from 5 to 17 months.

Results: Patients received two to seven sessions of respiratory retraining therapy. The mean severity score changed from 9.2 before therapy to 1.3 after therapy. All patients subjectively described an improvement in the severity of their cough. Transnasal flexible laryngoscopy demonstrated improvement in paradoxical vocal fold movement, and pulmonary function testing showed improvement in the FIV0.5/FIVC ratio.

Conclusion: Patients with laryngopharyngeal reflux and refractory cough in the absence of pulmonary disease should be evaluated for paradoxical vocal fold movement disorder. Respiratory retraining therapy may represent an effective therapy for cough in the absence of relief from standard management of laryngopharyngeal reflux.
A Genomic Predictor of Oral Squamous Cell Carcinoma
Authors: Whipple Mark E. , Mendez Eduardo , Farwell D Gregory , Agoff S Nicholas , Chen Chu
Published: July 2004

Objectives/Hypothesis: The objective was to identify a genomic profile that predicts the likelihood of oral squamous cell carcinoma compared with normal oral mucosa in unknown tissue samples.

Study Design: Using a training set of tissue samples that were histologically classified as oral squamous cell carcinoma or normal mucosa, the authors used principal component analysis to develop a genomic predictor for oral squamous cell carcinoma. On a separate test set of unclassified samples, the authors used the predictor to classify the samples, then evaluated the performance of the predictor using histological diagnosis.

Methods: The authors used a data set consisting of messenger RNA extracted from 29 oral squamous cell carcinoma and 19 normal oral mucosa tissue samples and hybridized to Affymetrix oligonucleotide microarrays containing probe sets for 7070 genes and expressed sequence tags. The samples were divided into a training set of 15 oral squamous cell carcinoma and 10 normal samples and a test set consisting of the remaining samples. Using principal component analysis on the training set, the authors found a composite gene expression vector (principal component vector), which they used to compute likelihood ratios for oral squamous cell carcinoma on the test set. By calculating the contribution of each gene to the principal component vector, the authors identified genes with the greatest predictive value.

Results: Using the likelihood ratio, the authors correctly classified all 23 samples in the test set as either oral squamous cell carcinoma or normal. The authors found that many of the most predictive genes are known to be markers of squamous cell carcinoma or normal mucosa.

Conclusion: Principal component analysis can be used with genomic microarray data to correctly predict the presence of oral squamous cell carcinoma in unknown tissue samples.
Effect of Magnetic Resonance Imaging on Internal Magnet Strength in Med‐El Combi 40+ Cochlear Implants
Authors: Wackym P Ashley , Michel Michelle A. , Prost Robert W. , Banks Kristin L. , Runge‐Samuelson Christina L. , Firszt Jill B.
Published: July 2004

Objective: Magnetic resonance imaging (MRI) has been contraindicated when cochlear implants containing an internal magnet are in place because of concerns regarding torque, force, demagnetization, artifacts, induced voltages, and heating. The objective was to determine the magnetic field strength of Med‐El Combi 40+ cochlear implant internal magnets after MRI studies.

Study Design/Methods: Two fresh cadavers were used to study demagnetization using a repeated measures design and a magnetometer. Pre‐ and postMRI measurement of magnetic field strength was completed. Five sets of sagittal T1‐weighted, axial T1‐weighted, and axial T2‐weighted sequences were performed on a cadaver at 0.2 Tesla in the device‐up and device‐down positions. In the other cadaver, 15 sets of sagittal T1‐weighted, axial T1‐weighted, and axial T2‐weighted sequences were performed on a cadaver at 1.5 Tesla were conducted, 5 each with the head oriented at 80, 90, and 100 degrees rotated around the yaw plane (rotated around the z‐axis). Subsequently, three cochlear implant patients completed 0.2 Tesla MRIs. For these patients, subjective and objective assessment of cochlear implant performance was performed.

Setting: Academic medical center.

Results: In the cadaver studies, analysis of variance showed no significant difference in the magnetic field strength after the 0.2 or 1.5 Tesla scans. There was no significant difference in the magnetic field strength for the three patients undergoing 0.2 Tesla MRIs and no adverse consequences, including no changes in telemetry, auditory sensations, nonauditory sensations, and sound quality.

Conclusions: No significant demagnetization of the internal magnet occurred during repeated 1.5 Tesla MRI scans with the head orientations used in this study. In the cochlear implant patients, no significant demagnetization of the internal magnet occurred after a 0.2 Tesla MRI.
Swallowing‐Related Quality of Life After Head and Neck Cancer Treatment
Authors: Gillespie M Boyd , Brodsky Martin B. , Day Terry A. , Lee Fu‐Shing , Martin‐Harris Bonnie
Published: July 2004

Objectives: To determine the role of treatment modality in swallowing outcome after head and neck cancer treatment and to identify potential risk factors for posttreatment dysphagia.

Study Design: Cross‐sectional survey of patients with no evidence of disease 12 months or more after the treatment of a stage III or IV squamous cell carcinoma of the oropharynx, larynx, or hypopharynx.

Methods: Potential subjects were stratified by tumor site and tumor T‐stage to achieve a balanced comparison between chemoradiation (n = 18) and surgery/radiation (n = 22) groups. Outcome measures included a dysphagia risk factor survey, the MD Anderson Dysphagia Inventory (MDADI), and the Short‐Form 36 (SF‐36).

Results: Patients who received chemoradiation for oropharyngeal primaries demonstrated significantly better scores on the emotional (P = .03) and functional (P = .02) subscales of the MDADI than did patients who underwent surgery followed by radiation. There were no significant differences between chemoradiation and surgery/radiation groups for laryngeal and hypopharyngeal primaries. Additional risk factors for posttreatment dysphagia include prolonged (>2 weeks) nothing by mouth (NPO) status (P = .002) and low SF‐36 Mental Health Subscale score (P = .002).

Conclusion: The study suggests that chemoradiation may provide superior swallowing outcome to surgery/radiation in patients with oropharyngeal primary. Patients with depressed mental health and prolonged feeding tubes may be at higher risk of long‐term dysphagia.
Prospective Evaluation of Endoscopic Approaches to the Thyroid Compartment
Authors: Terris David J. , Haus Brian M. , Nettar Kartik , Ciecko Shawn , Gourin Christine G.
Published: July 2004

Objective: To compare a number of endoscopic approaches to the thyroid compartment.

Design: Prospective, nonrandomized, experimental investigation in a porcine model.

Methods: We performed a consecutive series of 13 endoscopic thyroidectomies using 5 distinct approaches. The procedures differed by the direction of the approach, incision placement, and use of facilitative maneuvers. The parameters assessed included procedure duration, estimated blood loss, heart rate, blood pressure, temperature, oxygen saturation, and arterial blood gas levels. The thyroid specimens were weighed and examined histologically.

Results: Four of the endoscopic approaches were successfully used for resection of the thyroid (12 of 13 animals). The mean operative times were as follows: superior approach (n = 4), 47 ± 14.6 minutes; lateral axillary approach (n = 4), 67 ± 11.8 minutes; and superficial axillary (n = 3), 67.7 ± 22.3 minutes. The one axillary approach took 84 minutes. The precordial approach (n = 1) lasted 47 minutes and then required open conversion. The overall median estimated blood loss was 0 (range 0–100) mL. The mean change in blood pressure and pH from the beginning to the end of the procedure was −0.5 ± 24.1 mm Hg and 0.16 ± 0.07, respectively. The thyroid glands weighed 4.3 ± 0.9 g and had normal glandular architecture with no evidence of significant tissue trauma or thermal injury. There were no cases of pneumothorax, subcutaneous emphysema, or air embolism.

Conclusion: A number of approaches to the thyroid compartment are conceivable. The superior approach proved to be the fastest and easiest, whereas the lateral axillary and superficial axillary were the best approaches from a cosmetic and clinical standpoint.