bluuebunny/crossref_metadata_2025_split huggingface dataset:
A methodology for modeling vowel formant contours in CVC context
Authors: Broad David J. , Clermont Frantz 
Published: October 2005

Models for the formant-frequency contours of vowels in CVC′ context are presented and illustrated with an American English database comprising isolated syllables with C, C′=/b,d,g/ and V=/i,i,q,æ,a,c,U,u,v,W/. Both established and reinterpreted regularities among context effects are cast in a series of successively elaborated mathematical models. The first model (model I), in common with all its successors, embodies the notion of the superposition of CV and VC′ transitions, according to which a formant trajectory FCVC′(n) is modeled as  fCV(n)+TV+gVC′(n), where n is duration-normalized time, TV is a vowel target, and  fCV(n) and gVC′(n) are initial- and final-consonant transition functions. The rms errors for F1, F2, and F3 (30, 89, and 111 Hz) against independent test data are near the minimum theoretical values (32, 69, and 100 Hz) predicted from interrepetition variation and its contribution to uncertainty in the model elements. Subsequently, the elements of the additive model are individually characterized by further incorporating per-consonant transition shape similarity (model II), target-locus scaling (model III), exponential transition shapes (model IVa), and exponential duration dependence (model IVb).
In model II, the CV and VC′ trajectories are respectively defined as L+k f*(n) and L′+k′g*(n), with contour shape functions  f* and g*, scale factors k and k′, and consonant loci L and L′. The loci are herein defined as baselines about which families of formant transitions are scaled. This model fits the data nearly as well as theory allows, except for F2 of C/i/C′ and C/ud/. Then, in model III, the scale factors k and k′ are represented by forms proportional to the target-locus distances T−L and T−L′. The vowel target T is then redefined to best fit these forms. The target-locus scaling hypothesis fares quite well except for F2 of CV sequences. In model IVa, the shape functions  f* and g* are fit to exponentials with asymptotes associated with the vowel targets. Target-locus scaling is a corollary of this vowel target definition. Finally, in model IVb, the exponential model is redefined on a recovered real-time scale. The resulting context effect follows Lindblom’s [J. Acoust. Soc. Am. 35, 1773–1781 (1963)] in decaying exponentially with vowel duration.
Analysis of
Paramecium tetraurelia A-51
Surface Antigen Gene Mutants Reveals Positive-Feedback Mechanisms for Maintenance of Expression and Temperature-Induced Activation
Authors: Matsuda Atsushi , Forney James D. 
Published: October 2005

ABSTRACT

In
Paramecium tetraurelia
, variable surface antigen loci show mutually exclusive expression which is controlled primarily at the transcriptional level. Clonally stable expression of a single antigen has attracted models involving self-regulation by their gene products. However, direct demonstration of self-feedback at the molecular level has been complicated due to the inability to separate the functional gene from its product as well as copy number effects associated with injected extrachromosomal DNA in the polygenomic somatic nucleus. In this study, we exploited several germ line termination and frameshift mutations in the
A-51
surface antigen gene to analyze variable surface antigen expression. These mutant alleles have the same copy number as the wild-type allele and therefore eliminate possible copy number effects. The mutant alleles were not transcribed at 27°C, consistent with positive-feedback models for gene expression. However, further analysis showed that high temperatures (34°C) induced transcription of the mutant
A
genes even in the presence of a different antigen on the cell surface. Thus, transcription was temperature dependent. Unlike wild-type cells, transcription of the mutant
A
genes at high temperatures was not maintained after temperature shift back to 27°C in homozygous mutant cells. Importantly, transcription of the mutant allele was maintained at 27°C in heterozygous cells with one copy of the wild-type allele. These results indicate that expression of the wild-type gene is required to stabilize its own transcriptional state at 27°C.
Rho4 GTPase Is Involved in Secretion of Glucanases during Fission Yeast Cytokinesis
Authors: Santos Beatriz , Martín-Cuadrado Ana Belén , Vázquez de Aldana Carlos R. , del Rey Francisco , Pérez Pilar 
Published: October 2005

ABSTRACT

Rho GTPases are regulators of signaling pathways that control actin organization and cell polarity processes in all eukaryotic cells. In
Schizosaccharomyces pombe
, Rho4p is involved in the regulation of septum degradation during cytokinesis. Here we show that Rho4p participates in the secretion of the glucanases Eng1p and Agn1p, which are responsible for the septum degradation. First,
eng1
+
or
agn1
+
overexpression suppressed the
rho4Δ
multiseptation phenotype, and simultaneous overproduction of Rho4p and Eng1p or of Rho4p and Agn1p caused a dramatic lysis. Second, Rho4p was not necessary for Eng1p-mediated glucanase activity as measured in cell extracts; however,
rho4Δ
cells have a lower level of (1,3)-β-
d
-glucanase activity in the culture medium. Additionally, Eng1- or Agn1-green fluorescent protein did not properly localize to the septum in
rho4Δ
cells grown at 37°C. There was a decreased amount of these enzymes in the cell wall and in the culture medium of
rho4Δ
cells at 37°C. These results provide evidence that Rho4p is involved in the regulation of Eng1p and Agn1p secretion during cytokinesis.
Nuclear Accumulation of the GATA Factor AreA in Response to Complete Nitrogen Starvation by Regulation of Nuclear Export
Authors: Todd Richard B. , Fraser James A. , Wong Koon Ho , Davis Meryl A. , Hynes Michael J. 
Published: October 2005

ABSTRACT

Both the availability and the quality of nutrients affect cellular functions by controlling gene activity. AreA, a member of the GATA family of transcription factors, globally activates expression of genes involved in nitrogen source utilization in
Aspergillus nidulans.
The quality of the nitrogen source determines the level and activation capacity of AreA through controls at the level of
areA
mRNA stability and by interaction of AreA with the corepressor NmrA. The availability of potential nitrogen sources also affects the activation capacity of AreA. We show that the complete absence of a nitrogen source results in an enhanced level of AreA-dependent gene expression and that this response is independent of mechanisms regulating AreA activity in response to nitrogen source quality. During nitrogen starvation AreA accumulates in the nucleus, but the presence of a potential nitrogen source or carbon starvation prevents this accumulation. Furthermore, accumulated AreA is rapidly lost from the nuclei of nitrogen-starved cells when a nitrogen source is supplied or when a carbon source is absent, and this accompanies arrest of the AreA-dependent nitrogen starvation response on regulated gene expression. By the generation of a leptomycin B-sensitive mutant, we have been able to show that nuclear exit occurs via the CrmA exportin. We conclude that sensing mechanisms discriminate between starvation and the presence of potential nutrients that can signal to the AreA transcription factor. Nitrogen source availability, but not quality, affects nuclear accumulation by regulating nuclear exit of AreA, providing a rapid response to changes in the supply of nutrients.
Novel Regulatory Function for the CCAAT-Binding Factor in
Candida albicans
Authors: Johnson Duncan C. , Cano Kristin E. , Kroger Erika C. , McNabb David S. 
Published: October 2005

ABSTRACT

Candida albicans
is an opportunistic human pathogen that can sense environmental changes and respond by altering its cell morphology and physiology. A number of environmental factors have been shown to influence this dimorphic transition, including pH, starvation, serum, and amino acids. In this report, we investigate the function of the
C. albicans
CCAAT-binding factor. In
Saccharomyces cerevisiae
, this heterooligomeric transcriptional activator stimulates the expression of genes that encode proteins involved in respiration. To examine the function of this transcription factor in
C. albicans
, we cloned
CaHAP5
and generated a
hap5Δ/hap5Δ
mutant of
C. albicans
. Using mobility shift studies, we identified four separate complexes from
C. albicans
cell extracts whose DNA-binding activities were abolished in the
hap5Δ/hap5Δ
mutant, suggesting that they represented sequence-specific CCAAT-binding complexes. We found that the
C. albicans hap5Δ
homozygote was defective in hyphal development under a variety of conditions, and the mutant displayed a carbon source-dependent “hyperfilamentation” phenotype under certain growth conditions. In addition, the mRNA levels for two enzymes involved in respiration, encoded by
COX5
and
CYC1
, were overexpressed in the
hap5Δ/hap5Δ
mutant when grown in medium containing amino acids as the sole carbon and nitrogen source. Thus, the
C. albicans
CCAAT-binding factor appeared to function as a repressor of genes encoding mitochondrial electron transport components, in contrast to its activator function in
S. cerevisiae
. These data provide the first evidence that the CCAAT-binding factor can act as a transcriptional repressor and raise new and interesting questions about how carbon metabolism is regulated in this opportunistic human pathogen.
Global Role of the Protein Kinase Gcn2 in the Human Pathogen
Candida albicans
Authors: Tournu Hélène , Tripathi Gyanendra , Bertram Gwyneth , Macaskill Susan , Mavor Abigail , Walker Louise , Odds Frank C. , Gow Neil A. R. , Brown Alistair J. P. 
Published: October 2005

ABSTRACT

The pathogen
Candida albicans
responds to amino acid starvation by activating pseudohyphal development and the expression of amino acid biosynthetic genes (GCN response). In
Saccharomyces cerevisiae
, the GCN response is dependent on Gcn2, which regulates the translation of the transcription factor Gcn4. Therefore, we examined the role of Gcn2 in
C. albicans
by using molecular, cellular, and genomic approaches. We show that
C. albicans GCN2
encodes an eIF2α kinase, like its
S. cerevisiae
homologue. However,
GCN4
appears to be regulated mainly at the transcriptional level in
C. albicans
. Furthermore, the inactivation of
C. albicans
Gcn2 only partially attenuates growth under amino acid starvation conditions and resistance to the histidine analogue 3-aminotriazole. Our comparison of the Gcn4 and Gcn2 regulons by transcript profiling reinforces the view that Gcn2 contributes to, but is not essential for, the activation of general amino acid control in
C. albicans
.
Microtubules in
Candida albicans
Hyphae Drive Nuclear Dynamics and Connect Cell Cycle Progression to Morphogenesis
Authors: Finley Kenneth R. , Berman Judith 
Published: October 2005

ABSTRACT

Candida albicans
is an opportunistic fungal pathogen whose virulence is related to its ability to switch between yeast, pseudohyphal, and true-hyphal morphologies. To ask how long-distance nuclear migration occurs in
C. albicans
hyphae, we identified the fundamental properties of nuclear movements and microtubule dynamics using time-lapse microscopy. In hyphae, nuclei migrate to, and divide across, the presumptive site of septation, which forms 10 to 15 μm distal to the basal cell. The mother nucleus returns to the basal cell, while the daughter nucleus reiterates the process. We used time-lapse microscopy to identify the mechanisms by which
C. albicans
nuclei move over long distances and are coordinated with hyphal morphology. We followed nuclear migration and spindle dynamics, as well as the time and position of septum specification, defined it as the presumptum, and established a chronology of nuclear, spindle, and morphological events. Analysis of microtubule dynamics revealed that premitotic forward nuclear migration is due to the repetitive sliding of astral microtubules along the cell cortex but that postmitotic forward and reverse nuclear migrations are due primarily to spindle elongation. Free microtubules exhibit cell cycle regulation; they are present during interphase and disappear at the time of spindle assembly. Finally, a growth defect in strains expressing Tub2-green fluorescent protein revealed a connection between hyphal elongation and the nuclear cell cycle that is coordinated by hyphal length and/or volume.
Chlamydospore Formation during Hyphal Growth in
Cryptococcus neoformans
Authors: Lin Xiaorong , Heitman Joseph 
Published: October 2005

ABSTRACT

Cryptococcus neoformans
, a basidiomycetous fungal pathogen, infects hosts through inhalation and can cause fatal meningoencephalitis in individuals if untreated. This fungus undergoes a dimorphic transition from yeast to filamentous growth during mating and monokaryotic fruiting, which leads to the production of hyphae and airborne infectious basidiospores. Here we characterized a novel morphological feature associated with the filamentous stages of the life cycle of
C. neoformans
which resembles resting or survival structures known as chlamydospores in other fungi. The
C. neoformans
chlamydospore-like structure is rich in glycogen, suggesting that it might have a role as an energy store. However, characterization of mutants with decreased or increased levels of glycogen production showed that glycogen levels have little effect on filamentous growth, sporulation, or chlamydospore formation. These results suggest that the formation of chlamydospores is independent of glycogen accumulation level. We also show that chlamydospore formation does not require successful sporulation and that the presence of chlamydospores is not sufficient for sporulation. Although the biological functions of chlamydospores remain to be established for this pathogenic fungus, their formation appears to be an integral part of the filamentation process, suggesting that they could be necessary to support sexual sporulation under adverse conditions and thereby facilitate the production of infectious basidiospores or long-term survival propagules in harsh environments.
Upregulation of Proinflammatory Proteins Through NF-κB Pathway by Shed Membrane Microparticles Results in Vascular Hyporeactivity
Authors: Tesse Angela , Martínez M. Carmen , Hugel Bénédicte , Chalupsky Karel , Muller Christian D. , Meziani Ferhat , Mitolo-Chieppa Delia , Freyssinet Jean-Marie , Andriantsitohaina Ramaroson 
Published: October 2005

Objective—Microparticles are membrane vesicles with procoagulant and proinflammatory properties released during cell activation, including apoptosis. The present study was designed in dissecting the effects evoked by microparticles on vascular reactivity.Methods and Results—Microparticles from either apoptotic T lymphocytic cells or from plasma of diabetic patients with vascular complications induced vascular hyporeactivity in response to vasoconstrictor agents in mouse aorta. Hyporeactivity was reversed by nitric oxide (NO) synthase plus cyclooxygenase-2 inhibitors, and associated with an increased production of vasodilatory products such as NO and prostacyclin. Microparticles induced an upregulation of proinflammatory protein expressions, inducible NO-synthase and cyclooxygenase-2, mainly in the medial layer of the vessels as evidenced by immunochemical staining. In addition, microparticles evoke NF-κB activation probably through the interaction with the Fas/Fas Ligand pathway. Finally, in vivo treatment of mice with lymphocyte-derived MPs induces vascular hyporeactivity, which was reversed by the combination of NO and cyclooxygenase-2 inhibitors.Conclusion—These data provide a rationale to explain the paracrine role of microparticles as vectors of transcellular exchange of message in promoting vascular dysfunction during inflammatory diseases.
Effects of Local Administration of Vascular Endothelial Growth Factor on Properties of the in Situ Frozen-Thawed Anterior Cruciate Ligament in Rabbits
Authors: Ju Young-Jin , Tohyama Harukazu , Kondo Eiji , Yoshikawa Toshikazu , Muneta Takeshi , Shinomiya Kenichi , Yasuda Kazunori 
Published: October 2005

Background In the autogenous tendon for anterior cruciate ligament reconstruction, intrinsic fibroblasts are necrotized immediately after surgery, and repopulation and revascularization occur. Vascular endothelial growth factor is considered to be a potent mediator of angiogenesis. Hypothesis An application of vascular endothelial growth factor significantly enhances angiogenesis in the in situ frozen anterior cruciate ligament, and the application significantly affects mechanical properties of the in situ frozen anterior cruciate ligament. Study Design Controlled laboratory study. Methods Right anterior cruciate ligaments from 66 rabbits underwent the freeze-thaw treatment, and animals were then divided into 3 groups. Group I served as a freeze-thaw but otherwise untreated control. In group II, 0.2 mL phosphate-buffered saline alone was applied. In group III, 30 µ g vascular endothelial growth factor was applied. The groups were compared on the basis of histologic revascularization examinations using the Chalkley score, an indicator of the microvessel density, and mechanical evaluations, which included the anterior-posterior translation of the tibia relative to the femur during ± 10 N of anterior-posterior load and the mechanical properties of the anteromedial bundle of the anterior cruciate ligament. Results Group III's Chalkley score was significantly greater than that of groups I and II. The tensile strength and the tangent modulus of anterior cruciate ligaments in groups I, II, and III were significantly lower than those of a normal anterior cruciate ligament, although there were no significant differences among groups I, II, and III. Conclusion Vascular endothelial growth factor, as administered in this study, significantly promoted angiogenesis in the devitalized anterior cruciate ligament with in situ freeze-thaw treatment, but it did not affect the mechanical properties of the in situ frozen-thawed anterior cruciate ligament in the rabbit model. Clinical Relevance An application of the recombinant anterior cruciate ligament is a potential future strategy to enhance revascularization of the autograft in anterior cruciate ligament reconstruction.
Arthroscopic Single-Row versus Double-Row Suture Anchor Rotator Cuff Repair
Authors: Mazzocca Augustus D. , Millett Peter J. , Guanche Carlos A. , Santangelo Stephen A. , Arciero Robert A. 
Published: October 2005

Background Recurrent defects after open and arthroscopic rotator cuff repair are common. Double-row repair techniques may improve initial fixation and quality of rotator cuff repair. Purpose To evaluate the load to failure, cyclic displacement, and anatomical footprint of 4 arthroscopic rotator cuff repair techniques. Hypothesis Double-row suture anchor repair would have superior structural properties and would create a larger footprint compared to single-row repair. Study Design Controlled laboratory study. Methods Twenty fresh-frozen cadaveric shoulders were randomly assigned to 4 arthroscopic repair techniques. The repair was performed as either a single-row technique or 1 of 3 double-row techniques: diamond, mattress double anchor, or modified mattress double anchor. Angle of loading, anchor type, bone mineral density, anchor distribution, angle of anchor insertion, arthroscopic technique, and suture type and size were all controlled. Footprint length and width were quantified before and after repair. Displacement with cyclic loading and load to failure were determined. Results There were no differences in load to failure and displacement with cyclic loading between the single-row repair and each double-row repair. All repair groups demonstrated load to failure greater than 250 N. A significantly greater supraspinatus footprint width was seen with double-row techniques compared to single-row repair. Conclusions The single-row repair technique was similar to the double-row techniques in load to failure, cyclic displacement, and gap formation. The double-row anchor repairs consistently restored a larger footprint than did the single-row method. Clinical Relevance The arthroscopic techniques studied have strong structural properties that approached the reported performance of open repair techniques. Double-row techniques provide a larger footprint width; although not addressed by this study, such a factor may improve the biological quality of repair.
Effect of Gender and Maturity on Quadriceps-to-Hamstring Strength Ratio and Anterior Cruciate Ligament Laxity
Authors: Ahmad Christopher S. , Clark A. Martin , Heilmann Niels , Schoeb J. Scott , Gardner Thomas R. , Levine William N. 
Published: October 2005

Background Exercise programs have been introduced to reduce the ACL injury risk in female athletes. The most effective age at which to start these programs is not known. Hypothesis Age and gender affect ligament laxity and quadriceps-to-hamstring strength ratio. Study Design Cross-sectional study; Level of evidence, 3. Methods Fifty-three female and 70 male recreational soccer players, 10 to 18 years of age, were studied with physical examination, KT-1000 arthrometry, and manual maximum quadriceps and hamstring strength using a handheld dynamometer. The subjects were separated into 4 groups to examine maturity-related intergender differences: group G1, premenarchal girls (n = 24); group B1, boys 13 years and younger (n = 38); group G2, girls 2 or more years after menarche (n = 29); and group B2, boys 14 years and older (n = 32). Results Both knees of 123 soccer players were evaluated. The mean ages for groups G1, B1, G2, and B2 were 11.50 ± 1.69, 10.63 ± 1.85, 15.5 ± 1.43, and 15.59 ± 1.24 years, respectively, and the mean laxity measurements were 8.84 ± 2.12, 8.51 ± 1.61, 8.85 ± 1.86, and 7.33 ± 1.27 mm, respectively. Laxity was significantly less for the mature boys (P= .0015) than for the immature boys, mature girls, and immature girls. With increasing maturity, significant increases in both quadriceps and hamstring muscle strength were observed for both boys and girls (P< .05). Boys demonstrated a greater percentage increase in hamstring strength with maturity (179%) compared with girls (27%) (P< .05). Mature girls (2.06) had significantly greater quadriceps-tohamstring ratio when compared with immature girls (1.74), immature boys (1.58), and mature boys (1.48) (P< .05). Conclusion Female athletes after menarche increase their quadriceps strength greater than their hamstring strength, putting them at risk for anterior cruciate ligament injury. Anterior cruciate ligament–prevention programs based on improving dynamic control of the knee by emphasizing hamstring strengthening should be instituted for girls after menarche.
Antibody-induced neutrophil activation as a trigger for transfusion-related acute lung injury in an ex vivo rat lung model
Authors: Sachs Ulrich J. H. , Hattar Katja , Weissmann Norbert , Bohle Rainer M. , Weiss Timo , Sibelius Ulf , Bux Juergen 
Published: October 2005

AbstractTransfusion-related acute lung injury (TRALI) is a hazardous complication of transfusion and has become the leading cause of transfusion-related death in the United States and United Kingdom. Although leukoagglutinating antibodies have been frequently shown to be associated with the syndrome, the mechanism by which they induce TRALI is poorly understood. Therefore, we reproduced TRALI in an ex vivo rat lung model. Our data demonstrate that TRALI induction by antileukocyte antibodies is dependent on the density of the cognate antigen but does not necessarily require leukoagglutinating properties of the antibody or the presence of complement proteins. Rather, antibody-mediated activation of neutrophils seems to initiate TRALI, a process that could be triggered by neutrophil stimulation with fMLP. Antibody-mediated neutrophil activation and subsequent release of reactive oxygen species may thus represent key events in the pathophysiologic cascade that leads to immune TRALI.