bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tissue transglutaminase contributes to disease progression in the R6/2 Huntington's disease mouse model via aggregate‐independent mechanisms
Authors: Bailey Craig D. C. , Johnson Gail V. W. 
Published: January 2005

AbstractHuntington's disease (HD) is caused by an expansion of CAG repeats within the huntingtin gene and is characterized by intraneuronal mutant huntingtin protein aggregates. In order to determine the role of tissue transglutaminase (tTG) in HD aggregate formation and disease progression, we cross‐bred the R6/2 HD mouse model with a tTG knockout mouse line. R6/2 mice that were tTG heterozygous knockouts (R6/2 : tTG+/–) and tTG homozygous knockouts (R6/2 : tTG–/–) showed a very similar increase in aggregate number within the striatum compared with R6/2 mice that were wild‐type with respect to tTG (R6/2 : tTG+/+). Interestingly, a significant delay in the onset of motor dysfunction and death occurred in R6/2 : tTG–/– mice compared with both R6/2 : tTG+/+ and R6/2 : tTG+/– mice. As aggregate number was similarly increased in the striatum of both R6/2 : tTG+/– and R6/2 : tTG–/– mice, whereas only R6/2 : tTG–/– mice showed delayed disease progression, these data suggest that the contribution of tTG towards motor dysfunction and death in the R6/2 mouse is independent of its ability to negatively regulate aggregate formation. Moreover, the combined results from this study suggest that the formation of striatal huntingtin aggregates does not directly influence motor dysfunction or death in this HD mouse model.
The possible relationship between keratoconus and magnesium deficiency
Authors: Thalasselis Anfitritis 
Published: January 2005

AbstractThe cause of keratoconus is unknown. However, an earlier report demonstrated magnesium deficiency in keratoconus patients, and suggested that magnesium deficiency could pathologically affect the mechanisms of the cornea. Experimental and clinical papers concerning a possible relationship between keratoconus and magnesium deficiency were reviewed. These studies have demonstrated molecular and cellular alterations specific to the keratoconic cornea, including: thinning and fragmentation of membranes, degenerated cells and collagen fibres, swelling of the mitochondria, and biochemical abnormalities in protein synthesis. Similar alterations have reportedly been induced by magnesium deficiency. This review suggests a possible relationship between the specific keratoconic disorders and the alteration induced by magnesium deficiency at the intracellular and extracellular levels. Although the etiology of keratoconus is still unknown, this paper may give some new ideas for further experimental and clinical studies on the etiology of keratoconus.
Compensation of aniseikonia with toric intraocular lenses and spherocylindrical spectacles
Authors: Langenbucher Achim , Reese Sven , Huber Stefan , Seitz Berthold 
Published: January 2005

AbstractBackground and Purpose:  Magnification disparity between the two eyes (aniseikonia) is one of the major unresolved problems in modern cataract surgery, potentially degrading binocular visual function or causing diplopia. The purpose of this study is to describe a paraxial computing scheme using 4 × 4 system matrices to simulate a corrected pseudophakic ‘optical system eye’ with a meridional magnification that matches the magnification of a given contralateral eye.Methods:  Based on the definition of a centred optical system in the paraxial Gaussian space containing astigmatic surfaces using 4 × 4 refraction and translation matrices, we derived a methodology for calculating the refractive power and axis of toric intraocular lenses and spherocylindrical spectacle corrections for (i) fully correcting the optical system eye and (ii) realizing an arbitrary meridional magnification by solving a linear equation system.Results:  The capabilities of this computing scheme are demonstrated with two examples. In example 1 we calculate a toric lens and a spherocylindrical spectacle correction for compensation of a corneal astigmatism to realize a predefined iso‐meridional magnification. In example 2 we first determine the meridional magnification of the contralateral eye, which has been treated with cataract surgery and toric lens implantation, and then we compute the appropriate combination of a fully correcting toric lens and spherocylindrical spectacle refraction, which exactly matches the meridional magnification of the contralateral eye.Conclusion:  We presented an en bloc matrix based strategy for the calculation of an optical system eye containing an astigmatic cornea, a toric lens implant and a spherocylindrical spectacle correction, where the toric lens and the spherocylindrical spectacle correction are determined to fully correct the system and to realize an arbitrary meridional magnification i.e. to eliminate aniseikonia.
Foveal blur discrimination of the human eye
Authors: Wang Bin , Ciuffreda Kenneth J. 
Published: January 2005

AbstractAlthough the effect of retinal defocus on the foveal blur detection threshold has been well investigated, knowledge regarding the foveal blur discrimination threshold is limited. In the present study, both thresholds were assessed psychophysically using the ascending method of limits at the fovea with accommodation paralyzed. The unidirectional blur detection threshold was 0.87 ± 0.18 D (±1 S.E.M.). The subsequent blur discrimination thresholds were relatively constant and significantly smaller than the blur detection threshold, with an average value of 0.48 ± 0.006 D (±1 S.E.M.). We speculate that the difference in magnitude between these two thresholds may be attributed to the defocus‐related change in the ocular modulation transfer function (MTF) and its interaction with contrast discrimination ability, as well as to the presence of a neuroperceptual blur buffering mechanism.
Accuracy of intraoperative retinoscopy in corneal power and axial length estimation using a high plus soft contact lens
Authors: Ahmed I. , Toufeeq A. 
Published: January 2005

AbstractAim:  To assess the accuracy of intraoperative retinoscopy with high plus soft contact lens (CL) in estimating corneal power and the axial length compared with standard keratometry and biometry measurement.Methods:  Intraoperative retinoscopy was performed in 30 eyes prior to the implantation of an intraocular lens (IOL). A +10 D disposable soft contact lens was applied on the cornea to minimize retinoscopic error. Corneal power was derived from refraction using biometric axial length while the axial length was derived using keratometric measurement. Refraction derived corneal powers and axial lengths from 26 eyes within ±1.00 D of the target postoperative refraction were compared with preoperative standard keratometry and biometry measurements.Results:  In the 26 eyes, the mean difference between the corneal powers derived from refraction and keratometry was 0.35 D (S.D. = 1.678). The 95% limits of agreement were −3.006 to +3.706. The mean difference between the axial lengths derived from refraction and biometry was 0.15 mm (S.D. = 0.721). The 95% limits of agreement were −1.292 to 1.542.Conclusion:  Intraoperative retinoscopy with a high plus soft contact lens after phacoemulsification is useful but not accurate in estimating corneal power or axial length of the eye. It should be used cautiously in IOL power calculation as a substitute for standard keratometry or biometry machines when either of these is not available or in error.
Visual acuity in 5–7‐year‐old children: individual variability and dependence on observation distance
Authors: Rozhkova Galina I. , Podugolnikova Tatiana A. , Vasiljeva Nadezhda N. 
Published: January 2005

AbstractAccurate measurements of uncorrected binocular and monocular visual acuity were performed in 65 children aged 5–7 years at five viewing distances in the range 0.5–5.0 m by means of the test charts containing widely spaced E stimuli in four orientations. It was found that, in most children of this age, visual acuity (V) changed with test distance, as had been reported previously with older subjects. Visual acuity could be considered as practically independent of observation distance (Vmax−Vmin ≤ 0.2 decimal units) in <50% of children. The remaining children demonstrated evident distance dependence of visual acuity but the shape of the acuity–distance curve varied. The acuity–distance curve of most children peaked at an intermediate distance (1–2 m), the typical difference Vmax−Vmin being 0.4 decimal units. To explain the existence of an optimal observation distance in the majority of children, a number of developmental and environmental factors could be proposed that adjust the parameters of the visual system to the parameters of operational visual space and prevailing activity.
Advancing Human Rights Policy: Does Grassroots Mobilization and Community Dispute Resolution Matter? Insights from Chiapas, Mexico
Authors: Lopez Linda 
Published: January 2005

AbstractThis research examines the impact of grassroots organizing at the community level in Chiapas, Mexico, to address problems associated with human rights advocacy and implementation. Traditionally, the nation‐state has had the primary responsibility to address issues pertaining to human rights violations and the enforcement of international human rights principles and treaties. Local political struggles and acts of resistance by disenfranchised groups in Mexico offer insight to understand the impact of indigenous and other social movements in furthering human rights. Indigenous populations in the state of Chiapas use local community dispute resolution to contest the inadequacy of the state in responding to the problems that give rise to poverty, lack of human dignity, educational access, racial and ethnic discrimination, lack of political participation in government and the right to equality in economic, social, and political sectors. Drawing from research based on participant observations in Chiapas, Mexico, there is some evidence to suggest that since the 1994 EZLN (Zapatista National Liberation Army) uprising several micro‐level political and social movements have contested the power of the state through symbolic and pragmatic organizing efforts. These groups include, but are not limited to, nongovernmental organizations (NGOs), women's groups, and indigenous groups. After the Zapatista uprising, these groups were instrumental in making claims against the state through numerous activities: protests to end the war, the development of NGOs to observe human rights violations, civilian‐based Zapatista support groups (base de apoyo), peace camps, and open dialogue with the EZLN. I argue that collective mobilization in local communities serves both symbolic and pragmatic efforts in helping disenfranchised groups empower themselves to address economic, social, and political inequality. Local‐level activism has fueled a sense of self‐empowerment to change state institutional responses and to involve sectors of civil society domestically and internationally to initiate a proper resolution of issues that are fundamentally related to human rights.
Surface Proteins ofStreptococcus agalactiaeand Related Proteins in Other Bacterial Pathogens
Authors: Lindahl Gunnar , Stålhammar-Carlemalm Margaretha , Areschoug Thomas 
Published: January 2005

SUMMARYStreptococcus agalactiae(group B Streptococcus) is the major cause of invasive bacterial disease, including meningitis, in the neonatal period. Although prophylactic measures have contributed to a substantial reduction in the number of infections, development of a vaccine remains an important goal. While much work in this field has focused on theS. agalactiaepolysaccharide capsule, which is an important virulence factor that elicits protective immunity, surface proteins have received increasing attention as potential virulence factors and vaccine components. Here, we summarize current knowledge aboutS. agalactiaesurface proteins, with emphasis on proteins that have been characterized immunochemically and/or elicit protective immunity in animal models. These surface proteins have been implicated in interactions with human epithelial cells, binding to extracellular matrix components, and/or evasion of host immunity. Of note, severalS. agalactiaesurface proteins are related to surface proteins identified in other bacterial pathogens, emphasizing the general interest of theS. agalactiaeproteins. Because someS. agalactiaesurface proteins elicit protective immunity, they hold promise as components in a vaccine based only on proteins or as carriers in polysaccharide conjugate vaccines.
Proposed Function of the Accumulation of Plasma Membrane-Type Ca
2+
-ATPase mRNA in Resting Cysts of the Ciliate
Sterkiella histriomuscorum
Authors: Lescasse Rachel , Grisvard Jeanine , Fryd Ghislaine , Fleury-Aubusson Anne , Baroin-Tourancheau Anne 
Published: January 2005

ABSTRACT

From an mRNA differential-display analysis of the encystment-excystment cycle of the ciliate
Sterkiella histriomuscorum
, we have isolated an expressed sequence tag encoding a plasma membrane-type Ca
2+
-ATPase (PMCA). PMCAs are located either in the plasma membranes or in the membranes of intracellular organelles, and their function is to pump calcium either out of the cell or into the intracellular calcium stores, respectively. The
S. histriomuscorum
macronuclear
PMCA
gene (
ShPMCA
) and its corresponding cDNA were cloned; it is the first member of the Ca
2+
-ATPase family identified in
Sterkiella
. The predicted protein of 1,065 amino acids exhibits 37% identity with PMCAs of diverse organisms. A phylogenetic analysis showed its relatedness to homologs of two alveolates: the ciliate
Paramecium tetraurelia
and the apicomplexan
Toxoplasma gondii
. Overexpression of the protein ShPMCA failed to rescue the wild-type phenotype of three Ca
2+
-ATPase-defective mutant strains of
Saccharomyces cerevisiae
; this failure contrasts with the reported ability of the PMCAs of parasites to complement defects in yeast.
ShPMCA
mRNA is markedly accumulated during encystment and in resting cysts, suggesting a function during excystment. To address the possibility of a signaling role for calcium at excystment, the capacity of calcium to induce excystment was examined.
A Homolog of Ste6, the
a
-Factor Transporter in
Saccharomyces cerevisiae
, Is Required for Mating but Not for Monokaryotic Fruiting in
Cryptococcus neoformans
Authors: Hsueh Yen-Ping , Shen Wei-Chiang 
Published: January 2005

ABSTRACT

Fungal pheromones function during the initial recognition stage of the mating process. One type of peptide pheromone identified in ascomycetes and basidiomycetes terminates in a conserved CAAX motif and requires extensive posttranslational modifications to become mature and active. A well-studied representative is the
a
-factor of
Saccharomyces cerevisiae
. Unlike the typical secretory pathway utilized by most peptides, an alternative mechanism involving the ATP-binding cassette transporter Ste6 is used for the export of mature
a
-factor.
Cryptococcus neoformans
, a bipolar human pathogenic basidiomycete, produces CAAX motif-containing lipopeptide pheromones in both
MAT
a
and
MAT
α cells. Virulence studies with a congenic pair of
C. neoformans
serotype D strains have shown that
MAT
α cells are more virulent than
MAT
a
cells. Characterization of the
MAT
α pheromones indicated that an autocrine signaling loop may contribute to the differentiation and virulence of
MAT
α cells. To further address the role of pheromones in the signaling loop, we identified a
STE6
homolog in the
C. neoformans
genome and determined its function by gene disruption. The
ste6
mutants in either mating-type background showed partially impaired mating functions, and mating was completely abolished in a bilateral mutant cross. Surprisingly, the
MAT
α
ste6
mutant does not exhibit a defect in monokaryotic fruiting, suggesting that the activation of the autocrine signaling loop by the pheromone is via a Ste6-independent mechanism. MFα pheromone itself is essential for this process and could induce the signaling response intracellularly in
MAT
α cells. Our data demonstrate that Ste6 is evolutionarily conserved for mating and is not required for monokaryotic fruiting in
C. neoformans
.
Distinct Stress Responses of Two Functional Laccases in
Cryptococcus neoformans
Are Revealed in the Absence of the Thiol-Specific Antioxidant Tsa1
Authors: Missall Tricia A. , Moran Jason M. , Corbett John A. , Lodge Jennifer K. 
Published: January 2005

ABSTRACT

Laccases are thought to be important to the virulence of many fungal pathogens by producing melanin, a presumed oxygen radical scavenger. A laccase in
Cryptococcus neoformans
has been shown to synthesize melanin and contributes to the virulence and the survival in macrophages of this fungal pathogen. One
C. neoformans
laccase gene,
LAC1
, previously called
CNLAC1
, has been extensively studied, and we describe a homologous gene,
LAC2
, that is found 8 kb away from
LAC1
in the genome. In this study we report a role for both laccases, in addition to the thiol peroxidase, Tsa1, in oxidative and nitrosative stress resistance mechanisms of
C. neoformans
. With use of real-time PCR, similar changes in expression of the two laccase genes occur in response to oxidative and nitrosative stresses, but only the regulation of the
LAC2
gene during stress is influenced by Tsa1. Both laccases contribute to melanin production using L-dopa as a substrate and are differentially localized in the cell based on green fluorescent protein fusions. A single deletion of either
LAC1
or
LAC2
alone had no effect on sensitivity to H
2
O
2
or nitric oxide. However, deletion of either
LAC1
or
LAC2
in combination with a
TSA1
deletion resulted in a slight peroxide sensitivity, and a
lac2
Δ
tsa1
Δ deletion strain was sensitive to nitric oxide stress. In addition, the deletion of both laccases reduces survival of
C. neoformans
in primary macrophages. Based on our expression and functional analysis, we propose a novel model for the interaction of these two systems, which are both important for virulence.
Separation of the
Saccharomyces cerevisiae
Paf1 Complex from RNA Polymerase II Results in Changes in Its Subnuclear Localization
Authors: Porter Stephanie E. , Penheiter Kristi L. , Jaehning Judith A. 
Published: January 2005

ABSTRACT

The yeast Paf1 complex (Paf1C), composed of Paf1, Ctr9, Cdc73, Rtf1, and Leo1, associates with RNA polymerase II (Pol II) at promoters and in the actively transcribed portions of mRNA genes. Loss of Paf1 results in severe phenotypes and significantly reduced levels of the other Paf1C components. In contrast, loss of Rtf1 causes relatively subtle phenotypic changes and no reduction in the other Paf1C factors but disrupts the association of these factors with Pol II and chromatin. To elucidate the fate of the Paf1C when dissociated from Pol II, we examined the localization of the Paf1C components in
paf1
and
rtf1
mutant yeast strains. We found that although the Paf1C factors remain nuclear in
paf1
and
rtf1
strains, loss of Paf1 or Rtf1 results in a change in the subnuclear distribution of the remaining factors. In wild-type cells, Paf1C components are present in the nucleoplasm but not the nucleolus. In contrast, in both
paf1
and
rtf1
strains, the remaining factors are found in the nucleolus as well as the nucleoplasm. Loss of Paf1 affects nucleolar function; we observed that expression of
MAK21
and
RRP12
, important for rRNA processing, is reduced concomitant with an increase in rRNA precursors in a
paf1
strain. However, these changes are not the result of relocalization of the Paf1C because loss of Rtf1 does not cause similar changes in rRNA processing. Instead, we speculate that the change in localization may reflect a link between the Paf1C and newly synthesized mRNAs as they exit the nucleus.
Molecular Analysis Reveals Localization ofSaccharomyces cerevisiaeProtein Kinase C to Sites of Polarized Growth and Pkc1p Targeting to the Nucleus and Mitotic Spindle
Authors: Denis Valérie , Cyert Martha S. 
Published: January 2005

ABSTRACTThe catalytic activity and intracellular localization of protein kinase C (PKC) are both highly regulated in vivo. This family of kinases contains conserved regulatory motifs, i.e., the C1, C2, and HR1 domains, which target PKC isoforms to specific subcellular compartments and restrict their activity spatially.Saccharomyces cerevisiaecontains a single PKC isozyme, Pkc1p, which contains all of the regulatory motifs found in mammalian PKCs. Pkc1p localizes to sites of polarized growth, consistent with its main function in maintaining cell integrity. We dissected the molecular basis of Pkc1p localization by expressing each of its domains individually and in combinations as green fluorescent protein fusions. We find that the Rho1p-binding domains, HR1 and C1, are responsible for targeting Pkc1p to the bud tip and cell periphery, respectively. We demonstrate that Pkc1p activity is required for its normal localization to the bud neck, which also depends on the integrity of the septin ring. In addition, we show for the first time that yeast protein kinase C can accumulate in the nucleus, and we identify a nuclear exit signal as well as nuclear localization signals within the Pkc1p sequence. Thus, we propose that Pkc1p shuttles in and out of the nucleus and consequently has access to nuclear substrates. Surprisingly, we find that deletion of the HR1 domain results in Pkc1p localization to the mitotic spindle and that the C2 domain is responsible for this targeting. This novel nuclear and spindle localization of Pkc1p may provide a molecular explanation for previous observations that suggest a role for Pkc1p in regulating microtubule function.
Momentum Effects in Steady Nucleate Pool Boiling During Microgravity
Authors: MERTE HERMAN 
Published: January 2005

Abstract: Pool boiling experiments were conducted in microgravity on five space shuttle flights, using a flat plate heater consisting of a semitransparent thin gold film deposited on a quartz substrate that also acted as a resistance thermometer. The test fluid was R‐113, and the vapor bubble behavior at the heater surface was photographed from beneath as well as from the side. Each flight consisted of a matrix of three levels of heat flux and three levels of subcooling. In 26 of the total of 45 experiments conditions of steady‐state pool boiling were achieved under certain combinations of heat flux and liquid subcooling. In many of the 26 cases, it was observed from the 16‐mm movie films that a large vapor bubble formed, remaining slightly removed from the heater surface, and that subsequent vapor bubbles nucleate and grow on the heater surface. Coalescence occurs upon making contact with the large bubble, which thus acts as a vapor reservoir. Recently, measurements of the frequencies and sizes of the small vapor bubbles as they coalesced with the large bubble permitted computation of the associated momentum transfer. The transient forces obtained are presented here. Where these arise from the conversion of the surface energy in the small vapor bubble to kinetic energy acting away from the solid heater surface, they counter the Marangoni convection due to the temperature gradients normal to the heater surface. This Marangoni convection would otherwise impel the large vapor bubble toward the heater surface and result in dryout and unsteady heat transfer.
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