bluuebunny/crossref_metadata_2025 huggingface dataset:
Left ventricular mechanical dyssynchrony is load independent at rest and during endotoxaemia in a porcine model
Authors: A’roch R. , Steendijk P. , Oldner A. , Weitzberg E. , Konrad D. , Johansson G. , Haney M.
Published: March 2009

Aim:  In diseased or injured states, the left ventricle displays higher degrees of mechanical dyssynchrony. We aimed at assessing mechanical dyssynchrony ranges in health related to variation in load as well as during acute endotoxin‐induced ventricular injury.

Methods:  In 16 juvenile anaesthetized pigs, a five‐segment conductance catheter was placed in the left ventricle as well as a balloon‐tipped catheter in the inferior vena cava. Mechanical dyssynchrony during systole, including dyssynchrony time in per cent during systole and internal flow fraction during systole, were measured at rest and during controlled pre‐load reduction sequences, as well as during 3 h of endotoxin infusion (0.25 μg kg−1 h−1).

Results:  Systolic dyssynchrony and internal flow fraction did not change during the course of acute beat‐to‐beat pre‐load alteration. Endotoxin‐produced acute pulmonary hypertension by left ventricular dyssynchrony measures was not changed during the early peak of pulmonary hypertension. Endotoxin ventricular injury led to progressive increases in systolic mechanical segmental dyssynchrony (7.9 ± 1.2–13.0 ± 1.3%) and ventricular systolic internal flow fraction (7.1 ± 2.4–16.6 ± 2.8%), respectively for baseline and then at hour 3. There was no localization of dyssynchrony changes to segment or region in the ventricular long axis during endotoxin infusion.

Conclusion:  These results suggest that systolic mechanical dyssynchrony measures may be load independent in health and during acute global ventricular injury by endotoxin. More study is needed to validate ranges in health and disease for parameters of mechanical dyssynchrony.
Sentence Parsing in a Morphologically Rich Language – Finnish
Authors: Hyönä Jukka , Vainio Seppo
Published: March 2009

We review evidence on how sentences are parsed in Finnish – a morphologically rich language. The reviewed studies focus on effects of word order, morphological agreement, and morphological complexity. As regards word order, it has been shown that infrequent word orders are more difficult to process than frequent word orders. Moreover, pragmatic constraints can wipe out the effect of structural frequency, although the pragmatic influence is non‐immediate. Morphological agreement in modifier–head noun phrases facilitates their processing. The effect is delayed in nature, which (in combination with other evidence) suggests that facilitation operates at the level of syntactic integration. Finally, evidence is reviewed that demonstrates an effect of morphological complexity and density in the processing of complex verb constructions, but only when the complex and less complex constructions are equally frequent. This is not the case when the complex construction is more frequent, suggesting the structural frequency can override a morphological complexity effect.
An Investigation of Pre‐Activity Cardiovascular Screening Procedures in Health/Fitness Facilities—Part II: Rationale for Low Adherence With National Standards
Authors: Springer Judy B. , Eickhoff‐Shemek JoAnn M. , Zuberbuehler Ernest J.
Published: March 2009

The purpose of this study was to explore the rationale provided by program directors and general managers of health/fitness facilities for low adherence to nationally accepted standards related to pre‐activity cardiovascular screening procedures (PACSPs) for members and clients of personal trainers. Qualitative interviews were conducted with the directors/managers in a Midwest region representing 76 facilities who indicated they did not conduct PACSPs for members and clients of personal trainers. Analysis of the rationale provided revealed 6 major clusters: (1) Purpose or need for screening; (2) time and staffing; (3) barrier to participation; (4) personal responsibility for health and actions; (5) legal issues; and (6) company or franchise policy that categorized the reasons for low adherence to PACSPs. These findings highlight the need to increase awareness of the relevance of PACSPs among health/fitness managers, staff members, and current exercise science students as well as engage those in risk management for informed dialogue for consistent application of the standard of care.
Hypertension, Insulin Resistance, and Aldosterone: Sex‐Specific Relationships
Authors: Kidambi Srividya , Kotchen Jane M. , Krishnaswami Shanthi , Grim Clarence E. , Kotchen Theodore A.
Published: March 2009

African Americans, particularly men, have the highest morbidity and mortality rates from hypertension in the United States. The authors studied 527 African Americans in a general clinical research center to determine whether there are sex differences in the relationships between hypertension with insulin resistance (IR) and aldosterone, which are risk factors for cardiovascular disease. Measurements included ambulatory blood pressure (BP), anthropometric measures, plasma renin activity, plasma aldosterone (PA) concentration, and fasting serum lipids, glucose, and insulin. IR was estimated using the Homeostasis Model Assessment (HOMA) model. BP correlated with aldosterone in both sexes. However, both BP and PA correlated with IR in men, but not in women. Compared with men in the lower tertile of HOMA‐IR, men in the upper tertile had higher mean systolic BP, a higher odds ratio of having hypertension, and higher levels of PA. The association of IR with both hypertension and PA in men, but not in women, may contribute to the high prevalence of cardiovascular disease in African American men.
Viscoanaesthesia in cataract surgery: a prospective, randomized clinical trial
Authors: Välimäki Juha , Törnblom Riikka‐Maija
Published: March 2009

Purpose:  We aimed to compare viscoanaesthesia (VisThesia) with intracameral lidocaine in cataract surgery carried out under topical anaesthesia.

Methods:  In this prospective study 98 patients were randomly assigned to receive VisThesia (group 1, n = 49) or 0.5 cc of 1% unpreserved lidocaine (group 2, n = 49). All surgery was carried out by one surgeon using clear corneal technique. Pachymetry, the status of the cornea and anterior chamber, and intraocular pressure (IOP) were checked pre‐ and postoperatively.

Results:  Mean pain scores were 0.12 (maximum: 3) in group 1 and 0.37 in group 2; the difference between the groups was not statistically significant (95% confidence interval [CI] 0.003−0.487; p = 0.05). A total of 48 patients in group 1 (98%) and 49 in group 2 (100%) reported no discomfort or only mild discomfort. No significant differences in flare and cells in the anterior chamber or IOP were found between the two study groups. There was a significantly greater frequency of corneal oedema in group 1 (p = 0.001). Postoperative central corneal thickness values were also significantly higher in group 1 (95% CI 11.64−57.24; p = 0.003).

Conclusions:  Results suggest that viscoanaesthesia provides a level of comfort during cataract surgery under topical anaesthesia similar to that facilitated by intracameral lidocaine. However, patients who are given viscoanaesthesia may have increased risk for postoperative corneal oedema.
Occurrence of human papillomavirus in pterygia
Authors: Piecyk‐Sidor Marta , Polz‐Dacewicz Małgorzata , Zagórski Zbigniew , Żarnowski Tomasz
Published: March 2009

Purpose:  The aim of the study was to assess the occurrence of human papillomavirus (HPV) DNA in pterygium.

Methods:  The study involved 89 patients undergoing surgical procedures at the Department of Ophthalmology, Medical University of Lublin, Poland. Group 1 included 58 patients with clinically diagnosed pterygium. Group 2 consisted of 31 individuals with normal conjunctiva. The material was collected during elective surgical procedures. The presence of HPV genome was determined using polymerase chain reaction (PCR). Once the presence of HPV DNA was confirmed, 28 HPV genotypes were determined using reverse hybridization.

Results:  The determinations confirmed the presence of HPV DNA in pterygium. In the material collected from 58 cases of pterygium (group 1), HPV DNA was identified in 16 patients (27.6%). In the material from 31 diagnostic specimens of normal conjunctiva (group 2), the presence of HPV was demonstrated in three cases (9.7%). A statistically significant difference was found in the presence of HPV DNA between the patients from groups 1 and 2 (p = 0.041). HPV type 16 was most common and was demonstrated in 56% of HPV‐positive cases of pterygium. HPV 16 and HPV 6 co‐infections were found in 19% of cases, while HPV 18 and HPV 6 co‐infections were observed in 13%. In group 2, all three patients with HPV showed HPV 18.

Conclusion:  It seems that HPV is not necessary to induce pterygium; however, it might play a synergistic role in the multi‐stage process of its development.
Axonal loss occurs early in dominant optic atrophy
Authors: Milea Dan , Sander Birgit , Wegener Marianne , Jensen Hanne , Kjer Birgit , Jørgensen Thomas Martini , Lund‐Andersen Henrik , Larsen Michael
Published: March 2009

Purpose:  This study set out to investigate retinal nerve fibre layer (RNFL) thickness and best corrected visual acuity (BCVA) in relation to age in healthy subjects and patients with OPA1 autosomal dominant optic atrophy (DOA).

Methods:  We carried out a cross‐sectional investigation of RNFL thickness and ganglion cell layer density in 30 healthy subjects and 10 patients with OPA1 DOA using optical coherence tomography (OCT). We then performed a regression analysis of RNFL thickness and BCVA versus age.

Results:  Both healthy subjects and DOA patients demonstrated a gradual reduction in RNFL thickness with age; the relationship was best described statistically by a model that assumed a constant offset between the two groups. Best corrected VA decreased significantly with age in DOA patients, in whom BCVA was correlated with peripapillary RNFL thickness in the inferior and superior peripapillary quadrants and with total macular thickness at eccentricities of 500–3000 μm. The observations were best described by a constant offset of 41.9 μm separating the two groups and an annual decrease in RNFL thickness of 0.48 μm (p < 0.0001). In patients with DOA, increasing age was associated with decreasing BCVA (p = 0.046).

Conclusions:  This cross‐sectional study found evidence of comparable age‐related decreases in RNFL thickness in healthy subjects and in DOA patients, where the deficit in DOA patients is best described using a model that assumes the deficit between the groups does not vary with age. The gradual reduction of BCVA with age may be a consequence of a relative deficit in RNFL thickness that is established before the second decade of life.
Register and Genre in Course Design for Advanced Learners of Russian
Authors: Moskver Katherine V
Published: March 2009

Abstract: This article explores the possibility of combining in the same course heritage learners who are borderline or seminative speakers with advanced language learners of Russian. After providing typology of advanced language learners in Russian and establishing that register and genre can be the focal point of such a course, the article discusses the course design in terms of material selection in registers beyond the colloquial. Drawing on the systemic‐functional approach, suggestions on teaching and learning strategies and on predominant modes of communication are offered. The article concludes that register and genre‐based courses are beneficial for both heritage and advanced language learners in their use of Russian beyond the colloquial register.
A Study of Foreign Language Learning Outcomes Assessment in U.S. Undergraduate Education
Authors: Ricardo‐Osorio José G.
Published: March 2009

Abstract: This article reports on findings obtained from an online survey answered by 97 foreign language department chairs. The Web survey was pilot tested for validity and reliability and obtained a Cronbach's reliability coefficient of .80. The results suggest that student learning outcomes assessment in American undergraduate foreign language education combines performance‐based and traditional assessments. The use of translation as an assessment method supersedes the application of the ACTFL Oral Proficiency Interview (OPI) and exit exams to gauge language proficiency. The ACTFL Proficiency Guidelines and the National Standards are common in the assessment of oral proficiency, but infrequent in the development of assessment procedures of other skills. The article also reports on obstacles that institutions face in the implementation of standards‐based assessments (e.g., OPI and portfolios).
Language and Study Abroad Across the Curriculum: An Analysis of Course Development
Authors: Moreno‐Lopez Isabel , Saenz‐de‐Tejada Cristina , Smith Tami Kopischke
Published: March 2009

Abstract: Preparing undergraduates and training faculty to succeed in a global society requires colleges to infuse international and intercultural dimensions into the curriculum. A Title VI grant funded the development and pilot of six Integrated Intensive Courses Abroad (IICA). These courses incorporate discipline‐specific content studies with foreign language and ground them in a study abroad experience. Content and language instructors were paired and cross‐trained in each other's discipline to enable them to design and teach these interdisciplinary courses. This article outlines the purpose, development, essential resources, and preliminary outcomes of integrating UCAs into a college curriculum. Results from a postcourse survey suggest that the IICA model improved students' language proficiency and understanding of the content discipline beyond what would have been expected in a traditional course.
To Assign a Topic or Not: Observing Fluency and Complexity in Intermediate Foreign Language Writing
Authors: Bonzo Joshua D.
Published: March 2009

Abstract:The present study examines the written products of third‐semester German students' written productions during a timed, in‐class writing activity. Topic selection control was modulated from instructor to student during eight 10‐minute sessions. To account for order of treatment, two of the four groups were counterbalanced with the other two. Each written product was textually analyzed and categorized into a general fluency index and an overall grammatical complexity score, both of which were correlated and statistically analyzed (ANOVA). ANOVA results indicate that topic control did influence participants' written fluency but not grammatical complexity (though mean scores for complexity were higher during self‐selected topic writing). Participants' overall level of fluency was significantly higher when they selected their own topics.
Spinal Cord Stimulation Restores Locomotion in Animal Models of Parkinson's Disease
Authors: Fuentes Romulo , Petersson Per , Siesser William B. , Caron Marc G. , Nicolelis Miguel A. L.
Published: March 2009

Dopamine replacement therapy is useful for treating motor symptoms in the early phase of Parkinson's disease, but it is less effective in the long term. Electrical deep-brain stimulation is a valuable complement to pharmacological treatment but involves a highly invasive surgical procedure. We found that epidural electrical stimulation of the dorsal columns in the spinal cord restores locomotion in both acute pharmacologically induced dopamine-depleted mice and in chronic 6-hydroxydopamine–lesioned rats. The functional recovery was paralleled by a disruption of aberrant low-frequency synchronous corticostriatal oscillations, leading to the emergence of neuronal activity patterns that resemble the state normally preceding spontaneous initiation of locomotion. We propose that dorsal column stimulation might become an efficient and less invasive alternative for treatment of Parkinson's disease in the future.
Alfvén Waves in the Lower Solar Atmosphere
Authors: Jess David B. , Mathioudakis Mihalis , Erdélyi Robert , Crockett Philip J. , Keenan Francis P. , Christian Damian J.
Published: March 2009

The flow of energy through the solar atmosphere and the heating of the Sun's outer regions are still not understood. Here, we report the detection of oscillatory phenomena associated with a large bright-point group that is 430,000 square kilometers in area and located near the solar disk center. Wavelet analysis reveals full-width half-maximum oscillations with periodicities ranging from 126 to 700 seconds originating above the bright point and significance levels exceeding 99%. These oscillations, 2.6 kilometers per second in amplitude, are coupled with chromospheric line-of-sight Doppler velocities with an average blue shift of 23 kilometers per second. A lack of cospatial intensity oscillations and transversal displacements rules out the presence of magneto-acoustic wave modes. The oscillations are a signature of Alfvén waves produced by a torsional twist of ±22 degrees. A phase shift of 180 degrees across the diameter of the bright point suggests that these torsional Alfvén oscillations are induced globally throughout the entire brightening. The energy flux associated with this wave mode is sufficient to heat the solar corona.
The Disorder-Free Non-BCS Superconductor Cs
3
C
60
Emerges from an Antiferromagnetic Insulator Parent State
Authors: Takabayashi Yasuhiro , Ganin Alexey Y. , Jeglič Peter , Arčon Denis , Takano Takumi , Iwasa Yoshihiro , Ohishi Yasuo , Takata Masaki , Takeshita Nao , Prassides Kosmas , Rosseinsky Matthew J.
Published: March 2009

The body-centered cubic A15-structured cesium fulleride Cs
3
C
60
is not superconducting at ambient pressure and is free from disorder, unlike the well-studied face-centered cubic A
3
C
60
alkali metal fulleride superconductors. We found that in Cs
3
C
60
, where the molecular valences are precisely assigned, the superconducting state at 38 kelvin emerges directly from a localized electron antiferromagnetic insulating state with the application of pressure. This transition maintains the threefold degeneracy of the active orbitals in both competing electronic states; it is thus a purely electronic transition to a superconducting state, with a dependence of the transition temperature on pressure-induced changes of anion packing density that is not explicable by Bardeen-Cooper-Schrieffer (BCS) theory.
Ankyrin-G Promotes Cyclic Nucleotide–Gated Channel Transport to Rod Photoreceptor Sensory Cilia
Authors: Kizhatil Krishnakumar , Baker Sheila A. , Arshavsky Vadim Y. , Bennett Vann
Published: March 2009

Cyclic nucleotide–gated (CNG) channels localize exclusively to the plasma membrane of photosensitive outer segments of rod photoreceptors where they generate the electrical response to light. Here, we report the finding that targeting of CNG channels to the rod outer segment required their interaction with ankyrin-G. Ankyrin-G localized exclusively to rod outer segments, coimmunoprecipitated with the CNG channel, and bound to the C-terminal domain of the channel β1 subunit. Ankyrin-G depletion in neonatal mouse retinas markedly reduced CNG channel expression. Transgenic expression of CNG channel β-subunit mutants in
Xenopus
rods showed that ankyrin-G binding was necessary and sufficient for targeting of the β1 subunit to outer segments. Thus, ankyrin-G is required for transport of CNG channels to the plasma membrane of rod outer segments.
Flagellum Mediates Symbiosis
Authors: Shimoyama Takefumi , Kato Souichiro , Ishii Shun'ichi , Watanabe Kazuya
Published: March 2009

We report here molecular mechanisms underlying a bacteria-archaeon symbiosis. We found that a fermentative bacterium used its flagellum for interaction with a specific methanogenic archaeon. The archaeon perceived a bacterial flagellum protein and activated its metabolism (methanogenesis). Transcriptome analyses showed that a substantial number of genes in the archaeon, including those involved in the methanogenesis pathway, were up-regulated after the contact with the flagellum protein. These findings suggest that the bacterium communicates with the archaeon by using its flagellum.
Increased Myeloperoxidase Activity and Protein Nitration Are Indicators of Inflammation in Patients with Chagas' Disease
Authors: Dhiman Monisha , Estrada-Franco Jose Guillermo , Pando Jasmine M. , Ramirez-Aguilar Francisco J. , Spratt Heidi , Vazquez-Corzo Sara , Perez-Molina Gladys , Gallegos-Sandoval Rosa , Moreno Roberto , Garg Nisha Jain
Published: March 2009

In this study, we investigated whether inflammatory responses contribute to oxidative/nitrosative stress in patients with Chagas' disease. We used three tests (enzyme-linked immunosorbent assay, immuno-flow cytometry, and STAT-PAK immunochromatography) to screen human serum samples (
n
= 1,481) originating from Chiapas, Mexico, for
Trypanosoma cruzi
-specific antibodies. We identified 121 subjects who were seropositive for
T. cruzi-
specific antibodies, a finding indicative of an 8.5% seroprevalence in the rural population from Chiapas. Seropositive and seronegative subjects were examined for plasma levels of biomarkers of inflammation, i.e., myeloperoxidase (MPO), inducible nitric oxide synthase (iNOS), and xanthine oxidase (XOD), as well as for oxidative (advanced oxidation protein products [AOPPs]) and nitrosative (3-nitrotyrosine [3NT]) biomarkers. The seropositive subjects exhibited a significant increase in MPO activity and protein level, the indicator of neutrophil activation. Subsequently, a corresponding increase in AOPP contents, formed by MPO-dependent hypochlorous acid and chloramine formation, was noted in seropositive subjects. The plasma level of 3NT was significantly increased in seropositive subjects, yet we observed no change in XOD activity (O
2
−
source) and nitrate/nitrite contents (denotes iNOS activation and NO production), which implied that direct peroxynitrite formation does not contribute to increased nitrosative damage in chagasic subjects. Instead, a positive correlation between increased MPO activity and protein 3NT formation was observed, which suggested to us that MPO-dependent formation of nitrylchloride that occurs in the presence of physiological NO and O
2
−
concentrations contributes to protein nitration. Overall, our data demonstrate that
T. cruzi-
induced neutrophil activation is pathological and contributes to MPO-mediated collateral protein oxidative and nitrosative damage in human patients with Chagas' disease. Therapies capable of suppressing MPO activity may be useful in controlling the inflammation and oxidative/nitrosative pathology in chagasic cardiomyopathy.
Potential Use of the Hemagglutinin-Neuraminidase Glycoprotein of Newcastle Disease Virus Expressed in
Rachiplusia nu
Larvae as an Immunogen for Chickens
Authors: Chimeno Zoth Silvina , Gómez Evangelina , Carballeda Juan Manuel , Taboga Oscar , Carrillo Elisa , Berinstein Analía
Published: March 2009

The hemagglutinin-neuraminidase glycoprotein of Newcastle disease virus (NDV) was obtained as a recombinant antigen in
Rachiplusia nu
larvae. When it was used as an immunogen in chickens, a solid immune response, including neutralizing antibodies, was detected, demonstrating the potential use of this simple and economic strategy in the design of recombinant anti-NDV vaccines.
Cholera Outbreaks Caused by an Altered
Vibrio cholerae
O1 El Tor Biotype Strain Producing Classical Cholera Toxin B in Vietnam in 2007 to 2008
Authors: Nguyen Binh Minh , Lee Je Hee , Cuong Ngo Tuan , Choi Seon Young , Hien Nguyen Tran , Anh Dang Duc , Lee Hye Ri , Ansaruzzaman M. , Endtz Hubert P. , Chun Jongsik , Lopez Anna Lena , Czerkinsky Cecil , Clemens John D. , Kim Dong Wook
Published: March 2009

Vibrio cholerae
O1 isolates collected during cholera outbreaks occurring from late 2007 to early 2008 in northern Vietnam were revealed to represent an altered strain containing the RS1 element followed by a CTX prophage harboring El Tor type
rstR
and classical
ctxB
on the large chromosome.
Distribution of Hepatitis B Virus Genotypes among Patients with Chronic Infection in Japan Shifting toward an Increase of Genotype A
Authors: Matsuura Kentaro , Tanaka Yasuhito , Hige Shuhei , Yamada Gotaro , Murawaki Yoshikazu , Komatsu Masafumi , Kuramitsu Tomoyuki , Kawata Sumio , Tanaka Eiji , Izumi Namiki , Okuse Chiaki , Kakumu Shinichi , Okanoue Takeshi , Hino Keisuke , Hiasa Yoichi , Sata Michio , Maeshiro Tatsuji , Sugauchi Fuminaka , Nojiri Shunsuke , Joh Takashi , Miyakawa Yuzo , Mizokami Masashi
Published: March 2009

Acute hepatitis B virus (HBV) infection has been increasing through promiscuous sexual contacts, and HBV genotype A (HBV/A) is frequent in patients with acute hepatitis B (AHB) in Japan. To compare the geographic distribution of HBV genotypes in patients with chronic hepatitis B (CHB) in Japan between 2005 and 2006 and between 2000 and 2001, with special attention to changes in the proportion of HBV/A, a cohort study was performed to survey changes in genotypes of CHB patients at 16 hospitals throughout Japan. Furthermore, we investigated the clinical characteristics of each genotype and examined the genomic characteristics of HBV/A isolates by molecular evolutionary analyses. Of the 1,271 patients, 3.5%, 14.1%, and 82.3% were infected with HBV/A, -B, and -C, respectively. In comparison with our previous survey during 2000 and 2001, HBV/A was twice as frequent (3.5% versus 1.7%;
P
= 0.02). The mean age was lower in the patients with HBV/A than in those with HBV/B or -C. Based on phylogenetic analyses of 11 full-length genomes and 29 pre-S2/S region sequences from patients, HBV/A isolates were imported from Europe and the United States, as well as the Philippines and India. They clustered with HBV/A from AHB patients and have spread throughout Japan. HBV/A has been increasing in CHB patients in Japan as a consequence of AHB spreading in the younger generation through promiscuous sexual contacts, aided by a tendency of HBV/A to induce chronic hepatitis. The spread of HBV/A infection in Japan should be prevented by universal vaccination programs.
Evidence that Productive Human Immunodeficiency Virus Type 1 Assembly Can Occur in an Intracellular Compartment
Authors: Joshi Anjali , Ablan Sherimay D. , Soheilian Ferri , Nagashima Kunio , Freed Eric O.
Published: March 2009

Human immunodeficiency virus type 1 (HIV-1) assembly occurs predominantly at the plasma membrane of infected cells. The targeting of assembly to intracellular compartments such as multivesicular bodies (MVBs) generally leads to a significant reduction in virus release efficiency, suggesting that MVBs are a nonproductive site for HIV-1 assembly. In the current study, we make use of an HIV-1 Gag-matrix mutant, 29/31KE, that is MVB targeted. We previously showed that this mutant is severely defective for virus particle production in HeLa cells but more modestly affected in primary macrophages. To more broadly examine the consequences of MVB targeting for virus production, we investigated 29/31KE particle production in a range of cell types. Surprisingly, this mutant supported highly efficient assembly and release in T cells despite its striking MVB Gag localization. Manipulation of cellular endocytic pathways revealed that unlike Vpu-defective HIV-1, which demonstrated intracellular Gag localization as a result of Gag endocytosis from the plasma membrane, 29/31KE mutant Gag was targeted directly to an MVB compartment. The 29/31KE mutant was unable to support multiple-round replication; however, this defect could be reversed by truncating the cytoplasmic tail of the transmembrane envelope glycoprotein gp41 and by the acquisition of a 16EK change in matrix. The 16EK/29/31KE matrix mutant replicated efficiently in the MT-4 T-cell line despite maintaining an MVB-targeting phenotype. These results indicate that MVB-targeted Gag can be efficiently released from T cells and primary macrophages, suggesting that under some circumstances, late endosomal compartments can serve as productive sites for HIV-1 assembly in these physiologically relevant cell types.
Restriction of Human Polyomavirus BK Virus DNA Replication in Murine Cells and Extracts
Authors: Mahon Cathal , Liang Bo , Tikhanovich Irina , Abend Johanna R. , Imperiale Michael J. , Nasheuer Heinz P. , Folk William R.
Published: March 2009

BK virus (BKV) causes persistent and asymptomatic infections in most humans and is the etiologic agent of polyomavirus-associated nephropathy (PVAN) and other pathologies. Unfortunately, there are no animal models with which to study activation of BKV replication in the human kidney and the accompanying PVAN. Here we report studies of the restriction of BKV replication in murine cells and extracts and the cause(s) of this restriction. Upon infection of murine cells, BKV expressed large T antigen (TAg), but viral DNA replication and progeny were not detected. Transfection of murine cells with BKV TAg expression vectors also caused TAg expression without accompanying DNA replication. Analysis of the replication of DNAs containing chimeric BKV and murine polyomavirus origins revealed the importance of BKV core origin sequences and TAg for DNA replication. A sensitive assay was developed with purified BKV TAg that supported TAg-dependent BKV DNA replication with human but not with murine cell extracts. Addition of human replication proteins, DNA polymerase α-primase, replication protein A, or topoisomerase I to the murine extracts with BKV TAg did not rescue viral DNA replication. Notably, addition of murine extracts to human extracts inhibited BKV TAg-dependent DNA replication at a step prior to or during unwinding of the viral origin. These findings and differences in replication specificity between BKV TAg and the TAgs of simian virus 40 (SV40) and JC virus (JCV) and their respective origins implicate features of the BKV TAg and origin distinct from SV40 and JCV in restriction of BKV replication in murine cells.
Impaired Cholesterol Biosynthesis in a Neuronal Cell Line Persistently Infected with Measles Virus
Authors: Robinzon Shahar , Dafa-Berger Avis , Dyer Mathew D. , Paeper Bryan , Proll Sean C. , Teal Thomas H. , Rom Slava , Fishman Daniel , Rager-Zisman Bracha , Katze Michael G.
Published: March 2009

Measles virus remains a substantial cause of morbidity and mortality, producing acute infection with a potential for development of viral persistence. To study the events underlying acute and persistent measles virus infection, we performed a global transcriptional analysis on murine neuroblastoma cells that were acutely or persistently infected with measles virus. In general, we found that acute infection induced significantly more gene expression changes than did persistent infection. A functional enrichment analysis to identify which host pathways were perturbed during each of these infections identified several pathways related to cholesterol biosynthesis, including cholesterol metabolic processes, hydroxymethylglutaryl-coenzyme A (CoA) reductase activity, and acetyl-CoA C-acetyltransferase activity. We also found that measles virus colocalized to lipid rafts in both acute and persistent infection models and that the majority of genes associated with cholesterol synthesis were downregulated in persistent infection relative to acute infection, suggesting a possible link with the defective viral budding in persistent infection. Further, we found that pharmacological inhibition of cholesterol synthesis resulted in the inhibition of viral budding during acute infection. In summary, persistent measles viral infection was associated with decreased cholesterol synthesis, a lower abundance of cholesterol and lipid rafts in the cell membrane, and inhibition of giant-cell formation and release of viral progeny.
The C Terminus of the Polerovirus P5 Readthrough Domain Limits Virus Infection to the Phloem
Authors: Peter Kari A. , Gildow Frederick , Palukaitis Peter , Gray Stewart M.
Published: March 2009

Poleroviruses are restricted to vascular phloem tissues from which they are transmitted by their aphid vectors and are not transmissible mechanically. Phloem limitation has been attributed to the absence of virus proteins either facilitating movement or counteracting plant defense. The polerovirus capsid is composed of two forms of coat protein, the major P3 protein and the minor P3/P5 protein, a translational readthrough of P3. P3/P5 is required for insect transmission and acts in
trans
to facilitate long-distance virus movement in phloem tissue. Specific potato leafroll virus mutants lacking part or all of the P5 domain moved into and infected nonvascular mesophyll tissue when the source-sink relationship of the plant (
Solanum sarrachoides
) was altered by pruning, with the progeny virus now being transmissible mechanically. However, in a period of months, a phloem-specific distribution of the virus was reestablished in the absence of aphid transmission. Virus from the new phloem-limited infection showed compensatory mutations that would be expected to restore the production of full-length P3/P5 as well as the loss of mechanical transmissibility. The data support our hypothesis that phloem limitation in poleroviruses presumably does not result from a deficiency in the repertoire of virus genes but rather results from P3/P5 accumulation under selection in the infected plant, with the colateral effect of facilitating transmission by phloem-feeding aphid vectors.
Acquisition of a Polybasic Hemagglutinin Cleavage Site by a Low-Pathogenic Avian Influenza Virus Is Not Sufficient for Immediate Transformation into a Highly Pathogenic Strain
Authors: Stech Olga , Veits Jutta , Weber Siegfried , Deckers Daniela , Schröer Diana , Vahlenkamp Thomas W. , Breithaupt Angele , Teifke Jens , Mettenleiter Thomas C. , Stech Jürgen
Published: March 2009

Highly pathogenic avian influenza viruses (HPAIV) differ from all other strains by a polybasic cleavage site in their hemagglutinin. All these HPAIV share the H5 or H7 subtype. In order to investigate whether the acquisition of a polybasic cleavage site by an avirulent avian influenza virus strain with a hemagglutinin other than H5 or H7 is sufficient for immediate transformation into an HPAIV, we adapted the hemagglutinin cleavage site of A/Duck/Ukraine/1/1963 (H3N8) to that of the HPAIV A/Chicken/Italy/8/98 (H5N2), A/Chicken/HongKong/220/97 (H5N1), or A/Chicken/Germany/R28/03 (H7N7) and generated the recombinant wild-type and cleavage site mutants. In contrast to the wild type, multicycle replication of these mutants in tissue culture was demonstrated by positive plaque assays and viral multiplication in the absence of exogenous trypsin. Therefore, in vitro all cleavage site mutants resemble an HPAIV. However, in chicken they did not exhibit high pathogenicity, although they could be reisolated from cloacal swabs to some extent, indicating enhanced replication in vivo. These results demonstrate that beyond the polybasic hemagglutinin cleavage site, the virulence of HPAIV in chicken is based on additional pathogenicity determinants within the hemagglutinin itself or in the other viral proteins. Taken together, these observations support the notion that acquisition of a polybasic hemagglutinin cleavage site by an avirulent strain with a non-H5/H7 subtype is only one among several alterations necessary for evolution into an HPAIV.
Helices α2 and α3 of West Nile Virus Capsid Protein Are Dispensable for Assembly of Infectious Virions
Authors: Schlick Petra , Taucher Christian , Schittl Beate , Tran Janina L. , Kofler Regina M. , Schueler Wolfgang , von Gabain Alexander , Meinke Andreas , Mandl Christian W.
Published: March 2009

The internal hydrophobic sequence within the flaviviral capsid protein (protein C) plays an important role in the assembly of infectious virions. Here, this sequence was analyzed in a West Nile virus lineage I isolate (crow V76/1). An infectious cDNA clone was constructed and used to introduce deletions into the internal hydrophobic domain which comprises helix α2 and part of the loop intervening helices α2 and α3. In total, nine capsid deletion mutants (4 to 14 amino acids long) were constructed and tested for virus viability. Some of the short deletions did not significantly affect growth in cell culture, whereas larger deletions removing almost the entire hydrophobic region significantly impaired viral growth. Efficient growth of the majority of mutants could, however, be restored by the acquisition of second-site mutations. In most cases, these resuscitating mutations were point mutations within protein C changing individual amino acids into more hydrophobic residues, reminiscent of what had been observed previously for another flavivirus, tick-borne encephalitis virus. However, we also identified viable spontaneous pseudorevertants with more than one-third of the capsid protein removed, i.e., 36 or 37 of a total of 105 residues, including all of helix α3 and a hydrophilic segment connecting α3 and α4. These large deletions are predicted to induce formation of large, predominantly hydrophobic fusion helices which may substitute for the loss of the internal hydrophobic domain, underlining the unrivaled structural and functional flexibility of protein C.
Finite element analysis of an embankment on a soft estuarine deposit using an elastic–viscoplastic soil model
Authors: Kelln Curtis , Sharma Jitendra , Hughes David , Graham James
Published: March 2009

A new elastic–viscoplastic (EVP) soil model has been used to simulate the measured deformation response of a soft estuarine soil loaded by a stage-constructed embankment. The simulation incorporates prefabricated vertical drains installed in the foundation soils and reinforcement installed at the base of the embankment. The numerical simulations closely matched the temporal changes in surface settlement beneath the centerline and shoulder of the embankment. More importantly, the elastic–viscoplastic model simulated the pattern and magnitudes of the lateral deformations beneath the toe of the embankment — a notoriously difficult aspect of modelling the deformation response of soft soils. Simulation of the excess pore-water pressure proved more difficult because of the heterogeneous nature of the estuarine deposit. Excess pore-water pressures were, however, mapped reasonably well at three of the six monitoring locations. The simulations were achieved using a small set of material constants that can easily be obtained from standard laboratory tests. This study validates the use of the EVP model for problems involving soft soil deposits beneath loading from a geotechnical structure.
Biological and Chemical Approaches to Diseases of Proteostasis Deficiency
Authors: Powers Evan T. , Morimoto Richard I. , Dillin Andrew , Kelly Jeffery W. , Balch William E.
Published: March 2009

Many diseases appear to be caused by the misregulation of protein maintenance. Such diseases of protein homeostasis, or “proteostasis,” include loss-of-function diseases (cystic fibrosis) and gain-of-toxic-function diseases (Alzheimer's, Parkinson's, and Huntington's disease). Proteostasis is maintained by the proteostasis network, which comprises pathways that control protein synthesis, folding, trafficking, aggregation, disaggregation, and degradation. The decreased ability of the proteostasis network to cope with inherited misfolding-prone proteins, aging, and/or metabolic/environmental stress appears to trigger or exacerbate proteostasis diseases. Herein, we review recent evidence supporting the principle that proteostasis is influenced both by an adjustable proteostasis network capacity and protein folding energetics, which together determine the balance between folding efficiency, misfolding, protein degradation, and aggregation. We review how small molecules can enhance proteostasis by binding to and stabilizing specific proteins (pharmacologic chaperones) or by increasing the proteostasis network capacity (proteostasis regulators). We propose that such therapeutic strategies, including combination therapies, represent a new approach for treating a range of diverse human maladies.
Involvement of calpains in Ca2+-induced disruption of excitation-contraction coupling in mammalian skeletal muscle fibers
Authors: Verburg Esther , Murphy Robyn M. , Richard Isabelle , Lamb Graham D.
Published: March 2009

In skeletal muscle fibers, the coupling between excitation of the surface membrane and the release of Ca2+ from the sarcoplasmic reticulum is irreversibly disrupted if cytoplasmic Ca2+ concentration ([Ca2+]) is raised to micromolar levels for a prolonged period. This excitation-contraction (EC) uncoupling may contribute to muscle weakness after some types of exercise and in certain muscle diseases and has been linked to structural alteration of the triad junctions, but its molecular basis is unclear. Both μ-calpain, a ubiquitous Ca2+-activated protease, and muscle-specific calpain-3 become autolytically activated at micromolar Ca2+ and have been suggested to be responsible for the uncoupling. This study used controlled Ca2+ exposure in mechanically skinned fibers from extensor digitorum longus muscle to show that EC uncoupling still occurs in muscle fibers of calpain-3-deficient mice, with a Ca2+ dependence indistinguishable from that in normal mice and rats. Western blotting of muscle fibers that had been partially EC uncoupled by exposure to an intermediate Ca2+ level (∼5 μM Ca2+ for 3 min, no ATP) showed the presence of autolytic activation of a proportion of the μ-calpain present, but with little or no activation of calpain-3. Homogenates of normal and calpain-3-deficient muscles exposed to micromolar Ca2+ displayed similar levels of diffusible proteolytic activity, as gauged by the rate of decline of passive force in stretched, skinned muscle fibers. Exogenously added μ-calpain, preactivated by elevated [Ca2+] and applied in the presence of 1 μM Ca2+, disrupted EC coupling in a manner similar to raised [Ca2+]. We conclude that calpain-3 is not responsible for Ca2+-induced disruption of EC coupling, but that μ-calpain is a plausible candidate.
Sympathetic restraint of muscle blood flow during hypoxic exercise
Authors: Stickland Michael K. , Smith Curtis A. , Soriano Benjamin J. , Dempsey Jerome A.
Published: March 2009

Control of exercising muscle blood flow is a balance between local vasodilatory factors and the increase in global sympathetic vasoconstrictor outflow. Hypoxia has been shown to potentiate the muscle sympathetic nerve response to exercise, potentially limiting the increase in muscle blood flow. Accordingly, we investigated sympathetic restraint to exercising muscle during whole body exercise in hypoxia. Six dogs chronically instrumented with ascending aortic and hindlimb flow probes and a terminal aortic catheter were studied at rest and mild [2.5 miles/h (mph), 5% grade] and moderate (4.0 mph, 10% grade) exercise while breathing room air or hypoxia (PaO2 ∼45 mmHg) in the intact control condition and following systemic α-adrenergic blockade (phentolamine). Hypoxia caused an increase in cardiac output (CO), hindlimb flow (FlowL), and blood pressure (BP), while total (CondT) and hindlimb conductance (CondL) were unchanged at rest and mild exercise but increased with moderate exercise. During both mild and moderate exercise, α-blockade in normoxia resulted in significant vasodilation as evidenced by increases in CO (10%), FlowL (17%), CondT (33%), CondL (43%), and a decrease in BP (−18%), with the increase in CondL greater than the increase in CondT during mild exercise. Compared with the normoxic response, α-blockade in hypoxia during exercise resulted in a significantly greater increase in CondT (59%) and CondL (74%) and a correspondingly greater decrease in BP (−34%) from baseline. These findings indicate that there is considerable hypoxia-induced sympathetic restraint of muscle blood flow during both mild and moderate exercise, which helps to maintain arterial blood pressure in hypoxia.
Vasopressin-induced differential stimulation of AQP4 splice variants regulates the in-membrane assembly of orthogonal arrays
Authors: Van Hoek Alfred N. , Bouley Richard , Lu YingXian , Silberstein Claudia , Brown Dennis , Wax Martin B. , Patil Rajkumar V.
Published: March 2009

Aquaporin-4 (AQP4) is a basolateral water channel in collecting duct principal cells and assembles into orthogonal array particles (OAPs), the size of which appears to depend on relative expression levels of AQP4 splice variants. Because the higher-order organization of AQP4 was perturbed by vasopressin in Brattleboro rats and phosphorylation sites have been identified on AQP4, we investigated whether vasopressin and forskolin (Fk) affect AQP4 assembly and/or expression in LLC-PK1cells stably transfected with the AQP4 splice variant M23, which is responsible for formation of OAPs, and/or the splice variant M1, which does not form OAPs. Our data show that [lys8]-vasopressin (LVP) and Fk treatment led to differential increases in expression levels of M23-AQP4 and M1-AQP4 that varied as a function of incubation time. At early time points ( day 1) expression of M1 was significantly stimulated (4.5-fold), over that of M23 (1.6-fold), but after 3 days the expression of M23 became predominant (4.1-fold) over that of M1 (1.9-fold). This pattern of stimulation was dependent on an intact AQP4 residue serine 111 and required protein synthesis. In cells expressing both M1 and M23 (M1/M23 ∼ 1), with small sized OAPs at the membrane, the LVP/Fk-induced stimulation of M23 was modified and mimicked that of M1 when expressed alone, suggesting a dominant role for M1. In Brattleboro kidney inner medulla, an 8-day chronic exposure to the vasopressin agonist (dDAVP) led to reduction in M1 and a significant increase in M23 immunoblot staining (M1/M23 = 2/3 → 1/4). These results indicate that AQP4 organization and expression are regulated by vasopressin in vivo and in vitro and demonstrate that the dominant role for M1 is restricted to a one-to-one interaction between AQP4 splice variants that regulates the membrane expression of OAPs.
Inhibition of insulin-stimulated hydrogen peroxide production prevents stimulation of sodium transport in A6 cell monolayers
Authors: Markadieu Nicolas , Crutzen Raphaël , Boom Alain , Erneux Christophe , Beauwens Renaud
Published: March 2009

Insulin-stimulated sodium transport across A6 cell (derived from amphibian distal nephron) monolayers involves the activation of a phosphatidylinositol (PI) 3-kinase. We previously demonstrated that exogenous addition of H2O2to the incubation medium of A6 cell monolayers provokes an increase in PI 3-kinase activity and a subsequent rise in sodium transport (Markadieu N, Crutzen R, Blero D, Erneux C, Beauwens R. Am J Physiol Renal Physiol 288: F1201–F1212, 2005). We therefore questioned whether insulin would produce an intracellular burst of H2O2leading to PI 3-kinase activation and subsequent increase in sodium transport. An acute production of reactive oxygen species (ROS) in A6 cells incubated with the oxidation-sensitive fluorescent probe 5,6-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate was already detected after 2 min of insulin stimulation. This fluorescent signal and the increase in sodium transport were completely inhibited in monolayers incubated with peggylated catalase, indicating that H2O2is the main intracellular ROS produced upon insulin stimulation. Similarly, preincubation of monolayers with different chelators of either superoxide (O2•−; nitro blue tetrazolium, 100 μM) or H2O2(50 μM ebselen), or blockers of NADPH oxidase (Nox) enzymes (diphenyleneiodonium, 5 μM; phenylarsine oxide, 1 μM and plumbagin, 30 μM) prevented both insulin-stimulated H2O2production and insulin-stimulated sodium transport. Furthermore, diphenyleneiodonium pretreatment inhibited the recruitment of the p85 PI 3-kinase regulatory subunit in an anti-phosphotyrosine immunoprecipitate in insulin-stimulated cells. In contrast, PI-103, an inhibitor of class IA PI 3-kinase, inhibited insulin-stimulated sodium transport but did not significantly reduce insulin-stimulated H2O2production. Taken together, our data suggest that insulin induces an acute burst of H2O2production which participates in an increase in phosphatidylinositol 3,4,5- trisphosphate production and subsequently stimulation of sodium transport.