bluuebunny/crossref_metadata_2025 huggingface dataset:
Tacrolimus for Myasthenia Gravis
Authors: Ponseti José M. , Gamez Josep , Azem Jamal , López‐Cano Manuel , Vilallonga Ramón , Armengol Manuel
Published: June 2008

Tacrolimus is a macrolide T cell immunomodulator that is used in myasthenia gravis (MG) patients to affect muscle contraction (ryanodine receptor by modulating intracellular calcium‐release channels and increasing muscular strength), glucocorticoid receptors (increasing intracellular concentration of steroids and blocking the steroid export mechanism), and an increase in T cell apoptosis. In this study, we report the results of low‐dose tacrolimus (0.1 mg/kg/day) treatment in 212 MG patients. There were 110 thymectomized, cyclosporine‐ and prednisone‐dependent patients; 68 thymectomized patients who started tacrolimus early postoperatively (24 h after operation); and 34 patients over 60 years old with nonthymomatous generalized MG or in whom thymectomy was contraindicated. The mean follow‐up time was 49.3 ± 18.1 months. Muscular strength showed an increase of 23% after 1 month of treatment and 29% at the end of the study. The acetylcholine receptor antibodies decreased significantly from a mean of 33.5 nmol/L at base line to 7.8 nmol/L at the final visit. In the thymectomy group with combined prednisone and tacrolimus stratified by histology of the thymus, the mean probability to attain complete stable remission at 5 years was 80.8% in patients with hyperplasia, 48.1% in thymic involution, and 9.3% in patients with thymoma. In 4.9% of patients, tacrolimus was withdrawn because of major adverse effects. Our results suggest that a low dose of tacrolimus is effective for MG and could be included to the armamentarium for this autoimmune disease. The present results should be interpreted considering the limitations of a retrospective clinical study. Confirmation of these results in randomized studies is desirable.
Functional Organization and Conformational Dynamics of the Nicotinic Receptor
Authors: Taly Antoine , Changeux Jean‐Pierre
Published: June 2008

To understand the structural causes of myasthenic mutations, molecular models of the nicotinic acetycholine receptor were first constructed. Then, the gating transition between resting and open conformation was investigated in silico by normal mode analysis using a physically meaningful description of protein flexibility. This analysis revealed a global quaternary twist motion that opens the ion pore. Second, it was found that most (24/27) of the spontaneous mutations known to cause congenital myasthenia (and autosomal dominant nocturnal frontal lobe epilepsy) are located either at the interface between subunits or, within a given subunit, at the interface between rigid blocks. These interfaces are modified significantly by the twist mode together with significant changes of the tertiary organization of the subunits. These data provide a qualitative interpretation of the molecular phenotype of pathological mutations responsible for congenital myasthenia.
The Role of Glial Cells in the Formation and Maintenance of the Neuromuscular Junction
Authors: Feng Zhihua , Ko Chien‐Ping
Published: June 2008

The vertebrate neuromuscular junction (NMJ) is a “tripartite” synapse, composed of three cellular elements: the presynaptic nerve terminal, the postsynaptic specialization, and synapse‐associated glial cells, called perisynaptic Schwann cells (PSCs; also called terminal Schwann cells). During development, PSCs grow beyond nerve terminals and guide nerve terminal extension. Nerve terminals retract or stop extension after PSC ablation by complement‐mediated lysis in vivo, suggesting that PSCs can promote synaptic growth and maintenance at developing NMJs. Schwann cell–conditioned medium (SC‐CM), which may be mediated by transforming growth factor‐β1, can promote synapse formation in Xenopus nerve–muscle culture. In addition, SC‐CM contains small molecules (within 500–5000 Da), which can enhance spontaneous synaptic activities acutely and potently at developing frog NMJs. In adult muscles, PSCs can detect evoked synaptic activities and are capable of modulating transmitter release. Nerve terminals retract and synaptic efficacy is reduced at 1 week, but not within the first few hours, after PSC ablation. Thus, PSCs are essential for the long‐term, but not short‐term, maintenance of synaptic structure and function at the adult NMJ. During synaptic remodeling in adult muscles, PSC sprouts lead nerve terminal sprouts. After nerve injury, adult PSCs sprout extensive processes, which guide regenerating nerve terminals. Schwann cells express agrin and neuregulins, which may help the postsynaptic differentiation and synaptic repair. Furthermore, neuregulin‐ErbB signaling pathways play an essential role in synapse–glial interactions at the NMJ. These recent findings suggest that PSCs play multiple roles and actively participate in synaptic development, modulation, maintenance, and repair of the vertebrate NMJ.
Autoimmunizing Mechanisms in Thymoma and Thymus*
Authors: Willcox Nick , Leite Maria Isabel , Kadota Yoshihisa , Jones Margaret , Meager Anthony , Subrahmanyam Peddasomayajula , Dasgupta Bhaskar , Morgan B. Paul , Vincent Angela
Published: June 2008

Autoimmunizing mechanisms are very hard to study in humans, so we have focused on vital clues in thymomas and hyperplastic thymuses in myasthenia gravis (MG). According to our multi‐step hypothesis: thymic epithelial cells (TEC) present epitopes from the isolated acetylcholine receptor (AChR) subunits they express, and autoimmunize helper T cells; subsequently, these evoke “early antibodies” that then attack rare thymic myoid cells expressing intact AChR; in the resulting germinal centers, autoantibodies diversify to recognize native AChR. We have studied: 1) thymomas, to identify autoimmunizing cell types, focusing on IFN‐α, against which many patients have high titer autoantibodies, as in another highly informative autoimmune syndrome. Although IFN‐α is much easier to label than the sparse and delicate AChR subunits, we have not yet located obviously autoimmunizing micro‐environments; 2) hyperplastic MG thymuses, where we find (a) upregulation of complement receptors and regulators on hyperplastic TEC and deposition of activated C3b complement component on them, (b) absence of complement regulators from almost all myoid cells, indicating vulnerability to attack, and (c) deposition of C3b, and even of the terminal membrane attack complex, especially on the myoid cells close to the infiltrating germinal centers. The changes are very similar in over 50% of the so‐called seronegative patients with generalized MG (SNMG) but without detectable autoantibodies against AChR or MuSK, consistently with other evidence that they belong to the spectrum of AChR‐seropositive MG. Together, moreover, our findings implicate both myoid cells and TEC in autoimmunization, and thus strongly support our hypothesis.
Lambert–Eaton Myasthenic Syndrome
Authors: Titulaer Maarten J. , Verschuuren Jan J.G.M.
Published: June 2008

Half the patients with Lambert–Eaton myasthenic syndrome (LEMS) have a small cell lung carcinoma (SCLC). SCLC is an aggressive tumor and survival is poor. We studied the differences between LEMS patients with and without an SCLC. Several items were identified, among which are age, smoking behavior, sex, the progression of clinical symptoms, HLA, and presence of Sox1 serum antibodies. The relationship between these parameters is not fully elucidated. Data support a role for the LEMS‐related immune response in suppressing the tumor activity. We summarize the literature and present data from our Dutch cohort of 104 LEMS patients to compare the clinical and laboratory characteristics of tumor and nontumor related LEMS patients.
Lessons from Two Trials of Mycophenolate Mofetil in Myasthenia Gravis
Authors: Sanders Donald B. , Siddiqi Zaeem A.
Published: June 2008

Two randomized controlled trials of mycophenolate mofetil (MMF) in the treatment of myasthenia gravis (MG) were recently completed. Although neither study demonstrated efficacy of MMF in the population of patients studied, there are valuable lessons in the way these studies were developed and performed. After reviewing the design and results of these trials, we discuss possible reasons leading to negative results and the lessons learned, which should be useful for future clinical trials in MG.
CD4+ T Cells and Cytokines in the Pathogenesis of Acquired Myasthenia Gravis
Authors: Conti‐Fine Bianca M. , Milani Monica , Wang Wei
Published: June 2008

Although human and experimental acquired myasthenia gravis (MG) are prototypic antibody (Ab)‐mediated autoimmune diseases, synthesis of the pathogenic anti‐acetylcholine receptor (AChR) Abs, which are high affinity IgG, requires intervention of CD4+ T helper cells and their cytokines. Moreover, cytokine signaling is crucial for development, modulation, and downregulation of immune responses, and therefore influences the initiation and evolution of the anti‐AChR response in acquired MG. Cytokines are involved in the growth and differentiation of CD4+ T cells, and are secreted by activated CD4+ T cells as effectors of their functions: differentiated CD4+ T cells are classified into subtypes based on the cytokines they synthesize and secrete. Because cytokines are synthesized by and act on a variety of cells and because they may influence the synthesis and/or the activity of other cytokines, the effects of their signaling, in both normal and autoimmune responses, are complex and sometimes even contrasting, depending on the circumstances when the cytokine action took place. In this chapter, we will review studies on the effects on the development of acquired MG symptoms of several cytokines secreted by activated CD4+ T cells or influencing the activation of particular CD4+ T cell subsets.
In Vivo Regulation of Follicle-Stimulating Hormone Receptor by the Transcription Factors Upstream Stimulatory Factor 1 and Upstream Stimulatory Factor 2 Is Cell Specific
Authors: Hermann Brian P. , Hornbaker Kaori , Rice Daren A. , Sawadogo Michele , Heckert Leslie L.
Published: June 2008

Pituitary FSH promotes pubertal timing and normal gametogenesis by binding its receptor (FSHR) located on Sertoli and granulosa cells of the testis and ovary, respectively. Studies on Fshr transcription provide substantial evidence that upstream stimulatory factor (USF) 1 and USF2, basic helix-loop-helix leucine zipper proteins, regulate Fshr through an E-box within its promoter. However, despite the strong in vitro support for USF1 and USF2 in Fshr regulation, there is currently no in vivo corroborating evidence. In the present study, chromatin immunoprecipitation demonstrated specific binding of USF1 and USF2 to the Fshr promoter in both Sertoli and granulosa cells, in vivo. Control cells lacking Fshr expression showed no USF-Fshr promoter binding, thus correlating USF-promoter binding to gene activity. Evaluation of Fshr expression in Usf1 and Usf2 null mice further explored USF’s role in Fshr transcription. Loss of either gene significantly reduced ovarian Fshr levels, whereas testis levels were unaltered. Chromatin immunoprecipitation analysis of USF-Fshr promoter binding in Usf-null mice indicated differences in the composition of promoter-bound USF dimers in granulosa and Sertoli cells. Promoter-bound USF dimer levels declined in granulosa cells from both null mice, despite increased USF2 levels in Usf1-null ovaries. However, compensatory increases in promoter-bound USF homodimers were evident in Usf-null Sertoli cells. In summary, this study provides the first in vivo evidence that USF1 and USF2 bind the Fshr promoter and revealed differences between Sertoli and granulosa cells in compensatory responses to USF loss and the USF dimeric composition required for Fshr transcription.
Catecholamine Uptake, Storage, and Regulated Release by Ovarian Granulosa Cells
Authors: Greiner Monika , Paredes Alfonso , Rey-Ares Verónica , Saller Sabine , Mayerhofer Artur , Lara Hernán E.
Published: June 2008

Catecholamines present in the mammalian ovary are involved in many normal aspects of ovarian functions, including initial follicle growth, steroidogenesis, and pathological states such as polycystic ovary syndrome. Sympathetic nerve fibers are the largest source of norepinephrine (NE), but not the only one. Surgical denervation of the rat ovary reduces, but does not eliminate, the ovarian content of NE. The aim of this work was to explore which intraovarian cells may participate in the ovarian NE homeostasis and the mechanisms involved. It was found that denervated rat ovaries can take up NE and cocaine considerably, decreased its uptake, suggesting involvement of catecholamine transporters. Granulosa cells of rat ovarian follicles present dopamine transporter and NE transporter. Their functionality was confirmed in isolated rat granulosa cells while cocaine blocked the uptake of NE. Furthermore, the presence of the vesicular monoamine transporter 2, together with the exocytotic protein (synaptosome-associated protein of 25 kDa) in granulosa cells, implies catecholamine storage and regulated release. Regulated calcium-dependent release of NE was shown after depolarization by potassium, implying all neuron-like cellular machinery in granulosa cells. These results in rats may be of relevance for the human ovary because dopamine transporter, NE transporter, vesicular monoamine transporter 2, and synaptosome-associated protein of 25-kDa protein and mRNA are found in human ovarian follicles and/or isolated granulosa cells. Thus, ovarian nonneuronal granulosa cells, after taking up catecholamines, can serve as an intraovarian catecholamine-storing compartment, releasing them in a regulated way. This suggests a more complex involvement of catecholamines in ovarian functions as is currently being recognized.
Paracrine Insulin-Like Growth Factor Signaling Influences Primordial Germ Cell Migration: In Vivo Evidence from the Zebrafish Model
Authors: Sang Xianpeng , Curran Matthew S. , Wood Antony W.
Published: June 2008

IGF signaling has been shown to stimulate migration of multiple cell types in vitro, but few studies have confirmed an equivalent function for IGF signaling in vivo. We recently showed that suppression of IGF receptors in the zebrafish embryo disrupts primordial germ cell (PGC) migration, but the mechanism underlying these effects has not been elucidated. We hypothesized that PGCs are intrinsically dependent upon IGF signaling during the migratory phase of development. To test this hypothesis, we first examined the spatial expression patterns of IGF ligand genes (igf1, igf2a, and igf2b) in the zebrafish embryo. In situ analyses revealed distinct expression patterns for each IGF ligand gene, with igf2b mRNA expressed in a spatial pattern that correlates strongly with PGC migration. To determine whether PGC migration is responsive to IGF signaling in vivo, we synthesized gene hybrid expression constructs that permit conditional overexpression of IGF ligands by PGCs into the PGC microenvironment. Conditional overexpression of IGF ligands consistently disrupted PGC migration, confirming that PGC migration is sensitive to local aberrations in IGF signaling. Finally, we show that conditional suppression of IGF signaling, via PGC-specific overexpression of a mutant IGF-I receptor, disrupts PGC migration, confirming that zebrafish PGCs intrinsically require IGF signaling for directional migration in vivo. Collectively, these studies confirm an in vivo role for IGF signaling in cell migration and identify a candidate ligand gene (igf2b) regulating PGC migration in the zebrafish.
Maternal Hypothyroxinemia Impairs Spatial Learning and Synaptic Nature and Function in the Offspring
Authors: Opazo M. C. , Gianini A. , Pancetti F. , Azkcona G. , Alarcón L. , Lizana R. , Noches V. , Gonzalez P. A. , Porto M. , Mora S. , Rosenthal D. , Eugenin E. , Naranjo D. , Bueno S. M. , Kalergis A. M. , Riedel C. A.
Published: June 2008

Neurological deficits in the offspring caused by human maternal hypothyroxinemia are thought to be irreversible. To understand the mechanism responsible for these neurological alterations, we induced maternal hypothyroxinemia in pregnant rats. Behavior and synapse function were evaluated in the offspring of thyroid hormone-deficient rats. Our data indicate that, when compared with controls, hypothyroxinemic mothers bear litters that, in adulthood, show prolonged latencies during the learning process in the water maze test. Impaired learning capacity caused by hypothyroxinemia was consistent with cellular and molecular alterations, including: 1) lack of increase of phosphorylated c-fos on the second day of the water maze test; 2) impaired induction of long-term potentiation in response to theta-burst stimulation to the Schaffer collateral pathway in the area 1 of the hippocampus Ammon’s horn stratum radiatum, despite normal responses for input/output experiments; 3) increase of postsynaptic density protein 95 (PSD-95), n-methyl-d-aspartic acid receptor subunit 1, and tyrosine receptor kinase B levels in brain extracts; and 4) significant increase of PSD-95 at the PSDs and failure of this molecule to colocalize with n-methyl-d-aspartic acid receptor subunit 1, as it was shown by control rats. Our findings suggest that maternal hypothyroxinemia is a harmful condition for the offspring that can affect key molecular components for synaptic function and spatial learning.
Telephone assessment increases uptake of colonoscopy in a FOBT colorectal cancer-screening programme
Authors: Rodger J , Steele R J C
Published: June 2008

In faecal occult blood test (FOBT) screening for colorectal cancer, face-to-face consultation for pre-colonoscopy assessment has significant resource implications. For this reason, providing the option of telephone interview for this purpose was evaluated. In the second year of the third round of screening in Tayside, all FOBT-positive individuals were offered pre-colonoscopy assessment by means of telephone interview. This was evaluated by comparing the results with those obtained in the first year, when only face-to-face consultation was available. Of 388 individuals offered the choice of telephone interview or face-to-face consultation, 330 (85.1%) chose telephone interview, and all but two of the remainder underwent face-to-face consultation. When compared with the preceding year, there was a highly significant reduction in the numbers not attending for colonoscopy (0.8% versus 14.9%, P < 0.0001) Telephone interview is an acceptable form of pre-colonoscopy assessment for the majority of FOBT-positive participants in a colorectal screening programme, and the policy of offering this approach is associated with a marked reduction in the colonoscopy default rate.
Randomized trial of a self-administered decision aid for colorectal cancer screening
Authors: Trevena Lyndal J , Irwig Les , Barratt Alexandra
Published: June 2008

Objective

Previous studies have not assessed whether evidence-based information about the outcomes of colorectal cancer screening increases informed choice among people from a range of socioeconomic backgrounds nor have they assessed whether this can be administered away from a health-care provider.

Methods

Randomized controlled trial in six primary care locations. Three hundred and fourteen people aged 50–74 years received a self-administered decision aid (DA) booklet about outcomes of biennial faecal occult blood testing (FOBT) screening or government consumer guidelines (G).

Results

Significantly more DA recipients (20.9%) were ‘informed’ compared with G recipients (5.8%) ( P = 0.0001, OR 4.32; 95% CI 2.49 to 7.52); the DA did not affect values clarity (61.9% clear after DA versus 59.1% after G) nor screening decisions overall (87.3% would screen after DA versus 90.5% after G). Test uptake at one month was uniformly low (5.2% DA versus 6.6% G); mostly due to being ‘too busy’. DA recipients were more likely to make decisions ‘integrating’ knowledge with values (10.4% DA versus 1.5% G). Decisions not to screen were equally uncommon in both groups but more likely to be uninformed in G ( P = 0.03). More DA recipients from all education levels were ‘informed’ ( P = 0.02), particularly in lower education (50.0% DA versus 17.8% G) and university-educated groups (79.4% DA versus 32.1% G).

Conclusion

Detailed absolute risk and benefit information about FOBT screening can be effectively used at home by people to increase informed choice. The DA was effective in people with lower education levels.

Trial Registration

Unique Protocol ID 211705 ClinicalTrials.gov ID NCT 00148226.
Sociodemographic predictors of HPV testing and vaccination acceptability: results from a population-representative sample of British women
Authors: Marlow Laura A V , Waller Jo , Wardle Jane
Published: June 2008

Objectives

To examine sociodemographic predictors of self-reported screening attendance, intention to accept human papillomavirus (HPV) testing and willingness to accept vaccination for a daughter under 16.

Setting

Home-based, computer-assisted interviews with a population representative sample of British women.

Methods

Participants were selected using random probability sampling of the Postcode Address File, 994 women aged 25–64 were included in these analyses. Women reported their attendance at cervical screening and intention to accept an HPV test. A subsample of those with a daughter under 16 years ( n = 296) reported their willingness to accept HPV vaccination for their daughter.

Results

Screening attendance was associated with education level (odds ratio [OR] = 1.66, confidence interval [95% CI]: 1.07–2.56) and being married (OR = 2.04, 95% CI: 1.37–3.03). Acceptance of HPV testing was predicted by regular attendance for cervical screening (OR = 1.58, 95% CI: 1.03–2.42) and being from a white background (OR = 2.20, 95% CI: 1.18–4.13). Daughter's age was the only predictor of HPV vaccine acceptance, with mothers whose youngest daughter was 13–16 years old being the most likely to accept vaccination (OR = 2.91, 95% CI: 1.27–6.65).

Conclusion

In contrast to screening attendance, ethnicity plays an important role in HPV testing. Specific cultural barriers should be identified and addressed to ensure ethnic disparities in testing are limited. While marital status is associated with screening attendance, HPV testing could overcome this bias. Sociodemographic variables seem to play a limited role in HPV vaccine acceptance among mothers making vaccine decisions for their daughters, but as with other studies, age of daughter is important. The scientific reasons for vaccinating at 12–13 years should be emphasized in HPV information.
Newborn screening for glucose-6-phosphate dehydrogenase deficiency in Isfahan, Iran: a quantitative assay
Authors: Iranpour Ramin , Hashemipour Mahin , Talaei Seyed-Mojtaba , Soroshnia Mohsen , Amini Abasgholi
Published: June 2008

Objectives

To determine the prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency in Isfahan, the central state of Iran.

Methods

From February to March 2006, a total of 2501 samples were screened for the quantitative measurement of G6PD activity by enzymatic colorimetric assay by a commercial kit (GAMMA, Belgium). The neonates were referred from 17 delivery units to the Isfahan neonatal screening center at 3–7 days after birth. Any neonate with a value < 6.4 U/gHb was considered G6PD deficient.

Results

Of the 2501 newborns (1307 males, 1194 females) screened, 79 neonates were found to have G6PD deficiency (67 males, 12 females). The overall incidence of G6PD deficiency was 3.2%. Frequency in male population was 5.1 % (67 out of 1307 male neonates) and in female population was 1% (12 out of 1194 female neonates).The female:male ratio was 1:5.5 ( P = 0.0001). The mean enzyme activity in deficient patients was 3.22 ± 1.8 U/gHb (male deficient group; 3.17 ± 1.74 U/gHb, female deficient group; 3.49 ± 2.17 U/gHb, P = 0.58).

Conclusion

Routine neonatal screening in Isfahan, Iran with a relatively high prevalence of G6PD deficiency is justified and meets the World Health Organization recommendation.
MADS: A new and improved method for analysis of differential alternative splicing by exon-tiling microarrays
Authors: Xing Yi , Stoilov Peter , Kapur Karen , Han Areum , Jiang Hui , Shen Shihao , Black Douglas L. , Wong Wing Hung
Published: June 2008

We describe a method, microarray analysis of differential splicing (MADS), for discovery of differential alternative splicing from exon-tiling microarray data. MADS incorporates a series of low-level analysis algorithms motivated by the “probe-rich” design of exon arrays, including background correction, iterative probe selection, and removal of sequence-specific cross-hybridization to off-target transcripts. We used MADS to analyze Affymetrix Exon 1.0 array data on a mouse neuroblastoma cell line after shRNA-mediated knockdown of the splicing factor polypyrimidine tract binding protein (PTB). From a list of exons with predetermined inclusion/exclusion profiles in response to PTB depletion, MADS recognized all exons known to have large changes in transcript inclusion levels and offered improvement over Affymetrix's analysis procedure. We also identified numerous novel PTB-dependent splicing events. Thirty novel events were tested by RT-PCR and 27 were confirmed. This work demonstrates that the exon-tiling microarray design is an efficient and powerful approach for global, unbiased analysis of pre-mRNA splicing.
Sale or Lease? Durable-Goods Monopoly with Network Effects
Authors: Chien Hung-Ken , Chu C. Y. Cyrus
Published: June 2008

This paper studies the pricing problem of a durable-goods monopolist. It finds that contrary to the existing literature, profits from selling durable goods might be higher than from leasing when the products exhibit network effects. Under the influence of network effects, there exist multiple self-fulfilling equilibria that would sustain different network sizes at the same price. By using the assumption that consumers are cautious about network growth, we find that consumption externalities among heterogeneous groups of consumers generate a discontinuous demand function, which requires a lessor to offer a low price if she wants to reach the mass market. In contrast, a seller enjoys a relative advantage in that she can build a customer base by setting a lower initial price and raise the price later in the mass market. Our finding that selling can be more profitable than leasing holds when consumers are more cautious about the prospect of the product's success, which might be the case if, for example, the technology or manufacturer is relatively unknown.
NIR-Messsystem zur Erkennung von Verunreinigungen in Rohbaumwolle (NIR-Measurement System to Detect Foreign Matter in Row Cotton)
Authors: Böhmer Stephan , Budzier Helmut , Krause Volker , Pusch Thomas , Gerlach Gerald , Cherif Chokri , Hehl Jörg , Heitmann Uwe , Planck Heinrich
Published: June 2008

Die Erkennung von Fremdstoffen in Baumwollflockenströmen ist ein zentrales Problem der Qualitätssicherung in der Textilindustrie. In der Regel basiert die Detektion auf der Auswertung des Farbkontrastes zwischen der Baumwolle und den Fremdstoffen. Die Detektion von transparenten und weißen Folien erweist sich dabei als schwierig. Der Beitrag beschreibt ein Messsystem, das im Spektralbereich des nahen Infrarots (NIR) diese Stoffe erkennen kann.
Ganzheitliche Methoden zur zerstörungsfreien Prüfung von Betonbauteilen: Modellierung, Abbildung und Charakterisierung von Verpressfehlern in Hüllrohren (Integral Methods for Nondestructive Testing of Concrete Structural Components: Modelling, Imaging and Characterization of Grouting Defects in Tendon Ducts)
Authors: Marklein René , Mayer Klaus , Zimmer Alexander , Krause Martin
Published: June 2008

Für die zerstörungsfreie Prüfung großer Betonbauwerke unter dem Aspekt der Analyse von Spannkanälen hat sich die Ultraschalltechnik in den letzten Jahren als geeignete Methode herausgestellt, da sowohl die Messtechnik – insbesondere die Ultraschallwandler – als auch die numerischen Auswerteverfahren in einem Stadium sind, das es erlaubt, größere Messflächen und damit größere Volumina zu beschallen und abzubilden. Mit Hilfe der Modellierung der Ausbreitung elastischer Wellen in komplexen Medien können praxisrelevante Problemstellungen untersucht werden, auch unter dem Aspekt, Testkörper zu planen oder gar zu ersetzen. Durch die Auswertung der Phase der Rekonstruktion eines Streuvorgangs können Fehlstellen klassifiziert und damit Aussagen über die Bauwerkssicherheit signifikant objektiviert werden. Die Methoden werden, im Hinblick auf eine ganzheitliche Sichtweise von skalaren und polarimetrischen Abbildungsverfahren mit Unterstützung der Modellierung und der anschließenden Klassifizierung durch Phasenanalyse, an ausgewählten Beispielen erläutert.
Human Embryonic Stem Cells Have Enhanced Repair of Multiple Forms of DNA Damage
Authors: Maynard Scott , Swistowska Anna Maria , Lee Jae Wan , Liu Ying , Liu Su-Ting , Da Cruz Alexandre Bettencourt , Rao Mahendra , de Souza-Pinto Nadja C. , Zeng Xianmin , Bohr Vilhelm A.
Published: June 2008

Embryonic stem cells need to maintain genomic integrity so that they can retain the ability to differentiate into multiple cell types without propagating DNA errors. Previous studies have suggested that mechanisms of genome surveillance, including DNA repair, are superior in mouse embryonic stem cells compared with various differentiated murine cells. Using single-cell gel electrophoresis (comet assay) we found that human embryonic stem cells (BG01, I6) have more efficient repair of different types of DNA damage (generated from H2O2, UV-C, ionizing radiation, or psoralen) than human primary fibroblasts (WI-38, hs27) and, with the exception of UV-C damage, HeLa cells. Microarray gene expression analysis showed that mRNA levels of several DNA repair genes are elevated in human embryonic stem cells compared with their differentiated forms (embryoid bodies). These data suggest that genomic maintenance pathways are enhanced in human embryonic stem cells, relative to differentiated human cells.

Disclosure of potential conflicts of interest is found at the end of this article.
Induction of Proliferation and Monocytic Differentiation of Human CD34+ Cells by CD137 Ligand Signaling
Authors: Jiang Dongsheng , Yue Pei Shan Eunice , Drenkard Daniela , Schwarz Herbert
Published: June 2008

CD137 is a member of the tumor necrosis factor receptor family and is involved in the regulation of activation, proliferation, differentiation, and cell death of leukocytes. Bidirectional signaling exists for the CD137 receptor/ligand system, as CD137 ligand, which is expressed as a transmembrane protein, can also transduce signals into the cells on which it is expressed. In this study, we have identified expression of CD137 in human bone marrow and expression of CD137 ligand on a subset of CD34+ cells. Cross-linking of CD137 ligand on CD34+ cells by CD137 ligand agonists induces activation, prolongation of survival, proliferation, and colony formation. CD137 ligand agonists induce differentiation of early hematopoietic progenitor cells to colony-forming units-granulocyte/macrophage and subsequently to monocytes and macrophages but not to dendritic cells. These data uncover a novel function of CD137 and CD137 ligand by showing their participation in the growth and differentiation of hematopoietic progenitor cells.

Disclosure of potential conflicts of interest is found at the end of this article.
Application of Data Transmission to Offshore Operations
Authors: Gaymard R. , Peveraro R. , Ringot J. , Johns Clamart C.
Published: June 2008

With data taping and data processing already available to the Oil Companies, Schlumberger has completed the last link of its integrated log data handling system by offering data transmission.

Data transmission offers a solution for the Oil Companies to have offshore logsquickly delivered to their decision center.

Thanks to data transmission, also, the logging data may quickly reach the computing center when an urgent processing is required, such as log interpretation or dipmeter computation. Workable results arc transmitted back to the decision making people in no time.

The technique used ensures that the confidentiality of the system is maintained at all times.

Introduction

Drilling and Production operations offshore or in remote, difficult areas underline the need for a method of delivering logs to the Oil Company's office quickly. Schlumberger offers a solution by transmitting over radio, telephone and/or satellite, logging data which has been recorded digitally on magnetic tape at the wellsite. As soon as it is received the logging data can be readily converted into optical log films which duplicate those made at the wellsite. Thanks to the transmitted logs, decision making time is dramatically reduced and the presence at the wellsite of the Oil Company's key personnel is no longer required.

If immediate, comprehensive formation evaluation is required, data transmission ensures quick access of the logging data to the processing center and quick delivery of the results to the Oil Company.

The Data Handling System

Data transmission is part of a whole new concept of well log data handling which has been built around the digital recording of data. Data handling includes the following technologies:

* Data Taping, which is the recording of data in digital form on magnetic tape, the Field Tape.

* Data Transmission, by telecommunication network.

* Data Processing, by computer, and playback.

Log data taping was first introduced with the continuous dipmeter for high density data storage and computer processing considerations. It is now being extended to all types of logs and will eventually become the fundamental recording of well logging data.

Log data Processing consists of a complete array of services which range from True Vertical Depth playback for deviated hole to comprehensive Formation Evaluation from log data.
Field Performance Evaluation of Crosslinked Polymers to Increase Oil Recovery in The Wilmington Field, California
Authors: Fitch Jon P. , Canfield Carl M.
Published: June 2008

In the Wilmington Field, direct channeling of injection water from injector to producer has adversely affected oil recovery. The solution to this problem may be approached from two directions. The first is to seal off the channel at the injector. The second approach is to treat the affected producing wells. This approach has many advantages which will be explored in this discussion. Both methods have been used in portions of the Wilmington Field. This paper will examine new technology in crosslinking poly acrylamides to control water permeability in unconsolidated sands. Field data will be presented on treatment procedures, problems encountered and solutions for incurred problems.

Conclusions are:New in situ polymer gelling techniques provide an effective control over subsurface water movement.By excluding water production in the Wilmington Field, effective sand control has been achieved.Control of water entries in the producing wells can affect the sweep efficiency in the flood pattern.

Introduction

The Wilmington Field is located in the south central Los Angeles Basin between the Torrance and Huntington Beach oil fields. The Wilmington structure is a northeast, southwest trending asymmetrical anticline, which is transversed by numerous faults dividing the structure into nine major fault blocks. In the crestal area, there are seven major producing intervals of Lower Pliocene and Upper Miocene Age between 2200 feet and 5600 feet in depth. Each producing zone is composed of numerous individual sand members which vary from poorly-sorted, coarse-grained, unconsolidated sand in the upper zones to more consolidated sands, interbedded with shales and siltstones in the lower zones.
A Novel Method of Classifying Soil Profiles in the Field using Optical Means
Authors: Ben-Dor Eyal , Heller Daniela , Chudnovsky Alexandra
Published: June 2008

The rationale of this study was to develop a new, objective method for characterizing soil profiles in the field by using the optical means commonly available to most users. For that purpose, we used a field spectrometer (analytical spectral device, ASD) and a specific accessory used to read subsoil reflectance data, together with a multivariate spectral analysis approach. To that end, we developed and constructed a housing assembly that can be adapted to any portable field spectrometer, thus making subsoil spectral readings possible. This accessory, the sub‐surface spectral head device (termed 3S‐HeD), penetrates into the subsoil profile after a small hole, the size of the accessory, is drilled in the soil. To examine and demonstrate this idea, we selected and studied four different soil profiles from semiarid environments during the summer. Soil samples were taken from the drilled holes (40), near trenches (30), and a local soil bank (90). All of these samples were mixed together to create a working group against which multivariate spectral models were run, using the spectral and traditional soil laboratory information. The physical and chemical properties examined were soil moisture (SM), soil organic matter (OM), soil carbonates (SC), free iron oxides (Fed), and specific surface area (SSA). Spectra along the profile in the drilled holes were acquired by the 3S‐HeD and by a contact probe in nearby trenches and in the soil bank. The models were generated for each property separately by running several spectral manipulations and by applying partial least squares regression (PLSR) analyses. The models' performances were tested against an external fixed group that was selected before the spectral analytical procedure. The 3S‐HeD assembly was used to further examine the area of the drilled holes at 10‐cm vertical increments. In addition, soil color was extracted from the spectroscopy using several indices and further used to characterize the soil profile. Soil description by the traditional observation methods at nearby trenches and by the proposed optical method were in good agreement. It was concluded that by properly combining information obtained from the field spectrometer, the optical head assembly hooked to the spectrometer, and appropriate multivariate models it is possible to describe quantitatively and objectively the entire soil profile in situ. Importantly, this can be done without opening trenches or sending samples to the laboratory. This work demonstrated an application within four different soil profiles. However, validation of the method over independent locations is still required. Nevertheless, we concluded that the concept presented here can be further employed in developing a robust soil mapping method.
Phosphorus Retention on Soil Surface of Tilled and No‐tilled Soils
Authors: Gutiérrez Boem Flavio H. , Alvarez Carina R. , Cabello Maria J. , Fernández Patricia L. , Bono Alfredo , Prystupa Pablo , Taboada Miguel A.
Published: June 2008

Decreasing P buffer capacity of the soil surface in no‐tilled soils has been attributed to enrichment of both P and OM (OM). As soil surface enrichment with P and OM usually occurs simultaneously in no‐tilled soils, it is not clearly established whether the increase of soil OM affects the capacity of soils to retain P. A study was conducted to assess whether the variations in soil OM (total and particulate) at soil surface affects P retention capacity. Thirty five soils from the Rolling Pampa (17 tilled and 18 no‐tilled) were selected. All soils had medium to low levels of available P (PBray1 < 20 mg kg−1). Soil samples were taken from the top 5 cm, and several soil characteristics determined: available and total P, P sorption index, OM, particulate OM (POM) ( >53 μm), particle size distribution, and pH. Tilled and no‐tilled soils did not differ in soil texture, pH, total and available P content. On the contrary, no‐tilled soils had more OM (+14%) and POM (+56%) than tilled soils. The capacity of soils to retain added P was not different in both groups of soils. Phosphorus sorption index was not related to soil content of total OM or POM. Variation in P sorption index was only related to soil clay content (r2 = 0.44). This study provides evidence contradicting the long held assumption that the reported decrease in P sorption at the surface of no‐tilled soils was caused in part by OM enrichment.
Tillage Effects on Soil Carbon Balance in a Semiarid Agroecosystem
Authors: Bono Alfredo , Alvarez R. , Buschiazzo D. E. , Cantet R. J. C.
Published: June 2008

Tillage systems may affect soil C sequestration, with a potential impact on crop productivity or organic matter mineralization. We evaluated crop yield, C inputs to the soil, and in situ CO2–C fluxes under no‐till and conventional tillage (disk tillage) during the 3‐ to 6‐yr period from the installation of an experiment in an Entic Haplustoll of the Semiarid Pampean Region of Argentina to elucidate the mechanisms responsible for possible management‐induced soil organic matter changes. Yield and biomass production were greater under no‐till than disk tillage for all the crops included in the rotation (oat [Avena sativa L.] + hairy vetch [Vicia villosa Roth ssp. villosa], corn [Zea mays L.], wheat [Triticum aestivum L.], and oat). This result was attributed to the higher soil water content under no‐till. Carbon inputs to the soil averaged 4 Mg C ha−1 yr−1 under no‐till and 3 Mg C ha−1 yr−1 under disk tillage. Soil temperature was similar between tillage systems and CO2–C emission was about 4 Mg C ha−1 yr−1, with significant but small differences between treatments (∼0.2 Mg C ha−1 yr−1). Carbon balance of the soil was nearly equilibrated under no‐till; meanwhile, greater C losses as CO2 than inputs in crop residues were measured under conventional tillage. Organic C in the soil was 5.4 Mg ha−1 higher under no‐till than the disk tillage treatment 6 yr after initiation of the experiment. Results showed that in our semiarid environment, C sequestration occurred under no‐till but not conventional tillage. The sequestration process was attributed to the effect of the tillage system on crop productivity rather than on the mineralization intensity of soil organic pools.
Determination of Soil Bulk Density with Thermo‐Time Domain Reflectometry Sensors
Authors: Liu Xiaona , Ren Tusheng , Horton Robert
Published: June 2008

Surface soil bulk density varies with time and location. In most cases, destructive soil sampling has been used to monitor soil bulk density, ρb Recently the thermo‐time domain reflectometry (TDR) technique was shown in principle to be able to estimate ρb Thermo‐TDR sensors can measure soil volumetric heat capacity (ρc) and soil water content (θ). Since ρc depends on θ and ρb, measurements of ρc and θ can be used to estimate ρb Previous studies indicated, however, that there were large deviations between thermo‐TDR estimates and gravimetric measures of ρb Deviations were attributed mainly to the change of thermo‐TDR needle‐to‐needle spacing during sensor insertion into the soil. The objective of this study was to improve the thermo‐TDR sensor design to improve estimation of ρb The ability of three new prototype thermo‐TDR sensors, along with an existing thermo‐TDR sensor, to estimate ρb was investigated. Evaluation results indicated that a three‐needle sensor design with 2‐mm needle diameter, 40‐mm needle length, and 8‐mm needle‐to‐needle spacing provided the most accurate estimation of soil ρb For this sensor, the RMSEs of ρb estimates compared with gravimetric measures of ρb in laboratory evaluations were 0.055, 0.051, and 0.046 Mg m−3 for a silt loam, a clay loam, and a sand soil, respectively, and was 0.095 Mg m−3 in a field evaluation. In terms of relative error, this specific design was generally within 5% under laboratory conditions and within 10% under field conditions. The improved thermo‐TDR sensor provides an opportunity for obtaining accurate, nondestructive, repeated estimates of soil ρb
Effect of Age on Flow-Rate, Protein and Electrolyte Composition of Stimulated Whole Saliva in Healthy, Non-Smoking Women
Authors: Sevón Liisi , Laine Merja A , Karjalainen Sára , Doroguinskaia Anguelina , Helenius Hans , Kiss Endre , Lehtonen-Veromaa Marjo
Published: June 2008

As relatively little is known about the effect of age on salivary electrolytes we studied the composition of saliva as function of age to provide reference values for healthy non-smoking women. All non-medicated and non-smoking 30-59-year-old subjects (n=255) selected from among 1030 women participating in a screening program formed the material of the present study. Salivary calcium, inorganic phosphate, magnesium, sodium, potassium, protein and flow-rate of stimulated whole saliva were measured. We found age-related changes in salivary calcium and phosphate concentrations (p=0.001 and p=0.004, respectively, one-way ANOVA). Peak values occurred at around 50-54 years of age. Age had no effect on flow-rate, magnesium, sodium, potassium or proteins. The concentration of sodium correlated positively, while phosphate, potassium, magnesium and protein correlated negatively with the salivary flow-rate. Calcium was the only electrolyte which had no association with flow-rate. Our study provides reference values for salivary electrolytes of 30-59-year-old women.
Pharmacokinetics of Acetyl-L-Carnitine Given in Single or Multiple Doses to HIV-1 Infected Patients with Toxic Peripheral Polyneuropathy
Authors: Herzmann C , Whiting S.J , Thomas M , Byrne P. , Johnson M.A , Youle M
Published: June 2008

The use of nucleoside reverse transcriptase inhibitors in the treatment of HIV infection is associated with antiretroviral toxic polyneuropathy (ATN). Previous studies suggest that long term treatment with Acetyl-L-carnitine (ALCAR) 1.5 gram twice daily improves symptoms and promotes nerve regeneration. It is unknown whether the drug’s pharmacokinetic profile would allow for a once daily administration. Twenty three HIV-1 infected subjects taking ALCAR for ATN were enrolled in a cross over trial and switched from twice to once daily dosing. Their regimen was changed from 1.5g twice daily to 1g (4 patients), 2g (7), and 3g (12) once daily, respectively. Twelve healthy volunteers served as control. Plasma levels of ALCAR and its metabolite L-carnitine were measured. Patients receiving ALCAR had higher pre-dose levels than control subjects. Post dose levels were not significantly higher than pre dose levels in any treatment group. The pre / post dose ALCAR concentrations were 7.6 / 7.7, 7.1 / 6.8, 7.7 / 6.8, and 7.1 / 7.5 µmol/l for 1.5g twice daily, 1g once daily, 2g once daily, and 3g once daily, respectively. All values were significantly higher than the mean concentration in the control group (4.3 µmol/l). For ALCAR and L-carnitine, measurements for once daily regimens did not differ from the twice daily regimen. Once daily dosing of ALCAR can achieve similar plasma levels as twice daily dosing but intra-mitochondrial levels remain unknown. The pharmacokinetic profile of orally administered ALCAR is complex and likely to be highly affected by endogenous concentrations.