bluuebunny/crossref_metadata_2025 huggingface dataset:
A modified TILLING approach to detect induced mutations in tetraploid and hexaploid wheat
Authors: Uauy Cristobal , Paraiso Francine , Colasuonno Pasqualina , Tran Robert K , Tsai Helen , Berardi Steve , Comai Luca , Dubcovsky Jorge
Published: September 2009

Background

Wheat (Triticumssp.) is an important food source for humans in many regions around the world. However, the ability to understand and modify gene function for crop improvement is hindered by the lack of available genomic resources. TILLING is a powerful reverse genetics approach that combines chemical mutagenesis with a high-throughput screen for mutations. Wheat is specially well-suited for TILLING due to the high mutation densities tolerated by polyploids, which allow for very efficient screens. Despite this, few TILLING populations are currently available. In addition, current TILLING screening protocols require high-throughput genotyping platforms, limiting their use.

Results

We developed mutant populations of pasta and common wheat and organized them for TILLING. To simplify and decrease costs, we developed a non-denaturing polyacrylamide gel set-up that uses ethidium bromide to detect fragments generated by crude celery juice extract digestion of heteroduplexes. This detection method had similar sensitivity as traditional LI-COR screens, suggesting that it represents a valid alternative. We developed genome-specific primers to circumvent the presence of multiple homoeologous copies of our target genes. Each mutant library was characterized by TILLING multiple genes, revealing high mutation densities in both the hexaploid (~1/38 kb) and tetraploid (~1/51 kb) populations for 50% GC targets. These mutation frequencies predict that screening 1,536 lines for an effective target region of 1.3 kb with 50% GC content will result in ~52 hexaploid and ~39 tetraploid mutant alleles. This implies a high probability of obtaining knock-out alleles (P= 0.91 for hexaploid,P= 0.84 for tetraploid), in addition to multiple missense mutations. In total, we identified over 275 novel alleles in eleven targeted gene/genome combinations in hexaploid and tetraploid wheat and have validated the presence of a subset of them in our seed stock.

Conclusion

We have generated reverse genetics TILLING resources for pasta and bread wheat and achieved a high mutation density in both populations. We also developed a modified screening method that will lower barriers to adopt this promising technology. We hope that the use of this reverse genetics resource will enable more researchers to pursue wheat functional genomics and provide novel allelic diversity for wheat improvement.
Low-resolution structural studies of human Stanniocalcin-1
Authors: Trindade Daniel M , Silva Júlio C , Navarro Margareth S , Torriani Iris CL , Kobarg Jörg
Published: September 2009

Background

Stanniocalcins (STCs) represent small glycoprotein hormones, found in all vertebrates, which have been functionally implicated in Calcium homeostasis. However, recent data from mammalian systems indicated that they may be also involved in embryogenesis, tumorigenesis and in the context of the latter especially in angiogenesis. Human STC1 is a 247 amino acids protein with a predicted molecular mass of 27 kDa, but preliminary data suggested its di- or multimerization. The latter in conjunction with alternative splicing and/or post-translational modification gives rise to forms described as STC50 and "big STC", which molecular weights range from 56 to 135 kDa.

Results

In this study we performed a biochemical and structural analysis of STC1 with the aim of obtaining low resolution structural information about the human STC1, since structural information in this protein family is scarce. We expressed STC1 in both E. coli and insect cells using the baculo virus system with a C-terminal 6 × His fusion tag. From the latter we obtained reasonable amounts of soluble protein. Circular dichroism analysis showed STC1 as a well structured protein with 52% of alpha-helical content. Mass spectroscopy analysis of the recombinant protein allowed to assign the five intramolecular disulfide bridges as well as the dimerization Cys202, thereby confirming the conservation of the disulfide pattern previously described for fish STC1. SAXS data also clearly demonstrated that STC1 adopts a dimeric, slightly elongated structure in solution.

Conclusion

Our data reveal the first low resolution, structural information for human STC1. Theoretical predictions and circular dichroism spectroscopy both suggested that STC1 has a high content of alpha-helices and SAXS experiments revealed that STC1 is a dimer of slightly elongated shape in solution. The dimerization was confirmed by mass spectrometry as was the highly conserved disulfide pattern, which is identical to that found in fish STC1.
Transchromosomic cell model of Down syndrome shows aberrant migration, adhesion and proteome response to extracellular matrix
Authors: Delom Frédéric , Burt Emma , Hoischen Alex , Veltman Joris , Groet Jürgen , Cotter Finbarr E , Nizetic Dean
Published: September 2009

Background

Down syndrome (DS), caused by trisomy of human chromosome 21 (HSA21), is the most common genetic birth defect. Congenital heart defects (CHD) are seen in 40% of DS children, and >50% of all atrioventricular canal defects in infancy are caused by trisomy 21, but the causative genes remain unknown.

Results

Here we show that aberrant adhesion and proliferation of DS cells can be reproduced using a transchromosomic model of DS (mouse fibroblasts bearing supernumerary HSA21). We also demonstrate a deacrease of cell migration in transchromosomic cells independently of their adhesion properties. We show that cell-autonomous proteome response to the presence of Collagen VI in extracellular matrix is strongly affected by trisomy 21.

Conclusion

This set of experiments establishes a new model system for genetic dissection of the specific HSA21 gene-overdose contributions to aberrant cell migration, adhesion, proliferation and specific proteome response to collagen VI, cellular phenotypes linked to the pathogenesis of CHD.
Distribution and hormonal regulation of membrane progesterone receptors β and γ in ciliated epithelial cells of mouse and human fallopian tubes
Authors: Nutu Magdalena , Weijdegård Birgitta , Thomas Peter , Thurin-Kjellberg Ann , Billig Håkan , Larsson DG Joakim
Published: September 2009

Background

The controlled beating of cilia of the fallopian tube plays an important role in facilitating the meeting of gametes and subsequently transporting the fertilized egg to its implantation site. Rapid effects of progesterone on ciliary beat frequency have been reported in the fallopian tubes of cows, but the identity of the receptors mediating this non-genomic action of progesterone is not known. We recently identified a member of the non-genomic membrane progesterone receptor family, mPR gamma, as a candidate for mediating these actions of progesterone. Here, we investigated the possible presence of a related receptor, mPR beta, in the fallopian tubes of mice and women as well as the possible hormonal regulation of mPR beta and gamma.

Methods

Western blot and immunohistochemistry with specific antibodies were used to characterize the expression and cellular localization of the mPRs in mouse and human tissues. Taqman (Quantitative Polymerase Chain Reaction) assays were used to quantify mRNA levels in the fallopian tubes of two different mouse models after injections with different hormones and specific antagonists.

Results

In the fallopian tubes of both mouse and human, the expression of mPR beta and mPR gamma proteins was exclusively found in the ciliated cells. Whereas mPR beta was found on the cilia, mPR gamma was localized at the base of the same ciliated cells, as previously reported. In gonadotropin-primed mice, both mPRs genes were down-regulated after an injection with progesterone. Treatment with estradiol rapidly down-regulated the level of mPR beta mRNA and protein in immature mice. The mPR gamma protein was down-regulated around the time of ovulation in cycling women, similar to the regulation observed in mice stimulated to ovulate via gonadotropin injections.

Conclusion

Our findings show the presence and hormonal regulation of two distinct mPRs associated with the cilia of the fallopian tubes in both mice and women. It is hypothesized that these receptors are involved in the control of ciliary movement and, thus, gamete transport in the fallopian tubes of mammals.
Comparative structure analyses of cystine knot-containing molecules with eight aminoacyl ring including glycoprotein hormones (GPH) alpha and beta subunits and GPH-related A2 (GPA2) and B5 (GPB5) molecules
Authors: Alvarez Eva , Cahoreau Claire , Combarnous Yves
Published: September 2009

Background

Cystine-knot (cys-knot) structure is found in a rather large number of secreted proteins and glycoproteins belonging to the TGFbeta and glycoprotein hormone (GPH) superfamilies, many of which are involved in endocrine control of reproduction. In these molecules, the cys-knot is formed by a disulfide (SS) bridge penetrating a ring formed by 8, 9 or 10 amino-acid residues among which four are cysteine residues forming two SS bridges. The glycoprotein hormones Follicle-Stimulating Hormone (FSH), Luteinizing Hormone (LH), Thyroid-Stimulating Hormone (TSH) and Chorionic Gonadotropin (CG) are heterodimers consisting of non-covalently associated alpha and beta subunits that possess cys-knots with 8-amino-acyl (8aa) rings. In order to get better insight in the structural evolution of glycoprotein hormones, we examined the number and organization of SS bridges in the sequences of human 8-aa-ring cys-knot proteins having 7 (gremlins), 9 (cerberus, DAN), 10 (GPA2, GPB5, GPHα) and 12 (GPHβ) cysteine residues in their sequence.

Discussion

The comparison indicated that the common GPH-alpha subunit exhibits a SS bridge organization ressembling that of DAN and GPA2 but possesses a unique bridge linking an additional cysteine inside the ring to the most N-terminal cysteine residue. The specific GPHbeta subunits also exhibit a SS bridge organization close to that of DAN but it has two additional C-terminal cysteine residues which are involved in the formation of the "seat belt" fastened by a SS "buckle" that ensures the stability of the heterodimeric structure of GPHs. GPA2 and GPB5 exhibit no cys residue potentially involved in interchain SS bridge and GPB5 does not possess a sequence homologous to that of the seatbelt in GPH β-subunits. GPA2 and GPB5 are thus not expected to form a stable heterodimer at low concentration in circulation.

The 8-aa cys-knot proteins GPA2 and GPB5 are expected to form a heterodimer only at concentrations above 0.1 microM: this would be consistent with a short-term paracrine role but not with an endocrine role after dilution in circulation. Consequently, GPA2 and GPB5 could exert separate endocrine roles either during development and/or during adult life of both vertebrates and invertebrates.
Reflections on the United States Military 1941-1987
Authors: Mandels Mary , Eveleigh Douglas E
Published: September 2009

This article, 'Reflections on the United States Military 1941-1987' written by my grandmother, Mary Mandels, illustrates her passion for life. Her outreach article was considered most appropriate for publication in this forum. Her career activities are outlined in the prior article 'Mary Elizabeth Hickox Mandels, 90, Bioenergy Leader' while her accomplishments were fully recognized, for instance, nationally through the American Chemical Society and through her induction into the Hall of Fame at the US Army Soldier Systems Center in Natick, Massachusetts. As illustrated, along with Dr Elwyn Reese at Natick's Pioneering Research Laboratory, she headed a bioengineering group that is particularly remembered for developing a process for the enzymatic conversion of waste cellulosic biomass into soluble sugars that could be fermented to ethanol for an alternate liquid fuel (gasohol). This technology remains a subject of interest with growing environmental concerns and an oil shortage crisis.

Mary broke the promotional glass ceiling in her own field, all the more remarkable from the perspective that she was born 3 years before women gained the right to vote. Her talents as the family storyteller, enthralling her four siblings while growing up, later reflected her abilities as an outstanding mentor to young scientists. Mary's passions went beyond her career with a love of nature and the outdoors, taking frequent canoe, hiking, skiing, and camping trips. She had a broad fascination for science, foci including her encyclopedic knowledge of plants and wildlife. When not outdoors Mary enjoyed listening to music, from opera to 'Bobby' Dylan, as she called him. Her voracious appetite for books was apparent by the tomes that covered her coffee table. She was never shy to share her political opinions and would send long handwritten letters to politicians who did something to her disapproval. She was strong willed and passionate in everything that she did. In particular was her love of the nation and of the US Army, and this particular article reflects her passion. Mary was an inspiration to all of those who knew her. For me, she was not only my grandmother but also my friend and role model. I will forever miss her wisdom, spirit and passion for life.

Susan Roche
Appropriateness of hospitalization for CAP-affected pediatric patients: report from a Southern Italy General Hospital
Authors: Antonelli Fabio , De Brasi Daniele , Siani Paolo
Published: September 2009

Background

Community-acquired pneumonia (CAP) is a common disease, responsible for significant healthcare expenditures, mostly because of hospitalization. Many practice guidelines on CAP have been developed, including admission criteria, but a few on appropriate hospitalization in children. The aim of this study was to evaluate appropriate hospital admission for CAP in a pediatric population.

Methods

We evaluated appropriate admission to a Pediatric Unit performing a retrospective analysis on CAP admitted pediatric patients from a Southern Italy area. Diagnosis was made based on clinical and radiological signs. Appropriate hospital admission was evaluated following clinical and non-clinical international criteria. Family ability to care children was assessed by evaluating social deprivation status.

Results

In 2 winter seasons 120 pediatric patients aged 1-129 months were admitted because of CAP. Median age was 28.7 months. Raised body temperature was scored in 68.3% of patients, cough was present in 100% of cases, and abdominal pain was rarely evidenced. Inflammatory indices (ESR and CRP) were found elevated in 33.3% of cases. Anti-Mycoplasma pneumoniae antibodies were found positive in 20.4%. Trans-cutaneous (TC) SaO2 was found lower than 92% in 14.6%. Dyspnoea was present in 43.3%. Dehydration requiring i.v. fluid supplementation was scored in 13.3%. Evaluation of familial ability to care their children revealed that 76% of families (derived from socially depressed areas) were "at social risk", thus not able to appropriately care their children. Furthermore, analysis of CAP patients revealed that "at social risk" people accessed E.D. and were hospitalized more frequently than "not at risk" patients (odds ratio = 3.59, 95% CI: 1,15 to 11,12; p = 0.01), and that admitted "at social risk" people presented without clinical signs of severity (namely dyspnoea, and/or SaO2 ≤ 92%, and/or dehydration) more frequently than "not at risk" population (p = 0.005).

Conclusion

Dyspnoea was found to be the main clinical criterion to define an appropriate children admission for CAP. Other more objective evaluation (i.e. oxygen pulse oxymetry) could underestimate the necessity of hospitalization as patients discomfort could be more severe then indicated by TC SaO2. Furthermore, family inability to children care represents the main criterion for hospital admission in our geographic area. It reflects social deprivation status and it should be strongly considered in deciding for children hospital admission.
Diagnostic and prognostic value of antibodies against chimeric fibrin/filaggrin citrullinated synthetic peptides in rheumatoid arthritis
Authors: Sanmartí Raimon , Graell Eduard , Perez Maria L , Ercilla Guadalupe , Viñas Odette , Gómez-Puerta Jose A , Gratacós Jordi , Balsa Alejandro , Gómara Maria J , Larrosa Marta , Cañete Juan D , Haro Isabel
Published: September 2009

Introduction

Evidence suggests that citrullinated fibrin(ogen) may be a potential in vivo target of anticitrullinated protein/peptide antibodies (ACPA) in rheumatoid arthritis (RA). We compared the diagnostic yield of three enzyme-linked immunosorbent assay (ELISA) tests by using chimeric fibrin/filaggrin citrullinated synthetic peptides (CFFCP1, CFFCP2, CFFCP3) with a commercial CCP2-based test in RA and analyzed their prognostic values in early RA.

Methods

Samples from 307 blood donors and patients with RA (322), psoriatic arthritis (133), systemic lupus erythematosus (119), and hepatitis C infection (84) were assayed by using CFFCP- and CCP2-based tests. Autoantibodies also were analyzed at baseline and during a 2-year follow-up in 98 early RA patients to determine their prognostic value.

Results

With cutoffs giving 98% specificity for RA versus blood donors, the sensitivity was 72.1% for CFFCP1, 78.0% for CFFCP2, 71.4% for CFFCP3, and 73.9% for CCP2, with positive predictive values greater than 97% in all cases. CFFCP sensitivity in RA increased to 80.4% without losing specificity when positivity was considered as any positive anti-CFFCP status. Specificity of the three CFFCP tests versus other rheumatic populations was high (> 90%) and similar to those for the CCP2. In early RA, CFFCP1 best identified patients with a poor radiographic outcome. Radiographic progression was faster in the small subgroup of CCP2-negative and CFFCP1-positive patients than in those negative for both autoantibodies. CFFCP antibodies decreased after 1 year, but without any correlation with changes in disease activity.

Conclusions

CFFCP-based assays are highly sensitive and specific for RA. Early RA patients with anti-CFFCP1 antibodies, including CCP2-negative patients, show greater radiographic progression.
Neuronal Thy-1 induces astrocyte adhesion by engaging syndecan-4 in a cooperative interaction with αvβ3 integrin that activates PKCα and RhoA
Authors: Avalos Ana María , Valdivia Alejandra D. , Muñoz Nicolás , Herrera-Molina Rodrigo , Tapia Julio C. , Lavandero Sergio , Chiong Mario , Burridge Keith , Schneider Pascal , Quest Andrew F. G. , Leyton Lisette
Published: September 2009

Clustering of αvβ3 integrin after interaction with the RGD-like integrin-binding sequence present in neuronal Thy-1 triggers formation of focal adhesions and stress fibers in astrocytes via RhoA activation. A putative heparin-binding domain is present in Thy-1, raising the possibility that this membrane protein stimulates astrocyte adhesion via engagement of an integrin and the proteoglycan syndecan-4. Indeed, heparin, heparitinase treatment and mutation of the Thy-1 heparin-binding site each inhibited Thy-1-induced RhoA activation, as well as formation of focal adhesions and stress fibers in DI TNC1 astrocytes. These responses required both syndecan-4 binding and signaling, as evidenced by silencing syndecan-4 expression and by overexpressing a syndecan-4 mutant lacking the intracellular domain, respectively. Furthermore, lack of RhoA activation and astrocyte responses in the presence of a PKC inhibitor or a dominant-negative form of PKCα implicated PKCα and RhoA activation in these events. Therefore, combined interaction of the astrocyte αvβ3-integrin–syndecan-4 receptor pair with Thy-1, promotes adhesion to the underlying matrix via PKCα- and RhoA-dependent pathways. Importantly, signaling events triggered by such receptor cooperation are shown here to be the consequence of cell-cell rather than cell-matrix interactions. These observations are likely to be of widespread biological relevance because Thy-1–integrin binding is reportedly relevant to melanoma invasion, monocyte transmigration through endothelial cells and host defense mechanisms.
Collective cell migration in development
Authors: Weijer Cornelis J.
Published: September 2009

Collective cell migration is a key process during the development of most organisms. It can involve either the migration of closely packed mesenchymal cells that make dynamic contacts with frequently changing neighbour cells, or the migration of epithelial sheets that typically display more stable cell-cell interactions and less frequent changes in neighbours. These collective movements can be controlled by short- or long-range dynamic gradients of extracellular signalling molecules, depending on the number of cells involved and their distance of migration. These gradients are sensed by some or all of the migrating cells and translated into directed migration, which in many settings is further modulated by cell-contact-mediated attractive or repulsive interactions that result in contact-following or contact-inhibition of locomotion, respectively. Studies of collective migration of groups of epithelial cells during development indicate that, in some cases, only leader cells sense and migrate up an external signal gradient, and that adjacent cells follow through strong cell-cell contacts. In this Commentary, I review studies of collective cell migration of differently sized cell populations during the development of several model organisms, and discuss our current understanding of the molecular mechanisms that coordinate this migration.
Moesin orchestrates cortical polarity of melanoma tumour cells to initiate 3D invasion
Authors: Estecha Ana , Sánchez-Martín Lorena , Puig-Kröger Amaya , Bartolomé Rubén A. , Teixidó Joaquín , Samaniego Rafael , Sánchez-Mateos Paloma
Published: September 2009

Tumour cell dissemination through corporal fluids (blood, lymph and body cavity fluids) is a distinctive feature of the metastatic process. Tumour cell transition from fluid to adhesive conditions involves an early polarization event and major rearrangements of the submembrane cytoskeleton that remain poorly understood. As regulation of cortical actin-membrane binding might be important in this process, we investigated the role of ezrin and moesin, which are key crosslinking proteins of the ERM (ezrin, radixin, moesin) family. We used short interfering RNA (siRNA) to show that moesin is crucial for invasion by melanoma cells in 3D matrices and in early lung colonization. Using live imaging, we show that following initial adhesion to the endothelium or 3D matrices, moesin is redistributed away from the region of adhesion, thereby generating a polarized cortex: a stable cortical actin dome enriched in moesin and an invasive membrane domain full of blebs. Using Lifeact-GFP, a 17-amino-acid peptide that binds F-actin, we show the initial symmetry breaking of cortical actin cytoskeleton during early attachment of round cells. We also demonstrated that ezrin and moesin are differentially distributed during initial invasion of 3D matrices, and, specifically, that moesin controls adhesion-dependent activation of Rho and subsequent myosin II contractility. Our results reveal that polarized moesin plays a role in orienting Rho activation, myosin II contractility, and cortical actin stability, which is crucial for driving directional vertical migration instead of superficial spreading on the fluid-to-solid tissue interface. We propose that this mechanism of cortical polarization could sustain extravasation of fluid-borne tumour cells during the process of metastasis.
Sox2 is dispensable for the reprogramming of melanocytes and melanoma cells into induced pluripotent stem cells
Authors: Utikal Jochen , Maherali Nimet , Kulalert Warakorn , Hochedlinger Konrad
Published: September 2009

Induced pluripotent stem cells (iPSCs) have been derived at low frequencies from different cell types through ectopic expression of the transcription factors Oct4 and Sox2, combined with either Klf4 and c-Myc or Lin28 and Nanog. In order to generate iPSCs more effectively, it will be crucial to identify somatic cells that are easily accessible and possibly require fewer factors for conversion into iPSCs. Here, we show that both human and mouse melanocytes give rise to iPSCs at higher efficiencies than fibroblasts. Moreover, we demonstrate that a mouse malignant melanoma cell line, which has previously been reprogrammed into embryonic stem cells by nuclear transfer, remains equally amenable to reprogramming into iPSCs by these transcription factors. In contrast to skin fibroblasts, melanocytes and melanoma cells did not require ectopic Sox2 expression for conversion into iPSCs. iPSC lines from melanocytic cells expressed pluripotency markers, formed teratomas and contributed to viable chimeric mice with germ line transmission. Our results identify skin melanocytes as an alternative source for deriving patient-specific iPSCs at increased efficiency and with fewer genetic elements. In addition, our results suggest that cancer cells remain susceptible to transcription factor-mediated reprogramming, which should facilitate the study of epigenetic changes in human cancer.
Resistive testing in a patient with suspected zone I flexor tendon injury
Authors: Sudhagar Gangatharam , Leblanc Monique
Published: September 2009

Lacerations are the major cause of flexor tendon injury in zone I and they are most commonly missed due to incomplete examinations. We report a case of lacerated flexor tendon injury in Zone I closed without explorations and which was referred to occupational therapy with the diagnosis of stiff hand. The patient received therapy for his stiff hand following which he could flex the distal interphalangeal joint (DIP) on blocking the proximal interphalangeal joint but failed to flex his DIP joint on making a composite fist. With resistive testing the patient failed to initiate resistance on flexion. The patient was referred back to the hand surgeon and subsquently diagnosed with a flexor tendon injury.
Early sensory relearning after median nerve repair using mirror training and sense substitution
Authors: Svens Birgit , Rosén Birgitta
Published: September 2009

Background.

The design and protocol of sensory re-education programmes has not changed over the last decades – a fact that may appear surprising when considering the enormous advances in neuroscience, cognitive science and brain imaging techniques that have increased our understanding of brain plasticity. A multitude of intrinsic and extrinsic factors influence the functional outcome after a nerve repair. Timing of when the sensory relearning is begun is one of them.

Methods.

Here we present a case following median nerve repair, where sensory re-education was introduced in the second week following surgery, i.e. long before any signs of nerve regeneration in the hand and fingers (Phase 1 sensory relearning). The aim was to activate and maintain the cortical hand representation areas for median nerve innervated parts of the hand. Mirror training and a new method with auditory input that substitute temporary missing sensory input were used. For evaluation, the Model Instrument for Outcome after Nerve Repair was utilized.

Results.

There was an improvement in overall score especially in the sensory domain of the Model Instrument for Outcome after Nerve Repair over the 25 months and this exceeded the upper limit of the 95% reference interval for an adult population.

Conclusions.

The excellent outcome in this case adds to other studies indicating that very early introduction of sensory relearning can greatly enhance the outcome following nerve repair.
James Hector (1834–1907): Doctor, geologist, explorer of Western Canada
Authors: Loosmore Brian
Published: September 2009

A graduate of the University of Edinburgh, James Hector joined the Palliser Expedition of 1857 as a doctor and geologist. The objectives of the expedition were to explore the plains of North America along the 49th parallel of latitude, the recently agreed boundary between the USA and Canada, and investigate passes through the Rocky Mountains for possible railway passage. Hector's contribution was immense, his dedication and endurance contributing in large measure to the success of the venture.
Sleep disorders in pregnancy
Authors: Bourjeily Ghada
Published: September 2009

Sleep complaints are a common occurrence in pregnancy that are in part due to pregnancy-associated anatomic and physiological changes but may also be due to pathological causes. In the non-pregnant population, sleep deprivation has been associated with physical and cognitive issues; poor sleep may even be associated with adverse maternal outcomes. Maternal obesity, one of the most prevalent risk factors in obstetric practices, together with physiologic changes of pregnancy predispose to the development of sleep disordered breathing. Symptoms of sleep disordered breathing have also been associated with poor maternal outcomes. Management options of restless legs syndrome and narcolepsy pose a challenge in pregnancy; benefits of therapy need to be weighed against the potential harm to the fetus. This article briefly reviews the normal changes in pregnancy affecting sleep, gives an overview of certain sleep disorders occurring in pregnancy, and suggests management options specific for this population.
Sepsis in pregnancy and early goal-directed therapy
Authors: Joseph Julie , Sinha Aneeta , Paech Michael , Walters Barry N J
Published: September 2009

Sepsis is a major cause of serious morbidity and mortality in pregnant women and their babies. Conventional management has evolved over many years. Improved understanding of the underlying pathophysiology and randomized clinical trials have led to recommendations for the formalization and standardization of the management of severe sepsis in non-pregnant patients. Most of these recommendations are applicable to pregnancy. The Surviving Sepsis Campaign and Early Goal Directed Therapy have relevance to the care of pregnant women with serious infection and are reviewed here.
Effect of Storage on Air-Entraining Cements
Authors: McCoy WJ , Helms SB
Published: September 2009

This subject is introduced by reference to a previous study of the effect of storage on the properties of portland cement. Results of tests on samples of types I, IA, IIA, and IIIA portland cement stored under various conditions for periods up to 5 yr are reported. The effect of time and condition of storage on air content, ignition loss, specific surface, and free lime results was determined at intervals during the 5-yr period. These tests show that aging of cement does not cause any significant change in the above properties, or the setting time, or compressive strength if the cement is properly stored so as to prevent any reaction with moisture or carbon dioxide, as would be shown by no appreciable increase in the ignition loss.
The Partial Replacement of Portland Cement in Concrete
Authors: Mather B
Published: September 2009

Sixteen replacement materials, including representatives of six classes—blast-furnace slag, natural cement, fly ash, volcanic glass, calcined opaline shale, and uncalcined diatomite—were investigated together with five portland cements: two type I cements, of low- and high-alkali content, a type II, a type III, and a type IV. A total of 123 concrete mixtures containing crushed limestone aggregates up to 3/4 in. in size, 6 ± 1/2 per cent air, and having a slump of approximately 21/2 in. were proportioned. About half the mixtures had a water-cement ratio of 0.5 by weight, to represent structural concrete, the remainder, 0.8, to represent mass concrete. The 16 materials were used as partial replacements of the portland cement in various percentages by solid volume from 8 to 70. The performance of the replacement materials in concrete was rated against selected values for certain properties regarded as critical for the two classes of concrete studied. Structural concrete (0.5 water-cement ratio) was regarded as adequate if its bleeding did not exceed 5 per cent, its permeability, Kc, did not exceed 25, its resistance to laboratory freezing-and-thawing (DFE) was at least 60, its shrinkage did not exceed 0.070 per cent at 180 days, and its compressive strength at 28 and 90 days was at least 3000 and 4000 psi, respectively. Mass concrete (0.8 water-cement ratio) was rated against the following factors: bleeding not exceeding 7 per cent, permeability Kc, not exceeding 10, compressive strength at 3 and 90 days at least 500 and 2000 psi, respectively; in addition, credit was given for the degree to which the heat of hydration was reduced by the use of the replacement materials. Structural concrete (0.5 water-cement ratio) made with type II portland cement and having as high a rating as that containing no replacement material was obtained when part of the portland cement was replaced by the following materials in the indicated amounts: 50 per cent slags I and II or natural cement I; 35 per cent natural cements I and II; 30 per cent fly ash I; 25 per cent pumicite I; 20 per cent natural cement I, or calcined shale I; or 8, 12, or 16 per cent uncalcined diatomite. Mass concrete (0.8 water-cement ratio) made with type II portland cement and having a rating as high or higher than that containing no replacement material was obtained when part of the portland cement was replaced by the following materials in the indicated amounts: 50 per cent natural cement I; 40 per cent calcined shale I; 35 per cent natural cement I, pumicite II, or tuff; 30 per cent slag I, calcined shales I and II, or calcined diatomite; 25 per cent pumicite I; 20 per cent natural I, or calcined shale I; and 8, 12, or 16 per cent uncalcined diatomite.
Tests of Prestressed Expanded-Shale Concrete Beams Subjected to Short-Time and Sustained Loads
Authors: Davis RE , Troxell GE , McCall DO , McCann RA
Published: September 2009

This paper gives the results of tests on 19 flexural members of prestressed concrete, of lengths ranging from 24 to 65 ft and including beams of doubletee section for floors and roofs, box beams for floor systems of bridges and buildings, and girders and purlins of I-section for roofs. Most of the members were composed of expanded-shale lightweight concrete, and the steel was pretensioned. Most of the tests were made under loading which would produce failure in bending; others in shear. All flexural members were loaded until first cracking was observed and then unloaded to observe recovery. Thereafter, one beam was loaded immediately until failure was produced and four beams were subjected continuously to their design loads for a period of 3 1/2 months. Observations were made on all flexural members to determine deflections and cracking, and on selected beams to determine longitudinal strains in flexure or strength in shear. Auxiliary tests were made to determine compressive strength and modulus of elasticity of concrete, creep of concrete under sustained compressive stress, and loss of tension in steel reinforcement due to creep.

It was found that live loads required to produce first cracking in flexure ranged from 1.5 to 2.2 times the design loads. Shearing loads required to produce failure in diagonal tension ranged from 1.0 to 1.7 times those computed for conventionally reinforced-concrete beams of similar section. Live-load deflections under short-time loading were generally considerably less than was expected. When the design loads were released, elastic recovery was practically complete. When loads somewhat in excess of those required to produce flexural cracking were released, residual deflections were insignificantly small. Deflections under sustained design loads were small, and elastic-plus-creep deflections were within customary limitations except for one roof beam of very long span. Loss of tension in reinforcement under sustained loading was substantially equal to that assumed in design and was not greater for the expanded-shale aggregate than for natural aggregate. Creep under sustained load was of the same order of magnitude as that commonly observed for concrete containing natural aggregate. In general, the tests confirm the assumptions commonly made in design of prestressed concrete beams.
A Physical Method for Determining The Composition of Hardened Concrete
Authors: Polivka M , Kelly JW , Best CH
Published: September 2009

Determination of the proportions of materials in hardened concrete in structures becomes desirable when question arises as to the quality of the concrete actually placed. Existing methods of chemical analysis depend heavily on knowledge of the chemical composition of the aggregates, which is seldom available.

This paper describes a “point-count” method of determining the cement content of hardened portland-cement concrete by analysis of a cut section with a traveling microscope. The voids and aggregate content are estimated by direct observation; the cement content is then determined by difference, with correction for non-evaporable water in the cement paste. Sand-aggregate ratio is also computed.

Results of microscope analysis of various laboratory-mixed concretes are compared with original mix proportions. Comparisons are also made with results of chemical analysis according to ASTM Method C 85-54 and two other chemical methods developed during the investigation.

The precision of each method is estimated, and the advantages and limitations are discussed. It is concluded that the microscope analysis is at least as precise as the chemical methods, and that it requires less time and equipment. With further study and refinement, it offers promise of providing a reliable estimate of the cement content of hardened concrete within the precision of construction and sampling.
Metals Analysis with Thenoyltrifluoroacetone
Authors: Moore FL
Published: September 2009

The role of 2-thenoyltrifluoroacetone (TTA) in metals analysis is reviewed. The principle of the liquid-liquid extraction technique involving TTA is discussed. A survey of extraction systems using TTA in metals separations is presented. Radiochemical procedures based on this versatile chelating agent have been used successfully on the Atomic Energy Project for several years. Details for the specific determination of radiozirconium, radiocerium, plutonium, and neptunium are described and illustrate the application of the techniques of solvent choice, acidity, variation of metal oxidation state, the use of masking agents, and washing and stripping of the organic phase to effect high selectivity in TTA liquid-liquid extraction procedures. Recent investigations on the extraction of iron and columbium from strong acid solution are discussed.
Comparison of Standard Leak Rates Measured by Viscous and Molecular Flow Techniques
Authors: Maurer D. W.
Published: September 2009

It is well known that modern semiconductor devices are extremely sensitive to impurities. For this reason it is necessary to control the gaseous ambient in which they operate by hermetic encapsulation. Although neither the effective levels of contamination nor the identity of the contaminating gas has been rigidly established, leakage or diffusion into the device must be kept at a minimum in order to have a device with a very long lifetime. Leak rates usually are given in terms of a “standard leak rate.” This is the rate which would be measured on a given leak under certain arbitrary standard conditions such as 1 atmos on one side of the leak and 0 atmos on the other. The units commonly in use are the cu cm atmos per sec and the cu cm mm per sec or cu cm Torr per sec. The first is the gas volume in cu cm at 1 atmos pressure per sec; the second is the volume at 1 mm of Hg pressure per sec. One cu cm atmos per sec is roughly equal to 103 cu cm mm per sec. The cu cm atmos per sec will be used in this paper.
Determination of Trace Amounts of Oxygen in Protective Gaseous Ambients
Authors: Feder D. O. , Craft W. H.
Published: September 2009

In the fabrication and processing of electronic components, it is often necessary to use neutral or reducing protective atmospheres for various heat treating operations. Such operations as encapsulation, cleaning, brazing, glazing, surface oxide reduction and degassing of components all require the use of protective atmospheres in which oxidizing impurities must either be minimized or precisely controlled for optimum results. The presence of water or oxygen or both in amounts as small as a few parts per million can often profoundly affect the results of these operations. A variety of techniques has been reported for analysis of either of these impurities. A simple technique whereby a single instrument may be used to analyze for both of these constituents is described here.
Effects of Various Cleaning Methods on Electronic Components in the Micromodule
Authors: Vossen J. L.
Published: September 2009

This paper describes several interesting effects observed during evaluation of various procedures and solvents for cleaning electronic components used in micromodules. Cleaning is performed on partially fabricated components prior to the application of the encapsulant. All traces of flux and other contaminants must be removed from the components before encapsulation to ensure the high reliability required of each element and to provide a surface compatible with the final encapsulant.

Two cleaning methods were used in the tests. Each method was applied to 12 different components, including high-stability metal-film resistors, solid electrolytic tantalum capacitors, four types of ceramic capacitors, inductors having two different core materials, diodes similar to the 1N277 and 1N643, and transistors similar to the 2N404. Special emphasis was placed on the components which showed large changes in electrical chracteristics after cleaning. The method that removed the maximum amount of contaminants without damaging the components was selected. A complete analysis of the effect of the cleaning methods on each component is given, and the measures used to overcome damaging effects are outlined.
Noise-Tested Cathode Activation
Authors: Dlouhy F. , Schuetze H. J.
Published: September 2009

The plate current of an electron tube producing a reasonable shot-noise level reflects the variation of the oxide cathode activity during the activation and aging process. When operating several lots of tubes at different cathode temperatures in the range from 1000 to 1500 K under stand-by conditions a set of emission curves is obtained showing maxima. A straight line is obtained by plotting the activating temperature versus time corresponding to the maxima. This is the base for developing activation schedules giving optimum activity of the cathode in the shortest time. The solution of the problem consists in an activation procedure with several temperature steps while simultaneously considering electron bombardment of the electrodes that affect the cathode activity. The net result is an approximate parallel shift of the straight line responsible for the so-called single-step activation. The position and the slope of this line in semilogarithmic representation are affected by core material and processing.

Tubes activated thermally often undergo an emission slump during aging when high voltages are applied, especially if passive core materials are used. This phenomenon, although influenced by several processing and operating parameters, has been used as a tool for studying the effect of cathode environment upon its activity. The experiments described in this paper were performed on a pentode equivalent to the type 6 BX 6.
Effect of Notch Geometry on Rupture Strength at Elevated Temperatures
Authors: Davis E. A. , Manjoine M. J.
Published: September 2009

Three series of creep-rupture tests of notch bars with varying geometry of the notch were performed at elevated temperatures on several heat-resistant alloys. The effect on notch sensitivity of the following were also investigated: stress level, grain size, hardness, ductility, and heat treatment. Increasing the sharpness of the notch with constant-depth notches may raise or lower the notch sensitivity depending on the ductility and microstructure of the alloy. The size effect or effect of shank diameter can be practically eliminated by using a “standard” notch geometry. The notch sensitivity is accentuated by increasing the depth of the notch to about one-fourth of the shank diameter. It is postulated that the fracture originates just below the surface at the root of the notch.
Investigations into the Influence of Notches on Creep Strength at High Temperatures
Authors: Siegfried W.
Published: September 2009

It has been observed in the long-time testing of steels for high-temperature service that many of these steels are so sensitive to notching that notched specimens rupture sooner than smooth bars under the same load. The gas-turbine builder is therefore compelled to investigate this phenomenon to gain a clear idea of how it affects important components of design and as to what steels are likely to be susceptible to it. He must also be able to judge the degree by which a given component may be weakened by the influence of notches.
An Experimental Study of the Strength and Ductility of Steel at Elevated Temperatures
Authors: Glen J.
Published: September 2009

The object of the investigation was to explain the effect of various tempering treatments on the creep resistance of carbon and low-alloy steels and to elucidate the probable behavior of such steels during long-time service at high temperature. It was suspected that the problem was related to precipitation hardening since creep tests and tension tests carried out over a range of temperature showed that an increase or decrease in resistance to deformation could be brought about by different tempering treatments.

To follow up these preliminary tests true stress-strain tension tests were carried out on a series of low-carbon steels containing varied amounts of manganese and molybdenum. Similar steels killed with aluminum were also tested. In the absence of manganese and molybdenum a maximum in the stress for a given strain was obtained at about 200 C. When manganese was added a second maximum appeared at about 300 C, and with molybdenum at about 500 C. These maxima in stress are attributed to the precipitation of carbides during the process of straining, the type of carbide formed depending on the testing temperature and the alloying elements present. The influence of tempering is also indicated.

To each maximum in stress there corresponds a minimum in ductility. This suggests that the strain preceding rupture is also related to the precipitation of carbides, in this case at the grain boundaries.

From these tests it was possible to explain many of the effects of alloying elements on the creep resistance and ductility of steels under various conditions of testing. It was concluded that the factor which largely determined such effects was precipitation.
The Corrosion of Rolled Zinc in the Outdoor Atmosphere
Authors: Anderson E A
Published: September 2009

As part of a comprehensive study of the corrosion and corrosion testing of non-ferrous metals and alloys, outdoor exposure tests were initiated in 1931 by Subcommittee VI on Atmospheric Corrosion of A.S.T.M. Committee B-3 on Corrosion of Non-Ferrous Metals and Alloys. The intent of the work was to evaluate the metals under test and simultaneously to study two alternative test procedures. As the work progressed, it became increasingly evident that only by preparing a most voluminous report could the subcommittee hope to present a complete evaluation of their findings. Upon completion of the 10-yr. exposures, decision was reached to present only the actual data in the report of the committee as a whole and to have a series of analyses of the tests and results prepared by members of the subcommittee. The present discussion covers the results obtained with three grades of rolled zinc: metals AA, BB, and HH.