cssi/SciSciGPT-SciSciNet huggingface dataset:
Helicobacter pylori the Latent Human Pathogen or an Ancestral Commensal Organism

We dedicated this review to discuss Helicobacter pylori as one of the latest identified bacterial pathogens in humans and whether its role is mainly as a pathogen or a commensal. Diseases associated with this bacterium were highly prevalent during the 19th century and gradually have declined. Most diseases associated with H. pylori occurred in individuals older than 40 years of age. However, acquisition of H. pylori occurs mainly in young children inside the family setting. Prevalence and incidence of H. pylori has had a dramatic change in the last part of the 20th century and beginning of the 21th century. In developed countries there is a clear interruption of transmission and the lowest prevalence is observed in children younger than 10 years in these countries. A similar decline is observed but not at the same level in developing countries. Here we discuss the impact of the presence or absence of H. pylori in the health status of humans. We also discuss whether it is necessary or not to establish H. pylori eradication programs on light of the current decline in H. pylori prevalence.
Neuropharmacology of obesity: my receptors made me eat it.

Issue: Specific neurotransmitter and hormone receptors regulate appetite, eating behavior, and weight gain.
Die Behandlung des chronisch depressiven Patienten

»Psychologische Veranderungen konnen auch spater im Leben auftreten durch den Einfluss von einer oder mehreren ‚neuen‛ Bezugspersonen im Zusammenspiel mit der Entwicklung formaloperatorischen Denkens. Katherine L. Schaefer (2004)«
An overview of treatment options for lower airway obstruction.

Effectively treating airway stenosis is a challenging problem for the otolaryngologist–head and neck surgeon. A number of options are available. The most effective management requires an approach that is flexible and individualized for each patient. This article outlines the available options and highlights the indications, techniques, results, and potential complications of each.
Chemotaxis of Vascular Smooth Muscle Cells by Lysyl Oxidase

Purified bovine aorta lysyl oxidase conventionally oxidizes peptidyl lysine in elastin and collagen thus initiating the spontaneous formation of covalent crosslinkages between individual molecules of these fibrous proteins. The growing evidence that this catalyst may have additional functions in biology is enhanced by the present finding that it is a potent chemokine for vascular smooth muscle cells. This chemotactic effect requires the lysyl oxidase-catalyzed formation of hydrogen peroxide accompanying the oxidation of peptidyl lysine in a cell-associated substrate.
Spatial Partitioning of a Polygon by a Plane

Publisher Summary This chapter describes an algorithm that partitions a polygon lying in 3D space by a plane, resulting in three lists of zero or more polygons. If the plane intersects the polygon transversely, the algorithm cuts the polygon by the plane and returns a list of new polygons that lie above and a list of new polygons that lie below the plane. This algorithm underpins many BSP tree and polygon intersection libraries. Splitting a polygon is a common problem encountered in many 3D geometric applications such as boundary representation (B-Rep) to BSP tree conversion, B-Rep to MSP tree conversion, Boolean set operations on polyhedra, and convex decomposition. The algorithm presented in this chapter extends the convex-polygon splitting algorithm to non-convex polygons that may contain non-manifold and adjacent, collinear vertices. The algorithm is implemented in C++ and developed under GNU's C++ compiler version 2.5.8. The C++ code presented in this chapter is a stand-alone code using minimally sufficient abstract data types defined as classes.
Bacterial Metabolism in Biofilms

Bacteria that are attached to surfaces frequently appear to differ metabolically from their free-living counterparts. There are two probable reasons for such physiological differences: (1) the physicochemical conditions at the solid surface-liquid interface are not the same as those in the bulk phase, and thus influence bacterial metabolism through environmental effects, and (2) the bacteria in biofilms are often situated in close proximity to other bacteria, microorganisms, and often macroorganisms, and are influenced by synergistic, mutualistic, competitive, or antagonistic interactions among biofilm members.
High testicular salvage rate in torsion of the spermatic cord.

AbstractAcute, nontraumatic scrotal emergency operations were done on 104 patients. The testes were saved in 79 per cent of 67 patients with torsion of the spermatic cord. When the patients who presented late are excluded, aggressive treatment allowed a 93 per cent testicular salvage rate. Spontaneous or manipulative detorsion preoperatively resulted in a 100 per cent testicular salvage rate. If the patient seeks medical advice early a high testicular salvage rate can be obtained by proper diagnosis and prompt, aggressive detorsion either by manipulation when examined initially or at operation. These maneuvers are combined with bilateral orchiopexy to ensure permanent cure.
Passive sensing around the corner using spatial coherence

When direct vision is obstructed, detecting an object usually involves either using mirrors or actively controlling some of the properties of light used for illumination. In our paradigm, we show that a highly scattering wall can transfer certain statistical properties of light, which, in turn, can assist in detecting objects even in non-line-of-sight conditions. We experimentally demonstrate that the transformation of spatial coherence during the reflection of light from a diffusing wall can be used to retrieve geometric information about objects hidden around a corner and assess their location. This sensing approach is completely passive, assumes no control over the source of light, and relies solely on natural broadband illumination.
Lending relationships and labor market dynamics

Abstract Motivated by a negative link between credit spreads and labor force participation (LFP) and a positive link between these spreads and unemployment over the business cycle, we study the role of LFP as an amplification mechanism of financial shocks in a labor search model with endogenous LFP, lending relationships, and credit-market disruptions. Amid aggregate productivity and financial shocks that replicate the empirical volatility of LFP and credit spreads, the model produces highly volatile unemployment and vacancies, countercyclical credit spreads and unemployment, and procyclical LFP. When we quantitatively match the cyclical behavior of credit spreads, the interaction between endogenous LFP and financial shocks gives rise to much sharper vacancy fluctuations and plays a key role in generating quantitatively factual cyclical labor market dynamics.
Disease Detection in Weakly Annotated Volumetric Medical Images using a Convolutional LSTM Network.

We explore a solution for learning disease signatures from weakly, yet easily obtainable, annotated volumetric medical imaging data by analyzing 3D volumes as a sequence of 2D images. We demonstrate the performance of our solution in the detection of emphysema in lung cancer screening low-dose CT images. Our approach utilizes convolutional long short-term memory (LSTM) to "scan" sequentially through an imaging volume for the presence of disease in a portion of scanned region. This framework allowed effective learning given only volumetric images and binary disease labels, thus enabling training from a large dataset of 6,631 un-annotated image volumes from 4,486 patients. When evaluated in a testing set of 2,163 volumes from 2,163 patients, our model distinguished emphysema with area under the receiver operating characteristic curve (AUC) of .83. This approach was found to outperform 2D convolutional neural networks (CNN) implemented with various multiple-instance learning schemes (AUC=0.69-0.76) and a 3D CNN (AUC=.77).
A modular approach to prepare enantioenriched cyclobutanes: synthesis of (+)-rumphellaone A

A modular synthesis of enantioenriched polyfunctionalized cyclobutanes was developed that features an 8-aminoquinolinamide directed C-H arylation reaction. The C-H arylation products were derivatized through subsequent decarboxylative coupling processes. This synthetic strategy enabled a 9-step enantioselective total synthesis of the antiproliferative meroterpenoid (+)-rumphellaone A.
Fratricide in rebel movements: A network analysis of Syrian militant infighting:

Violent conflict among rebels is a common feature of civil wars and insurgencies. Yet, not all rebel groups are equally prone to such infighting. While previous research has focused on the systemic...
Cementless 3D Printed Highly Porous Titanium-Coated Baseplate Total Knee Arthroplasty: Survivorship and Outcomes at 2-Year Minimum Follow-Up

Newer generation cementless total knee arthroplasty (TKA) implants continue to develop with demonstrated clinical success in multiple recent reports. The purpose of this study was to investigate (1) survivorship, (2) complications, and (3) clinical outcomes of a newer generation cementless and highly porous titanium-coated base plate manufactured using three-dimensional (3D) printing technology. We reviewed a single-surgeon, longitudinally maintained database of patients who underwent primary TKA using cementless, highly porous titanium-coated base plate implants from July 1, 2013 to December 31, 2016. A total of 523 patients were identified. Of this cohort, 496 patients had a minimum of 2-year follow-up and were included in our final analysis. Among these patients, 72 had bilateral TKA yielding a total of 568 TKAs. There were 133 men and 363 women who had a mean body mass index of 33 kg/m2 (range, 20–61 kg/m2). The mean age was 66 years (range, 33–88 years). Average follow-up was 36 months (range, 24–48 months). Indications for TKA included osteoarthritis in 432 patients (87%), rheumatoid arthritis in 40 patients (8%), and knee osteonecrosis in 24 (5%) patients. Implant survivorship was defined as any revision leading to explantation of the base plate for any reason. Kaplan–Meier analysis was performed to determine all-cause implant survivorship at final follow-up for every patient. Complications were assessed using the Knee Society standardized list of TKA complications. Clinical outcomes were determined using the Knee Society pain and function scores. Range-of-motion values were also collected. There were a total of four failures, all were due to aseptic loosening with a survivorship rate of 99% at mean follow-up of 3 years (95% confidence interval = 0.984–0.999). In addition, there were a total of 12 surgical and 10 medical complications. Surgical complications did not affect the base plate or result in any additional implant revisions. A total of nine patients had thromboembolic disease complications; all received medical treatment and recovered adequately. Radiological evaluation did not show any signs of loosening or failures in other patients at final follow-up. Knee Society Scores for pain and function improved from 55 and 56 points preoperatively to 92 and 84 points at 2 years postoperatively. Our results are in concordance with the excellent clinical outcomes and survivorship demonstrated for the newer generation cementless TKA implants. In our experience, 3D printed titanium base plates demonstrated clinical success and excellent survivorship at minimum follow-up of 2 years.
Pacing and Defibrillation for Atrial Arrhythmias

Atrial arrhythmias and heart failure frequently coexist. A number of device-based therapies are available for the diagnosis, prevention, and treatment of these arrhythmias. This chapter reviews the clinical impact of atrial and ventricular pacing on atrial arrhythmias, the diagnosis of atrial arrhythmias via device-based data retrieval, the value of alternate site atrial pacing algorithms for prevention of atrial fibrillation, and the treatment of atrial arrhythmias with device-based pacing and defibrillation.
Force clamp approach for characterization of nano-assembly in amyloid beta 42 dimer

Amyloid β (Aβ) oligomers are formed at the early stages of the amyloidogenesis process and exhibit neurotoxicity. Development of oligomer specific therapeutics requires a detailed understanding of oligomerization processes. Amyloid oligomers exist transiently and single-molecule approaches are capable of characterizing such species. In this paper, we describe the application of an AFM based force clamp approach for probing of Aβ42 dimers. Aβ42 monomers were tethered to the AFM tip and surface and the dimers are formed during the approaching the tip to the surface. AFM force clamp experiments were performed at different force clamps. They revealed two types of transient states for dissociating Aβ42 dimers. The analysis showed that these states have distinct lifetimes of 188 ± 52 milliseconds (type 1, short lived) and 317 ± 67 milliseconds (type 2, long lived). Type 1 state prevails over type 2 state as the value of the applied force increases. The rupture lengths analysis led to the models of the dimer dissociation pathways that are proposed.
Are Premarital Agreements Really Unfair: An Empirical Study of Premarital Agreements

Are premarital agreements categorically unfair? Critics of premarital agreements cling to the (unfounded) belief that premarital agreements are categorically one-sided, coercive, and designed to benefit the wealthier spouse — usually the man. Courts, legislators, and scholars have too often relied on assumptions about premarital agreements without delving in to the facts. They have looked almost everywhere to support their views, except for the one place that really matters: the actual agreements. The result, predictably, is a paternalistic system predicated on a near religious belief that women who sign premarital agreements are uneducated, unsophisticated, economically dependent actors who need the state to protect them from the overreaching of their husbands and their own stupidity. For the few women this paternalistic system might protect, it harms a great many more by reinforcing negative stereotypes and eroding individual autonomy. This paper builds on my previous work and offers something that has been sorely lacking in the field — empirical data. This paper presents my initial findings of a study involving all of the premarital agreements between opposite-sex couples recorded in Jefferson Parish, Louisiana between January 1, 2013 and December 31, 2016 — a total of 474 premarital agreements. My findings cast considerable doubt upon many of the stereotypes about the parties that enter into premarital agreements. The quintessential stereotype of a couple with a premarital agreement is the rich businessman and his (much) younger “trophy” bride. For the couples in this study, however, large age discrepancies are the exception rather than the rule. We have long assumed that premarital agreements are most common in second marriages. Although that is generally true for the couples in this study, the reality is a good deal more nuanced. Nearly a quarter of the agreements in this study were entered into by two spouses with no prior marriages. Longstanding assumptions about substance and procedure are also challenged by my study. We have been suspicious of premarital agreements that are signed shortly before the wedding out of fear that they result from duress or coercion. Yet, the vast majority of the couples in this study signed their agreements shortly before their weddings. Isn’t it more likely that these couples procrastinated rather than coerced? We have long assumed that premarital agreements involve the waiver of property rights and spousal support by the poorer spouse for the benefit of the richer spouse. Again, the data paint a more complex and interesting picture.
Erratum for Smercina et al., "To Fix or Not To Fix: Controls on Free-Living Nitrogen Fixation in the Rhizosphere"

Volume 85, no. 6, e02546-18, 2019, [https://doi.org/10.1128/AEM.02546-18][1]. Page 12, Acknowledgments: Line 4 should read as follows. “…(DOE BER Office of Science DE-SC0018409 and DE-FC02-07ER64494). Data presented in Table 1 were collected under the Facilities Integrating Collaborations for
High geographic prevalence of pulmonary artery hypertension: associations with ethnicity, drug use, and altitude.

While estimates of pulmonary arterial hypertension incidence and prevalence commonly range from 1–3/million and 15–25/million, respectively, clinical experience at our institution suggested much hi...
Transnational intimacy and economic precarity of western men in northeast Thailand

This research examines the increasing migration of western men into Thailand, focusing on men in transnational intimate relationships in the northeastern region (Isan). Based on ethnographic fieldw...
Outer approximation for integer nonlinear programs via decision diagrams

As an alternative to traditional integer programming (IP), decision diagrams (DDs) provide a new solution technology for discrete problems exploiting their combinatorial structure and dynamic programming representation. While the literature mainly focuses on the competitive aspects of DDs as a stand-alone solver, we investigate their complementary role by introducing IP techniques that can be derived from DDs and used in conjunction with IP to enhance the overall performance. This perspective allows for studying problems with more general structure than those typically modeled via recursive formulations. In particular, we develop linear programming and subgradient-type methods to generate valid inequalities for the convex hull of the feasible region described by DDs. For convex IPs, these cutting planes dominate the so-called linearized cuts used in the outer approximation framework. These cutting planes can also be derived for nonconvex IPs, which leads to a generalization of the outer approximation framework. Computational experiments show significant optimality gap improvement for integer nonlinear programs over the traditional cutting plane methods employed in the state-of-the-art solvers.
Covered or Not, Here I Come: Stanford Type B Aortic Dissection Repair With a Covered and Uncovered Stent Hybrid Technique.

The complications resulting from aortic dissections are often devastating. Historically, when a Stanford B aortic dissection extended into the visceral abdominal aorta, only surgical management was considered to limit visceral organ malperfusion. Complications of surgical management for Stanford B aortic dissections are as high as 50%. The inherently high complication and mortality rate for any acute aortic dissection, in addition to the complication rates resulting from surgical management, have demonstrated poor outcomes. This is especially true when aortic dissections involve the visceral segment, where thoracic endovascular aortic repair (TEVAR) becomes limited or contraindicated. In the last two decades, various approaches for TEVAR have improved in both endograft design and interventional technique. The current literature demonstrates improved outcomes for patients that receive TEVAR for Stanford B aortic dissections, including those that involve the visceral segment. Despite favorable prognostic advancement in TEVAR, the proven management complexity of Stanford B aortic dissections continue to reflect the pitfalls of the endovascular devices that are currently available. We describe a covered and uncovered stent hybrid technique in patients with complicated Stanford B aortic dissections involving the visceral segment, considering these deficiencies. Hundred percent technical success was demonstrated in the short and mid-term surveillance periods.
Post-fire management targeting invasive annual grasses may have inadvertently released the exotic perennial forb Chondrilla juncea and suppressed its biocontrol agent

Top-down and bottom-up factors affecting invasive populations are rarely considered simultaneously, yet their interactive responses to disturbances and management interventions can be essential to understanding invasion patterns. We evaluated post-fire responses of the exotic perennial forb Chondrilla juncea (rush skeletonweed) and its biocontrol agents to landscape factors and a post-fire combined herbicide (imazapic) and bacteria (Pseudomonas fluorescens strain MB906) treatment that targeted invasive annual grasses in a sagebrush steppe ecosystem. Biocontrol agents released against C. juncea in previous decades included Cystiphora schmidti (gall midge), Aceria chondrillae (gall mite), and Puccinia chondrillina (rust fungus). C. juncea abundance was greater in sprayed than unsprayed plots, and where soils were coarser, slopes faced southwest, solar heat loads and topographic water accumulation were greater, and cover of deep-rooted native perennials was lower. Mite infestation was greater in unsprayed plots, midge infestation was greater at higher elevations on steeper slopes, and midges were more abundant while rust was less abundant on gravelly soils. Biocontrol infestation levels varied considerably between years and could not be predicted in 2019 from 2018 infestation levels. Multiple biocontrol species were often present at the same plots but were rarely present on the same C. juncea individuals. These results suggest that spatial patterns of invasion by C. juncea are related to deep-soil water availability, warmer conditions, and alleviation of competition. Treatments designed to reduce invasive annual grasses may inadvertently release C. juncea by both reducing plant competition for soil resources and affecting biocontrol agent (mite) abundance.
In Vivo Effects of LSD1 Inhibition By Small Chemical Inhibitors in Sickle Cell Mice

Abstract For the past decades the principal strategy for treating the β-globinopathies [sickle cell disease (SCD) and β-thalassemia] has been to devise methods for increasing the levels of fetal hemoglobin (HbF) in adult erythroid cells, as a strong clinical literature has demonstrated that high HbF levels ameliorate disease pathophysiology. We originally reported the lysine-specific histone demethylase 1 (LSD1) as a new protein involved in the regulation of the fetal γ-globin genes. Inhibition of LSD1 using either RNAi or by the momoamine oxidase inhibitor tranylcypromine in primary human erythroid progenitor cells induces HbF to therapeutic levels. Thus, inhibition of LSD1 activity presents a novel exploratory avenue as a therapeutic strategy to treat SCD. Subsequent studies using another inhibitor RN-1 showed that RN-1 treatment of SCD mice results in increased HbF synthesis and leads to effective improvement of many aspects of the disease pathology normally associated with sickle cell disease. Here we report studies designed to examine the in vivo effects of some additional, publically available small molecule chemical inhibitors of LSD1 on HbF synthesis and erythroid physiology in SCD mice. In control SCD mice treated with DMSO only, the number of HbF positive cells was about 2.5% of total in RBC, while in SCD mice exposed to GSK-LSD1, or OG-L002, there was a statistically significant increase in the percentage of HbF positive cells after 4 weeks of treatment (up to 8%, or 6% respectively). Furthermore, sickled RBCs and reticulocytes are significantly reduced while the number of mature erythrocytes increased markedly in the peripheral blood of GSK-LSD1, or OG-L002 treated SCD mice. These findings suggest that GSK-LSD1 and/or OG-L002 could be potentially new HbF inducers based on LSD1 inhibition. We believe that these experiments will be of wide general interest and will be the foundation for development of small molecule therapeutics with which to treat hemoglobinopathies. Disclosures No relevant conflicts of interest to declare.
Contrast in Post-Chill Eclosion Time Strategies Between Two Specialist Braconid Wasps (Hymenoptera: Braconidae) Attacking Rhagoletis Flies (Diptera: Tephritidae) in Western North America

Parasitoids comprise a speciose insect group, displaying a wide array of life history strategies. In the Pacific Northwest of the United States, the tephritid fruit flies Rhagoletis tabellaria (Fitch) and Rhagoletis indifferens Curran infest red osier dogwood, Cornus sericea L. (Cornaceae), and bitter cherry, Prunus emarginata (Douglas ex Hooker) Eaton (Rosaceae), respectively. The flies are parasitized by different braconid wasps at different life stages; Utetes tabellariae (Fischer) oviposits into R. tabellaria eggs, whereas Diachasma muliebre (Muesebeck) oviposits into R. indifferens larvae feeding in cherries. Because Rhagoletis only have one major generation a year and the wasps attack temporally distinct fly life stages, we predicted that eclosion times of U. tabellariae should more closely follow that of its host than the larval-attacking D. muliebre. As predicted, U. tabellariae eclosed on average 6.0–12.5 d later than R. tabellaria, whereas D. muliebre eclosed on average 32.1 d after R. indifferens. Unexpectedly, however, longer chill duration differentially affected the systems; longer overwinters minimally influenced eclosion times of R. tabellaria and U. tabellariae but caused earlier eclosion of both R. indifferens and D. muliebre. Results imply that in temperate regions, diapause timing in braconid wasps evolves in response to both host life stage attacked and fly eclosion characteristics, possibly reflecting differential effects of winter on host plant fruiting phenology. Differences in phenological sensitivity of the lower host plant trophic level to variation in environmental conditions may have cascading effects, sequentially and differentially affecting eclosion times in higher frugivore (fly) and parasitoid (wasp) trophic levels.
Language processing and reading ability in children: A study based on speech-shadowing techniques

Language-processing facility in good and poor readers was examined using two speech-shadowing experiments. A total of 54 children from the second, fifth, and eighth grades were tested (9 good and 9 poor readers at each grade level). The first experiment manipulated rate of presentation to study speed of processing auditory-linguistic information. Good readers were superior to poor readers in their ability to maintain shadowing accuracy at increased rates of presentation, although the performance patterns of the two groups varied according to grade level. In the second experiment, good and poor readers shadowed sentences exhibiting different degrees of grammatical acceptability. Unstructured word strings, without syntactic coherence, penalized good readers more than poor readers, relative to their performance on syntactically appropriate constructions. Poor readers did not differ from good readers in their
A sharing-oriented design strategy for networked knowledge organization systems

Designers of networked knowledge organization systems often follow a service-oriented design strategy, assuming an organizational model where one party outsources clearly delineated business processes to another party. But the logic of outsourcing is a poor fit for some knowledge organization practices. When knowledge organization is understood as a process of exchange among peers, a sharing-oriented design strategy makes more sense. As an example of a sharing-oriented strategy for designing networked knowledge organization systems, we describe the design of the PeriodO period gazetteer. We analyze the PeriodO data model, its representation using JavaScript Object Notation-Linked Data, and the management of changes to the PeriodO dataset. We conclude by discussing why a sharing-oriented design strategy is appropriate for organizing scholarly knowledge.
Why Context Matters: The Material Conditions of Caring in Zambia

This study utilized in depth interviewing, participant observation, and student diaries completed by participants to examine the quality of teacher-student relationships at a low-cost private school in the townships of Ndola, Zambia. Amidst economic decline and the HIV/AIDS epidemic facing Zambia today, teachers and students developed strong relationships that differed from those found in government secondary schools and were shaped by the economic and social realities in the larger society. These caring relationships were facilitated by official school policy, deliberative spaces created for caring such as longer school hours and smaller class sizes, and strict oversight of teachers by the school administration. Teachers’ efforts to provide students advice and resources related to the economic and health crises affecting their community resulted in the development of caring relationships that students noted were unique given their experiences in and exposure to government secondary schools. The findings of this study suggest that scholars of caring in the US and internationally should consider the material conditions of both students’ and teachers’ lives beyond the school environment in order to understand how caring relationships are structured, limited, and enabled in distinct moments by larger socio-economic and political realities.
Growth of Enveloped RNA Viruses in a Line of Chinese Hamster Ovary Cells with Deficient N-Acetyl-glucosaminyltransferase Activity

Abstract Sindbis and vesicular stomatitis viruses were grown in a line (termed 15B) of Chinese hamster ovary (CHO) cells that is deficient in a specific UDP-N-acetylglucosamine:glycoprotein N-acetylglucosaminyltransferase. Both viruses replicated normally in the cell line, but the glycoproteins of the released virus migrated faster on sodium dodecyl sulfate-polyacrylamide gels than did glycoproteins of virus grown in parent CHO cells. Digestion of the viral glycoproteins with Pronase followed by gel filtration demonstrated that the glycopeptides of Sindbis-15B virus were much smaller than the glycopeptides of Sindbis-CHO virus. In addition, Sindbis-15B viral glycopeptides but not Sindbis-CHO viral glycopeptides contained terminal α-mannose residues as shown by their susceptibility to α-mannosidase digestion. These findings demonstrate that the oligosaccharide units of the glycoproteins of vesicular stomatitis and Sindbis viruses are altered when the viruses are grown in 15B cells. We conclude that the N-acetylglucosaminyltransferase that is missing in 15B cells normally participates in the biosynthesis of the oligosaccharide units of the viral glycoproteins, and in the absence of this enzyme incomplete oligosaccharide chains are produced. Viruses released from 15B cells appear to retain full infectivity; Sindbis-15B virus, however, showed a significant decrease in hemagglutination titer compared with that of Sindbis-CHO virus.
Mutations to Penicillin Resistance in the Enterobacteriaceae That Affect Sensitivity to Serum and Virulence for the Mouse

Roantree, Robert J. (Stanford University School of Medicine, Stanford, Calif.), and John P. Steward. Mutations to penicillin resistance in the Enterobacteriaceae that affect sensitivity to serum and virulence for the mouse. J. Bacteriol 89:630-639. 1965.-Series of mutants resistant to benzylpenicillin or alpha-aminobenzylpenicillin were derived from serum-resistant strains of Escherichia coli and Salmonella by the gradientplate technique. Serum-sensitive mutants were detected in series derived from 16 of the 19 strains used, and these retained the parental O type. Most series were characterized by a mutational step to a high degree of sensitivity to serum. Penicillin-resistant mutants of virulent S. typhimurium and S. enteritidis were less virulent than the parent strains; those which were very sensitive to serum usually showed the greatest loss of virulence. One class of mutants from S. enteritidis was sensitive to human serum but virulent for mice. We found that the mice lack bactericidal antibody against this strain and that immunization with it leads to a high degree of protection.
Relationship between structural order and the anomalies of liquid water

In contrast to crystalline solids--for which a precise framework exists for describing structure--quantifying structural order in liquids and glasses has proved more difficult because even though such systems possess short-range order, they lack long-range crystalline order. Some progress has been made using model systems of hard spheres, but it remains difficult to describe accurately liquids such as water, where directional attractions (hydrogen bonds) combine with short-range repulsions to determine the relative orientation of neighbouring molecules as well as their instantaneous separation. This difficulty is particularly relevant when discussing the anomalous kinetic and thermodynamic properties of water, which have long been interpreted qualitatively in terms of underlying structural causes. Here we attempt to gain a quantitative understanding of these structure-property relationships through the study of translational and orientational order in a models of water. Using molecular dynamics simulations, we identify a structurally anomalous region--bounded by loci of maximum orientational order (at low densities) and minimum translational order (at high densities)--in which order decreases on compression, and where orientational and translational order are strongly coupled. This region encloses the entire range of temperatures and densities for which the anomalous diffusivity and thermal expansion coefficient of water are observed, and enables us to quantify the degree of structural order needed for these anomalies to occur. We also find that these structural, kinetic and thermodynamic anomalies constitute a cascade: they occur consecutively as the degree of order is increased.
Chapter 13 A Brief Introduction to Voltage-Gated K+ Channels

Publisher Summary This chapter discusses voltage-gated K + channels. Voltage-gated K + (Kv) channels are transmembrane proteins that control and regulate the flow of K + ions across cell membranes. In response to changes in the membrane potential, they undergo conformation changes, thereby allowing or blocking the conduction of ions. Structurally, Kv channels are formed by four subunits surrounding a central aqueous pore for K + permeation. Each subunit comprises six transmembrane segments, S1–S6, the first four transmembrane segments, S1–S4, constituting the voltage sensor domain, while the last two transmembrane segments, S5 and S6, from each of the four subunits join around a common axis to form a selective ion-conducting pore. Positively charged residues along S4, mostly arginines, appear to be mainly responsible for the coupling to the membrane voltage. Once all of the four subunits are in the activated state, opening of the pore gate occurs cooperatively via a concerted transition that is weakly voltage-dependent. After their opening, the channels start to enter into a non-conductive state via a process that is called slow inactivation.
Cell Type-Specific Cell Surface Antigens in the Cerebellum

Publisher Summary Cell–cell interactions have been developed to a high degree of precision in the nervous system as no other organ displays a similar wealth of cellular connections diverging and converging from one cell to another in time and space. Several surface antigens of neural cells have been characterized that allow the distinction between the major cell types in the cerebellum: neurons; astro- and oligodendroglia; and mesodermally derived accessory populations, such as fibroblasts, endothelial, and meningeal cells. The physical isolation of these cells is possible with immunoselective methods including complement-dependent cytolysis eliminating the antigen-positive cell class and fluorescence activated cell sorting that allows the simultaneous collection of both antigen-negative and -positive populations. The isolated cells are viable and can be maintained in vitro under conditions that permit growth of cellular extensions and cell division.
Peptide internalization enabled by folding: triple helical cell-penetrating peptides

Cell-penetrating peptides (CPPs) are known as efficient transporters of molecular cargo across cellular membranes. Their properties make them ideal candidates for in vivo applications. However, challenges in the development of effective CPPs still exist: CPPs are often fast degraded by proteases and large concentration of CPPs required for cargo transporting can cause cytotoxicity. It was previously shown that restricting peptide flexibility can improve peptide stability against enzymatic degradation and limiting length of CPP peptide can lower cytotoxic effects. Here, we present peptides (30-mers) that efficiently penetrate cellular membranes by combining very short CPP sequences and collagen-like folding domains. The CPP domains are hexa-arginine (R6) or arginine/glycine (RRGRRG). Folding is achieved through multiple proline-hydroxyproline-glycine (POG [proline-hydroxyproline-glycine])n repeats that form a collagen-like triple helical conformation. The folded peptides with CPP domains are efficiently internalized, show stability against enzymatic degradation in human serum and have minimal toxicity. Peptides lacking correct folding (random coil) or CPP domains are unable to cross cellular membranes. These features make triple helical cell-penetrating peptides promising candidates for efficient transporters of molecular cargo across cellular membranes.
Picenadol, a mixed opioid agonist/antagonist without κ opioid agonist activity in the rat urination test

Picenadol and its (+) and (−) isomers were compared to butorphanol and nalbuphine for their effects on urinary output in the normally hydrated rat. Butorphanol, a partial K agonist, increased urinary output markedly at all doses (0.32–20 mg/kg, s.c.). Nalbuphine (0.32–20 mg/kg, s.c.), picenadol (1.25–40 mg/kg, s.c.) and the two isomers (0.32–20 mg/kg, s.c.) had no tendency to increase urinary output within the 5-hr test period. Nalbuphine did not affect bremazocine-induced diuresis, whereas the (−) isomer of picenadol decreased bremazocine-induced diuresis through a κ-antagonist action and the (+) isomer of picenadol decreased the bremazocine-induced diuresis through a μ-opioid-like agonist action. These results were interpreted to mean that nalbuphine is a mixed agonist/antagonist without activity at κ receptors. Picenadol is a mixed agonist/antagonist with potent μ-opioid action in the (+) isomer and weak μ-and κ-antagonist action in the (−) isomer.
Electrostatic Assemblies of Fullerene−Porphyrin Hybrids: Toward Long-Lived Charge Separation

The Coulomb complex formation of a dendritic fullerene oligocarboxylate (18-) and an octapyridinium zinc porphyrin salt (ZnP8+) was investigated. A Job plot obtained by monitoring the Soret absorption of ZnP8+ upon addition of 1 in a phosphate buffer (pH 7.2, ionic strength = 0.012) indicated the formation of a 1:1 complex, ZnP8+/18-, for which an association constant of (3.5 ± 1.0) × 108 M-1 was determined. Parallel fluorescence titration experiments revealed that the ZnP8+ emission is strongly quenched in the ZnP8+/18- complex. In particular, the noted decrease of fluorescence intensity in ZnP8+ with variation of 18- and evidence for a new short-lived emissive component suggest a static quenching event inside a ZnP8+/18- complex. From the fluorescence titration, a value of (1.1 ± 0.1) × 108 M-1 for the association constant of the ZnP8+/18- complex at pH 7.2 was derived. The association constant decreased, however, when the ionic strength of the solution was raised. Electron-transfer quenching was confir...
Production of a DPP Activity Gradient in the Early Drosophila Embryo through the Opposing Actions of the SOG and TLD Proteins

During early Drosophila embryogenesis, several zygotic gene products act to establish a posttranscriptional activity gradient of the morphogen DPP. Among these molecules, Tolloid, a putative metalloprotease related to BMP-1, enhances DPP function, while SOG, an ortholog of the Xenopus organizer Chordin, inhibits DPP function. Using epistasis tests and a Xenopus secondary axis induction assay, we show that TLD negates the inhibitory effects of SOG/CHD on DPP/BMP-type ligands. In transient transfection assays, we demonstrate that TLD cleaves SOG and that cleavage is stimulated by DPP. We propose that formation of the embryonic DPP activity gradient involves the opposing effects of SOG inhibiting DPP and TLD processing SOG to release DPP from the inhibitory complex.
Chemistry of magnesium alkyls supported by 1,5,9-trimesityldipyrromethene and 2-[(2,6-diisopropylphenyl)amino]-4-[(2,6-diisopropylphenyl)imino]pent-2-ene. A comparative study

The compounds LMgBun(THF) and L′MgBun(THF) where L = 1,5,9-trimesityldipyrromethene and L′ = 2-[(2,6-diisopropylphenyl)amino]-4-[(2,6-diisopropylphenyl)imino]pent-2-ene have been prepared from reactions between MgBun2 and the protonated ligands LH and L′H, respectively. Single crystal X-ray crystallographic studies reveal that in each compound the Mg2+ ion is in a distorted tetrahedral environment and further that the ligand L is more sterically demanding with respect to access to the Mg–Bun group. Related alkyl complexes (R = Me, Et, Prn, Pri, n-hexyl and CH2CH2Ph) were prepared from reactions involving LLi(THF) or L′Li(THF) and the appropriate RMgX (X = Cl or Br) and characterized by 1H NMR spectroscopy. Those where R = CH2CH2X (X = alkyl or phenyl) have characteristic α-CH2 proton resonances which are the part of an AA′XX′ pattern. Reactions with alcohols ROH (1 equiv.) give the kinetic products LMg(OR)(THF) and L′Mg(OR)(THF) which are isolable and kinetically persistent when R = a bulky group such as But and the structure of LMg(OBut)(THF) is reported and compared with that of the known compound L′Mg(OBut)(THF). With less bulky groups the compounds are labile toward ligand scrambling and the compound L′MgBun(THF) reacts with alcohols (2 equiv.) to give L′H and Mg(OR)2. Reactions with amines and carbon dioxide are described which indicate the greater reactivity of the Mg–Bun group relative to both the L′ and L ligand. With PhCHO, Ph2CO and cyclohexanone both LMgBun(THF) and L′MgBun(THF) react via β-hydrogen atom transfer to generate the appropriate alkoxide with the elimination of 1-butene. Similarly L-lactide reacts by β-H transfer to give poly-L-lactide (P-L-LA) and 1-butene while rac-lactide yields atactic polylactide in toluene–dichloromethane solutions but in the presence of ≥10 equiv. of THF, heterotactic PLA is formed. The ring-opening polymerization of e-caprolactone also is initiated by β-H transfer and is about ten times faster than for lactide; kp(LA) = 10.7 M−1 s−1vs. kp(CL) = 110 M−1 s−1. Interestingly, the presence of lactide completely suppresses the polymerization of e-caprolactone.
Computational assessment of lexical differences in L1 and L2 writing

Abstract The purpose of this paper is to provide a detailed analysis of how lexical differences related to cohesion and connectionist models can distinguish first language (L1) writers of English from second language (L2) writers of English. Key to this analysis is the use of the computational tool Coh-Metrix, which measures cohesion and text difficulty at various levels of language, discourse, and conceptual analysis, and a statistical method known as discriminant function analysis. Results show that L1 and L2 written texts vary in several dimensions related to the writer's use of lexical choices. These dimensions correlate to lexical depth of knowledge, variation, and sophistication. These findings, together with the relevance of the new computational tools for the text analysis used in the study, are discussed.
Applying new solar particle event models to interplanetary satellite programs

Variability in the models and methods used for single event upset (SEU) calculations in microelectronic memory devices can lead to a range of possible upset rates. In order to compare the Adams 1986 interplanetary solar flare model to a new model proposed by scientists at the Jet Propulsion Laboratory (JPL92) the authors have calculated an array of upset rates using heavy ion and proton data for selected DRAM and SRAM memories and for Actel Field Programmable Gate Arrays (FPGAs). To make more general comparisons of the models the authors have produced a set of engineering curves of predicted upset rates versus hypothetical device cross-section parameters. The results show that use of this more realistic, although still conservative, JPL model can have significant benefits for satellite programs, especially those which must operate continuously during solar particle events. The benefits include more flexibility in model choice, a higher level of confidence in the environment, and potential cost savings by the calculation of less pessimistic SEU rates which allow designers to integrate commercial products into their spacecraft design with the use of Error Detection and Correction (EDAC) schemes. >
Teenage employment and career readiness

Most American youth hold a job at some point during adolescence, but should they work? This article presents a broad overview of teenage employment in the United States. It begins by describing which teenagers work and for how long and then focuses attention on the consequences (both good and bad) of paid work in adolescence. It then presents recent nationally representative data from the Monitoring the Future Study suggesting that limited hours of paid work do not crowd out developmentally appropriate after-school activities. A review of the literature also supports the idea that employment for limited hours in good jobs can promote career readiness and positive development. The article concludes with a discussion of the implications of youth work for practitioners and policymakers who are delivering career-related programming.
In situ acoustic and laboratory ultrasonic sound speed and attenuation measured in heterogeneous soft seabed sediments: Eel River shelf, California

Abstract We compared in situ and laboratory velocity and attenuation values measured in seafloor sediments from the shallow water delta of the Eel River, California. This region receives a substantial volume of fluvial sediment that is discharged annually onto the shelf. Additionally, a high input of fluvial sediments during storms generates flood deposits that are characterized by thin beds of variable grain-sizes between the 40- and 90-m isobaths. The main objectives of this study were (1) to investigate signatures of seafloor processes on geoacoustic and physical properties, and (2) to evaluate differences between geoacoustic parameters measured in situ at acoustic (7.5 kHz) and in the laboratory at ultrasonic (400 kHz) frequencies. The in situ acoustic measurements were conducted between 60 and 100 m of water depth. Wet-bulk density and porosity profiles were obtained to 1.15 m below seafloor (m bsf) using gravity cores of the mostly cohesive fine-grained sediments across- and along-shelf. Physical and geoacoustic properties from six selected sites obtained on the Eel margin revealed the following. (1) Sound speed and wet-bulk density strongly correlated in most cases. (2) Sediment compaction with depth generally led to increased sound speed and density, while porosity and in situ attenuation values decreased. (3) Sound speed was higher in coarser- than in finer-grained sediments, on a maximum average by 80 m s −1 . (4) In coarse-grained sediments sound speed was higher in the laboratory (1560 m s −1 ) than in situ (1520 m s −1 ). In contrast, average ultrasonic and in situ sound speed in fine-grained sediments showed only little differences (both approximately 1480 m s −1 ). (5) Greater attenuation was commonly measured in the laboratory (0.4 and 0.8 dB m −1 kHz −1 ) than in situ (0.02 and 0.65 dB m −1 kHz −1 ), and remained almost constant below 0.4 m bsf. We attributed discrepancies between laboratory ultrasonic and in situ acoustic measurements to a frequency dependence of velocity and attenuation. In addition, laboratory attenuation was most likely enhanced due to scattering of sound waves at heterogeneities that were on the scale of ultrasonic wavelengths. In contrast, high in situ attenuation values were linked to stratigraphic scattering at thin-bed layers that form along with flood deposits.