cssi/SciSciGPT-SciSciNet huggingface dataset:
Studies of All‐trans‐retinal as a Photooxidizing Agent¶

Abstract The photophysical properties of all-trans-retinal (RAL) have been extensively studied because of the importance of the retinoids in the visual process. However, little information is available regarding the participation of RAL in photochemical transformations such as photooxidation. RAL is one of several native chromophores that have been suggested to act as photosensitizers of damage in the human retina, and this damage would likely occur through oxidative pathways. Time-resolved and steady state techniques have been used to examine the photoreactivity of RAL toward several suitable substrates. The lifetime of the RAL triplet excited state is observed to decrease with increasing concentration of the well-known electron and hydrogen atom donors, 2,3,5,6-tetramethyl-1,4-phenylenediamine (DAD), hydroquinone (HQ), methylhydroquinone (MHQ), 2,3-dimethylhydroquinone (DMHQ) and trimethylhydroquinone (TMHQ), although the bimolecular rate constants for the reaction are much less than that of diffusion c...
Osteoclast recruitment to sites of compression in orthodontic tooth movement

Abstract Although it is widely acknowledged that osteoclasts are formed by the fusion of mononuclear cells of hematopoietic origin, it has been extremely difficult to understand how they originate after appliance activation. The purpose of this study was to quantify osteoclast recruitment at compression sites as a function of time following orthodontic force application. Appliances were placed in 96 rats. At day 0, the animals were randomized to either appliance activation or sham activation followed by the injection of 5-bromo-2′-deoxyuridine (BrdU). Thus, BrdU was incorporated into the nuclei of cells in S-phase, including hematopoietic stem cells. Groups of 10 to 13 rats were killed at 1, 3, 5, and 7 days after activation/sham, and the tissue samples were prepared. The numbers of BrdU-labeled cells positively stained with tartrate-resistant acid phosphatase (TRAP) were measured in the periodontium. A significant number of BrdU-positive preosteoclasts was observed in the periodontal ligament (PDL) and bone surface at day 3. The number of osteoclastic cells in the bone marrow also peaked at day 3; however, the highest percentage of cells in this location was observed at day 1. These data suggest that osteoclasts in the PDL originate by the fusion of recently recruited preosteoclasts from the marrow instead of from local PDL cells. Furthermore, the alveolar bone marrow plays a role in the formation of osteoclasts during orthodontic tooth movement. (Am J Orthod Dentofacial Orthop 2001;120:477-89)
Application of targeted quantitative proteomics analysis in human cerebrospinal fluid using a liquid chromatography matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometer (LC MALDI TOF/TOF) platform.

Targeted quantitative proteomics by mass spectrometry aims to selectively detect one or a panel of peptides/proteins in a complex sample and is particularly appealing for novel biomarker verification/validation because it does not require specific antibodies. Here, we demonstrated the application of targeted quantitative proteomics in searching, identifying, and quantifying selected peptides in human cerebrospinal spinal fluid (CSF) using a matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometer (MALDI TOF/TOF)-based platform. The approach involved two major components: the use of isotopic-labeled synthetic peptides as references for targeted identification and quantification and a highly selective mass spectrometric analysis based on the unique characteristics of the MALDI instrument. The platform provides high confidence for targeted peptide detection in a complex system and can potentially be developed into a high-throughput system. Using the liquid chromatography (LC) MALDI...
Automatic ogive scoring rules for the short form of the sentence completion test of EGO development

Short forms of the Washington University Sentence Completion Test (SCT) of ego development have been developed for large-scale survey and clinical research. However, automatic scoring rules based on the ogive scoring algorithm unique to the ego development model are not available. This article presents and tests the accuracy of automatic ogive scoring rules for the 12-stem SCT in a sample of middle-aged women (N = 87) who were participating in a longitudinal study of personality development. Results indicated that Total Protocol Ratings (TPR) of ego development for 12-stems computed with the scoring rules presented in this study correlated highly with TPR for 36-stems (r = .92). No stage of ego development was misrepresented selectively by the short form. The short form and the scoring rules presented here may provide a useful estimate of ego development for clinical research.
Contingency constrained economic dispatch in smart grids with correlated demands

Contingency constrained economic dispatch has been an extensively studied research topic. However, most existing works assume that the load demands at all buses are given. Such an assumption works well for conventional power grids, where the load demands are relatively easy to predict. We can select a few representative demand profiles and perform economic dispatch over them. However, such a practice will no longer work in smart grids, where the load demands fluctuate dramatically. We will need a huge number of demand profiles to cover all possible scenarios, which is computationally expensive. To address the problem, we propose a parameterized stochastic model through independent component analysis to capture both the spatial and temporal correlation of the load demands. Although this stochastic version of the contingency constrained economic dispatch problem is more difficult to solve, we show that it can be cast as a Semi-Infinite Programming problem, a solution to which can be established by adopting the Multivariate Remes Exchange framework. Our experiments based on IEEE power system testcases and data from Electric Reliability Council of Texas (ERCOT) have shown that our approach can achieve over 30× speedup with a similar generation cost when compared to the conventional practice of considering a number of demand profile samples and when the dispatch solutions from both methods satisfy the contingency constraints over all possible profiles.
Photoemission with picosecond lasers: fast electron dynamics at the GaAs [110] surface

Subpicosecond pulses of 10.7-eV radiation from a tunable laser-based source are used to carry out photoemission investigations of the electronic dynamics on the laser-excited surface of GaAs [110]. Angle-resolved studies have revealed a rapid surface intervalley scattering process that transfers electrons between the directly excited, surface Brillouin zone center to a previously unobserved valley within the bandgap at the surface zone edge. The scattering time has been determined to be 0.4+or-0.1 ps. A model that describes the scattering dynamics is presented. >
Magnetophotoselection applied to the triplet state observed by EPR in photosynthetic bacteria

Abstract Magnetophotoselection (MPS) techniques have been used to study the triplet state observed by electron paramagnetic resonance (epr) in photosynthetic bacteria. Intact R. rubrum chromatophores and systems in which the effects of energy transfer via antenna chlorophyll molecules have been minimized were examined. These preliminary results indicate that there is order in the bacteriochlorophyll antenna system, that the optical transition at 890 nm appears to be along the triplet y axis of the bacteriochlorophyll special pair (Bchlsp), and that the resultant transition moment associated with 800 nm is approximately parallel to the long wavelength transition moment of the Bchlsp.
Current Trait Factor Career Assessment: A Cognitive-Interactional Perspective:

A trait factor perspective on career assessment is presented. Adult career client and initial assessment issues are emphasized. A diagnostic taxonomy and conceptual models within person- environment psychology are used to guide the discussion. Specific assessment issues, strategies, and instruments for career choice and adjustment difficulties are reviewed. Trait factor career counseling is characterized as a model that is evolving through integrative efforts. Advances are moving this model in the direction of an articulated theory of career counseling.
Placodal Origin of Brn-3-Expressing Cranial Sensory Neurons

The Brn-3 class of POU-domain transcription factors includes three genes in mammals which have key roles in the development of specific groups of sensory neurons. Here, we have identified three avian genes which correspond to the murine genes Brn-3.0, Brn-3.1, and Brn-3.2. Using an in situ hybridization probe generic for this gene class, the earliest detectable expression of Brn-3 in the chick is at stage 15, in placodal and migrating precursors of the trigeminal ganglion. By stage 19, Brn-3.0 protein is detectable in the trigeminal and vestibulocochlear ganglia with Brn-3.0-specific antisera, and Brn-3 message expression has extended to the dorsal root ganglia. At later stages, when condensation of the trigeminal ganglion is complete, Brn-3.0-immunoreactive neurons are concentrated in the portion of the ganglion distal to the brain stem. To examine the developmental origin of the Brn-3 expressing cells, we combined lipophilic dye (DiI) labeling with in situ hybridization. DiI labeling of the placodal surface ectoderm and of premigratory neural crest cells in the neural tube reveals that all, or nearly all, of the Brn-3-expressing neurons in the trigeminal ganglia are derived from the sensory placodes and not from the neural crest, and thus, that Brn-3 is an early marker of the placode-derived sensory neural lineage.
Early onset of lipoperoxidation in rat liver after carbon tetrachloride administration.

Abstract Peroxidative decomposition of rat liver microsomal lipids, as evidenced by the appearance of diene conjugation absorption, is more than half-maximal within 5 minutes after intragastric administration of carbon tetrachloride in mineral oil. In the microsome fraction the degenerative process is complete within 15 minutes. Peroxidative decomposition of mitochondrial lipids is much slower than for microsomal lipids. To our knowledge this explosive peroxidative decomposition of liver cell microsomal lipids is the most rapid pathological alteration yet noted for carbon tetrachloride liver damage under comparable conditions of dosage and route of administration of this toxic haloalkane. The significance of this finding as supporting evidence for a lipoperoxidation hypothesis for carbon tetrachloride hepatotoxicity is discussed.
Automatically Inferring Metrics for Design Creativity

Measuring design creativity is crucial to evaluating the effectiveness of idea generation methods. Historically, there has been a divide between easily-computable metrics, which are often based on arbitrary scoring systems, and human judgement metrics, which accurately reflect human opinion but rely on the expensive collection of expert ratings. This research bridges this gap by introducing a probabilistic model that computes a family of repeatable creativity metrics trained on expert data. Focusing on metrics for variety, a combination of submodular functions and logistic regression generalizes existing metrics, accurately recovering several published metrics as special cases and illuminating a space of new metrics for design creativity. When tasked with predicting which of two sets of concepts has greater variety, our model matches two commonly used metrics to 96% accuracy on average. In addition, using submodular functions allows this model to efficiently select the highest variety set of concepts when used in a design synthesis system.
Feature Subset Selection, Class Separability, and Genetic Algorithms

The performance of classification algorithms in machine learning is affected by the features used to describe the labeled examples presented to the inducers. Therefore, the problem of feature subset selection has received considerable attention. Genetic approaches to this problem usually follow the wrapper approach: treat the inducer as a black box that is used to evaluate candidate feature subsets. The evaluations might take a considerable time and the traditional approach might be impractical for large data sets. This paper describes a hybrid of a simple genetic algorithm and a method based on class separability applied to the selection of feature subsets for classification problems. The proposed hybrid was compared against each of its components and two other feature selection wrappers that are used widely. The objective of this paper is to determine if the proposed hybrid presents advantages over the other methods in terms of accuracy or speed in this problem. The experiments used a Naive Bayes classifier and public-domain and artificial data sets. The experiments suggest that the hybrid usually finds compact feature subsets that give the most accurate results, while beating the execution time of the other wrappers.
Performance evaluation of directional adaptive range control in mobile ad hoc networks

This paper presents DARC (Directional Adaptive Range Control), a range control mechanism using directional antennas to be implemented across multiple layers. DARC uses directional reception for range control rather than directional transmission in order to achieve both range extension and high spatial reuse. It adaptively controls the communication range by estimating dynamically changing local network density based on the transmission activities around each network node. The experimental results using simulation with detailed physical layer, IEEE 802.11 DCF MAC, and AODV protocol models have shown the successful adaptation of communication range with DARC for varied network densities and traffic loads. DARC improves the packet delivery ratio by a factor of 9 at the maximum for sparse networks while it maintains the increased network capacity for dense networks. Further, as each node adaptively changes the communication range, the network delivers up to 20% more packets with DARC compared to any fixed range configurations.
Spatially localized 31P NMR measurements of longitudinal relaxation rates in the canine myocardium

FLAX-ISIS spatial localization was combined with inversion recovery to enable the measurement of spatially localized T1 values. This approach was applied to the transmural determination of creatine phosphate longitudinal relaxation times in the canine myocardium. By examining five voxels spanning the left myocardial wall, we observed that transmural T1 values for creatine phosphate ranged from 3.61 +/- 0.20 in the endocardium to 4.00 +/- 0.20 in the epicardium at 4.7 Tesla. As such, the canine myocardium exhibits no transmural variation in the T1 values of creatine phosphate. This simple approach can be extended to enable the in vivo measurement of transmural enzymatic rates.
Glutamine supplement with parenteral nutrition decreases whole body proteolysis in low birth weight infants

Objectives To examine the effect of supplemental glutamine (0.6 g.kg −1 .d −1 ) on whole body protein/nitrogen and glutamine kinetics in low birth weight (LBW) infants receiving parenteral nutrition in the immediate neonatal period. Study design Premature infants ≤32 weeks gestation with a birth weight from 694 to 1590 g were randomly assigned to either a glutamine-supplemented group (n=10) or to a control group (n=10). Tracer isotope studies were performed when the infants were 6 to 7 days old and had been receiving an amino acid intake of approximately 3.0 g.kg −1 .d −1 for at least 3 days. Whole body glutamine and nitrogen kinetics were measured with [5- 15 N]glutamine, [ 2 H 5 ]phenylalanine, [1- 13 C, 15 N]leucine, [ 15 N 2 ]urea, and GC-mass spectrometry. Results Supplemental glutamine was associated with a lower rate of appearance of glutamine ( P =.003), phenylalanine ( P =.001), and leucine C ( P =.003). There was no significant difference in leucine N turnover, urea turnover and plasma cortisol, and C-reactive protein levels in the 2 groups. Conclusion Parenteral glutamine supplement in LBW infants was associated with lower whole-body protein breakdown. Because the decrease in whole body proteolysis is associated with protein accretion, parenteral glutamine supplement may be beneficial in selected populations of LBW infants.
Public Libraries as Post-Crisis Information Hubs

Like the crisis responses to hurricanes, after a tornadic event public libraries play emergency roles both in the short and long term. Community members rely on public libraries for Internet access to request aid, to help find missing family and friends, to file Federal Emergency Management Agency (FEMA) and insurance claims, and, in general, to begin rebuilding their lives. This article reports the quality of services and activities public libraries performed in response and recovery in twelve different communities impacted by tornadoes. The discussion includes an evaluation of the quality of the responses and some recommendations to improve preparedness and response.
Human whole-nerve response to clicks of various frequency.

The averaged VIIIth nerve response to third-octave clicks at 500, 2 000 and 8 000 Hz was recorded from the promontory of four normal-hearing young adultsAs click frequency is lowered, the N1 latency increases in a manner consistent with the changes in velocity of the cochlear traveling wave. This finding suggests that clicks of different spectral content stimulate different regions of the basilar membraneN1 amplitude shows a general increase with frequency; this observation appears related to the increased synchrony of neural firing that results from the higher velocity of the traveling wave in the more basal portions of the cochlea
Digital tomosynthesis mammography: improvement of artifact reduction method for high-attenuation objects on reconstructed slices

One major image quality problem in digital tomosynthesis mammography (DTM) is the poor depth-resolution caused by the inherent incomplete sampling. This problem is more pronounced if high-attenuation objects, such as metallic markers and dense calcifications, are present in the breast. Strong ghosting artifacts will be generated in the depth direction in the reconstructed volume. Incomplete sampling of DTM can also cause visible ghosting artifacts in the x-ray source motion direction on the off-focus planes of the objects. These artifacts may interfere with radiologists' visual assessment and computerized analysis of subtle mammographic features. We previously developed an artifact reduction method by using 3D geometrical information of the objects estimated from the reconstructed slices. In this study, we examined the effect of imaging system blur in DTM caused by the focal spot and the detector modulation transformation function (MTF). The focal spot was simulated as a 0.3 mm square array of x-ray point sources. The detector MTF was simulated using the Burgess model with parameters derived from published data of a GE FFDM detector. The spatial-variant impulse responses for the DTM imaging system, which are required in our artifact reduction method, were then computed from the DTM imaging model and a given reconstruction technique. Our results demonstrated that inclusion of imaging system blur improved the performance of our artifact reduction method in terms of the visual quality of the corrected objects. The detector MTF had stronger effects than focal spot blur on artifact reduction under the imaging geometry used. Further work is underway to investigate the effects from other DTM imaging parameters, such as x-ray scattering, different polyenergetic x-ray spectra, and different configurations of angular range and angular sampling interval.
Methenyl-Dephosphotetrahydromethanopterin Is a Regulatory Signal for Acclimation to Changes in Substrate Availability in Methylobacterium extorquens AM1

ABSTRACT During an environmental perturbation, the survival of a cell and its response to the perturbation depend on both the robustness and functionality of the metabolic network. The regulatory mechanisms that allow the facultative methylotrophic bacterium Methylobacterium extorquens AM1 to effect the metabolic transition from succinate to methanol growth are not well understood. Methenyl-dephosphotetrahydromethanopterin (methenyl-dH 4 MPT), an early intermediate during methanol metabolism, transiently accumulated 7- to 11-fold after addition of methanol to a succinate-limited culture. This accumulation partially inhibited the activity of the methylene-H 4 MPT dehydrogenase, MtdA, restricting carbon flux to the assimilation cycles. A strain overexpressing the gene ( mch ) encoding the enzyme that consumes methenyl-dH 4 MPT did not accumulate methenyl-dH 4 MPT and had a growth rate that was 2.7-fold lower than that of the wild type. This growth defect demonstrates the physiological relevance of this enzymatic regulatory mechanism during the acclimation period. Changes in metabolites and enzymatic activities were analyzed in the strain overexpressing mch . Under these conditions, the activity of the enzyme coupling formaldehyde with dH 4 MPT (Fae) remained constant, with concomitant formaldehyde accumulation. Release of methenyl-dH 4 MPT regulation did not affect the induction of the serine cycle enzyme activities immediately after methanol addition, but after 1 h, the activity of these enzymes decreased, likely due to the toxicity of formaldehyde accumulation. Our results support the hypothesis that in a changing environment, the transient accumulation of methenyl-dH 4 MPT and inhibition of MtdA activity are strategies that permit flexibility and acclimation of the metabolic network while preventing the accumulation of the toxic compound formaldehyde. IMPORTANCE The identification and characterization of regulatory mechanisms for methylotrophy are in the early stages. We report a nontranscriptional regulatory mechanism that was found to operate as an immediate response for acclimation during changes in substrate availability. Methenyl-dH 4 MPT, an early intermediate during methanol oxidation, reversibly inhibits the methylene-H 4 MPT dehydrogenase, MtdA, when Methylobacterium extorquens is challenged to switch from succinate to methanol growth. Bypassing this regulatory mechanism causes formaldehyde to accumulate. Fae, the enzyme catalyzing the conversion of formaldehyde to methylene-dH 4 MPT, was also identified as another potential regulatory target using this strategy. The results herein further our understanding of the complex regulatory network in methylotrophy and will allow us to improve metabolic engineering strategies of methylotrophs for the production of value-added products.
Cellular identification of β-lactoglobulin synthesis in bovine mammary cell cultures

Abstract Approximately 50 per cent of the cells present in a collagenase dispersion of bovine mammary tissue were found to survive and grow when placed in in vitro culture. These cultures are composed of predominantly epithelial cells. A net synthesis of β-lactoglobulin could be demonstrated in the cultures by a quantitative immunological procedure until 20 days after their establishment. The use of the fluorescent-antibody technique indicated that the epithelial cells were those responsible for the synthesis of the β-lactoglobulin. Since previous studies have indicated that other specialized functions (i.e. lactose synthesis and UDPGal-4-epimerase activity) are lost in a non-parallel manner with the ability to synthesize β-lactoglobulin, these results indicate that the secretory cells survive and proliferate in culture but lose their ability with time to perform specialized functions due to a dedifferentiation or modulation in function.
CFTR expression and chloride secretion in polarized immortal human bronchial epithelial cells.

A major limitation in the study of vectorial ion transport, secretion, and differentiated function in the human airway epithelium has been the lack of suitable cell culture systems. Progress in this direction has been made through the transformation of primary cultured epithelial cells. However, these transformants tend to lose differentiated properties with increasing serial passage, particularly following crisis. The suc­ cessful establishment of a postcrisis SV40 large T-antigen transformed epithelial cell line derived from human bronchial epithelium is described. This cell line, 16HBEI40-, retains differentiated epithelial mor­ phology and functions. Cell cultures show the presence of tight junctions and cilia, and monolayers gener­ ate transepithelial resistance, as measured in Ussing chambers, and retain iJ-adrenergic stimulation of cAMP-dependent chloride ion transport, measured either by ,6CI- efflux or as short-circuit current in Ussing chambers. The cells also increase chloride transport in response to bradykinin or calcium iono­ phore. In addition, 16HBE140-cells express levels of both the cystic fibrosis transmembrane conductance regulator (CFTR) mRNA and protein readily detectable by Northern and Western hybridization analysis, respectively. These cells provide a valuable resource for studying the modulation of CFTR and its role in regulation of chloride ion transport in human airway epithelium as well as other aspects of human airway cell biology. The human airway epithelium is pseudostratified, consisting of highly organized layers of polar cells with specific dif­ ferentiated functions. It includes ciliated columnar cells, basal cells, and secretory goblet cells that are linked by tight junctions. The tight junctions provide a barrier between the airway lumen and the underlying tissues and divide the epi­ thelial cells into apical and basolateral domains. Both of these plasma membrane compartments contain different populations of proteins that allow for directional flux of ions
Ocular Findings in Patients with Autosomal Dominant Retinitis Pigmentosa and Rhodopsin, Proline-347-Leucine

We studied the ocular findings in eight unrelated patients with a form of autosomal dominant retinitis pigmentosa and the same cytosine-to-thymine transition in the second nucleotide of codon 347 of the rhodopsin gene. This mutation, detected in leukocyte DNA, corresponds to a substitution of leucine for proline in amino acid 347 of the rhodopsin protein, and, therefore, we designated this form of retinitis pigmentosa as rhodopsin, proline-347-leucine. On average, these patients had significantly smaller visual field areas and smaller electroretinogram amplitudes than 140 unrelated patients of comparable age with dominant retinitis pigmentosa without this mutation. The findings in eight relatives with this mutation from three of these families are presented to provide examples of the variability that exists in the clinical severity of this disease.
Ca2+ entry through cardiac L-type Ca2+ channels modulates beta-adrenergic stimulation in mouse ventricular myocytes.

β-adrenergic receptor (β-AR) stimulation increases cardiac L-type Ca2+ channel (CaCh) currents via cAMP-dependent phosphorylation. We report here that the affinity and maximum response of CaCh to isoproterenol (Iso), in mouse ventricular myocytes were significantly higher when Ba2+ was used as the charge carrier (IBa) instead of Ca2+ (ICa). The EC50 and maximum increase of peak currents were 43.7 ± 7.9 nM and 1.8 ± 0.1-fold for ICa and 23.3 ± 4.7 nM and 2.4 ± 0.1-fold for IBa. When cells were dialyzed with the faster Ca2+ chelator, BAPTA, both sensitivity and maximum response of ICa to Iso were significantly augmented compared to cells with EGTA (EC50 of 23.1 ± 5.2 nM and maximal increase of 2.2 ± 0.1-fold). Response of ICa to forskolin was also significantly increased when cells were dialyzed with BAPTA or when currents were measured in Ba2+. In contrast, depletion of the sarcoplasmic reticulum (SR) Ca2+ stores by ryanodine did not alter sensitivity of ICa to Iso or forskolin. These results suggest that the Ca2+ entering through CaCh regulates cAMP-dependent phosphorylation, and such negative feedback may play a significant role in cellular Ca2+ homeostasis and contraction in cardiac cells during β-AR stimulation.
Validity and reliability of the school physical activity environment questionnaire

The goal of the current study was to establish the factor validity of the Questionnaire Assessing School Physical Activity Environment (Robertson-Wilson, Levesque, & Holden, 2007) using confirmatory factor analysis procedures. Another goal was to establish internal reliability and test–retest reliability. The confirmatory factor analysis results of this study supported a slightly altered version of the Questionnaire Assessing School Physical Activity Environment's school physical activity environment subscale. Internal reliability was adequate, while test–retest reliability was questionable. In brief, the pattern of findings indicated that while the original Questionnaire Assessing School Physical Activity Environment is likely adequate for some research purposes, a slightly modified version (Questionnaire Assessing School Physical Activity Environment-R) was psychometrically stronger. However, given the distinct differences in samples used in the original validation study and the current study, more rese...
Vitamin E-deficiency in the guinea pig: effect of succinate on mitochondrial nad-linked oxidation.

Abstract Control of β-hydroxybutyrate oxidation by succinate occurred via two mechanisms in E+ liver mitochondria and one of these was energy-dependent (reversal of electron transport). Addition of an energy trapping system (Pi-acceptor) to E+ mitochondria resulted in loss of energy-dependent control by succinate. Pi-acceptor had no effect on control in E− mitochondria, indicating that reversal of electron transport was not functional in these preparations. ATP was inefficient as an energy source for succinate control in E− mitochondria. Menadione inhibited control of β-hydroxybutyrate oxidation in both E− and E+ mitochondria. The effect of menadione is consistent with its capacity to by-pass the NADH-Coenzyme Q reductase segment of the respiratory chain.
Writing for the online medium: a critical review

Three books that attempt to define online documentation are studied and the important theoretical and practical issues that are being raised by this communication medium are discussed (E. Barratt, 1988; S. Doheney-Farina, 1988; W.K. Horton, 1990). The focus is on how the intersection of research and practice is helping to construct this new definition, and the works are analyzed critically through the lens of active writing practices. A caution is raised regarding future research that could tend to be unreflective in nature. >
Mapping spatial proximities of sulfhydryl groups in proteins using a fluorogenic cross-linker and mass spectrometry

Chemical cross-linking of proteins in combination with mass spectrometric analysis of the reaction products has gained renewed interest as a method of obtaining distance constraints within a protein and determining a low-resolution three-dimensional structure. We present a method for identifying spatially close sulfhydryl groups in proteins employing chemical cross-linking with the Xuorogenic, homobifunctional cross-linker dibromobimane, which cross-links thiol pairs within »3–6 A. The applicability of our strategy was demonstrated by cross-linking the sulfhydryl groups of Cys-18 and Cys-78 in -crystallin F, which are within a distance of 3.57 A according to the X-ray structure. Intramolecularly cross-linked -crystallin was Wrst separated from reaction side products by reversed-phase chromatography on a C-4 column. Subsequently, the fraction containing the reacted protein was enzymatically digested with trypsin, and the resulting peptide mixture was separated by a second reversed-phase chromatographic step on a C-18 column, in which the cross-linked peptides were tracked by their Xuorescence. The cross-linking product between Cys-18 and Cys-78 in -crystallin F was identiWed by matrix-assisted laser desorption/ionization-time of Xight mass spectrometry. This strategy presents a rapid method for mapping sulfhydryl groups separated by a distance of »3–6 A within a protein.
Uterine transport of prostaglandin E2-releasing simulated embryonic vesicles in mares

Abstract Transrectal ultrasonography was used to test the hypothesis that prostaglandin E 2 (PGE 2 ) would increase the uterine transport of simulated embryonic vesicles in mares. Uterine transport of PGE 2 -releasing (PGE) vesicles, vehicle-releasing (sham) vesicles, and equine embryos was contrasted on Day 12 or Day 13 post ovulation. In Experiment 1, there was no difference (P>0.10) in transport of PGE vesicles, sham vesicles, Day-12 embryos, and Day-12 embryos after cervical manipulation (n = 3 per group). In Experiments 2 and 3, respectively, transport of PGE and sham vesicles was contrasted with transport of Day-13 embryos after the vesicles (1 vesicle per mare) were placed into the uterine lumen with the embryo, (n = 7 per group). In Experiment 2, PGE vesicles were transported less often (P 0.10) in the transport of PGE vesicles and embryos (Experiment 2) or sham vesicles and embryos (Experiment 3) together in the uterine lumen. In Experiment 4, transport of PGE and sham vesicles was contrasted by placing them together into the uterine lumen of nonpregnant mares on Day 13 (n = 7). There was no difference (P>0.10) in the transport of PGE and sham vesicles together in the uterine lumen. These results do not support the hypothesis that PGE 2 increases uterine transport of simulated embryonic vesicles. In addition, these results do not support the hypothesis that equine embryos stimulate uterine transport.
Learner vs. experimenter determination of subsequences in serial memorization

Five subjects each learned 132 word lists of varying lengths, where half of the lists were segmented into rows by the experimenter and half were left unsegmented for the subject to handle as he might elect. Segmented and unsegmented lists yielded similar length-difficulty relations, indicating that the source of list segmentation is not a determinant of learning difficulty.
Reading Knee-Deep

Freire told his audience at a seminar at the University of Massachusetts, “You need to read knee-deep in texts, for deeper than surface meanings, and you need to know the words to be able to do it” (quoted in Cleary, 2003). In a children's literature class, fifteen teachers and I traveled along a path that moved us toward reading knee-deep as we peered beneath the surface of the words on the page and into our personal responses to examine the worlds they each described. To help us along this path, we took two theoretical perspectives, transactional literary theory and critical literacy theory. While many of the students were familiar with transactional literary theory, few were familiar with critical literacy theory. It was not surprising, based on their experience with it, that students readily transacted with children's literature, living through the story worlds and making personal connections. However, they were hesitant, critical readers of children's literature and resisted critique, uncomfortable w...
Identification of isomeric hydroxy fatty acids in aerosol samples by capillary gas chromatography—mass spectrometry

Abstract Isomeric mixtures of 5- to (ω — 1)-monohydroxy fatty acids have been isolated from remote marine aerosols by methanolic potassium hydroxide extraction and silica gel column chromatography. Structures of the hydroxy acids were determined by comparison with high-resolution gas chromatography-mass spectrometry (GC—MS) of authentic standards, employing methyl esters and methyl ester trimethylsilyl (TMS) derivatives. A series of monohydroxy acid positional isomers have been identified in the range C7C15 with 5-hydroxyundecanoic and 10-hydroxyundecanoic acids as major isomers. Electron-impact mass spectra of hydroxy acid methyl esters show characteristic α-cleavage ions (e.g. m/z 131 for the 5-hydroxy homologue) and their methanol-eliminated ions (e.g. m/z 99). Mass spectra of the TMS derivatives also yield characteristic ions at m/z 133 + 14m (m ⩾ 5; m = position of carbon atom bearing the hydroxyl group). These specific ions provide a useful tool in mass chromatography to detect individual positional isomers of hydroxy fatty acids in environmental samples.
Micro-computer applications in environmental engineering

Abstract Micro-computers can have wide applications for simulating many processes in environmental engineering. Micro-computers can have potential applications in environmental engineering for (i) selection of the best optimized water distribution network models, (ii) selection of the best optimized sewerage network models, (iii) forecasting of chemical water quality variables in surface water and (iv) modeling of contaminant transport into groundwater.
CD4+ and CD8+ circulating alpha/beta T-cell repertoires are equally complex and are characterized by different levels of steady-state TCR expression.

Abstract The repertoire complexity of CD4+ and CD8 + T cells was measured in three healthy blood donors for a number of TCR BV gene families by TCR spectra-typing. This method subdivides V family-specific PCR products based on CDR3 length. Genomic DNA was analyzed to determine the distribution of the cells bearing particular V-J rearrangements. cDNA was analyzed to measure the levels of transcripts arising from those same cells. The complexity and distribution of T cells in each lineage were equal for most BV families. Certain families showed frequent skewing in CD8 cells. Analysis of the intensity profiles of RNA versus DNA spectratypes indicated that in general, there is a constant ratio of transcript per cell for all rearranged sizes within a particular family. This ratio appeared higher in CD4 cells. Thus, steadystate levels of TCR mRNA were measured and found to be higher in CD4+ than in CD8+ cells.
Slew-aware buffer insertion for through-silicon-via-based 3D ICs

Large parasitic capacitances of through-silicon-vias in 3D ICs cause signal slew and delay to increase. We propose a buffer insertion algorithm that further reduces delay by considering slew explicitly. Compared with the well-known van Ginneken algorithm and a commercial 2D tool, our algorithm improves full-chip timing with acceptable runtime overhead.
Assessment of Procedures for Screening Agents for Effects on Male Reproduction: Effects of Dibromochloropropane (DBCP) on the Rat

Abstract This study was designed to evaluate new protocols proposed for use as an initial screen or a dose-response test of an agent for adverse effects on male reproduction. Seven groups of adult male rats (15/group) were nongavaged or received orally 0.00, 0.94, 1.88, 3.75, 7.5, or 15.0 mg/kg of 1,2-dibromo-3-chloropropane (DBCP) in corn oil each day for 77 days. From Day 65 to Day 71, each male was caged with 2 untreated female rats. Pregnancy rate and the ratio between the numbers of embryos and corpora lutea were determined. Males were killed on Day 78 and blood was collected and one testis and epididymis were used to determine daily spermatozoal production and epididymal spermatozoal reserves. The contralateral testis was fixed for quantitative histologic evaluation. Considering only data for the 15.0 and 0.00 mg/kg doses, as in an initial screen, DBCP would have been identified as a compound of concern. Body weight, paired testicular weight, parenchymal weight of the left testis, daily spermatozoal production per testis, numbers of sperm in the caput-corpus or cauda epididymidis, mean diameter of seminiferous tubules, and the ratio of leptotene spermatocytes to Sertoli cells were reduced (p
Tandem antifibrotic actions of L-arginine supplementation and low protein diet during the repair phase of experimental glomerulonephritis

Tandem antifibrotic actions of L-arginine supplementation and low protein diet during the repair phase of experimental glomerulonephritis. Background Based upon the central role transforming growth factor-beta (TGF-β) overexpression appears to play in renal fibrotic diseases, we have recently advocated reduction of TGF-β as a therapeutic target. As part of efforts to determine the strength of this approach, we have undertaken studies to quantitate the effects of currently used and promising therapies in terms of their potential to reduce markers of disease in anti-thymocyte-serum (ATS)-glomerulonephritis in the rat. Here we assess the therapeutic effect of L-arginine supplementation, which has been shown to reduce fibrosis in a number of hypertensive models, given alone or in combination with low protein diet and started 24 hours after disease induction. Methods Glomerulonephritis was induced by intravenous injection of OX-7 monoclonal antibody into 200g Sprague-Dawley rats. Twenty-four hours later animals were placed in groups that were either untreated, treated with 1% L-arginine in drinking water or 6% protein diets or both. On the fifth day of disease 24-hour urine specimens were collected and systemic blood pressure was measured. On the sixth day rats were anesthetized. Kidneys were perfused, tissue was taken for PAS staining and glomeruli were isolated. Aliquots of glomeruli were used for RNA preparation and for culture to determine 72-hour production of TGF-β, fibronectin and plasminogen activator-type 1 (PAI-1), which were assayed by ELISA on culture supernatants. Measures of nitrate and nitrite (NOx) production included plasma NOx, urinary NOx and glomerular production of NOx in culture. Results All disease measures except proteinuria and including matrix accumulation, TGF-β, fibronectin and PAI-1 production and mRNA expression for TGF-β, fibronectin and PAI-1 were significantly and similarly reduced by about 50% in groups treated with L-arginine or with low protein diet. Proteinuria was reduced in low protein treated but not in L-arginine supplemented rats. Neither systemic blood pressure nor measures of NO synthesis showed differences between groups that could be attributed to L-arginine supplementation. In contrast, disease-related increases in glomerular production of NOx were markedly reduced by low protein. Combined therapy resulted in small, but statistically significant decreases in most measures of disease. Conclusions L-arginine supplementation reduces fibrotic disease in ATS-induced glomerulonephritis if started after disease induction. The absence of evidence for increased NO production related to L-arginine supplementation suggests that L-arginine is acting here through different pathways from those demonstrated in hypertensive models of disease. The data support the ideas that TGF-β reduction is a valid therapeutic target and that quantitation of TGF-β reduction is a useful approach for comparing antifibrotic drug candidates.
Bub1 is activated by the protein kinase p90(Rsk) during Xenopus oocyte maturation.

Abstract Background: The kinetochore attachment (spindle assembly) checkpoint arrests cells in metaphase to prevent exit from mitosis until all the chromosomes are aligned properly at the metaphase plate. The checkpoint operates by preventing activation of the anaphase-promoting complex (APC), which triggers anaphase by degrading mitotic cyclins and other proteins. This checkpoint is active during normal mitosis and upon experimental disruption of the mitotic spindle. In yeast, the serine/threonine protein kinase Bub1 and the WD-repeat protein Bub3 are elements of a signal transduction cascade that regulates the kinetochore attachment checkpoint. In mammalian cells, activated MAPK is present on kinetochores during mitosis and activity is upregulated by the spindle assembly checkpoint. In vertebrate unfertilized eggs, a special form of meiotic metaphase arrest by cytostatic factor (CSF) is mediated by MAPK activation of the protein kinase p90 Rsk , which leads to inhibition of the APC. However, it is not known whether CSF-dependent metaphase arrest caused by p90 Rsk involves components of the spindle assembly checkpoint. Results: xBub1 is present in resting oocytes and its protein level increases slightly during oocyte maturation and early embryogenesis. In Xenopus oocytes, Bub1 is localized to kinetochores during both meiosis I and meiosis II, and the electrophoretic mobility of Bub1 upon SDS-PAGE decreases during meiosis I, reflecting phosphorylation and activation of the enzyme. The activation of Bub1 can be induced in interphase egg extracts by selective stimulation of the MAPK pathway by c-Mos, a MAPKKK. In oocytes treated with the MEK1 inhibitor U0126, the MAPK pathway does not become activated, and Bub1 remains in its low-activity, unshifted form. Injection of a constitutively active target of MAPK, the protein kinase p90 Rsk , restores the activation of Bub1 in the presence of U0126. Moreover, purified p90 Rsk phosphorylates Bub1 in vitro and increases its protein kinase activity. Conclusions: Bub1, an upstream component of the kinetochore attachment checkpoint, is activated during meiosis in Xenopus in a MAPK-dependent manner. Moreover, a single substrate of MAPK, p90 Rsk , is sufficient to activate Bub1 in vitro and in vivo. These results indicate that in vertebrate eggs, kinetochore attachment/spindle assembly checkpoint proteins, including Bub1, are downstream of p90 Rsk and may be effectors of APC inhibition and CSF-dependent metaphase arrest by p90 Rsk .
Synthesis of Pt3Sn Alloy Nanoparticles and Their Catalysis for Electro-Oxidation of CO and Methanol

Monodisperse Pt3Sn alloy nanoparticles (NPs) were synthesized by a controlled coreduction of Pt(II) acetylacetonate and Sn(II) acetylacetonate at 180–280 °C in 1-octadecene. In the synthesis, oleylamine was used as a reducing agent, and oleylamine/oleic acid served as surfactants. The sizes of the Pt3Sn NPs were tuned from 4 to 7 nm by controlling the metal salt injection temperatures from 180 to 240 °C. These monodisperse Pt3Sn NPs were highly active for CO and methanol oxidation in 0.1 M HClO4 solutions, and their activity and stability could be further improved by a postsynthesis thermal treatment at 400 °C in Ar + 5% H2 for 1 h. They are promising as a practical catalyst for CO and methanol oxidation reactions in polymer electrolyte membrane fuel cell conditions.
A case of multiple extrahepatic manifestations in a patient with untreated, chronic hepatitis C virus infection

Chronic hepatitis C virus (HCV) infection is a complex, multi-organ disorder, not just limited to the liver. Mixed cryoglobulinemia (MC) type 2 is a common extrahepatic complication, in which immunoglobulin complexes deposit in vascular endothelium. This in turn creates a diffuse inflammatory reaction, leading to a variety of disorders involving multiple systems. We report the rare case of a patient with cryoglobulinemia, cutaneous vasculitis, membroproliferative glomerulonephritis, and B cell lymphoma with a variant t(6;10) translocation in the setting of an untreated, chronic HCV infection. This case highlights the challenge associated with diagnosing and managing such a complex presentation.
Mechanism of clot lysis.

THE availability of a large number of inhibitors of proteolytic enzymes, as well as the availability of highly purified streptokinase, plasminogen and plasmin, suggested to me the investigation of the nature of the enzyme or enzymes capable of dissolving fibrin clots. Proteolytic enzymes in general, but more particularly trypsin and chymotrypsin, are known for their ability to digest fibrin clots; certain snake venoms can also do this. The proteolysis of fibrinogen and fibrin by venoms, trypsin or plasmin appears to vary, depending upon which of the enzyme is used. The clotting of fibrinogen is the result of the splitting of an arginine peptide bond in the fibrinogen molecule1; this tends to produce a product (fibrin) which is much less susceptible to hydrolysis by trypsin and venoms than the parent substance, fibrinogen2,3. Fibrin, on the other hand, is as sensitive to plasmin as is fibrinogen3.
Planetary science: Shrinking wrinkling Mercury

As Mercury's interior cools and its massive iron core freezes, its surface feels the squeeze. A comprehensive global census of compressional deformation features indicates that Mercury has shrunk by at least 5 km in radius over the past 4 billion years.