Detection of multiple conformations of the E-domain of 5S rRNA from Escherichia coli in solution and in crystals by NMR spectroscopy

NMR spectroscopy of the E-domain fragment of Escherichia coli 5S rRNA indicates that this molecule exists in solution as either a stem-loop or as a duplex with two U-U base pairs in the bulge region. At temperatures below 27 degrees C, interconversion between the monomeric and dimeric forms in solution occurs on a time scale of weeks and allows the preparation of samples on which NMR structure determinations can be carried out on predominantly monomeric or dimeric species. The NMR results obtained provide comparison data for the distinction between A- and B-form E.coli 5S rRNA and for the possible kinetics of conversion between these forms. NMR evidence is presented that the duplex form also exists in crystals and suggestions are made for means to obtain stem-loop conformations of E-domain and other small RNA stem-loop sequences in crystals.     

Mucosal protection through active intestinal secretion: neural and paracrine modulation by 5-hydroxytryptamine

Sphingosine-1-phosphate (Sph-1-P), the initial product of sphingosine (Sph) catabolism, has been reported to inhibit motility of mouse melanoma B16/F1 and other types of cells at very low concentrations (10-100 nM). Sph-1-P (100 nM-1 microM) inhibited pseudopodium formation by blocking polymerization and reorganization of actin filaments in newly formed pseudopodia, and reduced F-actin by approximately 25% in F1 cells. A pyrene-labeled actin nucleation assay revealed that Sph-1-P (100 nM) inhibits actin nucleation mediated by F1 cell plasma membranes. These results suggest that Sph-1-P interacts with molecules associated with actin nucleation to inhibit reorganization of pseudopodium formation and cell motility.     

Does self-regulation require cognitive resources? Evaluation of resource allocation models of goal setting.

The resource allocation model of goal setting (R. Kanfer & P. L. Ackerman, 1989) maintains that self-regulation initiated through goal setting requires attentional resources that could be more productively applied to skill acquisition and complex task performance. The current study questioned this hypothesis because attentional resources had not been directly manipulated or measured in studies supporting the model. Thus, alternative explanations that are based on other complex task goal-setting models cannot be excluded. As a direct test of the resource allocation hypothesis, dual task methodology was used to measure the attentional resource requirements of self-regulation. Even at the limits of human information processing, participants who were assigned difficult, specific goals performed at least as well on the secondary task as did individuals with do-your-best goals. These findings suggest that self-regulation does not necessarily require attentional resources. Implications for theory and practice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

1.3 ?m InGaAsP DCPBH multiquantum-well lasers

We report the fabrication and performance characteristics of InGaAsP double-channel planar buried heterostructure (DCPBH) lasers with multiquantum-well active layers emitting at 1.3 ?m. These lasers have threshold currents in the range 40?50 mA at 30°C, external differential quantum efficiencies of ?50% at 30°C and T0 values ?160 to 180 K in the temperature range 10?60°C.     

Relations of cigarette smoking and dietary antioxidants with placental calcification

The purpose of this study was to evaluate the diagnostic efficacy of the double inversion recovery fast spin echo (DIR-FSE) sequence for brain imaging compared to the fluid-attenuated inversion recovery (FLAIR) sequence. DIR-FSE and FLAIR-FSE sequences were obtained and compared side by side. Image assessment criteria included lesion conspicuity, contrast between different types of normal tissue, image quality, and artifacts. In addition, contrast ratios and contrast-to-noise ratios were determined. Scan time of DIR-FSE was 33% longer than scan time of FLAIR-FSE. Overall lesion conspicuity was equal on DIR-FSE and FLAIR-FSE; however, DIR-FSE showed particular advantages for infratentorial lesions and lesions with only poor contrast on T2-weighted images, whereas FLAIR was slightly superior for small superficial cerebral abnormalities. Gray-white differentiation was better with DIR-FSE. Cerebrospinal fluid suppression was equal on both sequences; cerebrospinal fluid pulsation artifacts were more pronounced on DIR-FSE but did not cause diagnostic difficulties on these images. We conclude that DIR-FSE might be obtained if infratentorial lesions and abnormalities with only slightly prolonged T2 relaxation times are suspected. Otherwise, FLAIR-FSE seems preferable.     

Three different group I introns in the nuclear large subunit ribosomal DNA of the amoeboflagellate Naegleria

We have amplified the large subunit ribosomal DNA (LSUrDNA) of the 12 described Naegleria spp. and of 34 other Naegleria lineages that might be distinct species. Two strains yielded a product that is longer than 3 kb, which is the length of the LSUrDNA of all described Naegleria spp. Sequencing data revealed that the insert in one of these strains is a group I intron without an open reading frame (ORF), while the other strain contains two different group I introns, of which the second intron has an ORF of 175 amino acids. In the latter ORF there is a conserved His-Cys box, as in the homing endonucleases present in group I introns in the small subunit ribosomal DNA (SSUrDNA) of Naegleria spp. Although the group I introns in the LSUrDNA differ in sequence, they are more related to each other than they are to the group I introns in the SSUrDNA of Naegleria spp. The three group I introns in the LSUrDNA in Naegleria are at different locations and are probably acquired by horizontal transfer, contrary to the SSUrDNA group I introns in this genus which are of ancestral origin and are transmitted vertically.     

Psychiatric sequelae of low birth weight at 6 years of age

The study examined the association between low birth weight (LBW) (< or = 2,500 g) and attention deficit hyperactivity disorder (ADHD) in two socioeconomically disparate populations. LBW and normal birth weight (NBW) children from the 1983 to 1985 newborn lists of an urban and a suburban hospital in Southeast Michigan were randomly selected. A total of 823 children, 473 LBW and 350 NBW, participated. Data were gathered in 1990 to 1992, when the children were 6 to 7 years of age. The National Institute of Mental Health Diagnostic Interview Schedule for children-Parent version (DISC-P) was used to elicit information on DSM-III-R diagnoses of simple phobia, overanxious, separation anxiety, oppositional defiant, and ADHD. Teachers' ratings of behavior problems were obtained. LBW was associated with ADHD but not with childhood anxiety disorders or oppositional defiant disorder. The association was stronger in the urban than in the suburban population. Data from teachers' ratings revealed an association between LBW and attention problems. The prognostic significance of the observed psychopathology at 6 years of age requires follow-up assessment as the children mature.     

Techniques for Algorithm Animation

Allowing a user to interact with dynamically changing graphical representations of algorithms or data structures may help in teaching, research, or systems programming.     

Asthma. The states'' challenge

A brief overview of the theory of corrosion and the formation of galvanic couples is presented, followed by a discussion of the metals and alloys used in the fabrication of orthodontic appliances and devices. Attention is paid to the factors that contribute to establishment of corrosion cells in the mouth. Although oral corrosion generally does not cause significant destruction of metal, it can elicit in patients adverse physiological responses such as local irritation and metal hypersensitivity. There are indications that orthodontic treatment may lower the incidence of nickel hypersensitivity. Destructive attack on orthodontic appliances does occur, however, when certain types of denture cleanser are used to clean appliances that contain soldered joints.