Electrostatics of nanosystems: application to microtubules and the ribosome

Evaluation of the electrostatic properties of biomolecules has become a standard practice in molecular biophysics. Foremost among the models used to elucidate the electrostatic potential is the Poisson-Boltzmann equation; however, existing methods for solving this equation have limited the scope of accurate electrostatic calculations to relatively small biomolecular systems. Here we present the application of numerical methods to enable the trivially parallel solution of the Poisson-Boltzmann equation for supramolecular structures that are orders of magnitude larger in size. As a demonstration of this methodology, electrostatic potentials have been calculated for large microtubule and ribosome structures. The results point to the likely role of electrostatics in a variety of activities of these structures.

A dual representation theory of posttraumatic stress disorder

A cognitive theory of posttraumatic stress disorder (PTSD) is proposed that assumes traumas experienced after early childhood give rise to 2 sorts of memory, 1 verbally accessible and 1 automatically accessible through appropriate situational cues. These different types of memory are used to explain the complex phenomenology of PTSD, including the experiences of reliving the traumatic event and of emotionally processing the trauma. The theory considers 3 possible outcomes of the emotional processing of trauma, successful completion, chronic processing, and premature inhibition of processing We discuss the implications of the theory for research design, clinical practice, and resolving contradictions in the empirical data.

HLA-E is expressed on trophoblast and interacts with CD94/NKG2 receptors on decidual NK cells

Non-classical MHC class I molecule HLA-E is the ligand for CD94/NKG2 NK cell receptors. Surface expression of HLA-E requires binding of specific HLA class I leader sequences. The uterine mucosa in early pregnancy (decidua) is infiltrated by large numbers of NK cells, which are closely associated with placental trophoblast cells. In this study we demonstrate that trophoblast cells express HLA-E on their cell surface in addition to the previously reported expression of HLA-G and HLA-C. Furthermore, we show that the vast majority of decidual NK cells bind to HLA-E tetrameric complexes and this binding is inhibited by mAb to CD94. Thus, recognition of fetal HLA-E by decidual NK cells may play a key role in regulation of placentation. The functional consequences of decidual NK cell interaction were investigated in cytotoxicity assays using polyclonal decidual NK cells. The overall effect of CD94/NKG2 interaction with HLA-E is inhibition of cytotoxicity by decidual NK cells. However, since decidual NK cells are unable to kill trophoblast even in the presence of mAb to MHC class I molecules and NK cell receptors, HLA-E interaction with CD94/NKG2 receptors may regulate other functions besides cytolysis during implantation.

Psychometric evaluation of Horowitz's Impact of Event Scale: a review

Despite being developed before the formal introduction of posttraumatic stress disorder (PTSD) within the diagnostic literature, the Impact of Event Scale (Horowitz, Wilner, & Alvarez, 1979) remains one of the most widely used self-report measures of posttraumatic stress. This paper presents an overview of research using the IES in an attempt to assess its psychometric status. It is concluded that the psychometric properties of the IES are satisfactory (although not as a PTSD diagnostic measure) and that continued use of the IES as a measure of intrusive and avoidant processes is warranted.

Assessment of bully/victim problems in 8 to 11 year-olds

The aim of the present study was to develop two six-item self-report scales (the Bullying-Behaviour Scale and the Peer-Victimisation Scale) to assess bully-victim problems at school. These scales were designed so that they could be immersed within the Self-Perception Profile for Children (SPPC: Harter, 1985) thus reducing the saliency of the items. Internal reliability of both scales was found to be satisfactory (Cronbach's alpha = 0.83 and 0.82 respectively). Data are reported on the association between scores on both scales and scores on the SPPC and the Birleson Depression Inventory (Birleson, 1981) with 425 children (204 boys and 221 girls) ranging from 8 to 11 years (mean = 9.2 years). Forty-six per cent of the children were classified as bullies, victims, or both: 22 per cent were classified as victims only, 15 per cent as bully/victims, and 9 per cent as bullies only.

Surface expression of HLA-C antigen by human extravillous trophoblast

In this paper definitive evidence that the classical class I product, HLA-C, is expressed on the surface of normal trophoblast cells is provided. HLA-C transcripts were sequenced from cDNA isolated from first trimester trophoblast cells obtained by flow cytometric sorting. Both paternal and maternal alleles were transcribed. HLA-C proteins were demonstrated by biochemical analysis and found on the cell surface in association with beta(2)-microglobulin. Upregulation of cell surface HLA-C but not HLA-G expression after interferon (IFN)-gamma treatment was demonstrated by flow cytometric analysis. Immunohistology has confirmed HLA-C is expressed by all extravillous subpopulations in vivo. The question of whether trophoblast HLA-C molecules interact with decidual NK cells expressing killer Ig-like receptors (KIR) has also been addressed. Our results demonstrate that extravillous trophoblast expresses at least two HLA class I molecules, HLA-G and HLA-C on the cell surface.

Crisis support and psychiatric symptomatology in adult survivors of the Jupiter cruise ship disaster

The aim of the present study was to explore the relationship between crisis support and psychiatric symptomatology among adult survivors in the year following the Jupiter cruise ship disaster. Evidence is presented that support decreases over the following year, and that higher levels of crisis support are strongly related to better psychological outcome. Crisis support is shown to retain its association with symptomatology even when satisfaction with support is partialled out. These data are discussed with reference to the debate over the relative importance of received vs. perceived support.

Prevalence of overweight in urban Indian adolescent school children

The prevalence of diabetes mellitus (DM) and cardiovascular disease (CVD) is increasing in urban India. Overweight in adolescence is a marker of overweight in adult age, and it shows an association with the above diseases. There have been meagre data from India on the prevalence of childhood obesity. The objective of the study was to quantify the prevalence of overweight and its risk factors in adolescent children in urban India. School students in the age group of 13-18 years (n = 4700, M:F 2382:2318) were studied. Body mass index (BMI) was measured. Data on physical activity, food habits, occupation of parents and their economic status, birth weight of the children and age at menarche in girls were obtained by questionnaire. Age-adjusted prevalence of overweight was 17.8% for boys and 15.8% for girls. It increased with age and was higher in lower tertiles of physical activity and in higher socio-economic group. Birth weight and current BMI were positively associated. The study highlighted the high prevalence of overweight in adolescent children in urban India. Life style factors influenced BMI in adolescent age.

Increased marine production of N2O due to intensifying anoxia on the Indian continental shelf

Eutrophication of surface waters and hypoxia in bottom waters has been increasing in many coastal areas, leading to very large depletions of marine life in the affected regions. These areas of high surface productivity and low bottom-water oxygen concentration are caused by increasing runoff of nutrients from land. Although the local ecological and socio-economic effects have received much attention, the potential contribution of increasing hypoxia to global-change phenomena is unknown. Here we report the intensification of one of the largest low-oxygen zones in the ocean, which develops naturally over the western Indian continental shelf during late summer and autumn. We also report the highest accumulations yet observed of hydrogen sulphide (H2S) and nitrous oxide (N2O) in open coastal waters. Increased N2O production is probably caused by the addition of anthropogenic nitrate and its subsequent denitrification, which is favoured by hypoxic conditions. We suggest that a global expansion of hypoxic zones may lead to an increase in marine production and emission of N2O, which, as a potent greenhouse gas, could contribute significantly to the accumulation of radiatively active trace gases in the atmosphere.

Essential nucleotide sequences and secondary structure elements of the hairpin ribozyme

In vitro selection experiments have been used to isolate active variants of the 50 nt hairpin catalytic RNA motif following randomization of individual ribozyme domains and intensive mutagenesis of the ribozyme-substrate complex. Active and inactive variants were characterized by sequencing, analysis of RNA cleavage activity in cis and in trans, and by substrate binding studies. Results precisely define base-pairing requirements for ribozyme helices 3 and 4, and identify eight essential nucleotides (G8, A9, A10, G21, A22, A23, A24 and C25) within the catalytic core of the ribozyme. Activity and substrate binding assays show that point mutations at these eight sites eliminate cleavage activity but do not significantly decrease substrate binding, demonstrating that these bases contribute to catalytic function. The mutation U39C has been isolated from different selection experiments as a second-site suppressor of the down mutants G21U and A43G. Assays of the U39C mutation in the wild-type ribozyme and in a variety of mutant backgrounds show that this variant is a general up mutation. Results from selection experiments involving populations totaling more than 10(10) variants are summarized, and consensus sequences including 16 essential nucleotides and a secondary structure model of four short helices, encompassing 18 bp for the ribozyme-substrate complex are derived.

Recognition of trophoblast HLA class I molecules by decidual NK cell receptors--a review

During placentation the extravillous trophoblast (EVT) cells migrate through the decidua towards the maternal spiral arteries. The walls of the arteries are then destroyed by trophoblast resulting in an increased blood flow to the fetus. These EVT express HLA-G, HLA-E and HLA-C, an unusual combination of two non-classical and one classical MHC class I molecules. The decidua is infiltrated by distinctive uterine natural killer (NK) cells during the time of trophoblast invasion. These cells express a variety of receptors (CD94/NKG2, KIR and ILT) which are known to recognize HLA class I molecules. There is, therefore, a mechanism for molecular recognition of the placental trophoblast cells. The possible functional consequences of this uterine NK cell-trophoblast interactions are uncertain. One possible result is in an altered NK cell cytokine profile which modulates the invasive proclivity of the EVT. In this way placentation could be controlled.

Bully/victim problems and their association with Eysenck's personality dimensions in 8 to 13 year-olds

BACKGROUND

Previous research which has investigated the association between bully-victim problems and Eysenck's personality dimensions has shown an association between victimisation and introversion and an association between bullying and psychoticism (Slee & Rigby, 1993).

AIMS

The aim of the present study was to replicate these findings and to extend the investigation of the association between bully/victim problems and personality to children who are classified as both bullies and victims.

SAMPLE AND METHOD

One hundred and seventy nine children ranging in age from 8 to 13 years (mean age = 11 years) completed the Bullying-Behaviour Scale and the Peer-Victimization Scale (Austin & Joseph, 1996), the Self-Perception Profile for Children (SPPC: Harter, 1985), and the Junior Eysenck Personality Questionnaire (EPQ Junior: Eysenck & Eysenck, 1975).

RESULTS

Forty-nine per cent of children were classified as involved in bullying either as bullies (11 per cent), victims (20 per cent), or bully/victims (18 per cent). Bullies scored lower on the lie scale, victims scored lower on the extraversion scale, and bully/victims scored higher on the neuroticism and psychoticism scales than children who were classified as not involved in bullying.

CONCLUSION

These data provide evidence that bully/victims are a distinct group from either bullies or victims and that they may be the group of children who are most readily distinguished in terms of personality.

In vitro selection of active hairpin ribozymes by sequential RNA-catalyzed cleavage and ligation reactions

In vitro selection methods provide rapid and extremely powerful tools for elucidating interactions within and between macromolecules. Here, we describe the development of an in vitro selection procedure that permits the rapid isolation and evaluation of functional hairpin ribozymes from a complex pool of sequence variants containing an extremely low frequency of catalytically proficient molecules. We have used this method to analyze the sequence requirements of two regions of the ribozyme-substrate complex: a 7-nucleotide internal loop within the ribozyme that is essential for catalytic function and substrate sequences surrounding the cleavage-ligation site. Results indicate that only 3 of the 16,384 internal loop variants examined have high cleavage and ligation activity and that the ribozyme has a strong requirement for guanosine immediately 3' to the cleavage-ligation site.

EF-G-catalyzed translocation of anticodon stem-loop analogs of transfer RNA in the ribosome

Translocation, catalyzed by elongation factor EF-G, is the precise movement of the tRNA-mRNA complex within the ribosome following peptide bond formation. Here we examine the structural requirement for A- and P-site tRNAs in EF-G-catalyzed translocation by substituting anticodon stem-loop (ASL) analogs for the respective tRNAs. Translocation of mRNA and tRNA was monitored independently; mRNA movement was assayed by toeprinting, while tRNA and ASL movement was monitored by hydroxyl radical probing by Fe(II) tethered to the ASLs and by chemical footprinting. Translocation depends on occupancy of both A and P sites by tRNA bound in a mRNA-dependent fashion. The requirement for an A-site tRNA can be satisfied by a 15 nucleotide ASL analog comprising only a 4 base pair (bp) stem and a 7 nucleotide anticodon loop. Translocation of the ASL is both EF-G- and GTP-dependent, and is inhibited by the translocational inhibitor thiostrepton. These findings show that the D, T and acceptor stem regions of A-site tRNA are not essential for EF-G-dependent translocation. In contrast, no translocation occurs if the P-site tRNA is substituted with an ASL, indicating that other elements of P-site tRNA structure are required for translocation. We also tested the effect of increasing the A-site ASL stem length from 4 to 33 bp on translocation from A to P site. Translocation efficiency decreases as the ASL stem extends beyond 22 bp, corresponding approximately to the maximum dimension of tRNA along the anticodon-D arm axis. This result suggests that a structural feature of the ribosome between the A and P sites, interferes with movement of tRNA analogs that exceed the normal dimensions of the coaxial tRNA anticodon-D arm.

Suicide assessment: clinical interview vs. self-report

This study examined whether patients disclosed the same information about suicidal behaviors on a self-report instrument that they conveyed to a clinician in a face-to-face interview. The results indicated a generally high level of agreement between these two forms of suicide assessment. The one exception was the question that concerns recent suicidal ideation, where patients tended to disclose more on the self-report form.

Mapping the inside of the ribosome with an RNA helical ruler

The structure of ribosomal RNA (rRNA) in the ribosome was probed with hydroxyl radicals generated locally from iron(II) tethered to the 5' ends of anticodon stem-loop analogs (ASLs) of transfer RNA. The ASLs, ranging in length from 4 to 33 base pairs, bound to the ribosome in a messenger RNA-dependent manner and directed cleavage to specific regions of the 16S, 23S, and 5S rRNA chains. The positions and intensities of cleavage depended on whether the ASLs were bound to the ribosomal A or P site, and on the lengths of their stems. These data predict the three-dimensional locations of the rRNA targets relative to the positions of A- and P- site transfer RNAs inside the ribosome.

Multiple pathways governing Cdx1 expression during murine development

Cdx1 encodes a mammalian homeobox gene involved in vertebral patterning. Retinoic acid (RA) is likewise implicated in vertebral patterning. We have previously shown that Cdx1 is a direct retinoid target gene, suggesting that Cdx1 may convey some of the effects of retinoid signaling. However, RA appears to be essential for only early stages of Cdx1 expression, and therefore other factors must be involved in maintaining later stages of expression. Based on function and pattern of expression, Wnt family members, in particular Wnt3a, are candidates for regulation of expression of Cdx1. Consistent with this, we confirm prior results which demonstrated that Cdx1 can be directly regulated by Wnt signaling, and identify functional LEF/TCF response motifs essential for this response. We also find that Cdx1 expression is markedly attenuated in a stage- and tissue-specific fashion in the Wnt3a hypomorph vestigial tail, and present data demonstrating that Wnt3a and RA synergize strongly to activate Cdx1. Finally, we show that Cdx1 positively regulates its own expression. These data prompt a model whereby retinoid and Wnt signaling function directly and synergistically to initiate Cdx1 expression in the caudal embryo. Expression is then maintained, at least in part, by an autoregulatory mechanism at later stages.

Identification of molecular interactions between P-site tRNA and the ribosome essential for translocation

Translocation of the tRNA-mRNA complex is a fundamental step in the elongation cycle of protein synthesis. Our studies show that the ribosome can translocate a P-site-bound tRNA(Met) with a break in the phosphodiester backbone between positions 56 and 57 in the TPsiC-loop. We have used this fragmented P-site-bound tRNA(Met) to identify two 2'-hydroxyl groups at positions 71 and 76 in the 3'-acceptor arm that are essential for translocation. Crystallographic data show that the 2'-hydroxyl group at positions 71 and 76 contacts the backbone of 23S rRNA residues 1892 and 2433-2434, respectively, in the ribosomal E site. These results establish a set of functional interactions between P-site tRNA and 23S rRNA that are essential for translocation.

Substrate selection rules for the hairpin ribozyme determined by in vitro selection, mutation, and analysis of mismatched substrates

Substrate recognition by the hairpin ribozyme has been proposed to involve two short intermolecular helices, termed helix 1 and helix 2. We have used a combination of three methods (cleavage of mismatched substrates, in vitro selection, and site-specific mutational analysis) to systematically determine the substrate recognition rules for this RNA enzyme. Assays measuring substrate cleavage in trans under multiple turnover conditions were conducted using the wild-type ribozyme and substrates containing mismatches in all sites potentially recognized by the ribozyme. Molecules containing single- and multiple-base mismatches in helix 2 at sites distant from the cleavage site (g-4c, u-5a, g-4c: u-5a) were cleaved with reduced efficiency, whereas those with mismatches proximal to the cleavage site (c-2a, a-3c, c-2a: a-3c) were not cut. Analogous results were obtained for helix 1, where mismatches distal from the cleavage site (u+7a, u+8a, u+9a, u+7a: u+8a: u+9a) were used much more efficiently than those proximal to the cleavage site (c+4a, u-5a, g+6c, c+4a: u+5a: g+6c). In vitro selection experiments were carried out to identify active variants from populations of molecules in which either helix 1 or helix 2 was randomized. Results constitute an artificial phylogenetic data base that proves base-pairing of nucleotides at five positions within helix 1 and three positions within helix 2 and reveals a significant sequence bias at 3 bp (c+4.G6, c-2.G11, and a-3.U12). This sequence bias was confirmed at two sites by measuring relative cleavage rates of all 16 possible dinucleotide combinations at base pairs c+4.G6 and c-2.G11.(ABSTRACT TRUNCATED AT 250 WORDS)

The Depression-Happiness Scale

It is argued that there is a need for a measure which can quantify a continuum of affect and which is able to assess current frequency of mood for use in survey research with the general population. In a preliminary attempt to develop such a scale, a 40-item questionnaire containing items thought to tap feelings of depression and happiness was completed by 200 young people whose mean score on the Beck Depression Inventory was within that expected of a normal population. On the basis of factor analytic data, the 25 highest loading items were selected for inclusion into a bipolar Depression-Happiness Scale which was shown to have good internal reliability and concurrent validity with the Beck Depression Inventory.

Negative and depressive symptoms in schizophrenia

Ninety-five schizophrenic patients were assessed using the Present State Examination, the Brief Psychiatric Rating Scale and the Scale for the Assessment of Negative Symptoms. Negative and depressive symptoms were frequent, and significant relationships among negative symptom complexes and depressive syndromes were noted. Retardation, lack of energy, slowness, and other symptoms of depression were significantly associated with the negative symptoms of schizophrenia. Depressed affect per se did not have a significant correlation with negative symptoms.

Increased substance use in survivors of the Herald of Free Enterprise disaster

Cross-sectional data are reported on 73 survivors of the Herald of Free Enterprise disaster. Many reported an increase in their consumption of alcohol, cigarettes, sleeping tablets, antidepressants and tranquillizers at six and 30 months. The level of increased use was, however, lower at 30 months than at six months, although this was less evident for alcohol and cigarettes than the other substances. In addition, self-reports of increased substance use are associated with higher levels of psychological distress as measured by the General Health Questionnaire and the Impact of Events Scale. It is suggested that substance use might help to maintain subsequent psychological distress.

Percutaneous transluminal angioplasty of the subclavian artery in nonspecific aortoarteritis: results of long-term follow-up

PURPOSE

The results of percutaneous transluminal angioplasty (PTA) of the subclavian artery in nonspecific aortoarteritis (Takayasu disease) are analyzed.

PATIENTS AND METHODS

Twenty-four patients (15 men, nine women; age range, 18-47 years; mean, 37.1 years) with occlusive disease in 26 subclavian arteries, had symptoms due to vertebrobasilar insufficiency, upper limb claudication, or both. Aortography revealed stenosis in 19 arteries and occlusion in seven. The lesions were focal in 14 arteries (< 3 cm) and extensive in 12. Associated lesions involved the brachiocephalic artery in three patients, carotid arteries in five patients, and renal arteries in five patients.

RESULTS

Initial technical and clinical success was achieved in 21 of 26 arteries (81%, 17 of 19 stenoses and four of seven occlusions). The maximum follow-up was 82 months (mean, 26 months), during which time restenosis occurred in six arteries, all of which had extensive lesions. The cumulative primary, secondary, and overall patencies were 64%, 82%, and 65%, respectively, as analyzed by means of the life-table method. The cumulative patencies for short- and long-segment lesions were 100% and 50%, respectively (P = .0113). Minor complications were observed in four of 26 procedures (15%) and included vasospasm (three patients) and transient loss of consciousness (one patient). There were no major complications.

CONCLUSIONS

PTA is useful for treatment of occlusive disease of the subclavian artery in nonspecific aortoarteritis. The procedure is simple and associated with minimal morbidity. Long-term results are excellent in focal lesions but are less durable in the presence of more extensive disease.