Time-resolved relaxation and fragmentation of polycyclic aromatic hydrocarbons investigated in the ultrafast XUV-IR regime.

Polycyclic aromatic hydrocarbons (PAHs) play an important role in interstellar chemistry and are subject to high energy photons that can induce excitation, ionization, and fragmentation. Previous studies have demonstrated electronic relaxation of parent PAH monocations over 10-100 femtoseconds as a result of beyond-Born-Oppenheimer coupling between the electronic and nuclear dynamics. Here, we investigate three PAH molecules: fluorene, phenanthrene, and pyrene, using ultrafast XUV and IR laser pulses. Simultaneous measurements of the ion yields, ion momenta, and electron momenta as a function of laser pulse delay allow a detailed insight into the various molecular processes. We report relaxation times for the electronically excited PAH*, PAH+* and PAH2+* states, and show the time-dependent conversion between fragmentation pathways. Additionally, using recoil-frame covariance analysis between ion images, we demonstrate that the dissociation of the PAH2+ ions favors reaction pathways involving two-body breakup and/or loss of neutral fragments totaling an even number of carbon atoms.

Development of a cyclin-dependent kinase inhibitor devoid of ABC transporter-dependent drug resistance.

BACKGROUND: Cyclin-dependent kinases (CDKs) control cell cycle progression, RNA transcription and apoptosis, making them attractive targets for anticancer drug development. Unfortunately, CDK inhibitors developed to date have demonstrated variable efficacy. METHODS: We generated drug-resistant cells by continuous low-dose exposure to a model pyrazolo[1,5-a]pyrimidine CDK inhibitor and investigated potential structural alterations for optimal efficacy. RESULTS: We identified induction of the ATP-binding cassette (ABC) transporters, ABCB1 and ABCG2, in resistant cells. Assessment of features involved in the ABC transporter substrate specificity from a compound library revealed high polar surface area (>100 Å(2)) as a key determinant of transporter interaction. We developed ICEC-0782 that preferentially inhibited CDK2, CDK7 and CDK9 in the nanomolar range. The compound inhibited phosphorylation of CDK substrates and downregulated the short-lived proteins, Mcl-1 and cyclin D1. ICEC-0782 induced G2/M arrest and apoptosis. The permeability and cytotoxicity of ICEC-0782 were unaffected by ABC transporter expression. Following daily oral dosing, the compound inhibited growth of human colon HCT-116 and human breast MCF7 tumour xenografts in vivo by 84% and 94%, respectively. CONCLUSION: We identified a promising pyrazolo[1,5-a]pyrimidine compound devoid of ABC transporter interaction, highly suitable for further preclinical and clinical evaluation for the treatment of cancer.

Inhibiting estrogen responses in breast cancer cells using a fusion protein encoding estrogen receptor-alpha and the transcriptional repressor PLZF.

Estrogen receptor alpha (ERalpha) is a ligand-inducible transcription factor that acts to regulate gene expression by binding to palindromic DNA sequence, known as the estrogen response element, in promoters of estrogen-regulated genes. In breast cancer ERalpha plays a central role, where estrogen-regulated gene expression leads to tumor initiation, growth and survival. As an approach to silencing estrogen-regulated genes, we have studied the activities of a fusion protein between ERalpha and the promyelocytic leukemia zinc-finger (PLZF) protein, a transcriptional repressor that acts through chromatin remodeling. To do this, we have developed lines from the estrogen-responsive MCF-7 breast cancer cell line in which the expression of the fusion protein PLZF-ERalpha is conditionally regulated by tetracycline and shows that these feature long-term silencing of the expression of several well-characterized estrogen-regulated genes, namely pS2, cathepsin-D and the progesterone receptor. However, the estrogen-regulated growth of these cells is not inhibited unless PLZF-ERalpha expression is induced, an observation that we have confirmed both in vitro and in vivo. Taken together, these results show that PLZF-ERalpha is a potent repressor of estrogen-regulated gene expression and could be useful in distinguishing estrogen-regulated genes required for the growth of breast cancer cells.

Tricyclic drugs for depression in children and adolescents.

BACKGROUND: There is a need to identify effective and safe treatments for depression in children and adolescents. While tricyclic drugs are effective in treating depression in adults, individual studies involving children and adolescents have been equivocal. OBJECTIVES: To assess the effects of oral tricyclic antidepressants compared to placebo in the treatment of child and adolescent depression. SEARCH STRATEGY: We searched MEDLINE (1966-1997), EMBASE, Excerpta Medica (June 1974-1997), the Cochrane Collaboration Depression, Anxiety and Neurosis Group trials register (most recent search 25/1/2000) and bibliographies of previously published reviews and papers describing original research were cross-checked. Current Contents was screened for recent publications. We contacted authors of relevant abstracts in conference proceedings of the American Academy of Child and Adolescent Psychiatry, and we hand searched the Journal of the American Academy of Child and Adolescent Psychiatry (1978-1999). SELECTION CRITERIA: Randomised controlled trials comparing the efficacy of orally administered tricyclic medication with placebo in depressed people aged 6-18 years. DATA COLLECTION AND ANALYSIS: Most studies reported multiple outcome measures including depression scales and clinical global impression scales. For each study the best available depression measure was taken as the index measure of depression outcome. Predetermined criteria were established to assist in the ranking of measures. Where authors reported categorical outcomes we calculated individual and pooled odds ratios for the odds of improvement in treated compared with control subjects. For continuous outcomes pooled effect sizes were calculated as the number of standard deviations by which the change in depression scores for the treatment group exceeded those for the control groups. MAIN RESULTS: Thirteen trials (involving 506 participants) were included. No overall improvement with treatment compared to placebo was seen for children or adolescents (odds ratio = 0.84, 95% confidence interval 0.56 to 1.25). A statistically significant but small benefit of treatment over placebo was seen in reducing symptoms (effect size (standardised mean difference) = -0.31, 95% confidence interval -0.62 to -0.01). Subgroup analyses suggest a larger benefit among adolescents (effect size = -0.47, 95% confidence interval -0.92 to -0.02), and no benefit among children (effect size = 0.15, 95% confidence interval -0.34 to 0.64). Treatment with a tricyclic antidepressant caused more vertigo (odds ratio = 4.38, 95% confidence interval 2.33 to 8.25), orthostatic hypotension (odds ratio = 6.78, 95% confidence interval 2.06 to 22.26), tremor (odds ratio 6.29, 95% confidence interval 1.78 to 22.17) and dry mouth (odds ratio = 5.17, 95% confidence interval 2.68 to 29.99) than did placebo, but no statistically significant difference was found for other possible adverse effects. REVIEWER'S CONCLUSIONS: Data suggest tricyclic antidepressants are not useful in treating depression in pre pubertal children. There is marginal evidence to support the use of tricyclic antidepressants in the treatment of depression in adolescents, although the magnitude of effect is likely to be moderate at best.

Tricyclic drugs for depression in children and adolescents.

BACKGROUND: There is a need to identify effective and safe treatments for depression in children and adolescents. While tricyclic drugs have proven effectiveness in the treatment of depression in adults, individual studies involving children and adolescent have been equivocal. OBJECTIVES: To examine whether orally administered tricyclic antidepressants are superior to placebo in the treatment of child and adolescent depression SEARCH STRATEGY: We searched the literature using CD ROM Silver Platter and On-Line MEDLINE (1966-1997) and Excerpta Medica (June 1974-1997) data bases. Terms used for the search were: the exploded terms child and depression; the Medical Subject Headings of antidepressant drugs, tricyclic and affective disorders; individual tricyclic drugs by name; names of well-known researchers in the field; and school phobia. We searched the trials database of the Cochrane Collaboration Depression, Anxiety and Neurosis Group. Abstracts in English (of English and non-English papers) were reviewed. Bibliographies of previously published reviews and papers describing original research were cross-checked. Current Contents was screened for recent publications. We contacted authors of abstracts describing "work in progress" identified in conference proceedings of the American Academy of Child and Adolescent Psychiatry to determine whether they held data which could be included in the meta-analysis. We have hand searched the Journal of the American Academy of Child and Adolescent Psychiatry to identify randomized controlled trials. SELECTION CRITERIA: Randomized controlled trials comparing the efficacy of orally administered tricyclic medication with placebo in depressed subjects aged 6-18 years. DATA COLLECTION AND ANALYSIS: Most studies reported multiple outcome measures including depression scales and clinical global impression scales. For each study the best available depression measure was taken as the index measure of depression outcome. Predetermined criteria were established to assist in the ranking of measures. Where authors reported categorical outcomes we calculated individual and pooled odds ratios for the odds of improvement in treated compared with control subjects. For continuous outcomes pooled effect sizes were calculated as the number of standard deviations by which the change in depression scores for the treatment group exceeded those for the control groups. MAIN RESULTS: Twelve studies fulfilled the criteria for inclusion in the review, eight from which dichotomous outcome data could be extracted, and eleven from which continuous outcome data could be extracted. Pooled odds ratios calculated from the dichotomous data indicated no advantage of treatment over placebo for children or adolescents (odds ratio = 0.83, 95% confidence interval 0.48 to 1.42). Effect size calculations from the continuous data suggested a statistically significant but small benefit of treatment over placebo in reducing symptoms for the aggregate sample (effect size = -0.38, 95% confidence interval -0.74 to -0.02) with subgroup analyses suggesting a larger benefit among adolescents (effect size = -0.59, 95% confidence interval -1.12 to -0.06), and no benefit among children (effect size = 0.15, 95% confidence interval -0.34 to 0.64). Treatment with a tricyclic antidepressant caused more vertigo (odds ratio = 8.47, 95% confidence interval 1.40 to 51.0), orthostatic hypotension (odds ratio = 4.77, 95% confidence interval 1.11 to 20.49) and dry mouth (odds ratio = 5.19, 95% confidence interval 1.15 to 23.51) than did placebo, but there was no statistically significant difference in other possible adverse effects. REVIEWER'S CONCLUSIONS: Data suggest tricyclic antidepressants are of unlikely benefit in the treatment of depression in pre pubertal children. There is marginal evidence to support the use of tricyclic antidepressants in the treatment of depression in adolescents, although the magnitude of effect is likely to be moderate at best.

The lack of standardization of cardiac troponin I assay systems.

The lack of standardization of cardiac troponin I (cTnI) assay systems has meant an inability to compare absolute values between methods, and non-traceability of cTnI measurement in clinical laboratories. The present study tested whether a common calibrator for cTnI would harmonize values between different methods. Twenty fresh-frozen plasma samples and a common calibrator were analyzed in duplicate using the Dade Behring Stratus II, Chiron ACS:180, Abbott AxSYM, and Beckman Coulter Access immunoassay systems. Uncorrected cTnI values varied up to 60-fold between systems, and when correlated to the Stratus, linear regression slopes were 0.97 (ACS:180), 4.86 (AxSYM), and 0.03 (Access), verifying the differences in calibration. After correction for calibration differences by reference to the common calibrator, among-assay CV ranged from 2.7% to 55%, and was >25% for eight samples. However, the exclusion of Access results reduced the CV to 32% with only four outliers. The results show that comparable cTnI values between methods are possible by the use of a common calibrator. The lack of method harmonization for some samples may be due to non-equal antibody immunoreactivity of different plasma cTnI forms. The complete standardization of cTnI measurement requires both a secondary reference material and standardization of manufacturers' cTnI antibodies.

Effortful and automatic information processing in boys with ADHD and specific learning disorders.

Boys with Attention Deficit Hyperactivity Disorder (ADHD, N = 50), Specific Learning Disorder (LD, N = 45), combined Specific Learning Disorder and ADHD (LD/ADHD, N = 25), and controls (N = 51) completed effortful and automatic information processing tasks based on Treisman and Gelade's (1980) "information integration theory". ADHD and LD/ADHD subjects did not differ from controls at baseline or under feedback and reward conditions, suggesting that they were investing similar levels of mental effort in the tasks. The LD group had a superior performance in the effortful task and an inferior performance in the automatic task compared with the other groups at baseline. The data suggest a potential method of distinguishing primary LD from learning difficulties that occur secondary to ADHD.

Gravitropic responses of the Avena coleoptile in space and on clinostats. I. Gravitropic response thresholds.

We conducted a series of gravitropic experiments on Avena coleoptiles in the weightlessness environment of Spacelab. The purpose was to test the threshold stimulus, reciprocity rule and autotropic reactions to a range of g-force stimulations of different intensities and durations The tests avoided the potentially complicating effects of earth's gravity and the interference from clinostat ambiguities. Using slow-speed centrifuges, coleoptiles received transversal accelerations in the hypogravity range between 0.l and 1.0 g over periods that ranged from 2 to 130 min. All responses that occurred in weightlessness were compared to clinostat experiments on earth using the same apparatus. Characteristic gravitropistic response patterns of Atuena were not substantially different from those observed in ground-based experiments. Gravitropic presentation times were extrapolated. The threshold at 1.0 g was less than 1 min (shortest stimulation time 2 min), in agreement with values obtained on the ground. The least stimulus tested, 0.1 g for 130 min, produced a significant response. Therefore the absolute threshold for a gravitropic response is less than 0.1 g.

Gravitropic responses of the Avena coleoptile in space and on clinostats. II. Is reciprocity valid?

Experiments were undertaken to determine if the reciprocity rule is valid for gravitropic responses of oat coleoptiles in the acceleration region below 1 g. The rule predicts that the gravitropic response should be proportional to the product of the applied acceleration and the stimulation time. Seedlings were cultivated on 1 g centrifuges and transferred to test centrifuges to apply a transverse g-stimulation. Since responses occurred in microgravity, the uncertainties about the validity of clinostat simulation of weightlessness was avoided. Plants at two stages of coleoptile development were tested. Plant responses were obtained using time-lapse video recordings that were analyzed after the flight. Stimulus intensities and durations were varied and ranged from 0.1 to 1.0 g and from 2 to 130 min, respectively. For threshold g-doses the reciprocity rule was obeyed. The threshold dose was of the order of 55 g s and 120 g s, respectively, for two groups of plants investigated. Reciprocity was studied also at bending responses which are from just above the detectable level to about 10 degrees. The validity of the rule could not be confirmed for higher g-doses, chiefly because the data were more variable. It was investigated whether the uniformity of the overall response data increased when the gravitropic dose was defined as (gm x t) with m-values different from unity. This was not the case and the reciprocity concept is, therefore, valid also in the hypogravity region. The concept of gravitropic dose, the product of the transverse acceleration and the stimulation time, is also well-defined in the acceleration region studied. With the same hardware, tests were done on earth where responses occurred on clinostats. The results did not contradict the reciprocity rule but scatter in the data was large.

Nastic curvatures of wheat coleoptiles that develop in true microgravity.

Dark-grown wheat coleoptiles developed strong curvatures within 5 h of being transferred in orbit from a 1 g centrifuge to microgravity during an experiment flown on the IML-1 shuttle mission. The curving tendency was strongest in seedlings that were immature, with coleoptiles shorter than 10 mm at the time of transfer. The curvature direction was non-random, and directed away from the caryopsis (the coleptile face adjacent to the caryopsis becoming convex). The curvatures were most marked in the basal third of the coleoptiles, contrasting with phototropic responses, which occur in the apical third. We interpret these curvatures as being nastic, and related to the curvatures commonly reported to occur during clinostat rotation treatments.

Efficacy of tricyclic drugs in treating child and adolescent depression: a meta-analysis.

OBJECTIVE: To examine whether tricyclic antidepressants are superior to placebo in the treatment of child and adolescent depression. DESIGN: Meta-analysis of 12 randomised controlled trials comparing the efficacy of tricyclic antidepressants with placebo in depressed subjects aged 6-18 years. MAIN OUTCOME MEASURES: Most studies employed several depression rating scales. For each study the "best available" measure was chosen by using objective criteria, and individual and pooled effect sizes were calculated as the number of standard deviations by which the change scores for the treatment groups exceeded those for the control groups. Where authors had reported numbers "responding" to treatment we calculated individual and pooled ratios for the odds of improvement in treated compared with control subjects. RESULTS: From the six studies presenting data which enabled an estimation of effect size the pooled effect size was 0.35 standard deviations (95% confidence interval of -0.16 to 0.86) indicating no significant benefit of treatment. From the five studies presenting data on the number of "responders" in each group, the ratio of the odds of a response in the treated compared with the control subjects was calculated and the pooled odds ratio was 1.08 (95% confidence interval of 0.53 to 2.17); again indicating no significant benefit of treatment. The pooled sample had more than an 80% chance of detecting a treatment effect of 0.5 standard deviations or greater. There was an inverse relation between study quality and estimated treatment effect. CONCLUSIONS: Tricyclic antidepressants appear to be no more effective than placebo in the treatment of depression in children and adolescents.

Patterns of Staphylococcus aureus colonization, toxin production, immunity and illness in burned children.

Toxic shock syndrome toxin-one (TSST-1) produced from some but not all strains of Staphylococcus aureus is considered to be responsible for the development of the serious illness, toxic shock syndrome (TSS). The aim of this study was to establish the importance of S. aureus in the aetiology of suspected cases of TSS in acutely burned children. The pattern of colonization of S. aureus, and in particular toxic shock syndrome toxin-one (TSST-1) producing isolates, was studied in 53 burned children admitted as consecutive cases. S. aureus was not normally present on admission. Although it was the most common wound pathogen, it was acquired during the first few days after admission. Antibody status to TSST-1 on admission and at discharge was determined. Only half (49 per cent) of the children had antibodies to TSST-1. When it was possible to obtain paired admission and discharge samples in patients who had been given blood products, an assessment of seroconversion could be made. Two of the four patients given blood products during the resuscitation and postoperative period were antibody negative on admission (the other two were TSST-1 antibody positive). By discharge they had antibodies to TSST-1. Whilst the majority of donated blood products had antibodies to TSST-1 (76 per cent), some (24 per cent) did not. Seven of 53 children (13 per cent) developed a toxic shock-like illness which caused clinical concern.(ABSTRACT TRUNCATED AT 250 WORDS)

The Gravitational Plant Physiology Facility--description of equipment developed for biological research in Spacelab.

In January 1992, the NASA Shuttle mission STS 42 carried a facility designed to perform experiments on plant gravi- and photo-tropic responses. This equipment, the Gravitational Plant Physiology Facility (GPPF) was made up of a number of interconnected units mounted within a Spacelab double rack. The details of these units and the plant growth containers designed for use in GPPF are described. The equipment functioned well during the mission and returned a substantial body of time-lapse video data on plant responses to tropistic stimuli under conditions of orbital microgravity. GPPF is maintained by NASA Ames Research Center, and is flight qualifiable for future Spacelab missions.

Determination of temafloxacin, sarafloxacin, and difloxacin in bulk drug and dosage forms by high-performance liquid chromatography.

The fluoroquinolones, temafloxacin, sarafloxacin, and difloxacin, are determined in the bulk drug substances and in a variety of dosage form using high-performance liquid chromatography (HPLC). The HPLC system used is also applicable for ciprofloxacin and norfloxacin. The procedure uses UV detection at 280 nm, which provides a linear response of the subject compounds to at least 20 micrograms/ml. Assay precision (RSD) values were +/- 1.2% or better for the bulk drugs and ranged from +/- 0.42 to +/- 2.3% for suspension, capsule, and tablet formulations. Drug recoveries were quantitative from the dosage forms tested. Sensitivity of the subject compounds is approximately 50 ng/ml (2.5 ng on column).

Enhancement of phototropic response to a range of light doses in Triticum aestivum coleoptiles in clinostat-simulated microgravity.

The phototropic dose-response relationship has been determined for Triticum aestivum cv. Broom coleoptiles growing on a purpose-built clinostat apparatus providing gravity compensation by rotation about a horizontal axis at 2 rev min-1. These data are compared with data sets obtained with the clinostat axis vertical and stationary, as a 1 g control, and rotating vertically to examine clinostat effects other than gravity compensation. Triticum at 1 g follows the well-established pattern of other cereal coleoptiles with a first positive curvature at low doses, followed by an indifferent response region, and a second positive response at progressively increasing doses. However, these response regions lie at higher dose levels than reported for Avena. There is no significant difference between the responses observed with the clinostat axis vertical in the rotating and stationary modes, but gravity compensation by horizontal rotation increases the magnitude of first and second positive curvatures some threefold at 100 min after stimulation. The indifferent response is replaced by a significant curvature towards the light source, but remains apparent as a reduced curvature response at these dose levels.

The role of nodal and internodal responses in gravitropism and autotropism in Galium aparine L.

This time course and location of gravitropically induced curvatures in stems of goosegrass (Gallium aparine L.), a member of the Rubiaceae, have been investigated. In the early stages of the response (0-5 h), curvature develops throughout the growing region, and is followed by an autotropic straightening which affects the internodes only, leading to the production of essentially straight internodes some 15 h after the onset of gravistimulation. Curvatures developing in the nodal regions, however, continue to increase over this period, and are not subject to reversal by autotropism. The nodal curvatures are not entirely dependent on the presence of any other part of the plant, since marked curvatures can be induced in isolated nodal segments. This pattern of response leads ultimately to correction of the growth direction of the plant by means of curvature responses confined exclusively to the nodes, despite the initial participation of both nodes and internodes in the gravitropic reaction.

Enhancement of phototropic response to a range of light doses in Triticum aestivum coleoptiles in clinostat-simulated microgravity.

The phototropic dose-response relationship has been determined for Triticum aestivum cv. Broom coleoptiles growing on a purpose-built clinostat apparatus providing gravity compensation by rotation about a horizontal axis at 2 rev·min(-1). These data are compared with data sets obtained with the clinostat axis vertical and stationary, as a 1·g control, and rotating vertically to examine clinostat effects other than gravity compensation. Triticum at 1·g follows the wellestablished pattern of other cereal coleoptiles with a first positive curvature at low doses, followed by an indifferent response region, and a second positive response at progressively increasing doses. However, these response regions lie at higher dose levels than reported for Avena. There is no significant difference between the responses observed with the clinostat axis vertical in the rotating and stationary modes, but gravity compensation by horizontal rotation increases the magnitude of first and second positive curvatures some threefold at 100 min after stimulation. The indifferent response is replaced by a significant curvature towards the light source, but remains apparent as a reduced curvature response at these dose levels.