Force-induced denaturation of RNA

We describe quantitatively a RNA molecule under the influence of an external force exerted at its two ends as in a typical single-molecule experiment. Our calculation incorporates the interactions between nucleotides by using the experimentally-determined free energy rules for RNA secondary structure and models the polymeric properties of the exterior single-stranded regions explicitly as elastic freely-jointed chains. We find that in spite of complicated secondary structures, force-extension curves are typically smooth in quasi-equilibrium. We identify and characterize two sequence/structure-dependent mechanisms that, in addition to the sequence-independent entropic elasticity of the exterior single-stranded regions, are responsible for the smoothness. These involve compensation between different structural elements on which the external force acts simultaneously, and contribution of suboptimal structures, respectively. We estimate how many features a force-extension curve recorded in non-equilibrium, where the pulling proceeds faster than rearrangements in the secondary structure of the molecule, could show in principle. Our software is available to the public through a `RNA-pulling server'.Comment: final version (with a few minor changes) as will be published in Biophysical Journa

Predictors of course and outcome in hypochondriasis after cognitive-behavioral treatment

Background. Predictors of treatment outcome were evaluated in a clinical sample suffering from hypochondriasis. Methods: The sample consisted of 96 patients with hypochondriacal disorder according to DSM-IV or high syndrome scores on the Illness Attitude Scales (IAS) or Whiteley Index (WI). After intense inpatient cognitive-behavioral treatment (CBT), 60% of the patients were classified as responders because of substantial improvements or recovery from hypochondriacal symptomatology. Results: Non-responders were characterized by a higher degree of pre-treatment hypochondriasis, more somatization symptoms and general psychopathology (SCL-90R), more dysfunctional cognitions related to bodily functioning, higher levels of psychosocial impairments, and more utilization of the health care system as indicated by the number of hospital days and costs for inpatient treatments and medication. No predictive value was found for sociodemographic variables, comorbidity with other mental disorders and chronicity. Multiple linear regression showed that pre-treatment variables significantly predicted IAS scores at post-treatment (R-2 = 0.59), changes during treatment (0.10), IAS scores at follow-up two years later (0.41) and changes between baseline and follow-up (0.25). Conclusions: The results demonstrate the relevance of various psychopathological variables and health care utilization as important indicators for outcome and further course of clinical hypochondriasis. Copyright (C) 2002 S. Karger AG, Basel

Cognitive behavior therapy in panic disorder and comorbid major depression - A naturalistic study

Background: There is a lack of evidence about the effectiveness of cognitive behavior therapies (CBT) in settings of routine clinical care as well as in the treatment of panic and comorbid disorders. Methods: We investigated a group-oriented CBT approach for 80 patients with panic disorder including 35 patients with current comorbid major depression. Assessments took place 6 months before treatment, at the beginning and end of treatment, and 1 year later. Structured interviews and multiple clinical self-rating scales were used. Results: Panic patients with comorbid major depression showed higher anxiety-specific and nonspecific pathology. The most striking benefits were in reducing avoidance behavior, while improvements concerning catastrophic beliefs were smaller, but still significant. For most self-rating scale results, patients with and without comorbid depression improved to a comparable degree. However, the end-state functioning of patients with panic disorder and current comorbid depression at admission is significantly lower than for patients with panic disorder alone, Conclusions: The results point to the necessity to develop and improve treatment approaches for patients with comorbidity of panic disorder and current major depression. Copyright (C) 2000 S.Karger AG, Basel

Stretching Single Domain Proteins: Phase Diagram and Kinetics of Force-Induced Unfolding

Single molecule force spectroscopy reveals unfolding of domains in titin upon stretching. We provide a theoretical framework for these experiments by computing the phase diagrams for force-induced unfolding of single domain proteins using lattice models. The results show that two-state folders (at zero force) unravel cooperatively whereas stretching of non-two-state folders occurs through intermediates. The stretching rates of individual molecules show great variations reflecting the heterogeneity of force-induced unfolding pathways. The approach to the stretched state occurs in a step-wise "quantized" manner. Unfolding dynamics depends sensitively on topology. The unfolding rates increase exponentially with force f till an optimum value which is determined by the barrier to unfolding when f=0. A mapping of these results to proteins shows qualitative agreement with force-induced unfolding of Ig-like domains in titin. We show that single molecule force spectroscopy can be used to map the folding free energy landscape of proteins in the absence of denaturants.Comment: 12 pages, Latex, 6 ps figure

Why Reassurance Fails in Patients with Unexplained Symptoms—An Experimental Investigation of Remembered Probabilities

BACKGROUND: Providing reassurance is one of physicians' most frequently used verbal interventions. However, medical reassurance can fail or even have negative effects. This is frequently the case in patients with medically unexplained symptoms. It is hypothesized that these patients are more likely than patients from other groups to incorrectly recall the likelihoods of medical explanations provided by doctors. METHODS AND FINDINGS: Thirty-three patients with medically unexplained symptoms, 22 patients with major depression, and 30 healthy controls listened to an audiotaped medical report, as well as to two control reports. After listening to the reports, participants were asked to rate what the doctor thinks the likelihood is that the complaints are caused by a specific medical condition. Although the doctor rejected most of the medical explanations for the symptoms in his verbal report, the patients with medically unexplained complaints remembered a higher likelihood for medical explanations for their symptoms. No differences were found between patients in the other groups, and for the control conditions. When asked to imagine that the reports were applicable to themselves, patients with multiple medical complaints reported more concerns about their health state than individuals in the other groups. CONCLUSIONS: Physicians should be aware that patients with medically unexplained symptoms recall the likelihood of medical causes for their complaints incorrectly. Therefore, physicians should verify correct understanding by using check-back questions and asking for summaries, to improve the effect of reassurance

In vitro and in vivo pharmacological activities of 14-o-phenylpropyloxymorphone, a potent mixed mu/delta/kappa-opioid receptor agonist with reduced constipation in mice

Pain, particularly chronic pain, is still an unsolved medical condition. Central goals in pain control are to provide analgesia of adequate efficacy and to reduce complications associated with the currently available drugs. Opioids are the mainstay for the treatment of moderate to severe pain. However, opioid pain medications also cause detrimental side effects, thus highlighting the need of innovative and safer analgesics. Opioids mediate their actions via the activation of opioid receptors, with the mu-opioid receptor as the primary target for analgesia, but also for side effects. One long-standing focus of drug discovery is the pursuit for new opioids exhibiting a favorable dissociation between analgesia and adverse effects. In this study, we describe the in vitro and in vivo pharmacological profiles of the 14-O-phenylpropyl substituted analog of the mu-opioid agonist 14-O-methyloxymorphone (14-OMO). The consequence of the substitution of the 14-O-methyl in 14-OMO with a 14-O-phenylpropyl group on in vitro binding and functional activity, and in vivo behavioral properties (nociception and gastrointestinal motility) was investigated. In binding studies, 14-O-phenylpropyloxymorphone (POMO) displayed very high affinity at mu-, delta-, and kappa-opioid receptors (Ki values in nM, mu:delta:kappa = 0.073:0.13:0.30) in rodent brain membranes, with complete loss of mu-receptor selectivity compared to 14-OMO. In guinea-pig ileum and mouse vas deferens bioassays, POMO was a highly efficacious and full agonist, being more potent than 14-OMO. In the [35S]GTPγS binding assays with membranes from CHO cells expressing human opioid receptors, POMO was a potent mu/delta-receptor full agonist and a kappa-receptor partial agonist. In vivo, POMO was highly effective in acute thermal nociception (hot-plate test, AD50= 0.7 nmol/kg) in mice after subcutaneous administration, with over 70- and 9000-fold increased potency than 14-OMO and morphine, respectively. POMO-induced antinociception is mediated through the activation of the mu-opioid receptor, and it does not involve delta- and kappa-opioid receptors. In the charcoal test, POMO produced fourfold less inhibition of the gastrointestinal transit than 14-OMO and morphine. In summary, POMO emerges as a new potent mixed mu/delta/kappa-opioid receptor agonist with reduced liability to cause constipation at antinociceptive doses

Procedure to Approximately Estimate the Uncertainty of Material Ratio Parameters due to Inhomogeneity of Surface Roughness

Roughness parameters that characterize contacting surfaces with regard to friction and wear are commonly stated without uncertainties, or with an uncertainty only taking into account a very limited amount of aspects such as repeatability of reproducibility (homogeneity) of the specimen. This makes it difficult to discriminate between different values of single roughness parameters. Therefore uncertainty assessment methods are required that take all relevant aspects into account. In the literature this is scarcely performed and examples specific for parameters used in friction and wear are not yet given. We propose a procedure to derive the uncertainty from a single profile employing a statistical method that is based on the statistical moments of the amplitude distribution and the autocorrelation length of the profile. To show the possibilities and the limitations of this method we compare the uncertainty derived from a single profile with that derived from a high statistics experiment.Comment: submitted to Meas. Sci. Technol., 12 figure

Inservice Workships: Freshman Focus Curriculum Implementation

The purpose of this project was to create workshops to help teachers implement an existing Freshman Focus Curriculum. It was specifically intended for use at Eisenhower High School in Yakima, Washington. The workshops include ways to help teachers organize, prepare for and teach the curriculum which was written to help freshmen transition into high school. The workshops include lesson plans as well as supplemental materials needed to effectively teach the curriculum

Sifat Mekanis Beton Beragregat Kasar Peluru Plastik

The purpose of this research is to investigate the feasibility of using bullet plastic as coarse aggregate or as a substitute for air bubbles in the production of lightweight concrete. The mechanical properties of plastic bullet-aggregated concrete substituted with 25%, 50%, 75%, and 100% of the gravel volume were evaluated experimentally. The mechanical properties tested were compressive strength, split tensile strength, and flexural strength. The test results show the mixture of 75% and 100% plastic bullets yields an acceptable density value as a lightweight concrete, with compressive strengths of 15.56 MPa and 14.94 MPa. These findings suggest that using plastic bullets as coarse aggregate or as a replacement for air bubbles is feasible regarded to American Concree Institute (ACI)