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

A model for the force stretching double-stranded chain molecules

We modify and extend the recently developed statistical mechanical model for predicting the thermodynamic properties of chain molecules having noncovalent double-stranded conformations, as in RNA or ssDNA, and $\beta-$sheets in protein, by including the constant force stretching at one end of molecules as in a typical single-molecule experiment. The conformations of double-stranded regions of the chain are calculated based on polymer graph-theoretic approach [S-J. Chen and K. A. Dill, J. Chem. Phys. {\bf109}, 4602(1998)], while the unpaired single-stranded regions are treated as self-avoiding walks. Sequence dependence and excluded volume interaction are taken into account explicitly. Two classes of conformations, hairpin and RNA secondary structure are explored. For the hairpin conformations, all possible end-to-end distances corresponding to the different types of double-stranded regions are enumerated exactly. For the RNA secondary structure conformations, a new recursive formula incorporating the secondary structure and end-to-end distribution has been derived. Using the model, we investigate the extension-force curves, contact and population distributions and re-entering phenomena, respectively. we find that the force stretching homogeneous chains of hairpin and secondary structure conformations are very different: the unfolding of hairpins is two-state, while unfolding the latter is one-state. In addition, re-entering transitions only present in hairpin conformations, but are not observed in secondary structure conformations.Comment: 19 pages, 28 figure

Effects of Eye-phase in DNA unzipping

The onset of an "eye-phase" and its role during the DNA unzipping is studied when a force is applied to the interior of the chain. The directionality of the hydrogen bond introduced here shows oscillations in force-extension curve similar to a "saw-tooth" kind of oscillations seen in the protein unfolding experiments. The effects of intermediates (hairpins) and stacking energies on the melting profile have also been discussed.Comment: RevTeX v4, 9 pages with 7 eps figure

Structure and pressure drop of real and virtual metal wire meshes

An efficient mathematical model to virtually generate woven metal wire meshes is presented. The accuracy of this model is verified by the comparison of virtual structures with three-dimensional images of real meshes, which are produced via computer tomography. Virtual structures are generated for three types of metal wire meshes using only easy to measure parameters. For these geometries the velocity-dependent pressure drop is simulated and compared with measurements performed by the GKD - Gebr. Kufferath AG. The simulation results lie within the tolerances of the measurements. The generation of the structures and the numerical simulations were done at GKD using the Fraunhofer GeoDict software

Reversible stretching of homopolymers and random heteropolymers

We have analyzed the equilibrium response of chain molecules to stretching. For a homogeneous sequence of monomers, the induced transition from compact globule to extended coil below the $\theta$-temperature is predicted to be sharp. For random sequences, however, the transition may be smoothed by a prevalence of necklace-like structures, in which globular regions and coil regions coexist in a single chain. As we show in the context of a random copolymer, preferential solvation of one monomer type lends stability to such structures. The range of stretching forces over which necklaces are stable is sensitive to chain length as well as sequence statistics.Comment: 14 pages, 4 figure

Periodically driven stochastic un- and refolding transitions of biopolymers

Mechanical single molecule experiments probe the energy profile of biomolecules. We show that in the case of a profile with two minima (like folded/unfolded) periodic driving leads to a stochastic resonance-like phenomenon. We demonstrate that the analysis of such data can be used to extract four basic parameters of such a transition and discuss the statistical requirements of the data acquisition. As advantages of the proposed scheme, a polymeric linker is explicitly included and thermal fluctuations within each well need not to be resolved.Comment: 7 pages, 5 figures, submitted to EP

Force induced stretched state: Effects of temperature

A model of self avoiding walks with suitable constraint has been developed to study the effect of temperature on a single stranded DNA (ssDNA) in the constant force ensemble. Our exact calculations for small chains show that the extension (reaction co-ordinate) may increase or decrease with the temperature depending upon the applied force. The simple model developed here which incorporates semi-microscopic details of base direction provide an explanation of the force induced transitions in ssDNA as observed in experiments.Comment: 5 pages, 8 figures, RevTex

Two-phase stretching of molecular chains

While stretching of most polymer chains leads to rather featureless force-extension diagrams, some, notably DNA, exhibit non-trivial behavior with a distinct plateau region. Here we propose a unified theory that connects force-extension characteristics of the polymer chain with the convexity properties of the extension energy profile of its individual monomer subunits. Namely, if the effective monomer deformation energy as a function of its extension has a non-convex (concave up) region, the stretched polymer chain separates into two phases: the weakly and strongly stretched monomers. Simplified planar and 3D polymer models are used to illustrate the basic principles of the proposed model. Specifically, we show rigorously that when the secondary structure of a polymer is mostly due to weak non-covalent interactions, the stretching is two-phase, and the force-stretching diagram has the characteristic plateau. We then use realistic coarse-grained models to confirm the main findings and make direct connection to the microscopic structure of the monomers. We demostrate in detail how the two-phase scenario is realized in the \alpha-helix, and in DNA double helix. The predicted plateau parameters are consistent with single molecules experiments. Detailed analysis of DNA stretching demonstrates that breaking of Watson-Crick bonds is not necessary for the existence of the plateau, although some of the bonds do break as the double-helix extends at room temperature. The main strengths of the proposed theory are its generality and direct microscopic connection.Comment: 16 pges, 22 figure

Multiple passages of light through an absorption inhomogeneity in optical imaging of turbid media

The multiple passages of light through an absorption inhomogeneity of finite size deep within a turbid medium is analyzed for optical imaging using the ``self-energy'' diagram. The nonlinear correction becomes more important for an inhomogeneity of a larger size and with greater contrast in absorption with respect to the host background. The nonlinear correction factor agrees well with that from Monte Carlo simulations for CW light. The correction is about $50$ in near infrared for an absorption inhomogeneity with the typical optical properties found in tissues and of size of five times the transport mean free path.Comment: 3 figure