Titin extensibility in situ: entropic elasticity of permanently folded and permanently unfolded molecular segments

Titin (also known as connectin) is a giant protein that spans half of the striated muscle sarcomere. In the I-band titin extends as the sarcomere is stretched, developing what is known as passive force. The I-band region of titin contains tandem Ig segments (consisting of serially linked immunoglobulin-like domains) with the unique PEVK segment in between (Labeit, S., and B. Kolmerer. 1995. Science. 270:293-296). Although the tandem Ig and PEVK segments have been proposed to behave as stiff and compliant springs, respectively, precise experimental testing of the hypothesis is still needed. Here, sequence-specific antibodies were used to mark the ends of the tandem Ig and PEVK segments. By following the extension of the segments as a function of sarcomere length (SL), their respective contributions to titin's elastic behavior were established. In slack sarcomeres (approximately 2.0 micron) the tandem Ig and PEVK segments were contracted. Upon stretching sarcomeres from approximately 2.0 to 2.7 micron, the "contracted" tandem Ig segments straightened while their individual Ig domains remained folded. When sarcomeres were stretched beyond approximately 2.7 micron, the tandem Ig segments did not further extend, instead PEVK extension was now dominant. Modeling tandem Ig and PEVK segments as entropic springs with different bending rigidities (Kellermayer, M., S. Smith, H. Granzier, and C. Bustamante. 1997. Science. 276:1112-1116) indicated that in the physiological SL range (a) the Ig-like domains of the tandem Ig segments remain folded and (b) the PEVK segment behaves as a permanently unfolded polypeptide. Our model provides a molecular basis for the sequential extension of titin's different segments. Initially, the tandem Ig segments extend at low forces due to their high bending rigidity. Subsequently, extension of the PEVK segment occurs only upon reaching sufficiently high external forces due to its low bending rigidity. The serial linking of tandem Ig and PEVK segments with different bending rigidities provides a unique passive force-SL relation that is not achievable with a single elastic segment.     

Existence of optimal controls for partially observed linear diffusions

A unified framework for the separation approach to the control of partially observed linear diffusions is presented, which covers the case of bounded as well as unbounded controls.     

Evaluation of a chronic pain programme by referring physicians

A neglected source of treatment outcome evaluation is the opinion of the referring physicians. We report on 179 patients with chronic pain who were admitted to a 6 week inpatient inter-disciplinary pain programme. A retrospective 2 page mail questionnaire accompanied by initial letters of referral was sent to the referring physicians. We hypothesized that the main reason family physicians referred patients was to establish a management plan. The physician response rate was 70%, encompassing 72% of the patients. Intra-observer reliability was tested by a second mailing 3 months later (68% response rate). Test-retest reliability, and correlations between questions were significant and are reported for: reasons for referral, the utility of the discharge summary, coping, and behavioural changes at discharge and at time of the questionnaire. This appears to be the first report of a survey of the evaluation of a pain programme by referring physicians.     

Pursuing a maneuvering target which uses a random process for itscontrol

Since a pursuer pursuing a maneuvering target does not know what maneuvers an evading target will make, the maneuvers (the target's control law) appear as a random process to the pursuer. However, he has opinions about what the evader will do. From these, he can assign a prior probability distribution to the evader's maneuvers. For a linear pursuit evasion problem in which the evader's control law is modeled as a random process, in which the pursuer has partial noisy linear measurements of his own and the evader's relative position, and a quadratic optimality criterion is used, past results of the authors imply that the optimal control is a linear function of the “predicted miss”. Determining the predicted miss involves estimating the evader's terminal position from past system measurements. Nonlinear filtering techniques are used to give expressions for computing the conditional expectation of the evader's terminal position even in the presence of the random unknown maneuvers of the evader     

A perspective on developments in assessing psychopathology: A critical review of the MMPI and MMPI-2.

Many concerns have been raised about the MMPI, but the emphasis on continuity during its revision precluded addressing many of these problems in the new MMPI-2. In this review, problems with the MMPI and MMPI-2 are explicated in an effort to promote more informed use of this and other tests of psychopathology. Major theoretical concerns include the lack of a consistent measurement model, heterogeneous scale content, and suspect diagnostic criteria. Serious structural problems include the overlap among scales, lack of cross-validation of the scoring keys, inadequacy of measures of response styles, and suspect norms. Six minor problems and new issues for the MMPI-2 are also discussed. It is concluded that although the MMPI-2 is an improvement over the MMPI, both are suboptimal from the perspective of modern psychometric standards for the assessment of psychopathology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceived attitudes of schizophrenic inpatients in relation to rehospitalization.

Forty-nine schizophrenic inpatients who were ready for discharge completed the Influential Relationships Questionnaire. This instrument measures respondents' perceptions of three characteristic attitudes (care, overprotection, and criticism) demonstrated by two influential people in the patients' lives. The subjects were followed up for a 9-month period. Readmitted patients (N?=?21) rated the second-most-influential person higher on the Overprotection and Criticism scales and lower on the Care scale than did nonreadmitted patients (N?=?28). The implications of these findings in relation to rehospitalization are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clinical reliabilities and validities of the Basic Personality Inventory.

Using 112 adult patients from three psychiatric facilities, we examined the psychometric properties of the Basic Personality Inventory (BPI) scales. No differences across facilities were found, but there were sex differences on some of the scales. Reliability information suggested that the scales were internally consistent. Clinical staff ratings were used as criteria, and results demonstrated that scales possessed both convergent and discriminant validity. Overall, the findings strongly support the clinical application of the Basic Personality Inventory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparison of three MMPI short forms: Limited clinical utility in classification.

A multivariate classification method was used to compare the Mini-Mult, Faschingbauer Abbreviated MMPI, and MMPI-168 with the standard MMPI profiles of 252 psychiatric inpatients (mean age 27.4 yrs). Profiles were classified as 1 of 3 previous identified superordinate types (neurotic, psychotic, and sociopathic), using the standard MMPI profile as a criterion. Overall classification was below clinical utility, with distortions of profile shape the most serious error. No form was judged to be adequate for most clinical purposes. (9 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response styles and faking on the Basic Personality Inventory.

Examined the influence of response styles and explored approaches to detect faking on the Basic Personality Inventory (BPI). The BPI is a construct-based inventory designed to measure traditional areas of pathological content. Three groups of Ss completed the BPI: 182 normal adults, 404 psychiatric inpatients, and 180 undergraduates. The latter group completed the BPI with instructions to either fake good, fake bad, or straight take. The BPI was scored for several measures of stylistic responding as well as for its 12 scales. Results of instructions to fake, of the incidence of stylistic responding, and of the detection of faking using 3-discriminant functions are reported. The effects of manipulation and of incidence of stylistic responding on the BPI are also discussed. (48 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)