Results of medical treatment with psyllium, lactobacillus, and tryptophan (Plurilac® Trio) in obstructive defecation syndrome

IntroductionThe term “obstructive defecation syndrome” (ODS) describes a complex condition characterized by defecatory disorders. Such a condition represents a significant proportion of patients, which is estimated to be up to 30% of patients affected by chronic constipation. Presently, a broad agreement has been reached on diagnostic studies, whereas the choice of treatment that aims to improve the quality of life and/or correct the prevalent abnormalities or all anatomical abnormalities remains controversial.MethodsThis was a retrospective cohort study on 174 patients out of a total of 232 with ODS who were observed in a specialized university unit of surgical coloproctology between 2018 and 2022. Clinical assessment included examining the values of the Agachan–Wexner constipation score and Patient Assessment of Constipation (PAC)-quality of life (QoL) scores, a full digital anorectal examination, anoscopy, RX defecography, and a urogynecological consultation; a functional anorectal test, an endoanal ultrasound, and colonoscopy were performed in select patients. The patients were reevaluated after an 8–10-week course of medical treatment based on a high-fiber diet and fluid intake and 6 g of psyllium combined with lactobacillus and tryptophan b.i.d. The results were analyzed by means of the Wilcoxon rank-sum test, comparing pretreatment scores with the results at the first follow-up visit.ResultsAfter 8–10 weeks of conservative treatment, 128 patients declared full satisfaction, 29 reported moderate satisfaction, and 17 (9.7%) declared no improvement. Among these 17, there were 5 patients with paradoxical puborectal contractions. The value of the Agachan–Wexner constipation score after treatment decreased from the pretreatment Agachan–Wexner constipation score mean value of 23.4 ± 3.7 (mean ± SD range 15–27) to a mean value of 5.3 ± 0.7 (range 3–8, p < 0.001). The quality of life improved, as shown by the PAC-QoL score, indicating great improvement in social relationships.ConclusionsGiven the benefits of conservative therapies, they represent a cornerstone in the treatment of ODS, a complex disorder. Diet and bulking agents are mandatory forms of treatment prior to making any surgical attempt, also considering the fact that the psychosomatic component of ODS is an essential prerequisite to match patient expectations

A Consistency Analysis of Phase-Locked-Loop Testing and Control-Based Continuation for a Geometrically Nonlinear Frictional System

Two of the most popular vibration testing methods for nonlinear structures are control-based continuation and phase-locked-loop testing. In this paper, they are directly compared on the same benchmark system, for the first time, to demonstrate their general capabilities and to discuss practical implementation aspects. The considered system, which is specifically designed for this study, is a slightly arched beam clamped at both ends via bolted joints. It exhibits a pronounced softening-hardening behavior as well as an increasing damping characteristic due to the frictional clamping. Both methods are implemented to identify periodic responses at steady-state constituting the phase-resonant backbone curve and nonlinear frequency response curves. To ensure coherent results, the repetition variability is thoroughly assessed via an uncertainty analysis. It is concluded that the methods are in excellent agreement, taking into account the inherent repetition variability of the system

High surgeon volume and positive surgical margins can predict the risk of biochemical recurrence after robot-assisted radical prostatectomy

Background: The aim of this study was to determine whether any clinical factors are independent predictors of positive surgical margins (PSM), and to assess the association of PSM and biochemical recurrence (BR) after robot-assisted radical prostatectomy (RARP). Methods: The population included cases with negative surgical margins (control group) and patients with PSM (study group). Tumor grade was evaluated according to the International Society of Urologic Pathology (ISUP) system. A logistic regression model assessed the independent association of factors with the risk of PSM. The risk of BR was assessed by Cox\u2019s multivariate proportional hazards. Results: A total of 732 consecutive patients were evaluated. Extend pelvic lymph node dissection (ePLND) was performed in 342 cases (46.7%). Overall, 192 cases (26.3%) had PSM. The risk of PSM was positively associated with the percentage of biopsy positive cores (BPC; odds ratio, OR = 1.012; p = 0.004), extracapsular extension (pT3a; OR=2.702; p < 0.0001), invasion of seminal vesicle (pT3b; OR = 2.889; p < 0.0001), but inversely with body mass index (OR = 0.936; p = 0.021), and high surgeon volume (OR = 0.607; p = 0.006). Independent clinical factors associated with the risk of BR were baseline prostate-specific antigen (PSA; hazard ratio, HR = 1.064; p = 0.004), BPC (HR = 1.015; p = 0.027), ISUP biopsy grade group (BGG) 2/3 (HR = 2.966; p = 0.003), and BGG 4/5 (HR = 3.122; p = 0.022). Pathologic factors associated with the risk of BR were ISUP group 4/5 (HR = 3.257; p = 0.001), pT3b (HR = 2.900; p = 0.003), and PSM (HR = 2.096; p = 0.045). Conclusions: In our cohort, features related to host, tumor, and surgeon volume are associated with the risk of PSM, which is also an independent parameter predicting BR after RARP. The surgical volume of the operating surgeon is an independent factor that decreases the risk of PSM, and, as such, the risk of BR

Bridging the Gap Between Nonlinear Normal Modes and Modal Derivatives

Nonlinear Normal Modes (NNMs) have a clear conceptual relation to the classical linear normal modes (LNMs), yet they offer a solid theoretical framework for interpreting a wide class of non-linear dynamical phenomena with no linear counterpart. The main difficulty associated with NNMs is that their calculation for large-scale models is expensive, particularly for distributed nonlinearities. Repeated direct time integrations need to be carried out together with extensive sensitivity analysis to reproduce the frequency-energy dependence of the modes of interest. In the present paper, NNMs are computed from a reduced model obtained using a quadratic transformation comprising LNMs and Modal Derivatives (MDs). Previous studies have shown that MDs can capture the essential dynamics of geometrically nonlinear structures and can greatly reduce the computational cost of time integration. A direct comparison with the NNMs computed from another standard reduction technique highlights the capability of the proposed reduction method to capture the essential nonlinear phenomena. The methodology is demonstrated using simple examples with 2 and 4 degrees of freedom.BeIPD-COFUND outgoing fellowship: Managing bifurcations of nonlinear mechanical systems using experimental continuation technique

Nonlinear model order reduction for flexible multibody dynamics: A modal derivatives approach

An effective reduction technique is presented for flexible multibody systems, for which the elastic deflection could not be considered small. We consider here the planar beam systems undergoing large elastic rotations, in the floating frame description. The proposed method enriches the classical linear reduction basis with modal derivatives stemming from the derivative of the eigenvalue problem. Furthermore, the Craig–Bampton method is applied to couple the different reduced components. Based on the linear projection, the configuration-dependent internal force can be expressed as cubic polynomials in the reduced coordinates. Coefficients of these polynomials can be precomputed for efficient runtime evaluation. The numerical results show that the modal derivatives are essential for the correct approximation of the nonlinear elastic deflection with respect to the body reference. The proposed reduction method constitutes a natural and effective extension of the classical linear modal reduction in the floating frame.ISSN:1573-272XISSN:1384-564

A new, challenging benchmark for nonlinear system identification

peer reviewedThe progress accomplished during the past decade in nonlinear system identi fication in structural dynamics is considerable. The objective of the present paper is to consolidate this progress by challenging the community through a new benchmark structure exhibiting complex nonlinear dynamics. The proposed structure consists of two o ffset cantilevered beams connected by a highly flexible element. For increasing forcing amplitudes, the system sequentially features linear behaviour, localised nonlinearity associated with the buckling of the connecting element, and distributed nonlinearity resulting from large elastic deformations across the structure. A finite element-based code with time integration capabilities is made available at http://sem.org/TDIV-Nonlin.asp. This code permits the numerical simulation of the benchmark dynamics in response to arbitrary excitation signals