Trabecular bone remodeling in the aging mouse: A micro-multiphysics agent-based in silico model using single-cell mechanomics.

Bone remodeling is regulated by the interaction between different cells and tissues across many spatial and temporal scales. Notably, in silico models are regarded as powerful tools to further understand the signaling pathways that regulate this intricate spatial cellular interplay. To this end, we have established a 3D multiscale micro-multiphysics agent-based (micro-MPA) in silico model of trabecular bone remodeling using longitudinal in vivo data from the sixth caudal vertebra (CV6) of PolgA(D257A/D257A) mice, a mouse model of premature aging. Our in silico model includes a variety of cells as single agents and receptor-ligand kinetics, mechanomics, diffusion and decay of cytokines which regulate the cells' behavior. We highlighted its capabilities by simulating trabecular bone remodeling in the CV6 of five mice over 4 weeks and we evaluated the static and dynamic morphometry of the trabecular bone microarchitecture. Based on the progression of the average trabecular bone volume fraction (BV/TV), we identified a configuration of the model parameters to simulate homeostatic trabecular bone remodeling, here named basal. Crucially, we also produced anabolic, anti-anabolic, catabolic and anti-catabolic responses with an increase or decrease by one standard deviation in the levels of osteoprotegerin (OPG), receptor activator of nuclear factor kB ligand (RANKL), and sclerostin (Scl) produced by the osteocytes. Our results showed that changes in the levels of OPG and RANKL were positively and negatively correlated with the BV/TV values after 4 weeks in comparison to basal levels, respectively. Conversely, changes in Scl levels produced small fluctuations in BV/TV in comparison to the basal state. From these results, Scl was deemed to be the main driver of equilibrium while RANKL and OPG were shown to be involved in changes in bone volume fraction with potential relevance for age-related bone features. Ultimately, this micro-MPA model provides valuable insights into how cells respond to their local mechanical environment and can help to identify critical pathways affected by degenerative conditions and ageing.

Cancer care continuum at a tertiary care centre in India during the Covid-19 pandemic and nationwide lockdown: Healthcare delivery through telemedicine.

Background The Covid-19 pandemic and subsequent lockdown in India caused disruptions in cancer treatment due to the restriction on movement of patients. We aimed to maintain continuity in cancer treatment during the lockdown through teleconsultations. We tried to reach out to our patients using telephonic consultations by establishing a Teleconsult Centre facility run by a team of doctors and patient navigators. Methods We telephonically contacted all patients who had outpatient appointments from 23 March to 30 April 2020 at our centre through the Teleconsult Centre to understand their current circumstances, feasibility of follow-up, local resources and offered best possible alternatives to continue cancer treatment, if required. Results Of the 2686 patients scheduled for follow-up during this period, we could contact 1783 patients in 9 working days. Through teleconsultations, we could defer follow-ups of 1034 patients (57.99%, 95% confidence interval [CI] 55.6%-60.3%), thus reducing the need for patients to travel to the hospital. Change in systemic therapy was made in 75 patients (4.2%, 95% CI 3.3%-5.2%) as per the requirements and available resources. Symptoms suggestive of disease progression were picked up in 12 patients (0.67%, 95% CI 0.35%-1.17%), who were advised to meet local physicians. Conclusion Our study suggests that the majority of patients on follow-up can be managed with teleconsultation in times of crisis. Teleconsultation has the potential of being one of the standard methods of patient follow-up even during periods of normalcy.

Computational Analysis of Bone Remodeling in the Proximal Tibia Under Electrical Stimulation Considering the Piezoelectric Properties.

The piezoelectricity of bone is known to play a crucial role in bone adaptation and remodeling. The application of an external stimulus such as mechanical strain or electric field has the potential to enhance bone formation and implant osseointegration. Therefore, in the present study, the objective is to investigate bone remodeling under electromechanical stimulation as a step towards establishing therapeutic strategies. For the first time, piezoelectric bone remodeling in the human proximal tibia under electro-mechanical loads was analyzed using the finite element method in an open-source framework. The predicted bone density distributions were qualitatively and quantitatively assessed by comparing with the computed tomography (CT) scan and the bone mineral density (BMD) calculated from the CT, respectively. The effect of model parameters such as uniform initial bone density and reference stimulus on the final density distribution was investigated. Results of the parametric study showed that for different values of initial bone density the model predicted similar but not identical final density distribution. It was also shown that higher reference stimulus value yielded lower average bone density at the final time. The present study demonstrates an increase in bone density as a result of electrical stimulation. Thus, to minimize bone loss, for example, due to physical impairment or osteoporosis, mechanical loads during daily physical activities could be partially replaced by therapeutic electrical stimulation.

Finite element analysis of bone remodelling with piezoelectric effects using an open-source framework.

Bone tissue exhibits piezoelectric properties and thus is capable of transforming mechanical stress into electrical potential. Piezoelectricity has been shown to play a vital role in bone adaptation and remodelling processes. Therefore, to better understand the interplay between mechanical and electrical stimulation during these processes, strain-adaptive bone remodelling models without and with considering the piezoelectric effect were simulated using the Python-based open-source software framework. To discretise numerical attributes, the finite element method (FEM) was used for the spatial variables and an explicit Euler scheme for the temporal derivatives. The predicted bone apparent density distributions were qualitatively and quantitatively evaluated against the radiographic scan of a human proximal femur and the bone apparent density calculated using a bone mineral density (BMD) calibration phantom, respectively. Additionally, the effect of the initial bone density on the resulting predicted density distribution was investigated globally and locally. The simulation results showed that the electrically stimulated bone surface enhanced bone deposition and these are in good agreement with previous findings from the literature. Moreover, mechanical stimuli due to daily physical activities could be supported by therapeutic electrical stimulation to reduce bone loss in case of physical impairment or osteoporosis. The bone remodelling algorithm implemented using an open-source software framework facilitates easy accessibility and reproducibility of finite element analysis made.

Numerical Analysis of Electromechanically Driven Bone Remodeling Using the Open-source Software Framework.

Natural bone remodeling is the mechanism that regulates the relationship between bone morphology and external mechanical loads applied to it. This phenomenon has been studied extensively, including multiple numerical models that have been formulated to predict the density distribution and its evolution in several bone types. However, despite these models, bone remodeling mechanism under different stimuli is still not well understood. We implemented a recently proposed electromechanically driven bone remodeling model that encompasses both mechanical and therapeutic electrical stimuli using an open-source software framework, and studied a two-dimensional (2D) plate model and a femur bone model, respectively. For discretization, we employed the finite element method (FEM) for the spatial quantities and Euler scheme for the time derivatives. The simulation results demonstrate that the density distribution is changed under electrical stimulation, generally resulting in a greater mass deposition. This study supports the possibility of enhancing and accelerating the bone remodeling process via simultaneous application of electrical and mechanical stimulus.

A Finite Element Bendo-Tensegrity Model of Eukaryotic Cell.

Mechanical interaction of cell with extracellular environment affects its function. The mechanisms by which mechanical stimuli are sensed and transduced into biochemical responses are still not well understood. Considering this, two finite element (FE) bendo-tensegrity models of a cell in different states are proposed with the aim to characterize cell deformation under different mechanical loading conditions: a suspended cell model elucidating the global response of cell in tensile test simulation and an adherent cell model explicating its local response in atomic force microscopy (AFM) indentation simulation. The force-elongation curve obtained from tensile test simulation lies within the range of experimentally obtained characteristics of smooth muscle cells (SMCs) and illustrates a nonlinear increase in reaction force with cell stretching. The force-indentation curves obtained from indentation simulations lie within the range of experimentally obtained curves of embryonic stem cells (ESCs) and exhibit the influence of indentation site on the overall reaction force of cell. Simulation results have demonstrated that actin filaments (AFs) and microtubules (MTs) play a crucial role in the cell stiffness during stretching, whereas actin cortex (AC) along with actin bundles (ABs) and MTs are essential for the cell rigidity during indentation. The proposed models quantify the mechanical contribution of individual cytoskeletal components to cell mechanics and the deformation of nucleus under different mechanical loading conditions. These results can aid in better understanding of structure-function relationships in living cells.

An Unusual Case of Abdominal Leiomyoma Presenting as a Free Lying Intraperitoneal Mass in an Elderly Gentleman.

Introduction. Leiomyomas are common benign tumours of female reproductive tract and are rarely seen in extrauterine location. Case Report. We report an interesting case of a free lying abdominal leiomyoma presenting as a painless abdominal lump in an elderly gentleman. Discussion. Primary abdominal leiomyomas are uncommon and require surgical removal if symptomatic.

Design and optimization of bilayered tablet of Hydrochlorothiazide using the Quality-by-Design approach.

AIM: The aim of the present study is to develop an optimize bilayered tablet using Hydrochlorothiazide (HCTZ) as a model drug candidate using quality by design (QbD) approach. INTRODUCTION AND METHOD: The bilayered tablet gives biphasic drug release through loading dose; prepared using croscarmellose sodium a superdisintegrant and maintenance dose using several viscosity grades of hydrophilic polymers. The fundamental principle of QbD is to demonstrate understanding and control of pharmaceutical processes so as to deliver high quality pharmaceutical products with wide opportunities for continuous improvement. Risk assessment was carried out and subsequently 2(2) factorial designs in duplicate was selected to carry out design of experimentation (DOE) for evaluating the interactions and effects of the design factors on critical quality attribute. The design space was obtained by applying DOE and multivariate analysis, so as to ensure desired disintegration time (DT) and drug release is achieved. Bilayered tablet were evaluated for hardness, thickness, friability, drug content uniformity and in vitro drug dissolution. RESULT: Optimized formulation obtained from the design space exhibits DT of around 70 s, while DR T95% (time required to release 95% of the drug) was about 720 min. Kinetic studies of formulations revealed that erosion is the predominant mechanism for drug release. CONCLUSION: From the obtained results; it was concluded that independent variables have a significant effect over the dependent responses, which can be deduced from half normal plots, pareto charts and surface response graphs. The predicted values matched well with the experimental values and the result demonstrates the feasibility of the design model in the development and optimization of HCTZ bilayered tablet.