scholarly journals Biomechanical evaluation of the human mandible after temporomandibular joint replacement under different biting conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Manuel Pinheiro ◽  
Robin Willaert ◽  
Afaq Khan ◽  
Anouar Krairi ◽  
Wim Van Paepegem
Keyword(s):  
Temporomandibular Joint ◽  
Animal Studies ◽  
Principal Strain ◽  
Implant Design ◽  
Study Patient ◽  
Patient Specific ◽  
Functional Changes ◽  
Masticatory Function ◽  
The Impact

AbstractTemporomandibular joint (TMJ) replacement with an implant is only used when all other conservative treatments fail. Despite the promising short-term results, the long-term implications of TMJ replacement in masticatory function are not fully understood. Previous human and animal studies have shown that perturbations to the normal masticatory function can lead to morphological and functional changes in the craniomaxillofacial system. A clearer understanding of the biomechanical implications of TMJ replacement in masticatory function may help identify design shortcomings that hinder their long-term success. In this study, patient-specific finite element models of the intact and implanted mandible were developed and simulated under four different biting tasks. In addition, the impact of re-attaching of the lateral pterygoid was also evaluated. The biomechanics of both models was compared regarding both mandibular displacements and principal strain patterns. The results show an excessive mediolateral and anteroposterior displacement of the TMJ implant compared to the intact joint in three biting tasks, namely incisor (INC), left moral (LML), and right molar (RML) biting. The main differences in principal strain distributions were found across the entire mandible, most notably from the symphysis to the ramus of the implanted side. Furthermore, the re-attachment of the lateral pterygoid seems to increase joint anteroposterior displacement in both INC, LML and RML biting while reducing it during LGF. Accordingly, any new TMJ implant design must consider stabilising both mediolateral and anteroposterior movement of the condyle during biting activities and promoting a more natural load transmission along the entire mandible.

Impact of Hybrid Operating Rooms on Long-Term Clinical Outcomes Following Fenestrated and Branched Endovascular Aortic Repair

2021 ◽  
pp. 152660282199672
Author(s):  
Giovanni Tinelli ◽  
Marie Bonnet ◽  
Adrien Hertault ◽  
Simona Sica ◽  
Gian Luca Di Tanna ◽  
...  
Keyword(s):  
Operating Room ◽  
Clinical Outcomes ◽  
Cox Regression ◽  
Statistical Significance ◽  
Aortic Aneurysms ◽  
Study Patient ◽  
Cox Regression Analysis ◽  
Significant Difference ◽  
The Impact

Purpose: Evaluate the impact of hybrid operating room (HOR) guidance on the long-term clinical outcomes following fenestrated and branched endovascular repair (F-BEVAR) for complex aortic aneurysms. Materials and Methods: Prospectively collected registry data were retrospectively analyzed to compare the procedural, short- and long-term outcomes of consecutive F-BEVAR performed from January 2010 to December 2014 under standard mobile C-arm versus hybrid room guidance in a high-volume aortic center. Results: A total of 262 consecutive patients, including 133 patients treated with a mobile C-arm equipped operating room and 129 with a HOR guidance, were enrolled in this study. Patient radiation exposure and contrast media volume were significantly reduced in the HOR group. Short-term clinical outcomes were improved despite higher case complexity in the HOR group, with no statistical significance. At a median follow-up of 63.3 months (Q1 33.4, Q3 75.9) in the C-arm group, and 44.9 months (Q1 25.1, Q3 53.5, p=0.53) in the HOR group, there was no statistically significant difference in terms of target vessel occlusion and limb occlusion. When the endograft involved 3 or more fenestrations and/or branches (complex F-BEVAR), graft instability (36% vs 25%, p=0.035), reintervention on target vessels (20% vs 11%, p=0.019) and total reintervention rates (24% vs 15%, p=0.032) were significantly reduced in the HOR group. The multivariable Cox regression analysis did not show statistically significant differences for long-term death and aortic-related death between the 2 groups. Conclusion: Our study suggests that better long-term clinical outcomes could be observed when performing complex F-BEVAR in the latest generation HOR.

scholarly journals On the effect of antiresorptive drugs on the bone remodeling of the mandible after dental implantation: a mathematical model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mehran Ashrafi ◽  
Farzan Ghalichi ◽  
Behnam Mirzakouchaki ◽  
Manuel Doblare
Keyword(s):  
Mathematical Model ◽  
Bone Density ◽  
Bone Remodeling ◽  
Dental Implants ◽  
Implant Design ◽  
Patient Specific ◽  
Dental Implantation ◽  
Antiresorptive Agents ◽  
Antiresorptive Drugs

AbstractBone remodeling identifies the process of permanent bone change with new bone formation and old bone resorption. Understanding this process is essential in many applications, such as optimizing the treatment of diseases like osteoporosis, maintaining bone density in long-term periods of disuse, or assessing the long-term evolution of the bone surrounding prostheses after implantation. A particular case of study is the bone remodeling process after dental implantation. Despite the overall success of this type of implants, the increasing life expectancy in developed countries has boosted the demand for dental implants in patients with osteoporosis. Although several studies demonstrate a high success rate of dental implants in osteoporotic patients, it is also known that the healing time and the failure rate increase, necessitating the adoption of pharmacological measures to improve bone quality in those patients. However, the general efficacy of these antiresorptive drugs for osteoporotic patients is still controversial, requiring more experimental and clinical studies. In this work, we investigate the effect of different doses of several drugs, used nowadays in osteoporotic patients, on the evolution of bone density after dental implantation. With this aim, we use a pharmacokinetic–pharmacodynamic (PK/PD) mathematical model that includes the effect of antiresorptive drugs on the RANK/RANK-L/OPG pathway, as well as the mechano-chemical coupling with external mechanical loads. This mechano-PK/PD model is then used to analyze the evolution of bone in normal and osteoporotic mandibles after dental implantation with different drug dosages. We show that using antiresorptive agents such as bisphosphonates or denosumab increases bone density and the associated mechanical properties, but at the same time, it also increases bone brittleness. We conclude that, despite the many limitations of these very complex models, the one presented here is capable of predicting qualitatively the evolution of some of the main biological and chemical variables associated with the process of bone remodeling in patients receiving drugs for osteoporosis, so it could be used to optimize dental implant design and coating for osteoporotic patients, as well as the drug dosage protocol for patient-specific treatments.

scholarly journals Alteration of Genomic Imprinting after Assisted Reproductive Technologies and Long-Term Health

Life ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 728
Author(s):  
Eguzkine Ochoa
Keyword(s):  
Embryonic Development ◽  
Experimental Evidence ◽  
Genomic Imprinting ◽  
Animal Studies ◽  
Assisted Reproductive Technologies ◽  
Reproductive Technologies ◽  
Early Embryonic Development ◽  
Global Methylation ◽  
The Impact

Assisted reproductive technologies (ART) are the treatment of choice for some infertile couples and even though these procedures are generally considered safe, children conceived by ART have shown higher reported risks of some perinatal and postnatal complications such as low birth weight, preterm birth, and childhood cancer. In addition, the frequency of some congenital imprinting disorders, like Beckwith–Wiedemann Syndrome and Silver–Russell Syndrome, is higher than expected in the general population after ART. Experimental evidence from animal studies suggests that ART can induce stress in the embryo and influence gene expression and DNA methylation. Human epigenome studies have generally revealed an enrichment of alterations in imprinted regions in children conceived by ART, but no global methylation alterations. ART procedures occur simultaneously with the establishment and maintenance of imprinting during embryonic development, so this may underlie the apparent sensitivity of imprinted regions to ART. The impact in adulthood of imprinting alterations that occurred during early embryonic development is still unclear, but some experimental evidence in mice showed higher risk to obesity and cardiovascular disease after the restriction of some imprinted genes in early embryonic development. This supports the hypothesis that imprinting alterations in early development might induce epigenetic programming of metabolism and affect long-term health. Given the growing use of ART, it is important to determine the impact of ART in genomic imprinting and long-term health.

scholarly journals The Universal Prescription for Parkinson’s Disease: Exercise

2020 ◽  
Vol 10 (s1) ◽  
pp. S21-S27
Author(s):  
Jay L. Alberts ◽  
Anson B. Rosenfeldt
Keyword(s):  
Parkinson’S Disease ◽  
Heart Rate ◽  
Parkinson's Disease ◽  
Clinical Trials ◽  
Aerobic Exercise ◽  
Animal Studies ◽  
Clinical Findings ◽  
Patient Specific ◽  
Functional Changes ◽  
Beneficial Effects

Over the past two decades, aerobic exercise has emerged as a mainstream recommendation to aid in treating Parkinson’s disease (PD). Despite the acknowledgement of the benefits of exercise for people with PD (PwPD), frequently, exercise recommendations lack specificity in terms of frequency, intensity and duration. Additionally, conflating physical activity with exercise has contributed to providing vague exercise recommendations to PwPD. Therefore, the beneficial effects of exercise may not be fully realized in PwPD. Data provided by animal studies and select human trials indicate aerobic exercise may facilitate structural and functional changes in the brain. Recently, several large human clinical trials have been completed and collectively support the use of aerobic exercise, specifically high-intensity aerobic exercise, in improving PD motor symptoms. Data from these and other studies provide the basis to include aerobic exercise as an integral component in treating PD. Based on positive clinical findings and trials, it is advised that PwPD perform aerobic exercise in the following dose: 3x/week, 30–40-minute main exercise set, 60–80% of heart rate reserve or 70–85% of heart rate max. In lieu of heart rate, individuals can achieve an intensity of 14–17 on a 20-point RPE scale. Ongoing clinical trials, SPARX3 and CYCLE-II, have potential to further develop patient-specific exercise recommendations through prognostic modeling.

scholarly journals Impacts of forest management on soil properties: a fundamental research topic for Mexico

2020 ◽  
Vol 27 (1) ◽  
pp. 33-52 ◽  
Author(s):  
Karla Valladares-Samperio ◽  
◽  
Leopoldo Galicia-Sarmiento ◽  
Keyword(s):  
Forest Management ◽  
Boreal Forests ◽  
Negative Influence ◽  
Biological Properties ◽  
Ecosystem Functions ◽  
Functional Changes ◽  
Wood Harvesting ◽  
Intensive Forest Management ◽  
The Impact

Introduction: The increase in the intensity of wood harvesting has a negative influence on ecosystem functions of soils in temperate and boreal forests. Objective: To understand the impacts of intensive and extensive forest management methods on the physical, chemical and biological properties of soils, and consequences on nutrient availability and stabilization processes in temperate and boreal forests. Results and discussion: Intensive forest management methods can generate greater imbalance in the processes of availability and stabilization of nutrients, compared to selective methods. The impact is reflected in the deterioration of soil structure and the decrease of nutrient reserves and microbial communities. These damages affect fertility and functionality of soil, decreasing long-term productivity. Affectations depend on the intensity of biomass extracted, environmental conditions and site preparation. This makes evident the need to monitor forest management and its impact on soil ecology in temperate forests, which maintains long-term productivity and ensures the availability of wood volumes. Conclusion: In Mexico, the impact of forest management has been scarcely analyzed and it is indispensable to understand the functional changes in the processes that determine soil fertility and forest productivity.

scholarly journals The cognitive consequences of the COVID-19 epidemic: collateral damage?

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Karen Ritchie ◽  
Dennis Chan ◽  
Tam Watermeyer
Keyword(s):  
Neurological Disorders ◽  
Memory Impairment ◽  
Animal Studies ◽  
Epidemiological Studies ◽  
Neural Basis ◽  
Cognitive Difficulties ◽  
System A ◽  
Cognitive Consequences ◽  
The Impact

Abstract Recovery from coronavirus disease 2019 (COVID-19) will be principally defined in terms of remission from respiratory symptoms; however, both clinical and animal studies have shown that coronaviruses may spread to the nervous system. A systematic search on previous viral epidemics revealed that while there has been relatively little research in this area, clinical studies have commonly reported neurological disorders and cognitive difficulties. Little is known with regard to their incidence, duration or underlying neural basis. The hippocampus appears to be particularly vulnerable to coronavirus infections, thus increasing the probability of post-infection memory impairment, and acceleration of neurodegenerative disorders such as Alzheimer’s disease. Future knowledge of the impact of COVID-19, from epidemiological studies and clinical practice, will be needed to develop future screening and treatment programmes to minimize the long-term cognitive consequences of COVID-19.

Biomechanical and Functional Behavior of Implants

1999 ◽  
Vol 13 (1) ◽  
pp. 88-92 ◽  
Author(s):  
Clark M. Stanford
Keyword(s):  
Trabecular Bone ◽  
Viscoelastic Properties ◽  
Bone Growth ◽  
Implant Design ◽  
Clinical Issue ◽  
Type Iv ◽  
Functional Behavior ◽  
Bone Changes ◽  
The Impact

The ability to achieve a long-term stable implant interface is not a significant clinical issue when sufficient uni- or bi-cortical stabilization is available. Clinical outcomes studies suggest that the higher-risk implants are those placed in compromised cortical bone (thin, porous, etc.) in anatomic sites with minimal existing trabecular bone (characterized as type IV bone). In establishing and maintaining an implant interface in such an environment, one needs to consider the impact of masticatory forces. These forces, in turn, have the potential to create localized changes in interfacial stiffness through the viscoelastic properties of bone. Changes in these properties will alter the communication between osteocytes and osteoblasts, leading to an increase in new bone growth, a maintenance of established bone, or a loss (potentially catastrophic) of either cortical or trabecular bone. Therefore, a key to understanding the biomechanical and functional behavior at an implant interface is to control the extent of anticipated modeling and remodeling behavior through an optimal implant design combined with a thorough understanding of how tissues respond to the mechanically active environment.

scholarly journals Influence of Cholecystokinin-8 on Compound Nerve Action Potentials from Ventral Gastric Vagus in Rats

2018 ◽  
Vol 28 (09) ◽  
pp. 1850006 ◽  
Author(s):  
Khalid B. Mirza ◽  
Andrea Alenda ◽  
Amir Eftekhar ◽  
Nir Grossman ◽  
Konstantin Nikolic ◽  
...  
Keyword(s):  
Vagus Nerve ◽  
Closed Loop ◽  
Implant Design ◽  
Cervical Region ◽  
Patient Specific ◽  
Great Promise ◽  
C Fibers ◽  
Nerve Action ◽  
Gut Hormone ◽  
The Impact

Objective: Vagus Nerve Stimulation (VNS) has shown great promise as a potential therapy for a number of conditions, such as epilepsy, depression and for Neurometabolic Therapies, especially for treating obesity. The objective of this study was to characterize the left ventral subdiaphragmatic gastric trunk of vagus nerve (SubDiaGVN) and to analyze the influence of intravenous injection of gut hormone cholecystokinin octapeptide (CCK-8) on compound nerve action potential (CNAP) observed on the same branch, with the aim of understanding the impact of hormones on VNS and incorporating the methods and results into closed loop implant design. Methods: The cervical region of the left vagus nerve (CerVN) of male Wistar rats was stimulated with electric current and the elicited CNAPs were recorded on the SubDiaGVN under four different conditions: Control (no injection), Saline, CCK1 (100[Formula: see text]pmol/kg) and CCK2 (1000[Formula: see text]pmol/kg) injections. Results: We identified the presence of A[Formula: see text], B, C1, C2, C3 and C4 fibers with their respective velocity ranges. Intravenous administration of CCK in vivo results in selective, statistically significant reduction of CNAP components originating from A and B fibers, but with no discernible effect on the C fibers in [Formula: see text] animals. The affected CNAP components exhibit statistically significant ([Formula: see text] and [Formula: see text]) higher normalized stimulation thresholds. Conclusion: This approach of characterizing the vagus nerve can be used in closed loop systems to determine when to initiate VNS and also to tune the stimulation dose, which is patient-specific and changes over time.

Viewing Nonsuicidal Self-Injury in Adolescence Through a Developmental Neuroscience Lens: The Impact of Neural Sensitivity to Socioaffective Pain and Reward

2021 ◽  
pp. 216770262198932
Author(s):  
Logan R. Cummings ◽  
Aaron T. Mattfeld ◽  
Jeremy W. Pettit ◽  
Dana L. McMakin
Keyword(s):  
Animal Studies ◽  
Mortality Risks ◽  
Developmental Neuroscience ◽  
Self Injury ◽  
Affective Processes ◽  
Increase Risk ◽  
Self Harm ◽  
The Impact ◽  
Nonsuicidal Self Injury

Nonsuicidal self-injury (NSSI)—deliberate self-harm without the intent to die—is a high-risk and impairing behavior associated with long-term morbidity and mortality risks. The prevalence of NSSI escalates in adolescence, indicating a sensitive developmental period for the emergence of this behavior. Neurobiological, interpersonal, and affective processes leading to NSSI have been proposed. However, the link between neurodevelopment and the emergence of NSSI in adolescence remains unclear. Therefore, in this review, we integrate a diverse literature of human and animal studies that have examined features of NSSI and identify two neurodevelopmental mechanisms that increase risk of NSSI in adolescence: sensitivity to socioaffective pain and reward. We propose a two-step process in which neurodevelopmental sensitivity exacerbates socioaffective risk pathways leading to the onset of NSSI and strengthens the maintenance of self-harm in adolescence. We discuss implications of this theoretical framework for improving prevention and intervention strategies by capitalizing on developmental sensitivity in potentiating mechanisms.

scholarly journals The Effects of Psychosocial Stress on Memory and Cognitive Ability: A Meta-Analysis

2020 ◽  
Author(s):  
Elizabeth McManus ◽  
Deborah Talmi ◽  
Hamied Haroon ◽  
Nils Muhlert
Keyword(s):  
Social Interactions ◽  
Cognitive Abilities ◽  
Psychosocial Stress ◽  
Animal Studies ◽  
Web Of Science ◽  
Meta Analysis ◽  
Long Term Memory ◽  
Stress Induction ◽  
The Impact

AbstractThe impact of stress on cognitive abilities, such as memory, is well documented in animal studies but it is not yet clear how stress in human social interactions affects memory. This review systematically explored the evidence regarding the effects of psychosocial stress on memory and associated cognitive abilities. PubMed, PsycInfo and Web of Science databases were searched for studies assessing the effects of psychosocial stress on long-term memory or related cognitive functions. Fifty-one studies were identified and compared based on the timing of stress induction. No overall effect of psychosocial stress induction was seen on long-term or working memory regardless of whether stress induction occurred following encoding or before retrieval. Psychosocial stress had a moderate effect in studies comparing memory for emotional compared to neutral stimuli, but the direction of this effect varied across studies. Psychosocial stress decreased performance on executive function tasks. Our findings demonstrate that psychosocial stress may not have the clear effects on memory previously ascribed to it, suggesting potentially different mechanisms from physiological stressors.

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