Primary Objective: The interaction of cerebrospinal fluid with the brain parenchyma in an impact scenario is studied. Research Design: A computational fluid-structure interaction model is used to simulate the interaction of cerebrospinal fluid with a comprehensive brain model. Methods and Procedures: The method of smoothed particle hydrodynamics is used to simulate the fluid flow, induced by the impact, simultaneously with finite element analysis to solve the large deformations in the brain model. Main Outcomes and Results: Mechanism of injury resulting in concussion is demonstrated. The locations with the highest stress values on the brain parenchyma are shown. Conclusions: Our simulations found that the damage to the brain resulting from the contrecoup injury is more severe than that resulting from the coup injury. Additionally, we show that the contrecoup injury does not always appear on the side opposite from where impact occurs.

Due to the inherent complexity of biological applications that more often than not include fluids and structures interacting together, the development of computational fluid–structure interaction models is necessary to achieve a quantitative understanding of their structure and function in both health and disease. The functions of biological structures usually include their interactions with the surrounding fluids. Hence, we contend that the use of fluid–structure interaction models in computational studies of biological systems is practical, if not necessary. The ultimate goal is to develop computational models to predict human biological processes. These models are meant to guide us through the multitude of possible diseases affecting our organs and lead to more effective methods for disease diagnosis, risk stratification, and therapy. This review paper summarizes computational models that use smoothed-particle hydrodynamics to simulate the fluid–structure interactions in complex biological systems.

No abstract

No abstract

ImportanceA short cervix as assessed by transvaginal ultrasound is an established risk factor for preterm birth. Study findings for a cervical pessary to prevent preterm delivery in singleton pregnancies with transvaginal ultrasound evidence of a short cervix have been conflicting.ObjectiveTo determine if cervical pessary placement decreases the risk of preterm birth or fetal death prior to 37 weeks among individuals with a short cervix.Design, Setting, and ParticipantsWe performed a multicenter, randomized, unmasked trial comparing a cervical pessary vs usual care from February 2017 through November 5, 2021, at 12 centers in the US. Study participants were nonlaboring individuals with a singleton pregnancy and a transvaginal ultrasound cervical length of 20 mm or less at gestations of 16 weeks 0 days through 23 weeks 6 days. Individuals with a prior spontaneous preterm birth were excluded.InterventionsParticipants were randomized 1:1 to receive either a cervical pessary placed by a trained clinician (n = 280) or usual care (n = 264). Use of vaginal progesterone was at the discretion of treating clinicians.Main Outcome and MeasuresThe primary outcome was delivery or fetal death prior to 37 weeks.ResultsA total of 544 participants (64%) of a planned sample size of 850 were enrolled in the study (mean age, 29.5 years [SD, 6 years]). Following the third interim analysis, study recruitment was stopped due to concern for fetal or neonatal/infant death as well as for futility. Baseline characteristics were balanced between participants randomized to pessary and those randomized to usual care; 98.9% received vaginal progesterone. In an as-randomized analysis, the primary outcome occurred in 127 participants (45.5%) randomized to pessary and 127 (45.6%) randomized to usual care (relative risk, 1.00; 95% CI, 0.83-1.20). Fetal or neonatal/infant death occurred in 13.3% of those randomized to receive a pessary and in 6.8% of those randomized to receive usual care (relative risk, 1.94; 95% CI, 1.13-3.32).Conclusions and RelevanceCervical pessary in nonlaboring individuals with a singleton gestation and with a cervical length of 20 mm or less did not decrease the risk of preterm birth and was associated with a higher rate of fetal or neonatal/infant mortality.Trial RegistrationClinicalTrials.gov Identifier: NCT02901626

No abstract

Results of a recent experimental study challenge the widely-held belief that modern combat helmets are more effective at protecting soldiers against concussions. The research shows that helmets used during First World War without inner paddings may have an advantage in protecting soldiers’ brains from concussions when relying solely on cerebrospinal fluid. The present study explains this counterintuitive finding by revealing that while cerebrospinal fluid can prevent direct brain-to-skull contact during a single event, its protective capabilities diminish with each subsequent event occurring in quick succession—something conventional padded helmets appear to aggravate. The cerebrospinal fluid requires a certain amount of time to reset after an acceleration/deceleration event, which allows it to effectively provide cushioning for any subsequent events and protect against potential brain damage. However, an immediate occurrence of a subsequent event, when the fluid has no time to settle down, may significantly diminish the effectiveness of the fluid’s ability to provide adequate cushioning, thereby putting individuals at risk of serious injury. This new information may have implications for helmet design in the future and calls into question current assumptions regarding the best way to protect soldiers and athletes from concussions.

No abstract