691 research outputs found

    A description of the methods of the Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be (nuMoM2b)

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    OBJECTIVE: The primary aim of the "Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be" is to determine maternal characteristics, which include genetic, physiologic response to pregnancy, and environmental factors that predict adverse pregnancy outcomes. STUDY DESIGN: Nulliparous women in the first trimester of pregnancy were recruited into an observational cohort study. Participants were seen at 3 study visits during pregnancy and again at delivery. We collected data from in-clinic interviews, take-home surveys, clinical measurements, ultrasound studies, and chart abstractions. Maternal biospecimens (serum, plasma, urine, cervicovaginal fluid) at antepartum study visits and delivery specimens (placenta, umbilical cord, cord blood) were collected, processed, and stored. The primary outcome of the study was defined as pregnancy ending at <37+0 weeks' gestation. Key study hypotheses involve adverse pregnancy outcomes of spontaneous preterm birth, preeclampsia, and fetal growth restriction. RESULTS: We recruited 10,037 women to the study. Basic characteristics of the cohort at screening are reported. CONCLUSION: The "Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be" cohort study methods and procedures can help investigators when they plan future projects

    Development of an animal fracture model for evaluation of cement augmentation femoroplasty: an in vitro biomechanical study

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    Osteoporotic hip fracture is the most severe kind of fracture with high morbidity and mortality. Patients' ambulation and quality of life are significantly affected by the fracture because only 50% regain their prefracture functional status, even if they undergo surgeries. There are many issues associated with the current preventive methods e.g., cost, side effects, patient compliance, and time for onset of action. Femoroplasty, the injection of bone cement into the proximal femur to augment femoral strength and to prevent fracture, has been an option with great potential. However, until now femoroplasty has remained at the stage of biomechanical testing. No in vivo study has evaluated its safety and effectiveness; there is not even an animal model for such investigations. The objective of this study was to develop a proximal femur fracture goat model that consistently fractures at the proximal femur when subject to vertical load, simulating osteoporotic hip fractures in human. Six pairs of fresh frozen mature Chinese goats' femora were obtained and randomly assigned into two groups. For the experimental group, a cylindrical bone defect was created at the proximal femur, while the control was left untreated. In addition, a configuration to mimic the mechanical axis of the goat femur was developed. When subjected to load along the mechanical axis, all the specimens from the bone defect group experienced femoral neck fractures, while fractures occurred at the femoral neck or other sites of the proximal femur in the control group. The biomechanical property (failure load) of the bone defect specimens was significantly lower than that of the control specimens (p<0.05). Osteoporotic hip fractures of humans were simulated by a goat fracture model, which may serve as a reference for future femoroplasty studies in vivo. The newly developed configuration simulating a femoral mechanical axis for biomechanical tests was practicable during the study.published_or_final_versio

    Bear Minimum: Ultralight Composite Bear Canister

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    The ultralight backpacking community needs a strong, easy to use, safe bear canister that is lighter than current market products for trekking in the backcountry. A full design of the lid for the bear canister is to be completed. This includes the locking mechanism to ensure it is bear proof, the interface between the lid and the canister, and the structure of the lid so it passes the strength and weight specifications. The lid, along with the already designed canister body, is to be manufactured with formal documentation. The lid will initially be tested separately and then with the canister body as an assembly. All tests will be to either verify or reject one or more of the design specifications listed later in this document. The overarching goal of the project is to find a balance of two project requirements: making a rigid lid that is, when combined with the canister body, less than 1.3 lbf and still meeting the Interagency Grizzly Bear Committee (IGBC) certification strength requirements

    Evaluation of transfixation cast constructs in horses

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    Transfixation pin casts have been used to manage a variety of different equine fracture configurations, but are particularly useful in comminuted fractures of the distal limb. The objectives of this study were to investigate strain at the bone-pin interface, the cast, and the fracture site, as well as load transfer between the bone and cast in different equine transfixation pin cast configurations. Three transfixation pin cast configurations (5 forelimbs per group) were evaluated: Construct 1: Two, 6.3-mm diameter pins spaced 4-cm apart in the cannon bone; Construct 2: Two, 6.3-mm diameter pins spaced 5-cm apart; Construct 3: Four, 4.8-mm diameter pins spaced 2-cm apart. Strain gauges were attached to the cast, cannon bone, and adjacent to a simulated fracture in the proximal phalanx. Limbs were subjected to single cycle compressive loading to failure as well as cyclic loading that simulated 6 weeks of wearing a cast. A simplified finite element (FE) model of Construct 1 and 3 was used to further evaluate strain and load transfer between the bone and cast during load to failure and cyclic loading. The results indicated that there was no difference in strain between the two 2-pin constructs in load to failure or cyclic loading. Relative to the 2-pin constructs, the 4-pin construct had less strain at the bone-pin interface and more strain in the cast, indicating that more load is transferred to the cast with the 4-pin construct. In-line with these findings, FE analyses indicated that the 4-pin system had less bone strain at the bone-pin interface, less strain adjacent to the fracture site, and less load transferred to the bone. These results suggest that the 4-pin cast is more effective at unloading the fractured bone

    Fresh Versus Frozen Engineered Bone–Ligament–Bone Grafts for Sheep Anterior Cruciate Ligament Repair

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    Surgical intervention is often required to restore knee instability in patients with anterior cruciate ligament (ACL) injury. The most commonly used grafts for ACL reconstruction are tendon autografts or allografts. These current options, however, have shown failure rates requiring revision and continued instability in the long term. The mismatched biomechanical properties of the current tendon grafts compared with native ACL tissue are thought to contribute to these poor outcomes and potential risk of early onset osteoarthritis. As a possible solution to these issues, our laboratory has fabricated tissue-engineered ligament constructs that exhibit structural and functional properties similar to those of native ACL tissue after 6 months implantation. In addition, these tissue-engineered grafts achieve vascular and neural development that exceeds those of patellar tendon grafts. However, the utility of our tissue-engineered grafts is limited by the labor-intensive method required to produce the constructs and the need to use the constructs fresh, directly from the cell culturing system. Ideally, these constructs would be fabricated and stored until needed. Thus, in this study, we investigated the efficacy of freezing our tissue-engineered constructs as a method of preservation before use for ACL reconstruction. We hypothesized that frozen constructs would have similar histological and biomechanical outcomes compared with our fresh model. Our results showed that 6 months postimplantation as an ACL replacement graft, both our tissue-engineered fresh and frozen grafts demonstrated similar mechanical and histological outcomes, indicating that freezing is a suitable method for preserving and storing our graft before ACL reconstruction. The ability to use frozen constructs significantly increases the versatility of our graft technology expanding the clinical utility of our graft.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140250/1/ten.tec.2014.0542.pd

    Skylab mobile laboratory

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    The Skylab mobile laboratory was designed to provide the capability to obtain necessary data on the Skylab crewmen 30 days before lift-off, within 1 hour after recovery, and until preflight physiological baselines were reattained. The mobile laboratory complex consisted of six laboratories that supported cardiovascular, metabolic, nutrition and endocrinology, operational medicine, blood, and microbiology experiments; a utility package; and two shipping containers. The objectives and equipment requirements of the Skylab mobile laboratory and the data acquisition systems are discussed along with processes such as permanently mounting equipment in the individual laboratories and methods of testing and transporting the units. The operational performance, in terms of amounts of data collected, and the concept of mobile laboratories for medical and scientific experiments are evaluated. The Skylab mobile laboratory succeeded in facilitating the data collection and sample preservation associated with the three Skylab manned flights

    Systematic Evaluation of Skeletal Mechanical Function

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    Many genetic and environmental perturbations lead to measurable changes in bone morphology, matrix composition, and matrix organization. Here, straightforward biomechanical methods are described that can be used to determine whether a genetic or environmental perturbation affects bone strength. A systematic method is described for evaluating how bone strength is altered in the context of morphology and tissue‐level mechanical properties, which are determined in large part from matrix composition, matrix organization, and porosity. The methods described include computed tomography, whole‐bone mechanical tests (bending and compression), tissue‐level mechanical tests, and determination of ash content, water content, and bone density. This strategy is intended as a first step toward screening mice for phenotypic effects on bone and establishing the associated biomechanical mechanism by which function has been altered, and can be conducted without a background in engineering. The outcome of these analyses generally provides insight into the next set of experiments required to further connect cellular perturbation with functional change. Curr. Protoc. Mouse Biol. 3:39‐67 © 2013 by John Wiley & Sons, Inc.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143805/1/cpmo130027.pd
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