Development of a Computational Methodology for Evaluating In Vivo Vertebral Mechanics in Subjects Having Various Conditions of the Lumbar Spine

Treating and evaluating the causes of low back pain (LBP) is difficult and not fully understood. However, assessing the in vivo motions and loading characteristics in the lumbar spine may provide important data for progressing the diagnosis and treatment of pathologies linked with LBP. This dissertation describes the development of a comprehensive approach for collecting both the kinematics and kinetics of the lumbar vertebrae under in vivo conditions. Forty-four subjects representing healthy, symptomatic, pathological, and surgically implanted (pre- and post-operative) conditions of the lumbar spine were evaluated using dynamic fluoroscopy and 3D-to-2D image registration to assess the motions of the five lumbar vertebrae while patients performed an active flexion-extension, lateral flexion, and axial rotation of the spine. 3D kinematics were extracted describing the relative in-plane and coupled out-of-plane motions of the intervertebral joints. A computational methodology was then utilized for the development of a multi-body, inverse mathematical model based on principles from Kane’s dynamics. The kinematics, as well as patient-specific bone geometries, recreated from CT, and ground reaction forces, collected using force plates, served as inputs to the model. Vertebral bones were defined as rigid bodies, while massless frames represented non-specific bone geometries for the lower body, torso and abdominal wall. Soft tissue attachment sites were selected on the vertebral bones allowing for ligaments to be defined for constraint and modeled as linear springs. Relevant muscle groups were also included and solved for using the pseudo-inverse algorithm, which enabled for decoupling of the derived resultant torques and ultimately defined the kinetic trajectory for the muscles. These methodologies allowed for the theoretical modeling of the entire lumbar region and prediction of joint reaction contact forces, ligament constraint forces, and applied musculotendon forces. Results from the model were validated for the prescribed motions using experimental loading data measured directly using telemetrized vertebral implants and intervertebral disc pressure sensors. A comparative analysis of the predicted forces from the model with experimentally collected data showed good agreement in the force profiles and an average combined error around 6.9%. This demonstrated the use of this methodology for in vivo analyses of the lumbar spine

Removal of an Impaled Intraocular Hair Comb Following Self-inflicted Trauma

Ocular trauma is one of the most common and vision-threatening ophthalmic presentations with a wide spectrum of complications, such as bleeding, infection, vision loss, and enucleation. A 64-year-old-male presented to the emergency department (ED) with a self-inflicted orbital penetrating injury with a hair comb. Computed tomography showed the comb traversed the medial orbit inferior to the medial rectus but did not damage the optic nerve; there were no globe or orbital wall fractures. His ocular exam was significant for a right eye afferent pupillary defect and decreased visual acuity 20/800, consistent with optic neuropathy. Primary concerns were stabilizing and removing the foreign body without causing further damage in the setting of an uncooperative patient. The comb was removed with the aid of local and systemic analgesia using gentle traction and normal saline irrigation. The patient was admitted for systemic and topical antibiotics and showed improvement in visual acuity and resolution of his optic neuropathy. This case illustrates the importance of rapid ED assessment and management of complex penetrating ocular trauma. Examination should specifically look for signs of globe rupture and optic nerve injury. Expedited foreign body removal should be managed together with an ophthalmologist with procedural sedation and broad-spectrum antibiotics to avoid further visual and infectious complications

The Role of Librarians and Informationists in Disaster Response

The National Library of Medicine (NLM) Disaster Information Management Research Center (DIMRC) website provides a wealth of resources for disaster planning, deployment and reporting. Librarians can play a valuable role in training responders in use of tools such as WISER, CHEMM and REMM.https://digitalrepository.unm.edu/hslic-posters-presentations/1076/thumbnail.jp

Glucagon produces delayed increase in drinking-associated food intake

Glucagon is a pancreatic hormone and a brain-gut peptide thought to function as a short-term satiety signal in control of food intake. This study examined effects of glucagon injection on intake of alcohol, food, and water. Overnight water-deprived female and male Wistar rats (Ns = 10) were given access to 5% w/v ethanol and Purina chow. After adaptation to this schedule, rats received intraperitoneal (ip) injection of 0, 200, or 400 g/kg of glucagon, at 0 or 30 min prior to alcohol access. Food intake was significantly increased by glucagon at 30-60 min after either time of injection (0 or 30 min). Combined total caloric intake (from chow and ethanol) was decreased at 0-30 min after glucagon injection, and increased at 30-60 min after glucagon, reliably in male rats. Immediate declines and delayed increases in feeding after glucagon administration have been reported previously in other feeding paradigms. In addition to acting as a short-term satiety signal for caloric intake, glucagon may function further to sustain blood glucose levels through stimulation of delayed increase in food intake

Density Perturbations and the Cosmological Constant from Inflationary Landscapes

An anthropic understanding of the cosmological constant requires that the vacuum energy at late time scans from one patch of the universe to another. If the vacuum energy during inflation also scans, the various patches of the universe acquire exponentially differing volumes. In a generic landscape with slow-roll inflation, we find that this gives a steeply varying probability distribution for the normalization of the primordial density perturbations, resulting in an exponentially small fraction of observers measuring the COBE value of 10^-5. Inflationary landscapes should avoid this "\sigma problem", and we explore features that can allow them to do that. One possibility is that, prior to slow-roll inflation, the probability distribution for vacua is extremely sharply peaked, selecting essentially a single anthropically allowed vacuum. Such a selection could occur in theories of eternal inflation. A second possibility is that the inflationary landscape has a special property: although scanning leads to patches with volumes that differ exponentially, the value of the density perturbation does not vary under this scanning. This second case is preferred over the first, partly because a flat inflaton potential can result from anthropic selection, and partly because the anthropic selection of a small cosmological constant is more successful.Comment: 23 page

An Update and Report Failure of Surgical Syndactyly Repair in Harlequin Ichthyosis.

Harlequin ichthyosis (HI) is a rare congenital skin disorder caused by irregular epidermal differentiation. Syndactyly in HI is associated with thick hyperkeratotic skin flexion and angulation deformity of the hand and fingers resulting in limited function of the upper extremity. Traditional syndactyly release is limited as full-thickness skin grafts typically used in reconstruction are composed of diseased skin and require donor sites in a patient predisposed for adverse wound healing. This case report is a follow-up to a previous viewpoint written about digital escharotomies in a newborn with HI and outlines a second and fourth webspace syndactyly release with a dermal substitute. Despite early evidence of adequate release and improved hand function, recurrence of syndactyly was observed within 4 months of surgical release. Our experience described within this case report may suggest the limitations and possible alternatives of surgical release of syndactyly in the HI population