Impact of supportive housing health homes program on medicaid utilization for persons diagnosed with HIV (PDWH).

ABSTRACTUnstable housing among persons diagnosed with HIV (PDWH) has been consistently linked to poor HIV-related care engagement. We examined the relationship between enrollment in a supportive housing program and health care utilization (use of outpatient services, emergency department (ED) visits, and hospitalizations) for a group of unstably housed, Medicaid and Health Homes (HH)-enrolled PDWH in New York State. We analyzed monthly longitudinal data consisting of linked supportive housing data, HH data, and Medicaid claims from New York State (excluding New York City) between 2012 and 2017 using time series models. Participants who had at least six consecutive months of supportive housing at month t had 20% higher odds of using an outpatient service, 19% lower odds of visiting the ED, and 24% lower odds of being hospitalized compared to those with less than six consecutive months of supportive housing after adjusting for covariates. Supportive housing may promote better medical management by increasing outpatient visits among chronically homeless PDWH.

Sulcal Cavitation in Linear Head Acceleration: Possible Correlation With Chronic Traumatic Encephalopathy.

Traumatic Brain Injury (TBI) is a significant public health and financial concern that is affecting tens of thousands of people in the United States annually. There were over a million hospital visits related to TBI in 2017. Along with immediate and short-term morbidity from TBI, chronic traumatic encephalopathy (CTE) can have life-altering, chronic morbidity, yet the direct linkage of how head impacts lead to this pathology remains unknown. A possible clue is that chronic traumatic encephalopathy appears to initiate in the depths of the sulci. The purpose of this study was to isolate the injury mechanism/s associated with blunt force impact events. To this end, drop tower experiments were performed on a human head phantom. Our phantom was fabricated into a three-dimensional extruded ellipsoid geometry made out of Polyacrylamide gelatin that incorporated gyri-sulci interaction. The phantom was assembled into a polylactic acid 3D-printed skull, surrounded with deionized water, and enclosed between two optical windows. The phantom received repetitive low-force impacts on the order of magnitude of an average boxing punch. Intracranial pressure profiles were recorded in conjunction with high-speed imaging, 25 k frames-per-second. Cavitation was observed in all trials. Cavitation is the spontaneous formation of vapor bubbles in the liquid phase resulting from a pressure drop that reaches the vapor pressure of the liquid. The observed cavitation was predominately located in the contrecoup during negative pressure phases of local intracranial pressure. To further investigate the cavitation interaction with the brain tissue phantom, a 2D plane strain computational model was built to simulate the deformation of gyrated tissue as a result from the initiation of cavitation bubbles seen in the phantom experiments. These computational experiments demonstrated a focusing of strain at the depths of the sulci from bubble expansion. Our results add further evidence that mechanical interactions could contribute to the development of chronic traumatic encephalopathy and also that fluid cavitation may play a role in this interaction.

Localizing Clinical Patterns of Blast Traumatic Brain Injury Through Computational Modeling and Simulation.

Blast traumatic brain injury is ubiquitous in modern military conflict with significant morbidity and mortality. Yet the mechanism by which blast overpressure waves cause specific intracranial injury in humans remains unclear. Reviewing of both the clinical experience of neurointensivists and neurosurgeons who treated service members exposed to blast have revealed a pattern of injury to cerebral blood vessels, manifested as subarachnoid hemorrhage, pseudoaneurysm, and early diffuse cerebral edema. Additionally, a seminal neuropathologic case series of victims of blast traumatic brain injury (TBI) showed unique astroglial scarring patterns at the following tissue interfaces: subpial glial plate, perivascular, periventricular, and cerebral gray-white interface. The uniting feature of both the clinical and neuropathologic findings in blast TBI is the co-location of injury to material interfaces, be it solid-fluid or solid-solid interface. This motivates the hypothesis that blast TBI is an injury at the intracranial mechanical interfaces. In order to investigate the intracranial interface dynamics, we performed a novel set of computational simulations using a model human head simplified but containing models of gyri, sulci, cerebrospinal fluid (CSF), ventricles, and vasculature with high spatial resolution of the mechanical interfaces. Simulations were performed within a hybrid Eulerian-Lagrangian simulation suite (CTH coupled via Zapotec to Sierra Mechanics). Because of the large computational meshes, simulations required high performance computing resources. Twenty simulations were performed across multiple exposure scenarios-overpressures of 150, 250, and 500 kPa with 1 ms overpressure durations-for multiple blast exposures (front blast, side blast, and wall blast) across large variations in material model parameters (brain shear properties, skull elastic moduli). All simulations predict fluid cavitation within CSF (where intracerebral vasculature reside) with cavitation occurring deep and diffusely into cerebral sulci. These cavitation events are adjacent to high interface strain rates at the subpial glial plate. Larger overpressure simulations (250 and 500kPa) demonstrated intraventricular cavitation-also associated with adjacent high periventricular strain rates. Additionally, models of embedded intraparenchymal vascular structures-with diameters as small as 0.6 mm-predicted intravascular cavitation with adjacent high perivascular strain rates. The co-location of local maxima of strain rates near several of the regions that appear to be preferentially damaged in blast TBI (vascular structures, subpial glial plate, perivascular regions, and periventricular regions) suggest that intracranial interface dynamics may be important in understanding how blast overpressures leads to intracranial injury.

Materials Characterization of Cranial Simulants for Blast-Induced Traumatic Brain Injury.

INTRODUCTION: The mechanical response of brain tissue to high-speed forces in the blast and blunt traumatic brain injury is poorly understood. Object-to-object variation and interspecies differences are current limitations in animal and cadaver studies conducted to study damage mechanisms. Biofidelic and transparent tissue simulants allow the use of high-speed optical diagnostics during a blast event, making it possible to observe deformations and damage patterns for comparison to observed injuries seen post-mortem in traumatic brain injury victims. METHODS: Material properties of several tissue simulants were quantified using standard mechanical characterization techniques, that is, shear rheometric, tensile, and compressive testing. RESULTS: Polyacrylamide simulants exhibited the best optical and mechanical property matching with the fewest trade-offs in the design of a cranial test object. Polyacrylamide gels yielded densities of ~1.04 g/cc and shear moduli ranging 1.3-14.55 kPa, allowing gray and white matter simulant tuning to a 30-35% difference in shear for biofidelity. CONCLUSIONS: These materials are intended for use as layered cranial phantoms in a shock tube and open field blasts, with focus on observing phenomena occurring at the interfaces of adjacent tissue simulant types or material-fluid boundaries. Mechanistic findings from these studies may be used to inform the design of protective gear to mitigate blast injuries.

History of space medicine: the formative years at NASA.

Almost nothing was known about the effects of spaceflight on human physiology when, in May of 1961, President John F. Kennedy committed the United States to land a man on the Moon and return him safely to Earth within the decade. There were more questions than answers regarding the effects of acceleration, vibration, cabin pressure, CO2 concentration, and microgravity. There were known external threats to life, such as solar and ultraviolet radiation, meteorites, and extreme temperatures as well as issues for which the physicians and scientists could not even formulate the questions. And there was no time for controlled experiments with the required numbers of animal or human subjects. Of necessity, risks were evaluated and mitigated or accepted based on minimal data. This article summarizes presentations originally given as a panel at the 79th Annual Scientific Meeting of the Aerospace Medical Association in Boston in 2008. In it, five pioneers in space medicine at NASA looked back on the development of their field. The authors related personal anecdotes, discussed the roles of various people and presented examples of contributions to emerging U.S. initiatives for human spaceflight. Topics included the development of quarantine facilities for returning Apollo astronauts, the struggles between operational medicine and research personnel, and observations from the first U.S. medical officer to experience weightlessness on orbit. Brief biographies of the authors are appended to document their participation in these historic events.

Human health and performance for long-duration spaceflight.

Future long-duration spaceflights are now being planned to the Moon and Mars as a part of the "Vision for Space Exploration" program initiated by NASA in 2004. This report describes the design reference missions for the International Space Station, Lunar Base, and eventually a Mars Expedition. There is a need to develop more stringent preflight medical screening for crewmembers to minimize risk factors for diseases which cannot be effectively treated in flight. Since funding for space life sciences research and development has been eliminated to fund program development, these missions will be enabled by countermeasures much like those currently in use aboard the International Space Station. Artificial gravity using centrifugation in a rotating spacecraft has been suggested repeatedly as a "universal countermeasure" against deconditioning in microgravity and could be an option if other countermeasures are found to be ineffective. However, the greatest medical unknown in interplanetary flight may be the effects of radiation exposure. In addition, a Mars expedition would lead to a far greater level of isolation and psychological stress than any space mission attempted previously; because of this, psychiatric decompensation remains a risk. Historically, mortality and morbidity related to illness and injury have accounted for more failures and delays in new exploration than have defective transportation systems. The medical care system on a future Mars expedition will need to be autonomous and self-sufficient due to the extremely long separation from definitive medical care. This capability could be expanded by the presence of a physician in the crew and including simple, low-technology surgical capability.

Eating in space--from an astronaut's perspective.

Food systems and meal components are constantly under review and development at the National Aerospace and Space Administration. The goal of this work is to generate a diet that meets the nutrient requirements of astronauts and satiates them. The constraints involved in shorter- and longer-term missions are described. The insight provided by observations of astronauts from the Skylab and Shuttle eras will allow researchers to consider the fact that, for any nutritional regimen to work, it must consider the limitations and taste buds of the individuals involved. Otherwise, the best diet design generated by their work may never be consumed.