The purpose of this work was to establish a methodology to enable the isolation and study of osteocytes from skeletally mature young (4-month-old) and old (22-month-old) mice. The location of ...osteocytes deep within bone is ideal for their function as mechanosensors. However, this location makes the observation and study of osteocytes in vivo technically difficult. Osteocytes were isolated from murine long bones through a process of extended collagenase digestions combined with EDTA-based decalcification. A tissue homogenizer was used to reduce the remaining bone fragments to a suspension of bone particles, which were placed in culture to yield an outgrowth of osteocyte-like cells. All of the cells obtained from this outgrowth that displayed an osteocyte-like morphology stained positive for the osteocyte marker E11/GP38. The osteocyte phenotype was further confirmed by a lack of staining for alkaline phosphatase and the absence of collagen1a1 expression. The outgrowth of osteocytes also expressed additional osteocyte-specific genes such as
and
. This technique facilitates the isolation of osteocytes from skeletally mature bone. This novel enabling methodology should prove useful in advancing our understanding of the roles mature osteocytes play in bone health and disease.
Quantitative Pupillometry in the Intensive Care Unit Bower, Matthew M.; Sweidan, Alexander J.; Xu, Jordan C. ...
Journal of Intensive Care Medicine,
04/2021, Letnik:
36, Številka:
4
Book Review, Journal Article
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Quantitative pupillometry provides a noninvasive and objective assessment within the neurological examination. This review details the physiology of the pupillary light response, the clinical ...significance of changes in pupillary reactivity, and the variables that compose the Neurological Pupil index or NPi are discussed. This article reviews the most recent applications and advances in quantitative pupillometry for noninvasive intracranial pressure monitoring, postcardiac arrest prognostication, and subarachnoid hemorrhage. Also discussed are the limitations and confounders of quantitative pupillometry in the modern neurological intensive care unit.
Abstract Skeletal muscle relies upon regeneration to maintain homeostasis and repair injury. This process involves the recruitment of the tissue's resident stem cell, the muscle progenitor cell, and ...a subsequent proliferative response by newly generated myoblasts, which must then align and fuse to generate new muscle fibers. During regeneration, cells rely on environmental input for direction. Extracellular matrix (ECM) represents a crucial component of a cell's microenvironment that aids in guiding muscle regeneration. We hypothesized that ECM extracted from skeletal muscle would provide muscle progenitor cells and myoblasts with an ideal substrate for growth and differentiation ex vivo . To test this hypothesis, we developed a method to extract ECM from the large thigh muscles of adult rats and present it to cells as a surface coating. Myogenic cells cultured on ECM extract experienced enhanced proliferation and differentiation relative to standard growth surfaces. As the methodology can be applied to any size muscle, these results demonstrate that bioactive ECM can be readily obtained from skeletal muscle and used to develop biomaterials that enhance muscle regeneration. Furthermore, the model system demonstrated here can be applied to the study of interactions between the ECM of a particular tissue and a cell population of interest.
Abstract There is currently no optimal system to expand and maintain the function of human adult hepatocytes in culture. Recent studies have demonstrated that specific tissue-derived extracellular ...matrix (ECM) can serve as a culture substrate and that cells tend to proliferate and differentiate best on ECM derived from their tissue of origin. The goal of this study was to investigate whether three-dimensional (3D) ECM derived from porcine liver can facilitate the growth and maintenance of physiological functions of liver cells. Optimized decellularization/oxidation procedures removed up to 93% of the cellular components from porcine liver tissue and preserved key molecular components in the ECM, including collagen-I, -III, and -IV, proteoglycans, glycosaminoglycans, fibronectin, elastin, and laminin. When HepG2 cells or human hepatocytes were seeded onto ECM discs, uniform multi-layer constructs of both cell types were formed. Dynamic culture conditions yielded better cellular infiltration into the ECM discs. Human hepatocytes cultured on ECM discs expressed significantly higher levels of albumin over a 21-day culture period compared to cells cultured in traditional polystyrene cultureware or in a collagen gel “sandwich”. The culture of hepatocytes on 3D liver-specific ECM resulted in considerably improved cell growth and maintained cell function; therefore, this system could potentially be used in liver tissue regeneration, drug discovery or toxicology studies.
The Alice ultraviolet spectrograph on the European Space Agency Rosetta spacecraft observed comet 67P/Churyumov-Gerasimenko in its orbit around the Sun for just over two years. Alice observations ...taken in 2015 October, two months after perihelion, show large increases in the comet's Lyβ, O i 1304, O i 1356, and C i 1657 atomic emission that initially appeared to indicate gaseous outbursts. However, the Rosetta Plasma Consortium instruments showed a coronal mass ejection (CME) impact at the comet coincident with the emission increases, suggesting that the CME impact may have been the cause of the increased emission. The presence of the semi-forbidden O i 1356 emission multiplet is indicative of a substantial increase in dissociative electron impact emission from the coma, suggesting a change in the electron population during the CME impact. The increase in dissociative electron impact could be a result of the interaction between the CME and the coma of 67P or an outburst coincident with the arrival of the CME. The observed dissociative electron impact emission during this period is used to characterize the O2 content of the coma at two peaks during the CME arrival. The mechanism that could cause the relationship between the CME and UV emission brightness is not well constrained, but we present several hypotheses to explain the correlation.
Abstract
The Alice ultraviolet spectrograph on board the Rosetta orbiter provided the first near-nucleus ultraviolet observations of a cometary coma from arrival at comet 67P/Churyumov-Gerasimenko in ...2014 August through 2016 September. The characterization of atomic and molecular emissions in the coma revealed the unexpected contribution of dissociative electron impact emission at large heliocentric distances and during some outbursts. This mechanism also proved useful for compositional analysis, and Alice observed many cases that suggested elevated levels of the supervolatile O
2
, identifiable in part to their emissions resulting from dissociative electron impact. In this paper, we present the first two-dimensional UV maps constructed from Alice observations of atomic emission from 67P during an increase in cometary activity on 2015 November 7–8. Comparisons to observations of the background coma and an earlier collimated jet are used to describe possible changes to the near-nucleus coma and plasma. To verify the mapping method and place the Alice observations in context, comparisons to images derived from the MIRO and VIRTIS-H instruments are made. The spectra and maps we present show an increase in dissociative electron impact emission and an O
2
/H
2
O ratio of ∼0.3 for the activity; these characteristics have been previously identified with cometary outbursts seen in Alice data. Further, UV maps following the increases in activity show the spatial extent and emission variation experienced by the near-nucleus coma, informing future UV observations of comets that lack the same spatial resolution.
The Alice far-ultraviolet imaging spectrograph onboard Rosetta observed emissions from atomic and molecular species from within the coma of comet 67P/Churyumov-Gerasimenko during the entire escort ...phase of the mission from 2014 August to 2016 September. The initial observations showed that emissions of atomic hydrogen and oxygen close to the surface were produced by energetic electron impact dissociation of H2O. Following delivery of the lander, Philae, on 2014 November 12, the trajectory of Rosetta shifted to near-terminator orbits that allowed for these emissions to be observed against the shadowed nucleus that, together with the compositional heterogeneity, enabled us to identify unique spectral signatures of dissociative electron impact excitation of H2O, CO2, and O2. CO emissions were found to be due to both electron and photoexcitation processes. Thus, we are able, from far-ultraviolet spectroscopy, to qualitatively study the evolution of the primary molecular constituents of the gaseous coma from start to finish of the escort phase. Our results show asymmetric outgassing of H2O and CO2 about perihelion, H2O dominant before and CO2 dominant after, consistent with the results from both the in situ and other remote sensing instruments on Rosetta.
Summary
The epidermis of the skin, acting as the primary physical barrier between self and environment, is a dynamic tissue whose maintenance is critical to the survival of an organism. Like most ...other tissues and organs, the epidermis is maintained and repaired by a population of resident somatic stem cells. The epidermal stem cells reside in the proliferative basal cell layer and are believed to persist for the lifetime of an individual. Acting through intermediaries known as transit amplifying cells, epidermal stem cells ensure that the enormous numbers of keratinocytes required for epidermal homeostasis to be maintained are generated. This continual demand for new cell production must be met over the entire lifetime of an individual. Breakdown of the epidermal barrier would have catastrophic consequences. This leads us to question whether or not epidermal stem cells represent a unique population of cells which, by necessity, might be resistant to cellular aging. We hypothesized that the full physiologic functional capacity of epidermal stem cells is maintained over an entire lifetime. Using murine skin epidermis as our model system, we compared several properties of young and old adult epidermal stem cells. We found that, over an average mouse's lifetime, there was no measurable loss in the physiologic functional capacity of epidermal stem cells, leading us to conclude that murine epidermal stem cells resist cellular aging.
Abstract
Cometary outbursts offer a valuable window into the composition of comet nuclei with their forceful ejection of dust and volatiles in explosive events, revealing the interior components of ...the comet. Understanding how different types of outbursts influence the dust properties and volatile abundances, to better interpret what signatures can be attributed to primordial composition and what features are the result of processing, is an important task best undertaken with a multi-instrument approach. The European Space Agency Rosetta mission to 67P/Churyumov–Gerasimenko carried a suite of instruments capable of carrying out this task in the near-nucleus coma with unprecedented spatial and spectral resolution. In this work, we discuss two outbursts that occurred 2015 November 7 and were observed by three instruments on board: the Alice ultraviolet spectrograph, the Visual Infrared and Thermal Imaging Spectrometer, and the Optical, Spectroscopic, and Infrared Remote Imaging System. Together, the observations show that mixed gas and dust outbursts can have different spectral signatures representative of their initiating mechanisms, with the first outburst showing indicators of a cliff collapse origin and the second more representative of fresh volatiles being exposed via a deepening fracture. This analysis opens up the possibility of remote spectral classification of cometary outbursts with future work.
Connections between students and faculty on campus may influence students’ sense of belonging, and a greater sense of belonging has a positive effect on student success. We developed a low-cost, ...faculty-led program of community-building events and implemented the program in the biology department at a small liberal-arts institution with the goal of improving students’ sense of community. Student responses to surveys indicated that the majority of students felt connected to faculty and students in the department; however, Black or African American students initially felt a lower level of connection to faculty than did white students. After implementing our series of community-building events, students surveyed reported high levels of satisfaction with the events. Furthermore, there was a trend toward a higher percentage of Black or African American students than white students reporting that they were more likely to reach out to faculty after participating in the community-building events. Thus, our low-cost program improved connections between students and faculty in the biology department. Collectively, our results suggest that academic departments can implement community-building programs to improve students’ sense of belonging.
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