An overview of the American trauma system.

The American trauma system is designed to provide an organized response to injury. It draws its foundations from lessons learned from America's involvement in the wars of the 20th century as well as principles developed in urban community hospitals. Although run at the local and state government level, it is guided by national societies and has become a world class example. It also currently faces challenges with declining reimbursement and providing equal access to care for all Americans. Professional societies and legislative bodies are continuing to work together for fair and equitable solutions to these issues.

How Does the Gibbs Inequality Condition Affect the Stability and Detachment of Floating Spheres from the Free Surface of Water?

Floating objects on the air-water interfaces are central to a number of everyday activities, from walking on water by insects to flotation separation of valuable minerals using air bubbles. The available theories show that a fine sphere can float if the force of surface tension and buoyancies can support the sphere at the interface with an apical angle subtended by the circle of contact being larger than the contact angle. Here we show that the pinning of the contact line at the sharp edge, known as the Gibbs inequality condition, also plays a significant role in controlling the stability and detachment of floating spheres. Specifically, we truncated the spheres with different angles and used a force sensor device to measure the force of pushing the truncated spheres from the interface into water. We also developed a theoretical modeling to calculate the pushing force that in combination with experimental results shows different effects of the Gibbs inequality condition on the stability and detachment of the spheres from the water surface. For small angles of truncation, the Gibbs inequality condition does not affect the sphere detachment, and hence the classical theories on the floatability of spheres are valid. For large truncated angles, the Gibbs inequality condition determines the tenacity of the particle-meniscus contact and the stability and detachment of floating spheres. In this case, the classical theories on the floatability of spheres are no longer valid. A critical truncated angle for the transition from the classical to the Gibbs inequality regimes of detachment was also established. The outcomes of this research advance our understanding of the behavior of floating objects, in particular, the flotation separation of valuable minerals, which often contain various sharp edges of their crystal faces.

The Floatability of Single Spheres versus Their Pairs on the Water Surface.

Particle floatability at the water surface encountered in nature and industrial systems often occurs in the presence of many particles, but the available theoretical developments are based on the flotation of single particles. Here experiments were conducted to compare the floatabilities of single and multiple spheres on the air-water interfaces. Specifically, the forces on floating single spheres and their pairs versus the depth of deformed interface were measured using a force sensor combined with high-speed video microscopy and modeled based on the 3D Young-Laplace equation which was numerically solved. The experimental and theoretical results for the vertical forces supporting the floatability of the pairs of spheres agree well. The maximum measured forces on the pairs were equal to the sum of the maximum forces measured on two single spheres individually, but the forces measured on the single spheres and their pairs at different depths of interface deformation were different. The vertical forces supporting the floatability of the sphere pairs can better tolerate the interface deformation than the same force on two single particles. This evidence is also supported by the experiments with multiple particles floating at the surface of water-ethanol mixtures. Adding ethanol into water reduced the surface tension of water and the floatability of particles at the water surface, but the floatability of multiple particles was sustainable at much lower critical surface tensions than that for single particles, invalidating the classical theories. Lateral interparticle interactions influence the floatability of particles and should be considered in its modeling.

Effect of contact angle and contact angle hysteresis on the floatability of spheres at the air-water interface.

The floatability of solid particles on the water surface governs many natural phenomena and industrial processes including film flotation and froth flotation separation of coal and valuable minerals. For many years, the contact angle (CA) has been postulated as the key factor in determining the particle floatability. Indeed, the maximum force (tenacity) supporting the flotation of fine spheres was conjectured to occur when the apical angle of the contact circle is equal to the contact angle. In this paper, the model predictions are reviewed and compared with experimental results. It is shown that CA can be affected by many physical and chemical factors such as surface roughness and chemical heterogeneity and can have a range of values known as the CA hysteresis. This multiple-valued CA invalidates the available theories on the floatability of spheres. Even the intuitive replacement of CA by the advancing (maximum) CA in the classical theories can be wrong. A few new examples are also reviewed and analyzed to demonstrate the significance of CA variation in controlling the particle floatability. They include the pinning of the contact line at the sharp edge, known as the Gibbs inequality condition, and the nearby interaction among floating particles, known as lateral inter-particle interaction. It is concluded that our quantitative understanding of the floatability of real particles being irregular and heterogeneous both morphologically and chemically is still far from being satisfactory.

Advances in molecular mechanism of cardioprotection induced by helium.

Helium has been classified as a kind of inert gas that is not effortless to spark chemical reactions with other substances in the past decades. Nevertheless, the cognition of scientists has gradually changed accompanied with a variety of studies revealing the potential molecular mechanism underlying organ-protection induced by helium. Especially, as a non-anesthetic gas which is deficient of relevant cardiopulmonary side effects, helium conditioning is recognized as an emerging and promising approach to exert favorable effects by mimicking the cardioprotection of anesthetic gases or xenon. In this review we will summarize advances in the underlying biological mechanisms and clinical applicability with regards to the cardioprotective effects of helium.

Neuroprotection provided by isoflurane pre-conditioning and post-conditioning.

Isoflurane, a volatile and inhalational anesthetic, has been extensively used in perioperative period for several decades. A large amount of experimental studies have indicated that isoflurane exhibits neuroprotective properties when it is administrated before or after (pre-conditioning and post-conditioning) neurodegenerative diseases (e.g., hypoxic ischemia, stroke and trauma). Multiple mechanisms are involved in isoflurane induced neuroprotection, including activation of glycine and γ-aminobutyric acid receptors, antagonism of ionic channels and alteration of the function and activity of other cellular proteins. Although neuroprotection provided by isoflurane is observed in many animal studies, convincing evidence is lacking in human trials. Therefore, there is still a long way to go before translating its neuroprotective properties into clinical practice.

The role of nitric oxide in stroke.

Stroke is considered to be an acute cerebrovascular disease, including ischemic stroke and hemorrhagic stroke. The high incidence and poor prognosis of stroke suggest that it is a highly disabling and highly lethal disease which can pose a serious threat to human health. Nitric oxide (NO), a common gas in nature, which is often thought as a toxic gas, because of its intimate relationship with the pathological processes of many diseases, especially in the regulation of blood flow and cell inflammation. However, recent years have witnessed an increased interest that NO plays a significant and positive role in stroke as an essential gas signal molecule. In view of the fact that the neuroprotective effect of NO is closely related to its concentration, cell type and time, only in the appropriate circumstances can NO play a protective effect. The purpose of this review is to summarize the roles of NO in ischemic stroke and hemorrhagic stroke.

Roles of autophagy and endoplasmic reticulum stress in intracerebral hemorrhage-induced secondary brain injury in rats.

OBJECTIVES: This study aimed to evaluate the roles of autophagy and endoplasmic reticulum (ER) stress in intracerebral hemorrhage (ICH)-induced secondary brain injury (SBI) in rats. METHODS: Autophagy inducer (rapamycin) and inhibitor (3-methyladenine), as well as ER stress activator (tunicamycin, TM) and inhibitor (tauroursodeoxycholic acid, TUDCA), were used. Bafilomycin A1, an inhibitor of autophagosome-lysosome fusion, was used to assess autophagic flux. RESULTS: Autophagy and ER stress were enhanced in the week after ICH. At 6 hours after ICH, autophagy was excessive, while the autophagic flux was damaged at 72 hours and return to be intact at 7 days after ICH. At 6 hours after ICH, ER stress induction by TM could enhance autophagy and lead to caspase 12-mediated apoptosis and neuronal degeneration, which was further aggravated by autophagy induction. At 7 days after ICH, ER stress inhibition by TUDCA still could suppress ICH-induced SBI. And, the effects of TUDCA were enhanced by autophagy induction. CONCLUSIONS: At 6 hours after ICH, excessive autophagy may participate in ER stress-induced brain injury; at 7 days after ICH, autophagy could enhance the protection of ER stress inhibitor possibly via clearing up the cell rubbish generated due to the early-stage damaged autophagic flux.

Anatomical study of endoscope-assisted far lateral keyhole approach to the ventral craniocervical region with neuronavigational guidance.

BACKGROUND: Image-guided neurosurgery, endoscopic-assisted neurosurgery and the keyhole approach are three important parts of minimally invasive neurosurgery and have played a significant role in treating skull base lesions. This study aimed to investigate the potential usefulness of coupling of the endoscope with the far lateral keyhole approach and image guidance at the ventral craniocervical junction in a cadaver model. METHODS: We simulated far lateral keyhole approach bilaterally in five cadaveric head specimens (10 cranial hemispheres). Computed tomography-based image guidance was used for intraoperative navigation and for quantitative measurements. Skull base structures were observed using both an operating microscope and a rigid endoscope. The jugular tubercle and one-third of the occipital condyle were then drilled, and all specimens were observed under the microscope again. We measured and compared the exposure of the petroclivus area provided by the endoscope and by the operating microscope. Statistical analysis was performed by analysis of variance followed by the Student-Newman-Keuls test. RESULTS: With endoscope assistance and image guidance, it was possible to observe the deep ventral craniocervical junction structures through three nerve gaps (among facial-acoustical nerves and the lower cranial nerves) and structures normally obstructed by the jugular tubercle and occipital condyle in the far lateral keyhole approach. The surgical area exposed in the petroclival region was significantly improved using the 0° endoscope (1147.80 mm(2)) compared with the operating microscope ((756.28 ± 50.73) mm(2)). The far lateral retrocondylar keyhole approach, using both 0° and 30° endoscopes, provided an exposure area ((1147.80 ± 159.57) mm(2) and (1409.94 ± 155.18) mm(2), respectively) greater than that of the far lateral transcondylar transtubercular keyhole approach ((1066.26 ± 165.06) mm(2)) (P < 0.05). CONCLUSIONS: With the aid of the endoscope and image guidance, it is possible to approach the ventral craniocervical junction with the far lateral keyhole approach. The use of an angled-lens endoscope can significantly improve the exposure of the petroclival region without drilling the jugular tubercle and occipital condyle.