Transport of solutes through brain involves diffusion and convection. The importance of convective flow in the subarachnoid and paravascular spaces has long been recognized; a recently proposed ...'glymphatic' clearance mechanism additionally suggests that aquaporin-4 (AQP4) water channels facilitate convective transport through brain parenchyma. Here, the major experimental underpinnings of the glymphatic mechanism were re-examined by measurements of solute movement in mouse brain following intracisternal or intraparenchymal solute injection. We found that: (i) transport of fluorescent dextrans in brain parenchyma depended on dextran size in a manner consistent with diffusive rather than convective transport; (ii) transport of dextrans in the parenchymal extracellular space, measured by 2-photon fluorescence recovery after photobleaching, was not affected just after cardiorespiratory arrest; and (iii)
gene deletion did not impair transport of fluorescent solutes from sub-arachnoid space to brain in mice or rats. Our results do not support the proposed glymphatic mechanism of convective solute transport in brain parenchyma.
In this study, Gaussian mixture model clustering analysis was carried out to examine characteristics of Global Precipitation Measurement (GPM) Dual‐frequency Precipitation Radar (DPR)‐retrieved ...mass‐weighted mean diameter (Dm), and normalized intercept parameter (Nw) of the drop size distribution (DSD) for heavy rainfalls (>10 mm h−1) for 6 years (2014–2019). Three objective DSD types – continental, oceanic deep, and oceanic shallow convective types – emerged. The means and standard deviations of Dm and Nw obtained for the three types are in good agreement with various ground‐based observations, indicating that global view of DSD characteristics can be obtained from DPR‐derived DSD parameters. Global distributions of occurrence and contribution of each DSD type to total heavy rainfall are produced for the first time, which will help examine the dominant DSD type, its contribution to total heavy rainfall, and composition of different convective types in the rainfall system at a given location.
Plain Language Summary
The surface rainfall is composed of a variety of spectrum of raindrops, which can be best represented by mean drop size and number concentration of droplets. Thus, those magnitude and shape may well describe rainfall‐related features such as convective type and associated atmospheric environments. Thus, information on the rain drop size distribution is important for improving the remote sensing capability or modeling the rainfall phenomena. From the analysis of satellite‐derived rain drop size distribution, it is noted that the heavy rainfall can be largely classified into three types – continental, oceanic deep, and oceanic shallow convective types. Satellite‐derived mean diameter and drop size distribution for heavy rain are found to be very consistent with ground observations from limited local areas, indicating that the global view of drop size distributions can be synthesized from the satellite observations. The newly obtained global features overcome the spatial limitations of existing studies using ground‐based observations. Furthermore, estimated contribution to the heavy rainfall from each classified type shows that a largest portion is from the oceanic deep convective type, and the oceanic shallow convective type contributes as much as the continental type.
Key Points
Global synthesis of drop size distributions for heavy rainfall using satellite‐borne radar measurements
Three heavy rainfall types emerged – continental, oceanic deep, and oceanic shallow convective types
Geographic distributions of occurrence frequencies and rain contributions of three types are presented
The pathway to the maxillary sinus is anatomically curved and narrow. Thus, the conventional approach using a straight endoscope and surgical tools is difficult to diagnose and treat some blind ...regions of the maxillary sinus through the nostrils. Such cases are usually dealt with by an approach with an external incision that causes large invasive surgery. In order to approach the blind regions without any external incision, a new bendable device and an image-guided robotic approach for the maxillary sinus surgery are required. This work reports design, development, and validation of an image-guided dual master-slave robotic system for the maxillary sinus surgery. Initially, specifications of the robotic system for sinus surgery are decided by analysis of the anatomical structure of the sinus. A method for determining the design parameters of continuum type salve robot is also presented. Based on the specifications and the design parameter determining method, a compact design of bendable dual slave robotic system for inspection and biopsy operation of the maxillary sinus area is devised and workspace analysis for verifying the robot design is conducted. The performance of the dual master-slave system equipped with flexible devices is validated through several phantom tests. The results suggest that bendable end-effectors and navigation software are useful to navigate and treat blind regions inside general sinus areas as well as the maxillary sinus.
A "glymphatic system," which involves convective fluid transport from para-arterial to paravenous cerebrospinal fluid through brain extracellular space (ECS), has been proposed to account for solute ...clearance in brain, and aquaporin-4 water channels in astrocyte endfeet may have a role in this process. Here, we investigate the major predictions of the glymphatic mechanism by modeling diffusive and convective transport in brain ECS and by solving the Navier-Stokes and convection-diffusion equations, using realistic ECS geometry for short-range transport between para-arterial and paravenous spaces. Major model parameters include para-arterial and paravenous pressures, ECS volume fraction, solute diffusion coefficient, and astrocyte foot-process water permeability. The model predicts solute accumulation and clearance from the ECS after a step change in solute concentration in para-arterial fluid. The principal and robust conclusions of the model are as follows: (a) significant convective transport requires a sustained pressure difference of several mmHg between the para-arterial and paravenous fluid and is not affected by pulsatile pressure fluctuations; (b) astrocyte endfoot water permeability does not substantially alter the rate of convective transport in ECS as the resistance to flow across endfeet is far greater than in the gaps surrounding them; and (c) diffusion (without convection) in the ECS is adequate to account for experimental transport studies in brain parenchyma. Therefore, our modeling results do not support a physiologically important role for local parenchymal convective flow in solute transport through brain ECS.
We observe a notable decreasing trend of June rainfall over the Korean peninsula in recent 20 years. This drought condition is found to be linked to the polarizing trend of rainfall intensity; more ...non‐rain and drizzle‐like rain, less moderate‐intensity rain, and more heavy rain events. Overall, the June drought over the Korean peninsula is found to be associated with less occurring moderate‐intensity rain. This feature is interpreted as that the dominant warm‐type heavy rain systems with a medium storm height tends to be less frequent while cold‐type heavy rains characterized by taller storm become more frequent during last 20 years. The northwestward expansion of the North Pacific high in June appears to weaken the continuous moisture supply to the Korean peninsula, which is a main element of forming the warm‐type heavy rain there.
Climatological mean (left) and linear trend (right) for the frequency distribution of storm height normalized by near‐surface radar reflectivities over the Korean domain (June 1998–2017).
Recent satellite observations suggested that medium‐depth heavy rain systems (i.e., warm‐type heavy rainfall) were predominantly found in the Korean peninsula under moist‐adiabatically near neutral ...conditions in contrast to the traditional view that deep convection induced by convective instability produced heavy rainfall (i.e., cold‐type heavy rainfall). In order to examine whether a numerical model could explain the microphysical evolution of the warm‐type as well as cold‐type heavy rainfall, numerical experiments were implemented with idealized thermodynamic conditions. Under the prescribed humid and weakly unstable conditions, the warm‐type experiments resulted in a lower storm height, earlier onset of precipitation, and heavier precipitation than was found for the cold‐type experiments. The growth of ice particles and their melting process were important for developing cold‐type heavy rainfall. In contrast, the collision and coalescence processes between liquid particles were shown to be the mechanism for increasing the radar reflectivity toward the surface in the storm core region for the warm‐type heavy rainfall.
Key Points
Numerical experiments are performed with idealized thermodynamic conditions to understand the formation of “warm‐type” heavy rainfall
Under humid and moist‐adiabatically near neutral conditions, “warm‐type” clouds with a lower storm height can also produce heavy rainfall
The collision‐coalescence process of raindrops is responsible for producing the warm‐type heavy rainfall
Aquaporin 1 (AQP1) is a plasma membrane water‐transporting protein expressed strongly in tumor microvascular endothelia. We previously reported impaired angiogenesis in implanted tumors in ...AQP1‐deficient mice and reduced migration of AQP1‐deficient endothelial cells in vitro. Here, we investigated the consequences of AQP1 deficiency in mice that spontaneously develop well‐differentiated, luminal‐type breast adenomas with lung metastases mouse mammary tumor virus‐driven polyoma virus middle T oncogene (MMTV‐PyVT). AQP1+/+ MMTV‐PyVT mice developed large breast tumors with total tumor mass 3.5 ± 0.5 g and volume 265 ± 36 mm3 (se, 11 mice) at age 98 d. Tumor mass (1.6±0.2 g) and volume (131±15 mm3, 12 mice) were greatly reduced in AQP1–/– MMTV‐PyVT mice (P<0.005). CD31 immunofluorescence showed abnormal microvascular anatomy in tumors of AQP1–/– MMTV‐PyVT mice, with reduced vessel density. HIF‐1α expression was increased in tumors in AQP1–/– MMTV‐PyVT mice. The number of lung metastases (5± 1/mouse) was much lower than in AQP1+/+ MMTV‐PyVT mice (31±8/mouse, P<0.005). These results implicate AQP1 as an important determinant of tumor angiogenesis and, hence, as a potential drug target for adjuvant therapy of solid tumors.—Esteva‐Font, C., Jin, B.‐J., Verkman, A. S. Aquaporin‐1 gene deletion reduces breast tumor growth and lung metastasis in tumor‐producing MMTV‐PyVT mice. FASEB J. 28, 1446–1453 (2014). www.fasebj.org
Robotic magnetic manipulation systems offer a wide range of potential benefits in medical fields, such as precise and selective manipulation of magnetically responsive instruments in ...difficult‐to‐reach vessels and tissues. However, more preclinical/clinical studies are necessary before robotic magnetic interventional systems can be widely adopted. In this study, a clinically translatable, electromagnetically controllable microrobotic interventional system (ECMIS) that assists a physician in remotely manipulating and controlling microdiameter guidewires in real time, is reported. The ECMIS comprises a microrobotic guidewire capable of active magnetic steering under low‐strength magnetic fields, a human‐scale electromagnetic actuation (EMA) system, a biplane X‐ray imaging system, and a remote guidewire/catheter advancer unit. The proposed ECMIS demonstrates targeted real‐time cardiovascular interventions in vascular phantoms through precise and rapid control of the microrobotic guidewire under EMA. Further, the potential clinical effectiveness of the ECMIS for real‐time cardiovascular interventions is investigated through preclinical studies in coronary, iliac, and renal arteries of swine models in vivo, where the magnetic steering of the microrobotic guidewire and control of other ECMIS modules are teleoperated by operators in a separate control booth with X‐ray shielding. The proposed ECMIS can help medical physicians optimally manipulate interventional devices such as guidewires under minimal radiation exposure.
The clinically translatable, electromagnetically controllable microrobotic interventional system (ECMIS) comprises a microrobotic guidewire capable of active magnetic steering, a human‐scale electromagnetic actuation system, a biplane X‐ray imaging system, and a remote master–slave advancer unit. The ECMIS assists a physician to remotely control microdiameter interventional tools precisely and instantly in a real‐time manner while being protected from ionizing radiation.
A total of 10 years (2002-11) of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) reflectivities, signaling heavy rainfall (>10 mm h super(-1)), were objectively classified by ...applying the K-means clustering method in order to obtain typical reflectivity profiles associated with heavy rainfall over East Asia. Two types of heavy rainfall emerged as the most important rain processes over East Asia: type 1 (cold type) characterized by high storm height and abundant ice water under convectively unstable conditions, developing mostly over inland China; and type 2 (warm type) associated with a lower storm height and lower ice water content, developing mostly over the ocean. These two types also show sharp contrasts in relation to their seasonal changes and in the diurnal variation of frequency maxima, in addition to other contrasting meteorological parameters. The PR-derived heavy rain events were observed over the Korean peninsula and their spatiotemporal evolution was examined using 10-yr composites of 11- mu m brightness temperature from geostationary satellites and Interim ECMWF Re-Analysis (ERA-Interim) data. Cold-type heavy rainfall over Korea is characterized by an eastward moving cloud system with an oval shape while the warm type shows a comparatively wide spatial distribution over an area extending from the southwest to northeast. Overall the warm-type process appears to link the low-level moisture convergence area to the vertically aligned divergence area formed over the jet stream level. This setup continuously pushes air upward under moist-adiabatically near-neutral conditions and thus yields heavy rainfall. As warm-type heavy rainfall persists longer, it is considered to be more responsible for flood events occurring over the Korean peninsula.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Purpose
Intubation in patients with respiratory failure can be avoided by high-flow nasal cannula (HFNC) use. However, it is unclear whether waiting until HFNC fails, which would delay intubation, ...has adverse effects. The present retrospective observational study assessed overall ICU mortality and other hospital outcomes of patients who received HFNC therapy that failed.
Methods
All consecutive patients in one tertiary hospital who received HFNC therapy that failed and who then required intubation between January 2013 and March 2014 were enrolled and classified according to whether intubation started early (within 48 h) or late (at least 48 h) after commencing HFNC.
Results
Of the 175 enrolled patients, 130 (74.3 %) and 45 (25.7 %) were intubated before and after 48 h of HFNC, respectively. The groups were similar in terms of most baseline characteristics. The early intubated patients had better overall ICU mortality (39.2 vs. 66.7 %;
P
= 0.001) than late intubated patients. A similar pattern was seen with extubation success (37.7 vs. 15.6 %;
P
= 0.006), ventilator weaning (55.4 vs. 28.9 %;
P
= 0.002), and ventilator-free days (8.6 ± 10.1 vs. 3.6 ± 7.5;
P
= 0.011). In propensity-adjusted and -matched analysis, early intubation was also associated with better overall ICU mortality adjusted odds ratio (OR) = 0.317,
P
= 0.005; matched OR = 0.369,
P
= 0.046.
Conclusions
Failure of HFNC might cause delayed intubation and worse clinical outcomes in patients with respiratory failure. Large prospective and randomized controlled studies on HFNC failure are needed to draw a definitive conclusion.
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