Capillary

Porous polymer monoliths emerged about two decades ago. Despite this short time, they are finding applications in a variety of fields. In addition to the most common and certainly best known use of this new category of porous media as stationary phases in liquid chromatography, monolithic materials also found their applications in other areas. This review article focuses on monoliths in capillaries designed for separations in gas chromatography.

Oxygen uptake, carbon dioxide elimination, cutaneous and systemic blood flows (measured by microsphere technique) and the number of perfused capillaries in the hind foot web have been measured at 25 °C in unanaesthetized bullfrogs (Rana catesbeiana) both while breathing air as they float in water and while resting totally out of water in humidified air. The gas exchange ratio, approximately 1 while breathing with both water and air, fell to 0.5 or lower during 4 h of complete air exposure. A concomitant decrease occurred in both cutaneous blood flow and the proportion of perfused to non-perfused capillaries in the hind foot web. Upon returning to floating at the water surface, cutaneous blood flow and capillary recruitment increased again and the gas exchange ratio increased to above 2 for several hours. These data suggest that a partial inhibition of CO 2 excretion is linked with a decrease in the extent and pattern of blood flow through the skin, which is the major site of CO 2 elimination.

The tick Rhipicephalus microplus is an ectoparasite harmful to livestock, a vector of disease agents that affects meat and milk production. However, resistance to acaricides reflects the need for alternative tick control methods, among which vaccines have gained increasing relevance. In this scenario, monoclonal antibodies can be used to identify and characterize antigens that can be used as vaccine immunogens. Capillary tube artificial feeding of partially engorged R. microplus females with monoclonal antibodies against proteins from the gut of tick were used to test the effects of immunoglobulins in the physiology of the parasite. The results of artificial feeding showed that female ticks over 25 mg and under 60 mg in weight performed better in the artificial feeding process, with a 94-168% weight increase after 24 h of feeding. Results showed that artificial feeding of ticks proved to be a viable technique to study the effects of antibodies or drugs in the physiology of the parasite. One monoclonal antibody (BrBm2) induced decreased oviposition. Moreover, the antigen recognized by BrBm2 was identified as a 27-kDa protein and immunolabeled on digestive vesicles membranes of digestive cells of partially and fully engorged females.

A meta-analysis determined whether capillary blood gases accurately reflect arterial blood samples. A mixed effects model was used on 29 relevant studies obtained from a PubMed/Medline search. From 664 and 222 paired samples obtained from the earlobe and fingertip, respectively, earlobe compared to fingertip sampling shows that the standard deviation of the difference is about 2.5× less (or the precision is 2.5× better) in resembling arterial PO 2 over a wide range of arterial PO 2 's (21-155 mmHg). The lower the arterial PO 2 , the more accurate it is when predicting arterial PO 2 from any capillary sample (p < 0.05). However, while earlobe sampling predicts arterial PO 2 (adjusted r 2 = 0.88, mean bias = 3.8 mmHg compared to arterial), fingertip sampling does not (adjusted r 2 = 0.48, mean bias = 11.5 mmHg compared to arterial). Earlobe sampling is slightly more accurate compared to fingertip sampling in resembling arterial PCO 2 (arterial versus earlobe, adjusted r 2 = 0.94, mean bias = 1.9 mmHg; arterial versus fingertip, adjusted r 2 = 0.95, mean bias = 2.2 mmHg compared to arterial) but both sites can closely reflect arterial PCO 2 (880 total paired samples, range 10-114 mmHg). No real difference between sampling from the earlobe or fingertip were found for pH as both sites accurately reflect arterial pH over a wide range of pH (587 total paired samples, range 6.77-7.74, adjusted r 2 = 0.90-0.94, mean bias = 0.02). In conclusion, sampling blood from the fingertip or earlobe (preferably) accurately reflects arterial PCO 2 and pH over a wide range of values. Sampling blood, too, from earlobe (but never the fingertip) may be appropriate as a replacement for arterial PO 2 , unless precision is required as the residual standard error is 6 mmHg when predicting arterial PO 2 from an earlobe capillary sample.

Mural cells (smooth muscle cells and pericytes) regulate blood flow and contribute to vessel stability. We examined whether mural cell changes accompany age-related alterations in the microvasculature of the central nervous system. The retinas of young adult and aged Wistar rats were subjected to immunohistofluorescence analysis of ␣-smooth muscle actin (SMA), caldesmon, calponin, desmin, and NG2 to identify mural cells. The vasculature was visualized by lectin histochemistry or perfusion of horseradish peroxidase, and vessel walls were examined by electron microscopy. The early stage of aging was characterized by changes in peripheral retinal capillaries, including vessel broadening, thickening of the basement membrane, an altered length and orientation of desmin filaments in pericytes, a more widespread SMA distribution and changes in a subset of pre-arteriolar sphincters. In the later stages of aging, loss of capillary patency, aneurysms, distorted vessels, and foci of angiogenesis were apparent, especially in the peripheral deep vascular plexus. The capillary changes are consistent with impaired vascular autoregulation and may result in reduced pericyte-endothelial cell contact, destabilizing the capillaries and rendering them susceptible to angiogenic stimuli and endothelial cell loss as well as impairing the exchange of metabolites required for optimal neuronal function. This metabolic uncoupling leads to reactivation of "physiological hypoxia" and angiogenesis in CNS aging.

Because regional blood flow increases in association with the increased metabolic demand generated by localized increases in neural activity, functional imaging researchers often assume that changes in blood flow are an accurate read-out of changes in underlying neural activity. An understanding of the mechanisms that link changes in neural activity to changes in blood flow is crucial for assessing the validity of this assumption, and for understanding the processes that can go wrong during disease states such as ischaemic stroke. Many studies have investigated the mechanisms of neurovascular regulation in arterioles but other evidence suggests that blood flow regulation can also occur in capillaries, because of the presence of contractile cells, pericytes, on the capillary wall. Here we review the evidence that pericytes can modulate capillary diameter in response to neuronal activity and assess the likely importance of neurovascular regulation at the capillary level for functional imaging experiments. We also discuss evidence suggesting that pericytes are particularly sensitive to damage during pathological insults such as ischaemia, Alzheimer's disease and diabetic retinopathy, and consider the potential impact that pericyte dysfunction might have on the development of therapeutic interventions and on the interpretation of functional imaging data in these disorders.

This paper presents experimental results on the shut-down and start-up characteristics of a residential split system R410A air-conditioner with a capillary tube. During shut-down, the transient characteristics are evaluated by measuring the high and low side pressures and temperatures of the system. The dynamic behavior of the system after start-up is also investigated, at the high temperature cooling test condition. All experiments are performed in a psychrometric calorimeter. The cooling capacity, power consumption, dehumidification capacity and cycle characteristics after start-up are analyzed. The test results show that cooling capacity after start-up can be expressed as the combination of two exponential functions of time, approaching the cooling capacity of steady state.

Wong LE, Garland T Jr., Rowan SL, Hepple RT. Anatomic capillarization is elevated in the medial gastrocnemius muscle of mighty mini mice. House mice selectively bred for high voluntary wheel running display a mini-muscle (MM) phenotype wherein mass-specific mitochondrial enzyme activities are double that of normal, but muscle mass is reduced by half. In addition, mini-muscles are characterized by small muscle fibers in the superficial region of the plantaris and medial gastrocnemius muscles. To determine the structural alterations facilitating aerobic metabolism in these mini-muscles, cross-sections of the medial gastrocnemius muscle of normal (N; n ϭ 6) and minimuscle (MM; n ϭ 6) mice were histo-and immunochemically labeled and analyzed for fiber size, capillarization, and fiber type. On the basis of the higher mitochondrial enzyme activities in muscles of MM mice, we hypothesized that they would have greater fiber capillarization in the medial gastrocnemius than N mice. Furthermore, we hypothesized that augmented capillarization in MM would principally be a function of the smaller fibers in the superficial aspect of this muscle. On average, MM had higher capillary-to-fiber ratio and higher capillary density. Binning fibers according to size revealed that it was primarily the normal-sized fibers of the MM that had higher capillarity. The small fibers seen in the superficial region of MM were distinct from N mice in that they had heterogeneous myofibrillar ATPase staining and patchy succinate dehydrogenase staining in the interior of the fibers. These results support the hypothesis that the MM have higher indexes of capillarity, caused primarily by greater capillary number around normally sized fibers. These alterations are consistent with the superior mass-specific aerobic function of these muscles.

After a brief review of the main areas of research in X-ray optics and an analysis of the development of capillary optics, a general theory of radiation propagation through capillary structures is described in both geometrical optics and wave optics approximations. Analysis of the radiation field structure inside a capillary waveguide shows that wave propagation in channels can be of a purely modal nature, with the transmitted energy mostly concentrated in the immediate neighborhood of the capillary inner walls. A qualitative change in radiation scattering with decreasing channel diameter Ð namely, the transition from surface channeling in microcapillaries to bulk channeling in nanocapillaries Ð is discussed.

Microvascular stability and regulation of capillary tonus are regulated by pericytes and their interactions with endothelial cells (EC). While the RhoA/Rho kinase (ROCK) pathway has been implicated in modulation of pericyte contractility, in part via regulation of the myosin light chain phosphatase (MLCP), the mechanisms linking Rho GTPase activity with actomyosin-based contraction and the cytoskeleton are equivocal. Recently, the myosin phosphatase-RhoA-interacting protein (MRIP) was shown to mediate the RhoA/ROCK-directed MLCP inactivation in vascular smooth muscle. Here we report that MRIP directly interacts with the β-actin-specific capping protein βcap73. Furthermore, manipulation of MRIP expression influences pericyte contractility, with MRIP silencing inducing cytoskeletal remodeling and cellular hypertrophy. MRIP knockdown induces a repositioning of βcap73 from the leading edge to stress fibers; thus MRIP-silenced pericytes increase F-actin-driven cell spreading twofold. The...

This paper presents an investigation of gravity-driven flow in porous media using angular capillary tubes. Gravity is important in many fluid transport processes, such as ground water flow, oil flow in reservoir, and water flow in subsurface in CO 2 sequestration processes. In these processes, density contrast of the fluids is generally large, e.g., water vs. gas, or oil vs. gas. Gravity-driven flow of the denser fluid largely takes control in these processes. In particular, gravity-driven flow falls into two regimes in regarding to the denser fluid: the bulk flow (steady-state) and the film/corner flow (unsteady-state) that follows. The geometrically complicated flow channels in a porous medium are represented by shaped capillary tubes. As far as the author knows, this work models for the first time the unsteady-state laminar flow of Newtonian fluids in angular channels. The fluid distribution or the tail of the flow above the fluid contact (Fig. 1) is governed by the fluid dynamics. Theoretical and numerical simulations of the film/corner flow are conducted for the corner-shapes. The results of this study provide basis for more detailed network models, which describe rock-fluid systems at microscopic level with deterministic solutions. The modeling procedure and results are useful for modeling the performance of gravity dominated improved oil recovery processes, ground water filtration, and water movement in a CO 2 plume in CO 2 sequestration processes.

This study presents characterizations of weathering forms of the same oolitic limestone from four quarries and eight monuments exposed on various environmental conditions focusing on the waterproofing effect of endolithic organic matter. Patinas were analyzed by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX), capillarity coefficient through weathered and unweathered sides, gypsum content and porous network morphology by epoxy resin molding. Study of weathering forms on old quarries indicates that lichens colonization (Verrucaria nigrescens and Caloplaca aurantia) can fill the superficial porous network with a dense network of lichenised fungal hyphae. Capillary coefficient measurement on natural and calcinated samples showed that endolithic organic matter can waterproof the stone and could act as a sulfate contamination barrier. Similar endolithic organic layer due to ancient lichens growth are found on some antique monuments of the Nîmes downtown and could explain their well-preserved state, unlike decayed 19th century churches that were never colonized by lichens.

Purpose The increasing demand for radiopharmaceuticals to be provided reproducibly and flexibly with high frequency for clinical application and animal imaging would be better met by improved or even new strategies for automated tracer production. Radiosynthesis in microfluidic systems, i.e. narrow tubing with a diameter of approximately 50-500 μm, holds promise for providing the means for repetitive multidose and multitracer production. In this study, the performance of a conceptually simple microfluidic device integrated into a fully automated synthesis procedure for in-capillary radiosynthesis (ICR) of clinical grade [ 18 F]FDG was evaluated. Materials and methods The instrumental set-up consisted of pumps for reagent and solvent delivery into small mixing chambers, μ-fluidic capillaries, in-process radioactivity monitoring, solid-phase extraction and on-column deprotection of the 18 F-labelled intermediate followed by on-line formulation of [ 18 F]FDG. Results In-capillary 18 F-fluorination of 2.1 μmol 1,3,4, 6-tetra-O-acetyl-2-O-trifluoromethanesulphonyl-beta-Dmannopyranose (TATM; precursor for [ 18 F]FDG) in acetonitrile (MeCN) at a flow rate of 0.3 ml/min within 40 s and subsequent on-line hydrolysis of the intermediate by treatment with 0.3 M NaOH for 1 min at 40°C resulted in a radiochemical yield of 88±4% within <7 min. Reproducibility, robustness and suitability as a fast and efficient radiopharmaceutical research tool for 18 F-fluorination was demonstrated by eight independent, sequentially performed ICRs which provided identical tracer quality (radiochemical purity >97%, MeCN <5 μg/ml) and similar absolute yields (approximately 1.4 GBq). Conclusion The described ICR process is a simple and efficient alternative to classic radiotracer production systems and provides a comparatively cheap instrumental methodology for the repetitive production of [ 18 F]FDG with remarkably high efficiency and high yield under fully automated conditions. Although the results concerning the levels of activity need to be confirmed after installation of the equipment in a suitable GMP hot-cell environment, we expect the instrumental design to allow up-scaling without major difficulties or fundamental restrictions. Furthermore, we are convinced that similar or nearly identical procedures, and thus instrumentation, will allow ICR of other 18 F-labelled radiopharmaceuticals.

Characterizing diffusion of gases and liquids within pores is important in understanding numerous transport processes and affects a wide range of practical applications. Previous measurements of the pulsed gradient stimulated echo (PGSTE) signal attenuation, E(q), of water within nerves and impermeable cylindrical microcapillary tubes showed it to be exquisitely sensitive to the orientation of the applied wave vector, q, with respect to the tube axis in the high-q regime. Here, we provide a simple three-dimensional model to explain this angular dependence by decomposing the average propagator, which describes the net displacement of water molecules, into components parallel and perpendicular to the tube wall, in which axial diffusion is free and radial diffusion is restricted. The model faithfully predicts the experimental data, not only the observed diffraction peaks in E(q) when the diffusion gradients are approximately normal to the tube wall, but their sudden disappearance when the gradient orientation possesses a small axial component. The model also successfully predicts the dependence of E(q) on gradient pulse duration and on gradient strength as well as tube inner diameter. To account for the deviation from the narrow pulse approximation in the PGSTE sequence, we use Callaghan's matrix operator framework, which this study validates experimentally for the first time. We also show how to combine average propagators derived for classical one-dimensional and two-dimensional models of restricted diffusion (e.g. between plates, within cylinders) to construct composite three-dimensional models of diffusion in complex media containing pores (e.g. rectangular prisms and/ or capped cylinders) having a distribution of orientations, sizes, and aspect ratios. This three-dimensional modeling framework should aid in describing diffusion in numerous biological systems and in a myriad of materials sciences applications.

1] Over the last decade, the picture that has emerged from several geologic disciplines is that the Earth's crust is permeable to great depths and that fluids are more or less constantly moving, transporting both heat and mass and affecting virtually every geologic process. In contrast, workers in the petroleum industry have maintained that sections of the crust contain impermeable pressure seals and hydraulically sealed compartments. We show that these starkly different conceptions can be reconciled by a theory of self-sealing through gas generation in sedimentary basins. The model especially applies to older sedimentary basins where overpressuring cannot be readily explained as the result of ongoing sedimentation and compaction disequilibrium. In our conceptual model, overpressuring is created by catagenic gas generation and maintained by a combination of vertical and horizontal gas capillary seals. Data from the Anadarko Basin in Oklahoma provide support for the self-sealing hypothesis. Well logs reveal the presence of 9 or 10 gas-water interfaces over a 30-m overpressured interval. Capillary pressure measurements show that the force necessary for gas to displace water from a shale is $3 Â 10 6 Pa, a pressure equivalent to that exerted by a column of water 300 m high. A theory of selfsealing explains the anomalous overpressuring observed in some older sedimentary basins by invoking known mechanisms and forces; it is both parsimonious and falsifiable.

Capillary electrophoretic separations of high efficiency and resolution were obtained using poly-(acryloylaminoethoxyethanol)-coated capillaries. The polymer was covalently attached to a silica surface previously modified with a a-methacryloxylpropyl functionality. The latter was realized by catalytic hydrosilylation of allyl methacrylate on an Sill-modified fused-silica capillary. The lifetime of the new type of coating used at pH 8.5 was more than twice that of conventional polyacrylamide.

Ž . Ž . The bronchial system BS , the pulmonary artery PA and the pulmonary vein PV of the lung of the domestic pig, Sus scrofa were simultaneously cast with silicone rubber and studied. Asymmetrical dichotomous bifurcation preponderated in the tree-like arrangement of the three conducting systems. Lengths and diameters of the various generations were measured. At the extremities of the BS and the PA, alveoli and blood capillaries related very closely. In the cranial and middle lobes of the right and left lungs, topographically, the PA and the PV closely followed the BS, but in the Ž . accessory and the caudal diaphragmatic lobes, only the PA accompanied the BS: the PV run intersegmentally. Certain similarities and differences were observed between the diameters and lengths of the various generations of the three conducting systems. The strong correlations between some of the structural parameters indicated a high level of structural optimization. While morphometric variations suggest that the air and the blood flow dynamics may somewhat differ between the three conducting systems, they may also register structural features unique to the lung of the domestic pig, an animal that has been highly genetically exploited for fast growth and now leads an indolent lifestyle in captivity. ᮊ

In previous work, we have demonstrated by radiolabeling, mass spectrometry and sitedirected mutagenesis that nerve growth factor (NGF) as well as brain-derived neurotrophic factor (BDNF) and fibroblast growth factor 2 (FGF2) are capable of ATP-binding and that this binding appears to be essential for their neuroprotective activity. In this study, we attempted to shed some light on the question whether ATP is a general prerequisite for neuroprotection. Therefore, we used the non-ATP-binding granulocyte colony-stimulating factor (GCSF), the calcium antagonist nimodipine and the NMDA antagonist dizocilpine to find out whether they need ATP for neuroprotection comparable to NGF and BDNF. However, ATP was not necessary for the neuroprotective effects of GCSF, nimodipine and dizocilpine on primary cultures of rat cortical neurons damaged by oxygen-glucose deprivation whereas neuroprotection was demonstrable for NGF and BDNF only when ATP was present in the culture medium at a concentration higher than ca. 0.4 nmol/l. In circular dichroism studies ATP caused changes of the secondary structure of NGF but not of GCSF. Taken together, we suggest that ATP is not a general prerequisite for neuroprotectivity but some growth factors like NGF and BDNF can stimulate their receptors only if they have bound ATP. Insel, P.A., 2006. inhibition of apoptosis by P2Y2 receptor activation: novel pathways for neuronal survival. J. Neurosci. 26, 3798-3804.

The instability of a self-gravitating fluid cylinder surrounded by a self-gravitating tenuous medium pervaded by transverse varying electric field is discussed under the combined effect of the capillary, self-gravitating, and electric forces. This has been done for all axisymmetric and nonaxisymmetric modes of perturbation. The problem is formulated and solved with excluding the singular solutions, and the stability criterion is derived. Several published works are obtained as limiting cases from the present general case and investigated, and moreover the results are interpreted physically. The model is stable due to the stabilizing effect of the transverse electric field in all modes of perturbation. The destabilizing effect of the capillary and self-gravitating forces is found in small domain in the axisymmetric perturbation. However, the stabilizing effects of the capillary and self-gravitating forces in large axisymmetric domains and in all nonaxisymmetric domains modify and imp...

The inner walls of 50 mm fused-silica capillaries are etched by ammonium hydrogendifluoride and then modified by the silanization / hydrosilation method with a chiral selector. Three different types of selectors were evaluated: lactone, b-cyclodextrin and naphthylethylamine. Each of the bonded chiral stationary phases provided at least partial separation for one type of racemic solute. These results confirm that bonded organic moieties on the etched inner wall of a capillary can provided sufficient solute-bonded phase interactions to influence the retention of molecules driven through a capillary by electroosmosis or a combination of electroosmosis and electrophoretic mobility.

Cryogenic trapping of solutes leads to narrowing of the chromatographic band. By placing the trap at the end of a capillary column, it is possible to study the effectiveness of the trap in terms of producing a sharpened elution profile. The trap may be heated by supplementary heating, but here convective heating from the GC oven is employed simply by turning off the cryogenic coolant. It is estimated that it takes about 50 s for the trap to heat up sufficiently to allow trapped solute to be remobilized, although this depends upon the oven temperature and thermal mass of the trap. It can also be shown that the more volatile solutes mobilize faster from the trap in this particular mode of operation. The recovery of trapped components shows that there is essentially quantitative trapping, and the solutes are trapped just at the leading edge of the trap.

The development and experimental optimization of a novel flow injection-capillary electrophoresis (FI-CE) analyzer employing UV-visible fiber optic detection is described. The analyzer incorporates a miniature charge-coupled device (CCD) spectrometer and operates in a graphical programming environment. Data from experimental optimization studies and small molecule separations involving affinity capillary electrophoresis (ACE) and indirect detection of anions are presented. Future directions in terms of instrument automation and incorporation into a microfluidic format are also discussed.

In striated muscle, the number of capillaries containing moving red blood cells increases with increasing metabolic demand. This phenomenon, termed capillary recruitment, has long been recognized but its mechanism has been unclear. Here, a theoretical model for metabolic blood flow regulation in a heterogeneous network is used to test the hypothesis that capillary recruitment occurs as a result of active control of arteriolar diameters, combined with unequal partition of hematocrit at diverging microvascular bifurcations. The network structure is derived from published observations of hamster cremaster muscle in control and dilated states. The model for modulation of arteriolar diameters includes length-tension characteristics of vascular smooth muscle and responses of smooth muscle tone to myogenic, shear-dependent, and metabolic stimuli. Blood flow is simulated including non-uniform hematocrit distribution. Convective and diffusive oxygen transport in the network is simulated. Oxy...

Blood is a concentrated suspension of red blood cells (RBCs). Motion and deformation of RBCs can be analyzed based on knowledge of their mechanical characteristics. Axisymmetric models for single-file motion of RBCs in capillaries yield predictions of apparent viscosity in good agreement with experimental results for diameters up to about 8 micron. Two-dimensional simulations, in which each RBC is represented as a set of interconnected viscoelastic elements, predict that offcentre RBCs in an 8-micron channel take asymmetric shapes and drift toward the centre-line. Predicted trajectories agree with observations in microvessels of the rat mesentery. An isolated RBC initially positioned near the wall of a 20-micron channel is deformed into an asymmetric shape, migrates away from the wall, and then enters a complex tumbling motion with continuous shape change. Realistic simulation of multiple interacting RBCs in microvessels remains as a major challenge.

Acute kidney injury induces the loss of renal microvessels, but the fate of endothelial cells and the mechanism of potential vascular endothelial growth factor (VEGF)-mediated protection is unknown. Cumulative cell proliferation was analyzed in the kidney of Sprague-Dawley rats following ischemia-reperfusion (I/R) injury by repetitive administration of BrdU (twice daily) and colocalization in endothelial cells with CD31 or cablin. Proliferating endothelial cells were undetectable for up to 2 days following I/R and accounted for only ∼1% of BrdU-positive cells after 7 days. VEGF-121 preserved vascular loss following I/R but did not affect proliferation of endothelial, perivascular cells or tubular cells. Endothelial mesenchymal transition states were identified by localizing endothelial markers (CD31, cablin, or infused tomato lectin) with the fibroblast marker S100A4. Such structures were prominent within 6 h and sustained for at least 7 days following I/R. A Tie-2-cre transgenic cr...

MRI is used to study the role of capillary and gravitational forces in controlling mass transport of water during isothermal drying of granular beds of nonporous particles. A new model is presented that shows how capillary and gravitational forces relate to Fickian diffusion driven by a chemical potential gradient. In granular beds, where capillary and gravitational forces dominate, the image profiles give direct information on the dependence of the degree of saturation on capillary suction pressure. The effects of changing particle size and surface tension on the profiles is investigated quantitatively, and it is shown that high capillary pressures create anomalies in the drying profiles.

Whereas a pronounced correlation exists between local cerebral glucose utilization (LCGU) and capillary density in different regions of the brain, it is not known whether these parameters also correlate with the overall density of nuclei (cellularity). Therefore, cellularity was determined by diamidino-phenylindol (DAPI) fluorescent staining of nuclei in acetone-fixed frozen sections of the rat brain. A comparison of the density of nuclei in different brain regions showed much less variation than that observed in LCGU and capillary density. No correlation was found between nuclear density and either LCGU or capillary densities. In conclusion the cellular density is not a determinant of variation in LCGU and capillary density.

We studied the effects of different protocols of post-disuse rehabilitation on angiogenesis and myosin heavy chain (MHC) content in rat hindlimb muscles after caudal suspension. Thirty female Wistar rats were divided into five groups: (1) Control I, (2) Control II, (3) Suspended, (4) Suspended trained on declined treadmill, and (5) Suspended trained on flat treadmill. Fragments of the soleus and tibialis anterior (TA) muscles were frozen and processed by electrophoresis and immunohistochemistry (CD31 antibody). Hindlimb suspension caused reduction of capillary/fiber (C/F) ratios and contents of MHC type I (MHCI) in the soleus in parallel to increased capillary density. Flat treadmill protocols increased the content of the MHCI isoform. The C/F ratio was increased by concentric training after hypokinesis, but was not modified by eccentric training, which caused a greater reduction of capillary density compared to the other protocols. In the TA muscle, hindlimb suspension caused a non-significant increase in capillary density and C/F ratio with limited changes in MHC. The present data demonstrate that the different training protocols adopted and the functional performance of the muscles analyzed caused specific changes in capillarization and in the content of the various MHC types.

The focus of contrast-enhanced ultrasound research has developed beyond visualizing the blood pool and its flow to new areas such as perfusion imaging, drug and gene therapy, and targeted imaging. In this work comparison between the application of polymer-and phospholipid-shelled ultrasound contrast agents (UCAs) for characterization of the capillary microcirculation is reported. All experiments are carried out using a microtube as a vessel phantom. The first set of experiments evaluates the optimal concentration level where backscattered signal from microbubbles depends on concentration linearly. For the polymer-shelled UCAs the optimal concentration level is reached at a value of about 2 Â 10 4 MB/ml, whereas for the phospholipid-shelled UCAs the optimal level is found at about 1 Â 10 5 MB/ml.

1] Over the last decade, the picture that has emerged from several geologic disciplines is that the Earth's crust is permeable to great depths and that fluids are more or less constantly moving, transporting both heat and mass and affecting virtually every geologic process. In contrast, workers in the petroleum industry have maintained that sections of the crust contain impermeable pressure seals and hydraulically sealed compartments. We show that these starkly different conceptions can be reconciled by a theory of self-sealing through gas generation in sedimentary basins. The model especially applies to older sedimentary basins where overpressuring cannot be readily explained as the result of ongoing sedimentation and compaction disequilibrium. In our conceptual model, overpressuring is created by catagenic gas generation and maintained by a combination of vertical and horizontal gas capillary seals. Data from the Anadarko Basin in Oklahoma provide support for the self-sealing hypothesis. Well logs reveal the presence of 9 or 10 gas-water interfaces over a 30-m overpressured interval. Capillary pressure measurements show that the force necessary for gas to displace water from a shale is $3 Â 10 6 Pa, a pressure equivalent to that exerted by a column of water 300 m high. A theory of selfsealing explains the anomalous overpressuring observed in some older sedimentary basins by invoking known mechanisms and forces; it is both parsimonious and falsifiable.

Pericytes surround capillary endothelial cells and exert contractile forces modulating microvascular tone and endothelial growth. We previously described pericyte contractile phenotype to be Rho GTPase-and !"smooth muscle actin (!SMA)-dependent. However, mechanisms mediating adhesion-dependent shape changes and contractile force transduction remain largely equivocal. We now report that the neutral cysteine protease, calpain, modulates pericyte contractility and cellular stiffness via talin, an integrin-binding and F-actin associating protein. Digital imaging and quantitative analyses of living cells reveal significant perturbations in contractile force transduction detected via deformation of silicone substrata, as well as perturbations of mechanical stiffness in cellular contractile subdomains quantified via atomic force microscope (AFM)-enabled nanoindentation. Pericytes overexpressing GFP-tagged talin show significantly enhanced contractility (~two-fold), which is mitigated when either the calpain-cleavage resistant mutant talin L432G or vinculin are expressed. Moreover, the cellpenetrating, calpain specific inhibitor termed CALPASTAT reverses talin-enhanced, but not Rho GTP-dependent, contractility. Interestingly, our analysis revealed that CALPASTAT, but not its inactive mutant, alters contractile cell-driven substrata deformations while increasing mechanical stiffness of subcellular contractile regions of these pericytes. Altogether, our results reveal that calpain-dependent cleavage of talin modulates cell contractile dynamics, which in pericytes may prove instrumental in controlling normal capillary function or microvascular pathophysiology.

Large-volume sample stacking with an electroosmotic flow pump Partial filling affinity capillary electrophoresis Glycoprotein-derived oligosaccharides a b s t r a c t An online preconcentration technique, large-volume sample stacking with an electroosmotic flow pump (LVSEP) was combined with partial filling affinity capillary electrophoresis (PFACE) to realize highly sensitive analysis of the interaction of glycoprotein-derived oligosaccharides with some plant lectins. Oligosaccharides derivatized with 8-aminopyrene-1,3,6-trisulfonic acid (APTS) were delivered to an entire neutrally-coated capillary and then lectin solution was hydrodynamically introduced from the outlet of the capillary as a short plug. A negative voltage was then applied after immersion of both ends of the capillary in 100 mM Tris-acetate buffer, pH 7.0 containing 0.5% hydroxypropylcellulose as electrophoresis buffers. A low concentration of electrolytes in the sample solution causes a significant flow by electroendosmosis from anode to cathode and the APTS-labeled oligosaccharides move quickly towards the anode and concentrate in the lectin phase. Finally, electroosmotic flow becomes negligible when the capillary is filled with the background electrolyte delivered from the anodic reservoir and APTSlabeled saccharides pass through the lectin plug and are detected at the anodic end. If the APTS-labeled oligosaccharides are recognized by the lectin, the migration profiles should be altered. The sensitivity was enhanced by a factor of ca. 900 compared to typical hydrodynamic injection (3.45 kPa, 10 s). By this method, increased residence time of APTS-saccharides in the lectin plug indicates highly efficient interaction with lectins, which differs completely from the results obtained by ordinary lectin PFACE. The run-to-run repeatability (n = 18) of the migration time and peak area was high, with relative standard deviations of less than 0.7% and 6.1%, respectively.

Thyroid nodules can be biopsied by fine needle aspiration (FNA) or fine needle capillary (FNC) biopsies. However, there is controversy on whether one technique is superior to another. In a randomized cytopathologistblinded cross-sectional study, 260 patients (238 females, age 43.2±12.6) with nodular (82.7%) and diffuse goiter (17.3%) underwent 520 FNAs and 520 FNCs (not guided by ultrasound). Smears were scored for sample adequacy, and diagnosed as malignant, benign, suspicious, or nondiagnostic. Diagnostic accuracy was calculated based on the histological findings of 58 patients submitted to surgery. Intra-technique diagnostic accuracy and sample adequacy was seen in all samples. FNA and FNC provided similar cytological diagnosis, respectively (benign: 75.8% vs. 74.2%, p=0.600; malignant: 3.8% vs. 3.8%, p=0.871; suspicious: 10.4% vs. 10.8%, p=0.913; and nondiagnostic: 10.0% vs. 11.2%, p=0.598). Adequacy scores were similar by FNA (7.94±2.84) and FNC (7.96±2.81, p=0.909). The same proportion of adequate or superior samples was seen in both techniques (91.6%). Sensitivity was equal to 85.7% for FNA and 100% for FNC. Similarly, specificity was 100% for both techniques. FNA and FNC provide the similar sample adequacy and diagnostic accuracy. The choice of technique should be based on the operator's personal preferences and experience.

High-performance separation of small inorganic anions on a methacrylate-based polymer monolith grafted with [2(methacryloyloxy)ethyl] trimethylammonium chloride A glycidyl methacrylate-co-ethylene dimethacrylate monolith in capillary format (100 lm/id) has been grafted with chains of poly([2(methacryloyloxy)ethyl] trimethylammonium chloride (poly-META) and applied to the ion-chromatographic separation of selected inorganic anions. Grafting chains of META onto the generic monolithic scaffold resulted in a monolith with , electrolyte responsive flow permeability', which manifested as increased permeability in the presence of electrolyte solutions. Using an eluent of 2 mM sodium benzoate and on-column contactless conductivity detection, a test mixture of six common anions was isocratically separated and detected within 12 min, with the first four anions baseline resolved within a retention time window of 3.2 min. Retention time precision was f1.2% for all anions tested. Separation efficiencies of 15 000 N/m were achieved for fluoride at 1 lL/min, with column efficiencies up to 29 500 N/m obtained at a lower flow rate of 100 nL/min. Furthermore, repeatability of the column modification procedure using photografting methods was acceptable, with retention times between replicate columns matching within 9%.

The fluid dynamics video shows three-dimensional experimental and numerical investigations of open channel flows in microgravity. The dynamic reorientation of the free surface from 1g to 0g environment can be observed in a wedge-shaped channel for subcritical and for supercritical flow rate with a collapse of the interface. In addition three-dimensional computations determine important characteristics of the flow, such as the free surface shape, the velocity field, the dynamics of the reorientation and the flow rate depended collapse of the free surface. The good agreement validates the capabilities of the numerical solver.

Data obtained by capillary electrophoresis with diode array detection (CE-DAD) were modeled with the purpose to discriminate Argentinean white wines samples produced from three grape varieties (Torrontés, Chardonnay, and Sauvignon blanc). Thirty eight samples of commercial white wine from four wine-producing provinces of Argentina (Mendoza, San Juan, Salta, and Rio Negro) were analyzed. CE-DAD matrices with dimensions of 421 elution times (from 1.17 to 7.39 minutes) × 71 wavelengths (from 227 to 367 nm) were joined in a three way data array and decomposed by Tucker3 method under non-negativity constraint, employing 18, 18 and 6 factors in the modes 1, 2 and 3, respectively. Using the scores of Tucker model, it was possible to discriminate samples of Argentinean white wine by linear discriminant analysis and Kernel linear discriminant analysis. Core element analysis of the Tucker3 model allows identifying the loading profiles in spectral mode related to Argentinean white wine samples...

Characterizing diffusion of gases and liquids within pores is important in understanding numerous transport processes and affects a wide range of practical applications. Previous measurements of the pulsed gradient stimulated echo (PGSTE) signal attenuation, E(q), of water within nerves and impermeable cylindrical microcapillary tubes showed it to be exquisitely sensitive to the orientation of the applied wave vector, q, with respect to the tube axis in the high-q regime. Here, we provide a simple three-dimensional model to explain this angular dependence by decomposing the average propagator, which describes the net displacement of water molecules, into components parallel and perpendicular to the tube wall, in which axial diffusion is free and radial diffusion is restricted. The model faithfully predicts the experimental data, not only the observed diffraction peaks in E(q) when the diffusion gradients are approximately normal to the tube wall, but their sudden disappearance when the gradient orientation possesses a small axial component. The model also successfully predicts the dependence of E(q) on gradient pulse duration and on gradient strength as well as tube inner diameter. To account for the deviation from the narrow pulse approximation in the PGSTE sequence, we use Callaghan's matrix operator framework, which this study validates experimentally for the first time. We also show how to combine average propagators derived for classical one-dimensional and two-dimensional models of restricted diffusion (e.g. between plates, within cylinders) to construct composite three-dimensional models of diffusion in complex media containing pores (e.g. rectangular prisms and/ or capped cylinders) having a distribution of orientations, sizes, and aspect ratios. This three-dimensional modeling framework should aid in describing diffusion in numerous biological systems and in a myriad of materials sciences applications.

To examine the effects of unweighting on the structural and metabolic adaptations of a non-postural muscle, deltoideus muscle biopsies were taken in seven male healthy subjects, before and after a 37 day bedrest. Myofibrillar ATPase histochemistry demonstrated no change in fibre type distributions (I, IIA, IIB), in fibre cross-sectional areas nor in capillary supply. No difference was noted in enzyme activities of oxidative metabolism (citrate synthase, 3-hydroxy-acyl-CoA dehydrogenase), and glycolysis (hexokinase, lactate dehydrogenase). Electron microscopy showed a decrease in the volume density of lipids but no change in mitochondrial volume density and distribution. The results indicate that bedrest induces no major morphological and biochemical changes in deltoideus muscle, contrary to what was previously reported in vastus lateralis muscle. This lack of changes is probably related to an unaltered deltoideus muscle use.