Journal articles on the topic 'Capillaire laser'
To see the other types of publications on this topic, follow the link: Capillaire laser.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Capillaire laser.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Scapolan, S., E. Ansoborlo, C. Moulin, and C. Madic. "Etude de la spéciation de l'uranium en milieu biologique par Electrophorèse Capillaire et Spectrofluorimétrie Laser à Résolution Temporelle." Radioprotection 32, no. 5 (December 1997): 645–57. http://dx.doi.org/10.1051/radiopro:1997123.
2
Wang, Jie, Li Qiang Wang, Yan Shi, Hua Zheng, and Zu Kang Lu. "Study of Stray Light and Cross-Talk of the Capillary Array Electrophoresis." Key Engineering Materials 364-366 (December 2007): 1128–32. http://dx.doi.org/10.4028/www.scientific.net/kem.364-366.1128.
Abstract:
Capillary array electrophoresis (CAE) is founded with the laser induced fluorescence detection (LIFD) system. The same model as the detection system is simulated in Tracepro and the stray light caused by capillaries is analyzed. The stray light distribution of the observation surface is plotted when the laser scans the different sections of a capillary in the array. The results of simulation indicate that the stray light is strongest when scanning the inner center of a capillary and decreases at edges; in two cases (50μm and 75μm inner diameter, ID) when the ID is larger, the stray light is stronger as a whole. Different ID of capillaries which affects the stray light is analyzed; considering many factors, 50μm ID of capillary is appropriate. Based on the analysis of stray light cross-talk by other capillaries in an array, the spacing between capillaries in an array is suggested more than 50μm which the stray light is steady-going and simple to operate. The results can be helpful for the mode of the laser scanning different capillaries in an array sequentially.
3
Stöckl, C., and G. D. Tsakiris. "Experiments with laser-irradiated cylindrical targets." Laser and Particle Beams 9, no. 3 (September 1991): 725–47. http://dx.doi.org/10.1017/s0263034600003736.
Abstract:
Results of novel experiments with laser-heated capillary targets are presented. In these experiments the interior of gold capillaries having a 200- or 700-μm inner diameter and a 2–12-mm length was axially irradiated by injection of the laser energy through one of the end openings. A frequency-doubled Nd:glass laser (λ = 0.53 μm) was employed, delivering 8-J energy in 3 ns. The experiments showed no significant backreflection of laser light. Depending on the capillary diameter and length, most of the laser energy is either transmitted or absorbed inside the capillary. The transmission of laser light was measured as a function of capillary length and found to be in good agreement with the predictions of a simple theoretical model. Two extreme cases could be identified. Capillaries with a 700-μm diameter show uninhibited laser light propagation due to multireflections off the inner wall. In contrast, at the entrance of capillaries with a 200-μm inner diameter a plasma plug forms that absorbs most of the laser energy. In both cases significant energy transport was observed to occur in the axial direction. A stable and strongly radiating plasma column is formed along the capillary axis by the collision of the radially imploding plasma. During the collision, part of the hydrodynamic energy of the plasma is converted into radiative energy. In a special case-a lower limit of ≊7% could be inferred for the conversion efficiency from laser light into X-ray radiation emitted from the rear opening of the capillary.
4
LEVIN, M., S. EISENMANN, T. PALCHAN, A. ZIGLER, K. SUGIYAMA, K. NAKAJIMA, D. KAGANOVICH, et al. "GUIDING OF HIGH LASER INTENSITIES IN LONG PLASMA CHANNELS." International Journal of Modern Physics B 21, no. 03n04 (February 10, 2007): 361–71. http://dx.doi.org/10.1142/s0217979207042136.
Abstract:
Plasma channels have been widely used to guide intense laser pulses over many Rayleigh lengths. Using optimized segmented capillary discharges, we demonstrated guided propagation of ultra short (100 fs) high intensity (1016 W/cm-2, limited by the laser system) pulses over distances up to 12.6 cm and intensities above 1018W/cm2 for 1.5cm boron nitride capillary. Both radial and longitudinal density profiles of plasma channels were studied under various discharge conditions. A new diagnostic technique is presented in which the transport of a guided laser pulse at different delay times from the initiation of the discharge is sampled on a single discharge shot. Using external, 10 nsec Nd YAG laser of several tenths of milijoules to ignite polyethylene capillaries we have demonstrated channels of various length in density range of 1017 - 1019 cm -3 and up to 25% deep. The longitudinal profiles were found to be remarkably uniform in both short and long capillaries. The Boron Nitride capillary has provided a guiding medium that can withstand more than 1000 shots. Using these capillaries we have guided laser intensities above 1018W/cm2. The laser ignition of capillary discharge provided reliable almost jitter free approach. The concerns related to influence of relatively high current density flow through capillary on the injected electrons were studied extensively by us both theoretically and experimentally using a simple injection method. The method is based on the interaction of a high intensity laser pulse with a thin wire placed near capillary entrance. The influence of magnetic fields was found to be insignificant. Using this method we have studied transport of electrons though capillary discharge.
5
Golub, Aleksander S., and Roland N. Pittman. "Erythrocyte-associated transients in Po2 revealed in capillaries of rat mesentery." American Journal of Physiology-Heart and Circulatory Physiology 288, no. 6 (June 2005): H2735—H2743. http://dx.doi.org/10.1152/ajpheart.00711.2004.
Abstract:
Mathematical models have predicted the existence of Po2 gradients between erythrocytes in capillaries in the usual case where plasma contributes substantial resistance to oxygen diffusion. According to theoretical predictions, these gradients could be detected as rapid Po2 fluctuations (erythrocyte-associated transients, EATs) along the capillary. However, verification of a model and correct choice of its parameters can be made only on the basis of direct experimental measurements. We used phosphorescence quenching microscopy to measure Po2 in 52 capillaries of rat mesentery to obtain plasma Po2 values 100 times/s at a given point along a capillary. A 532-nm laser generated 10-μs pulses of light, concentrated by a ×100 objective, onto a spot 0.9 μm in diameter. The presence of erythrocytes in the excitation region was detected on the basis of phosphorescence amplitude (PA), proportional to the amount of plasma encountered by the laser beam, and on the basis of the intensity of transmitted laser light (LT), detected by a photodiode placed under the capillary. The data revealed correlated waveforms in PA, LT, and Po2 in capillaries. The magnitude of the Po2 gradients between erythrocytes and plasma was correlated with average capillary Po2. EATs in Po2 were more readily detected in capillaries with relatively low oxygenation. The correlation coefficients between PA and Po2 for the half of the capillaries ( n = 26) below the median Po2 (mean Po2 = 17 mmHg; R = −0.72) was higher than that for the other half (mean Po2 = 39 mmHg; R = −0.38). These results support the theoretical predictions of EATs and plasma Po2 gradients in capillaries.
6
Tsai, Amy G., Pedro Cabrales, Paul C. Johnson, and Marcos Intaglietta. "Effect of oxygen consumption by measuring method on Po2 transients associated with the passage of erythrocytes in capillaries of rat mesentery." American Journal of Physiology-Heart and Circulatory Physiology 289, no. 4 (October 2005): H1777—H1779. http://dx.doi.org/10.1152/ajpheart.00503.2005.
Abstract:
Golub, Aleksander S., and Roland N. Pittman. Erythrocyte-associated transients in PO2 revealed in capillaries of rat mesentery. Am J Physiol Heart Circ Physiol 288: H2735–H2743 , 2005. Mathematical models have predicted the existence of Po2 gradients between erythrocytes in capillaries in the usual case where plasma contributes substantial resistance to oxygen diffusion. According to theoretical predictions, these gradients could be detected as rapid Po2 fluctuations (erythrocyte-associated transients, EATs) along the capillary. However, verification of a model and correct choice of its parameters can be made only on the basis of direct experimental measurements. We used phosphorescence quenching microscopy to measure Po2 in 52 capillaries of rat mesentery to obtain plasma Po2 values 100 times/s at a given point along a capillary. A 532-nm laser generated 10-μs pulses of light, concentrated by a ×100 objective, onto a spot 0.9 μm in diameter. The presence of erythrocytes in the excitation region was detected on the basis of phosphorescence amplitude (PA), proportional to the amount of plasma encountered by the laser beam, and on the basis of the intensity of transmitted laser light (LT), detected by a photodiode placed under the capillary. The data revealed correlated waveforms in PA, LT, and Po2 in capillaries. The magnitude of the Po2 gradients between erythrocytes and plasma was correlated with average capillary Po2. EATs in Po2 were more readily detected in capillaries with relatively low oxygenation. The correlation coefficients between PA and Po2 for the half of the capillaries ( n = 26) below the median Po2 (mean Po2 = 17 mmHg; R = −0.72) was higher than that for the other half (mean Po2 = 39 mmHg; R = −0.38). These results support the theoretical predictions of EATs and plasma Po2 gradients in capillaries.
7
WIGGINS, S. M., M. P. REIJNDERS, S. ABUAZOUM, K. HART, G. VIEUX, G. H. WELSH, R. C. ISSAC, X. YANG, D. R. JONES, and D. A. JAROSZYNSKI. "Straight and linearly tapered capillaries produced by femtosecond laser micromachining." Journal of Plasma Physics 78, no. 4 (February 2, 2012): 355–61. http://dx.doi.org/10.1017/s0022377812000062.
Abstract:
AbstractGas-filled capillary discharge waveguides are a commonly employed medium in laser–plasma interaction applications, such as the laser wakefield accelerator, because they can simultaneously guide high-power laser pulses while acting as the medium for acceleration. In this paper, the production of both straight and linearly tapered capillaries using a femtosecond laser micromachining technique is presented. A tapered capillary is shown to possess a smooth variation in diameter (from 305 μm to 183 μm) along its entire 40 mm length, which would lead to a longitudinal plasma density gradient, thereby dramatically improving the laser–plasma interaction efficiency in applications. Efficient guiding with up to 82% energy transmission of the fundamental Gaussian mode of a low intensity, 50 fs duration laser pulse is shown for both types of capillary waveguide.
8
Yushina, Tatiana E., N. E. Gorbatova, and O. O. Sarukhanyan. "PROBLEM OF TREATMENT OF THE CAPILLARY ANGIODYSPLASIA OF SKIN IN CHILDREN." Russian Journal of Pediatric Surgery 23, no. 2 (July 9, 2019): 72–77. http://dx.doi.org/10.18821/1560-9510-2019-23-2-72-77.
Abstract:
Capillary angiodysplasia of the skin presents by itself pathologically dilated capillaries located under the basal zone of the growth of the epidermis. There are many options for the correction of this vascular pathology of the skin, including general and local methods. In recent years, laser treatments for capillary angiodysplasia have become widespread. According to many authors, the most effective and promising method is laser photodestruction by radiation of the yellow-green spectral range. Unfortunately, the optimal ranges of the parameters of exposure to laser radiation in the treatment of specific forms of capillary angiodysplasia of the skin, taking into account nature and age characteristics of the skin in children, have not yet been determined.
9
Wu, Jiaqi, Peter Frank, and Janusz Pawliszyn. "Diode Laser-Based Concentration Gradient Detector for Detection of Capillary Isoelectric Focusing." Applied Spectroscopy 46, no. 12 (December 1992): 1837–40. http://dx.doi.org/10.1366/0003702924123610.
Abstract:
A diode laser-based concentration gradient detector was used in a compact capillary isoelectric focusing (CIEF) instrument which also includes a short piece of 20- μm-i.d. capillary. The diode laser was mounted with a focusing lens and driving circuit in an 8-cm-long, 2-cm-diameter aluminium barrel, and was powered by a 9-V battery. The size of the whole instrument is about 25 cm × 15 cm—much smaller than that of any other capillary electrophoresis (CE) instrument. In order to focus the laser beam into the narrow capillary, optical geometry of the detector was optimized. This diode laser-based detector is the first one which has been applied to CE with capillaries narrower than 50 μm. The detection limit in concentration for ovalbumin reaches 2.0 × 10−7 M, which corresponds to a 7.0 fmol on-column detection limit for the protein. This on-column detection limit of the universal detector is within the same order of magnitude as that of a diode laser-based fluorescence CE detector. The resolution of the instrument is about 0.02 pH units, and small amounts of protein samples in a wide isoelectric point range can be separated and detected by the compact instrument without derivatization in less than 12 minutes.
10
Pin, Christophe, Ryohei Otsuka, Hideki Fujiwara, and Keiji Sasaki. "Optical transport of fluorescent diamond particles inside a tapered capillary." EPJ Web of Conferences 215 (2019): 16002. http://dx.doi.org/10.1051/epjconf/201921516002.
Abstract:
Optical forces provide an efficient way to sort particles and biological materials according to their optical properties. However, both enhanced optical forces and a large interaction volume are needed in order to optically sort a large number of nanoparticles. We investigate the use of a tapered glass capillary as an optofluidic platform for optical manipulation and optical sorting applications. Tapered capillaries with micrometre and sub-micrometre sizes are fabricated. After filling the tapered capillary with a colloidal solution of red fluorescent diamond particles, a green laser light is coupled into the capillary. The tapered capillary acts both as a microfluidic channel and as an optical waveguide, making it possible for the light to interact with the particles inside the sample solution. Using an incident laser power of few tens of milliwatts, we achieve optical transportation of the brightest particles inside the tapered part of the capillary. Particle velocities as high as few tens of micrometres per second are measured.
11
Fujino, Hidemi, Hisaharu Kohzuki, Isao Takeda, Takahiko Kiyooka, Takehiro Miyasaka, Satoshi Mohri, Juichiro Shimizu, and Fumihiko Kajiya. "Regression of capillary network in atrophied soleus muscle induced by hindlimb unweighting." Journal of Applied Physiology 98, no. 4 (April 2005): 1407–13. http://dx.doi.org/10.1152/japplphysiol.00961.2004.
Abstract:
Little is known about the mechanisms responsible for the adaptation and changes in the capillary network of hindlimb unweighting (HU)-induced atrophied skeletal muscle, especially the coupling between functional and structural alterations of intercapillary anastomoses and tortuosity of capillaries. We hypothesized that muscle atrophy by HU leads to the apoptotic regression of the capillaries and intercapillary anastomoses with their functional alteration in hemodynamics. To clarify the three-dimensional architecture of the capillary network, contrast medium-injected rat soleus muscles were visualized clearly using a confocal laser scanning microscope, and sections were stained by terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL) and with anti-von Willebrand factor. In vivo, the red blood cell velocity of soleus muscle capillaries were determined with a pencil-lens intravital microscope brought into direct contact with the soleus surface. After HU, the total muscle mass, myofibril protein mass, and slow-type myosin heavy chain content were significantly lower. The number of capillaries paralleling muscle fiber and red blood cells velocity were higher in atrophied soleus. However, the mean capillary volume and capillary luminal diameter were significantly smaller after HU than in the age-matched control group. In addition, we found that the number of anastomoses and the tortuosity were significantly lower and TUNEL-positive endothelial cells were observed in atrophied soleus muscles, especially the anastomoses and/or tortuous capillaries. These results indicate that muscle atrophy by HU generates structural alterations in the capillary network, and apoptosis appears to occur in the endothelial cell of the muscle capillaries.
12
Grothusen, John R. "Laser Doppler Imaging: Usefulness in Chronic Pain Medicine." Pain Physician 5;14, no. 5;9 (September 14, 2011): 491–98. http://dx.doi.org/10.36076/ppj.2011/14/491.
Abstract:
Sympathetic nervous system dysfunction is thought to be a factor in neuropathic pain conditions such as Complex Regional Pain Syndrome and in vascular conditions such as Raynaud’s phenomenon. Laser Doppler fluxmetry has been used as a fast non-invasive method to quantify changes in skin capillary blood flow which reflect activation of sympathetically mediated vasoconstriction of the arterioles that supply the capillaries. Studies of dynamic change of skin capillary blood flow with sympathetic activation such as cold or inspiratory gasp have generally used single point laser Doppler systems where the probe is in contact with the skin. The results are a single line tracing representing the capillary flow at a single point on the skin a few millimeters in diameter. Laser Doppler imaging (moorLDI laser Doppler imager, Moor Instruments Ltd.) allows for non-contact recording of skin blood flow of an area as large as 50 centimeters square with a resolution of 256 by 256 pixels and 4 milliseconds per pixel. Most work with laser Doppler imaging has studied changes that occur between successive scans. We have found it useful to look at changes that occur during a scan. In this way we obtain data that is comparable to the time resolution of single point laser Doppler methods, but with the larger spatial information that is available with laser Doppler imaging. We present a small series of case reports in which inspiratory gasp during laser Doppler imaging was able to provide quick, useful and unequivocal clinical information regarding the status of regional bilateral skin capillary response to sympathetic activation. This may be useful for distinguishing sympathetically mediated from sympathetically independent pain. We believe the methods described may provide the basis for future quantitative studies similar to those that use single point laser Doppler methods. Key words: Laser doppler, laser Doppler imaging, sympathetically maintained pain, Raynaud’s phenomen, complex regional pain syndrome
13
Safin, D. A., and N. E. Gorbatova. "Evaluation of the effectiveness of laser treatment capillary malformation in children (systematic review)." Russian Journal of Pediatric Surgery 26, no. 4 (August 26, 2022): 214–19. http://dx.doi.org/10.55308/1560-9510-2022-26-4-214-219.
Abstract:
Background. Capillary angiodysplasia is a common vascular malformation represented by an increase in the number of dilated capillaries of the skin. Being located in the face area, this defect contributes to the development of an inferiority complex in a child. Various methods are used for treatment, but all of them are not effective enough. Currently, the most effective and promising method is laser photodestruction.Aim. To study the efficacy and safety of laser treatment of skin сapillary angiodysplasia in children with various laser devices (PDL 585 nm, Nd:YAG 1064 nm, Nd:YAG/KTP 532 nm), based on a systematic review of modern literature for the period from 2000 to 2020.Materials and methods. A systematic review was conducted in foreign and Russian databases for the period from 2000 to 2020. Keywords were used for the search: capillary angiodysplasia, capillary malformation, wine stain, vascular malformation, laser treatment. Out of 1543 literature sources, 9 full-text articles are included in the review.Results. Comparing the results of treatment using different types of lasers, it was noted that a very good result was achieved in 33.8% of cases, good in 33.7%, average in 20.4%, no effect in 1.2%. The total number of complications was 62 cases (9.5%): hyperpigmentation in 32 patients, scars in 15 cases, hypopigmentation in 12, skin atrophy in three.Discussion. The conducted systematic review indicates the effectiveness and disadvantages of using various laser radiation for the treatment of capillary angiodysplasia of the skin. The articles lack information on the relationship between the effectiveness of treatment from morphological and hemodynamic features of vascular formations and the selectivity of laser radiation to skin chromophores.Conclusion. It is necessary to conduct research to select the optimal laser radiation, taking into account the morphological and hemodynamic features of capillary angiodysplasia, which will ensure minimal skin damage and improve treatment results.
14
Nishimura, Nozomi, Nathanael L. Rosidi, Costantino Iadecola, and Chris B. Schaffer. "Limitations of Collateral Flow after Occlusion of a Single Cortical Penetrating Arteriole." Journal of Cerebral Blood Flow & Metabolism 30, no. 12 (September 15, 2010): 1914–27. http://dx.doi.org/10.1038/jcbfm.2010.157.
Abstract:
Occlusions of penetrating arterioles, which plunge into cortex and feed capillary beds, cause severe decreases in blood flow and are potential causes of ischemic microlesions. However, surrounding arterioles and capillary beds remain flowing and might provide collateral flow around the occlusion. We used femtosecond laser ablation to trigger clotting in single penetrating arterioles in rat cortex and two-photon microscopy to measure changes in microvessel diameter and red blood cell speed after the clot. We found that after occlusion of a single penetrating arteriole, nearby penetrating and surface arterioles did not dilate, suggesting that alternate blood flow routes are not actively recruited. In contrast, capillaries showed two types of reactions. Capillaries directly downstream from the occluded arteriole dilated after the clot, but other capillaries in the same vicinity did not dilate. This heterogeneity in capillary response suggests that signals for vasodilation are vascular rather than parenchymal in origin. Although both neighboring arterioles and capillaries dilated in response to topically applied acetylcholine after the occlusion, the flow in the territory of the occluded arteriole did not improve. Collateral flow from neighboring penetrating arterioles is neither actively recruited nor effective in improving blood flow after the occlusion of a single penetrating arteriole.
15
Netten, Paetrick M., Hub Wollersheim, Theo Thien, and Jos A. Lutterman. "Skin Microcirculation of the Foot in Diabetic Neuropathy." Clinical Science 91, no. 5 (November 1, 1996): 559–65. http://dx.doi.org/10.1042/cs0910559.
Abstract:
1. In the feet of patients with diabetic neuropathy, total skin blood flow is increased due to an increased shunt flow. The question is, does this increased anastomotic shunt flow lead to either under- or overperfused nutritive capillaries. 2. To solve this question, skin microcirculation tests of the left big toe were performed in 20 healthy control subjects and in 40 insulin-dependent diabetic patients without macroangiopathy, 20 without and 20 with neuropathy. Skin temperature measurements and laser Doppler fluxmetry were performed to record mainly shunt flow and capillaroscopy to study nailfold capillary blood flow. 3. The insulin-dependent diabetic patients with neuropathy had a higher baseline skin temperature (mean ± SEM; 30.0 ± 0.6°C) and laser Doppler fluxmetry [26.2 ± 2.2 perfusion units (pu)] than patients without neuropathy (27.2 ± 0.8°C, P < 0.01; 16.1 ± 2.0 pu, P < 0.01) and healthy control subjects (27.9 ± 0.7°C, P < 0.05; 18.6 ± 2.8 pu, P < 0.05). Sympathetic stimulation (inspiratory gasp) resulted in a smaller laser Doppler fluxmetry decrease in the neuropathic patients (31.4 ± 4.6%) compared with non-neuropathic patients (48.2 ± 5.1%, P < 0.05) and control subjects (49.0 ± 3.8%, P < 0.05), while no difference between the three groups was seen in the laser Doppler fluxmetry decrease during a postural vasoconstriction test. The number of visible capillaries was highest in the neuropathic patients (10.2 ± 0.6/0.5 mm2), when compared with non-neuropathic patients (8.7 ± 1.2/0.5 mm2, P < 0.05) and control subjects (8.3 ± 0.3/0.5 mm2, P < 0.001). Capillary blood-cell velocity was significantly higher in the neuropathic patients (0.32 ± 0.05 mm/s) compared with non-neuropathic patients (0.23 ± 0.03 mm/s, P < 0.05) and control subjects (0.23 ± 0.02 mm/s, P < 0.01). 4. We conclude that there is an overperfused nutritive capillary circulation in the feet of patients with diabetic neuropathy. This is in contradiction to the capillary steal phenomenon and favours the hyperdynamic hypothesis to explain the decreased healing potential in diabetic neuropathic foot ulceration.
16
Lu, Xiandan, and Edward S. Yeung. "Optimization of Excitation and Detection Geometry for Multiplexed Capillary Array Electrophoresis of DNA Fragments." Applied Spectroscopy 49, no. 5 (May 1995): 605–9. http://dx.doi.org/10.1366/0003702953963986.
Abstract:
A new on-column excitation and detection geometry for multiplexed array capillary electrophoresis is evaluated. The detection limit is improved 100-fold for the same laser power because of more efficient coupling of the laser beam. The illumination is also more uniform over the entire array. Stray light and cross-talk are effectively suppressed by immersing the capillaries in water to roughly match the refractive index. A charge-coupled-device (CCD) camera combined with cutoff filters provides adequate sensitivity and speed for high-speed DNA sequencing based on sieving in a polymer-matrix solution.
17
Stefanovic, Bojana, Elizabeth Hutchinson, Victoria Yakovleva, Vincent Schram, James T. Russell, Leonardo Belluscio, Alan P. Koretsky, and Afonso C. Silva. "Functional Reactivity of Cerebral Capillaries." Journal of Cerebral Blood Flow & Metabolism 28, no. 5 (December 5, 2007): 961–72. http://dx.doi.org/10.1038/sj.jcbfm.9600590.
Abstract:
The spatiotemporal evolution of cerebral microcirculatory adjustments to functional brain stimulation is the fundamental determinant of the functional specificity of hemodynamically weighted neuroimaging signals. Very little data, however, exist on the functional reactivity of capillaries, the vessels most proximal to the activated neuronal population. Here, we used two-photon laser scanning microscopy, in combination with intracranial electrophysiology and intravital video microscopy, to explore the changes in cortical hemodynamics, at the level of individual capillaries, in response to steady-state forepaw stimulation in an anesthetized rodent model. Overall, the microcirculatory response to functional stimulation was characterized by a pronounced decrease in vascular transit times (20% ± 8%), a dilatation of the capillary bed (10.9% ± 1.2%), and significant increases in red blood cell speed (33.0% ± 7.7%) and flux (19.5% ± 6.2%). Capillaries dilated more than the medium-caliber vessels, indicating a decreased heterogeneity in vessel volumes and increased blood flow-carrying capacity during neuronal activation relative to baseline. Capillary dilatation accounted for an estimated ˜18% of the total change in the focal cerebral blood volume. In support of a capacity for focal redistribution of microvascular flow and volume, significant, though less frequent, local stimulation-induced decreases in capillary volume and erythrocyte speed and flux also occurred. The present findings provide further evidence of a strong functional reactivity of cerebral capillaries and underscore the importance of changes in the capillary geometry in the hemodynamic response to neuronal activation.
18
Aoki, Takuya, Yukio Suzuki, Kazumi Nishio, Kouichi Suzuki, Atsusi Miyata, Yutaka Iigou, Hiroshi Serizawa, et al. "Role of CD18-ICAM-1 in the entrapment of stimulated leukocytes in alveolar capillaries of perfused rat lungs." American Journal of Physiology-Heart and Circulatory Physiology 273, no. 5 (November 1, 1997): H2361—H2371. http://dx.doi.org/10.1152/ajpheart.1997.273.5.h2361.
Abstract:
This study aimed to examine the behavior of stimulated leukocytes in the pulmonary microcirculation. The leukocyte-endothelium interaction was visualized under physiological shear rates in perfused rat lungs using high-speed confocal laser video microscopy. Leukocytes labeled with carboxyfluorescein were stimulated with cytokine-induced neutrophil chemoattractant (CINC/gro), which caused L-selectin shedding and inverse upregulation of CD18. Neither unstimulated nor stimulated leukocytes exhibited rolling in either pulmonary arterioles or venules, whereas both were sequestered in capillaries. Approximately 50% of stimulated leukocytes showed a transient cessation of movement in pulmonary capillaries. The CINC/gro stimulation, which inhibited leukocyte rolling and adhesion to mesenteric venules, reduced leukocyte velocity and increased leukocytes in pulmonary capillaries. Pretreatment with monoclonal antibodies against intercellular adhesion molecule-1 (ICAM-1) or CD18 attenuated these changes. Confocal microfluorography revealed constitutive expression of ICAM-1 not only in venules but also abundantly in capillary networks. These results suggest that selectin-independent, CD18-ICAM-1-dependent capillary sequestration is one of the major mechanisms by which activated leukocytes accumulate in the lungs.
19
Wagner, Roger, Denis Van Loo, Fred Hossler, Kirk Czymmek, Elin Pauwels, and Luc Van Hoorebeke. "High-Resolution Imaging of Kidney Vascular Corrosion Casts with Nano-CT." Microscopy and Microanalysis 17, no. 2 (December 2, 2010): 215–19. http://dx.doi.org/10.1017/s1431927610094201.
Abstract:
AbstractA vascular corrosion cast of an entire mouse kidney was scanned with a modular multiresolution X-ray nanotomography system. Using an isotropic voxel pitch of 0.5 μm, capillary systems such as the vasa recta, peritubular capillaries and glomeruli were clearly resolved. This represents a considerable improvement over corrosion casts scanned with microcomputed tomography systems. The resolving power of this system was clearly demonstrated by the unique observation of a dense, subcapsular mat of capillaries enveloping the entire outer surface of the cortical region. Resolution of glomerular capillaries was comparable to similar models derived from laser scanning confocal microscopy. The high-resolution, large field of view and the three-dimensional nature of the resulting data opens new possibilities for the use of corrosion casting in research.
20
Kai, Y., W. Garen, T. Schlegel, and U. Teubner. "A novel shock tube with a laser–plasma driver." Laser and Particle Beams 35, no. 4 (September 13, 2017): 610–18. http://dx.doi.org/10.1017/s0263034617000635.
Abstract:
AbstractA novel method to generate shock waves in small tubes is demonstrated. A femtosecond laser is applied to generate an optical breakdown an aluminum film as target. Due to the sudden appearance of this non-equilibrium state of the target, a shock wave is induced. The shock wave is further driven by the expanding high-pressure plasma (up to 10 Mbar), which serves as a quasi-piston, until the plasma recombines. The shock wave then propagates further into a glass capillary (different square capillaries with hydraulic diameter D down to 50 µm are applied). Shock wave propagation is investigated by laser interferometry. Although the plasma is an unsteady driver, due to the geometrical confinement of the capillaries, rather strong micro shocks can still propagate as far as 35 times D. In addition to the experiments, the initial conditions of this novel method are investigated by hydrocode simulations using MULTI-fs.
21
Knochenmuss, Richard. "Laser Desorption/Ablation Plumes from Capillary-Like Restricted Volumes." European Journal of Mass Spectrometry 15, no. 2 (April 2009): 189–98. http://dx.doi.org/10.1255/ejms.960.
Abstract:
Laser desorption/ionization from structured surfaces has been the object of recently renewed interest. Conditions in the plume of material ablated from such surfaces may differ from those of a sample which is ablated in bulk. Since recombination and secondary ion–molecule reactions in the plume play a major role in determining the types and quantities of ions observed at the detector, these differences are analytically relevant. Desorption/ionization substrates with channels of high aspect ratio are modeled as capillary nozzles, from which free jets are emitted. A previously developed matrix-assisted laser desorption/ionization ablation/ionization model is adapted for these jets. More primary ions reach the detector when ablated from a capillary orifice, but fewer analye ions are created in secondary reactions. These differences in ion yield can persist for arrays of capillaries on the surface, depending on the ratio of their diameter to spacing.
22
Wagner, Jonas, Christian Hagenlocher, Marc Hummel, Alexander Olowinsky, Rudolf Weber, and Thomas Graf. "Synchrotron X-ray Analysis of the Influence of the Magnesium Content on the Absorptance during Full-Penetration Laser Welding of Aluminum." Metals 11, no. 5 (May 14, 2021): 797. http://dx.doi.org/10.3390/met11050797.
Abstract:
Full-penetration laser beam welding is characterized by a weld seam whose depth equals the material thickness. It is associated with a stable capillary and is therefore widely used for welding of sheet metal components. The realization of lightweight concepts in car body production requires the application of high-strength aluminum alloys that contain magnesium as an alloying element, which significantly influences the evaporation temperature and pressure. This change of the evaporation processes influences the geometry of the capillary and therefore its absorptance. In order to quantify the influence of magnesium on the capillary, their geometries were captured by means of high-speed synchrotron X-ray imaging during the welding process of the aluminum alloys AA1050A (Al99.5), AA5754 (AlMg3) and AA6016 (AlSi1.2Mg0.4). The 3D-geometries of the capillaries were reconstructed from the intensity distribution in the recorded X-ray images and their absorptance of the incident laser beam was determined by the analysis of the reconstructed 3D-geometry with a raytracing algorithm. The results presented in this paper capture for the first time the influence of the magnesium content in high-strength aluminum alloys on the aspect ratio of the capillary, which explains the reduced absorptance in case of full-penetration laser beam welding of aluminum alloys with a high content of volatile elements. In order to improve the absorptance in full-penetration welding, these findings provide the information required for the deduction of new optimization approaches.
23
Hakim, T. S., E. Gilbert, and E. M. Camporesi. "Blood flow, volume, and transit time in the pulmonary microvasculature using laser-Doppler." Journal of Applied Physiology 76, no. 6 (June 1, 1994): 2643–50. http://dx.doi.org/10.1152/jappl.1994.76.6.2643.
Abstract:
Capillary transit time is determined by the ratio of capillary volume to flow rate. Exercise-induced hypoxemia is thought to occur because of the short transit time of erythrocytes in capillaries. The effect of flow rate on capillary volume (recruitment vs. distension) is controversial. In a perfused left lower lobe preparation in canine lungs, we used laser-Doppler flowmetry (model ALF21R) to monitor changes in blood flow, volume, and transit time in the microvasculature near the subpleural surface. Changes in total flow, blood volume, and total transit time (tt) were also measured. The results showed that microvascular volume approached maximum when flow rate was at resting value (0.4 l/min) and pressure in the pulmonary artery was > 6 mmHg relative to the level of the capillaries. In contrast, the total blood volume increased gradually over a wide range of flow rates. When flow increased 4.2 times (from 155 to 650 ml/min), tt decreased from 7.32 to 3.53 s; meanwhile, microvascular flow increased from 6.0 to 12.7 units and microvascular transit time decreased from 3.14 to 1.81 units. The changes in microvascular volume and transit time were essentially independent of whether the venous pressure was higher or lower than alveolar pressure. At very high flow (6–10 times resting value), tt fell gradually to approximately 1 s. Direct monitoring of transit time with the laser-Doppler also revealed a gradual decline in microvascular transit time as flow rate increased from 2 to 10 times the normal flow. (ABSTRACT TRUNCATED AT 250 WORDS)
24
Milkiewicz, Malgorzata, and Tara L. Haas. "Effect of mechanical stretch on HIF-1α and MMP-2 expression in capillaries isolated from overloaded skeletal muscles: laser capture microdissection study." American Journal of Physiology-Heart and Circulatory Physiology 289, no. 3 (September 2005): H1315—H1320. http://dx.doi.org/10.1152/ajpheart.00284.2005.
Abstract:
Under physiological nonhypoxic conditions, angiogenesis can be driven by mechanical forces. However, because of the limitations of the specific gene expression analysis of microvessels from in vivo experiments, the mechanisms regulating the coordinated expression of angiogenic factors implicated in the process remain intangible. In this study, the technique of laser capture microdissection (LCM) was adapted for the study of angiogenesis in skeletal muscles. With a combination of LCM and real-time quantitative PCR it was demonstrated that capillary endothelial cells produce matrix metalloproteinase (MMP)-2 and that mechanical stretch of capillaries within muscle tissue markedly increases MMP-2 mRNA (2.5-fold increase vs. control; P < 0.05). In addition, we showed that transcription factor hypoxia-inducible factor (HIF)-1α expression was 13.5-fold higher in capillaries subjected to stretch compared with controls ( P < 0.05). These findings demonstrate the feasibility of this approach to study angiogenic gene regulation and provide novel evidence of HIF-1α induction in stretched capillary endothelial cells.
25
Williams, S. A., S. Wasserman, D. W. Rawlinson, R. I. Kitney, L. H. Smaje, and J. E. Tooke. "Dynamic measurement of human capillary blood pressure." Clinical Science 74, no. 5 (May 1, 1988): 507–12. http://dx.doi.org/10.1042/cs0740507.
Abstract:
1. Capillary blood pressure was measured in man using a dynamic servo-nulling system and direct micropuncture. This enabled assessments of the normal variations in pressure which influence fluid filtration and reabsorption. 2. Seventy-eight capillaries in 19 subjects were punctured in one of three positions around the capillary loop with the hand at the level of the sternal angle. Mean pressure around the loop fell from 37.7 ± 3.7 mmHg (arteriolar limb, mean ± sem, n = 12) to 19.4 ± 1.0 mmHg (apex, n = 25) to 14.6 ± 0.5 mmHg (venular limb, n = 41) at skin temperatures of 18.7–33.1°C. These values agree closely with Landis' original studies in 1930 [E. Landis (1930) Heart, 15, 209–228]. 3. The mean filtration/reabsorption state of any particular capillary limb was not static because of cardiac, vasomotor and respiratory fluctuations in capillary pressure. From a total of 38 capillaries in which recordings were analysed for 30 s, the fluctuations in pressure were such that 27 capillaries probably had periods of both filtration and reabsorption. 4. Computerized superimposition and coherent averaging of trains of capillary pulses enabled an accurate description of the pulse waveform to be made in three capillaries. This was remarkably similar to waveforms from the radial artery, albeit at reduced amplitude (average 3.6 ± 3.4 mmHg, mean ± sd overall). The time for the pulse to travel between the radial artery and the finger capillary was approximately 10 ms, which implies a propagation velocity of several metres per second. 5. Fourteen long recordings of capillary pressure (mean 154 s) were subjected to computerized Fourier analysis and cross-correlation with other parameters. Low frequency fluctuations between 0.02 and 0.2 Hz (0.086 ± 0.05 Hz, mean ± sd) correlated closely with vasomotion in simultaneously recorded (laser-Doppler) skin blood flow (0.080 ± 0.5 Hz), although they were not synchronous. Higher frequencies between 0.2 and 0.6 Hz (0.28 ± 0.03 Hz) correlated well with respiration (0.29 ± 0.03 Hz), were synchronous and probably relate to respiratory fluctuations in venous pressure. The dynamic system has thus enabled us to describe the considerable variations in normal capillary pressure and to relate this variability to physiological influences.
26
De Sanctis, M. T., L. Incandela, G. Belcaro, and M. R. Cesarone. "Topical Treatment of Venous Microangiopathy in Patients with Venous Ulceration with Essaven Gel." Angiology 52, no. 3_suppl (December 2001): S29—S34. http://dx.doi.org/10.1177/0003319701052003s07.
Abstract:
The involvement of the microcirculation in chronic venous insufficiency (CVI), due to venous hypertension, causes venous hypertensive microangiopathy (VHM) and ulceration. VHM is char acterized by enlarged, convoluted capillaries; microvascular thrombosis; obliteration of some capillaries; increase in flux, permeability, and edema and altered microlymphatics. PO 2 is decreased and CO2 increased. Capillary exchanges are altered and nutritional alterations even tually lead to venous ulcers. Edema is associated with increased capillary pressure, reduced clearance, and increased exchange surface of capillaries, which become tortuous and glomerular-like. The aim of this randomized, placebo-controlled study was to evaluate local treatment with Essaven gel (EG) in subjects with venous microangiopathy and ulcers. Measurements of laser Doppler flux, PO2, and PCO2 in standardized conditions showed positive changes (a significant decrease of the abnormally increased flux and CO2 while PO2 increased) in the EG treatment group. Changes in the placebo and control group were more limited (changes in the placebo group were mainly associated with skin manipulation when placebo- EG was applied). In conclusion, Essaven gel, in comparison with placebo, acutely improves the microcirculation in VHM even with a single acute application.
27
Hudetz, Antal G., Hui Shen, and John P. Kampine. "Nitric oxide from neuronal NOS plays critical role in cerebral capillary flow response to hypoxia." American Journal of Physiology-Heart and Circulatory Physiology 274, no. 3 (March 1, 1998): H982—H989. http://dx.doi.org/10.1152/ajpheart.1998.274.3.h982.
Abstract:
We investigated, using a direct, intravital microscopic technique, whether nitric oxide (NO) from neuronal nitric oxide synthase (nNOS) plays a role in the cerebral capillary flow response to acute hypoxia. Erythrocyte flow in subsurface capillaries of the frontoparietal cortex of adult Sprague-Dawley rats was visualized using epifluorescence videomicroscopy after fluorescent labeling of red blood cells (RBC) in tracer concentrations. The velocity of labeled RBC in individual capillaries was measured off-line using an image analysis system. Hypoxia was produced by lowering the inspired O2 concentration to 15% for 5 min in control animals and in those pretreated with the selective nNOS inhibitor 7-nitroindazole (7-NI; 20 mg/kg ip). In the control group, hypoxia increased RBC velocity by 34 ± 8%. In the group treated with 7-NI, this response was reversed to a statistically significant 8 ± 3% decrease. This paradoxical response to hypoxia after 7-NI was observed in nearly all capillaries. 7-NI itself decreased the baseline RBC velocity by 12 ± 4%. The cerebral hyperemic response to hypoxia was also assessed with the laser Doppler flow (LDF) technique. In control animals, hypoxia produced a 33 ± 6% increase in LDF, similar to the increase in RBC velocity. After 7-NI treatment, the response to hypoxia was moderately attenuated but still significant at a 19 ± 2% increase in LDF. These results support the role of NO from nNOS in the cerebral hyperemic response to hypoxia. They imply that 7-NI interfered with a physiological mechanism that was fundamental to cerebral capillary flow regulation and provide direct evidence that cerebral capillary perfusion may be dissociated from a concurrent change in regional tissue perfusion as reflected by LDF. In conclusion, NO from nNOS contributes to the maintenance of RBC flow in cerebral capillaries and plays a critically important role in the selective regulation of cerebral capillary flow during hypoxia.
28
Cui Huaiyu, 崔怀愈, 申玉杰 Shen Yujie, 赵东迪 Zhao Dongdi, 安博 An Bo, and 赵永蓬 Zhao Yongpeng. "毛细管放电46.9 nm极紫外激光应用研究进展." Chinese Journal of Lasers 51, no. 7 (2024): 0701009. http://dx.doi.org/10.3788/cjl230867.
29
Tomita, Yutaka, Nathalie Kubis, Yolande Calando, Alexy Tran Dinh, Philippe Méric, Jacques Seylaz, and Elisabeth Pinard. "Long-Term in Vivo Investigation of Mouse Cerebral Microcirculation by Fluorescence Confocal Microscopy in the Area of Focal Ischemia." Journal of Cerebral Blood Flow & Metabolism 25, no. 7 (March 9, 2005): 858–67. http://dx.doi.org/10.1038/sj.jcbfm.9600077.
Abstract:
This study was designed to assess that mouse pial and cortical microcirculation can be monitored in the long term directly in the area of focal ischemia, using in vivo fluorescence microscopy. A closed cranial window was placed over the left parieto-occipital cortex of C57BL/6J mice. Local microcirculation was recorded in real time through the window using laser-scanning confocal fluorescence microscopy after intravenous injection of fluorescent erythrocytes and dextran. The basal velocity of erythrocytes through intraparenchymal capillaries was 0.53 ± 0.30 mm/sec ( n = 121 capillaries in 10 mice). Two branches of the middle cerebral artery were topically cauterized through the window. Blood flow evaluated by laser-Doppler flowmetry in two distinct areas indicated the occurrence of an ischemic core (15.2% ± 5.9% of baseline for at least 2 h) and a penumbral zone. Magnetic resonance imaging and histology were used to characterize the ischemic area at 24 h after occlusion. The infarct volume was 7.3 ± 3.2 mm3 ( n = 6). Microcirculation was repeatedly videorecorded using fluorescence confocal microscopy over the next month. After the decrease following arterial occlusion, capillary erythrocyte velocity was significantly higher than baseline 1 week later, and attained 0.74 ± 0.51 mm/sec ( n = 76 capillaries in six mice, P<0.005) after 1 month, while venous and capillary network remodeling was assessed, with a marked decrease in tortuosity. Immunohistochemistry revealed a zone of necrotic tissue into the infarct epicenter, with activated astrocytes at its border. Such long-term investigations in ischemic cortex brings new insight into the microcirculatory changes induced by focal ischemia and show the feasibility of long-term fluorescence studies in the mouse cortex.
30
Barker, Matthew C., Aleksander S. Golub, and Roland N. Pittman. "Erythrocyte-associated transients in capillary Po2: an isovolemic hemodilution study in the rat spinotrapezius muscle." American Journal of Physiology-Heart and Circulatory Physiology 292, no. 5 (May 2007): H2540—H2549. http://dx.doi.org/10.1152/ajpheart.00915.2006.
Abstract:
Mathematical simulations of oxygen delivery to tissue from capillaries that take into account the particulate nature of blood flow predict the existence of oxygen tension (Po2) gradients between erythrocytes (RBCs). As RBCs and plasma alternately pass an observation point, these gradients are manifested as rapid fluctuations in Po2, also known as erythrocyte-associated transients (EATs). The impact of hemodilution on EATs and oxygen delivery at the capillary level of the microcirculation has yet to be elucidated. Therefore, in the present study, phosphorescence quenching microscopy was used to measure EATs and Po2 in capillaries of the rat spinotrapezius muscle at the following systemic hematocrits (Hctsys): normal (39%) and after moderate (HES1; 27%) or severe (HES2; 15%) isovolemic hemodilution using a 6% hetastarch solution. A 532-nm laser, generating 10-μs pulses concentrated onto a 0.9-μm spot, was used to obtain plasma Po2 values 100 times/s at points along surface capillaries of the muscle. Mean capillary Po2 (Pc[Formula: see text]; means ± SE) significantly decreased between conditions (normal: 56 ± 2 mmHg, n = 45; HES1: 47 ± 2 mmHg, n = 62; HES2: 27 ± 2 mmHg, n = 52, where n = capillary number). In addition, the magnitude of Po2 transients (ΔPo2) significantly decreased with hemodilution (normal: 19 ± 1 mmHg, n = 45; HES1: 11 ± 1 mmHg, n = 62; HES2: 6 ± 1 mmHg, n = 52). Results suggest that the decrease in Pc[Formula: see text] and ΔPo2 with hemodilution is primarily dependent on Hctsys and subsequent microvascular compensations.
31
Seylaz, Jacques, Robert Charbonné, Kazunori Nanri, Dominique Von Euw, Josiane Borredon, Kamel Kacem, Philippe Méric, and Elisabeth Pinard. "Dynamic In Vivo Measurement of Erythrocyte Velocity and Flow in Capillaries and of Microvessel Diameter in the Rat Brain by Confocal Laser Microscopy." Journal of Cerebral Blood Flow & Metabolism 19, no. 8 (August 1999): 863–70. http://dx.doi.org/10.1097/00004647-199908000-00005.
Abstract:
A new method for studying brain microcirculation is described, Both fluorescently labeled erythrocytes and plasma were visualized on-line through a closed cranial window in anesthetized rats, using laser-scanning two-dimension confocal microscopy, Video images of capillaries, arterioles, and venules were digitized off-line to measure microvessel diameter and labeled erythrocyte flow and velocity in parenchymal capillaries up to 200 μm beneath the brain surface, The method was used to analyze the rapid adaptation of microcirculation to a brief decrease in perfusion pressure, Twenty-second periods of forebrain ischemia were induced using the four-vessel occlusion model in eight rats, EEG, arterial blood pressure, and body temperature were continuously controlled, In all conditions, labeled erythrocyte flow and velocity were both very heterogeneous in capillaries, During ischemia, capillary perfusion was close to 0, but a low blood flow persisted in arterioles and venules, while EEG was flattening, The arteriole and venule diameter did not significantly change, At the unclamping of carotid arteries, there was an instantaneous increase (by about 150%) of arteriole diameter. Capillary erythrocyte flow and velocity increased within 5 seconds, up to, respectively, 346 ± 229% and 233 ± 156% of their basal value, No capillary recruitment of erythrocytes was detected, All variables returned to their basal levels within less than 100 seconds after declamping, The data are discussed in terms of a possible involvement of shear stress in the reperfusion period.
32
Incandela, L., G. Belcaro, M. R. Cesarone, M. T. De Sanctis, and M. Griffin. "Microangiopathy and Venous Ulceration: Topical Treatment with Essaven Gel." Angiology 52, no. 3_suppl (December 2001): S17—S21. http://dx.doi.org/10.1177/0003319701052003s05.
Abstract:
The involvement of the microcirculation in chronic venous insufficiency (CVI) due to venous hypertension causes venous hypertensive microangiopathy (VHM) and venous ulceration. VHM is characterized by the presence of enlarged convoluted capillaries; microvascular thrombosis with obliteration of some capillaries; increase in flux, permeability, and edema; and altered function of microlymphatics. PO2 is decreased and CO2 increased. Capillary exchanges are altered, and nutritional alterations eventually lead to venous ulcers. Edema is associated with increased capillary pressure, reduced clearance, and an increased exchange surface of capillaries, which become tortuous and glomerular-like. The aim of this randomized, placebo-controlled study was to evaluate the effect of local treatment with Essaven gel (EG) in 28 subjects with venous microangiopathy due to severe CVI and ulcers treated with a single acute application. Measurements of laser Doppler flux, PO2 and PCO2 in standardized conditions of application showed positive microcirculatory changes (significant decrease of the abnormally increased flux and CO2 while PO 2 increased) in the EG treatment group. Changes in the placebo and control group were more limited (changes in the placebo group were mainly associated with skin manipulation when placebo-EG was applied). ln conclusion, Essaven gel, in comparison with placebo, acutely improves the microcirculation in VHM even with a single application.
33
Pinard, Elisabeth, Nicolas Engrand, and Jacques Seylaz. "Dynamic Cerebral Microcirculatory Changes in Transient Forebrain Ischemia in Rats: Involvement of Type I Nitric Oxide Synthase." Journal of Cerebral Blood Flow & Metabolism 20, no. 12 (December 2000): 1648–58. http://dx.doi.org/10.1097/00004647-200012000-00004.
Abstract:
The diameter of surface microvessels and the erythrocyte velocity and flux through intraparenchymal capillaries in the parietal cortex were measured during transient global cerebral ischemia and reperfusion using laser-scanning confocal fluorescence microscopy in anesthetized rats. The role of nitric oxide (NO) from neurons in the microcirculatory changes was also investigated using 7-nitro-indazole (7-NI, 25 mg/kg, IP). Wistar rats (4 per group) equipped with a closed cranial window were given fluorescein isothiocyanate (FITC)-Dextran and FITC-labeled erythrocytes intravenously to respectively visualize the microvessels and the erythrocytes in the capillaries. Experiments were videorecorded on-line. Forebrains were made ischemic for 15 minutes and then reperfused for 120 minutes under the microscope. Ischemia was associated with a flattened EEG, a low persistent blood flow, and a transient leakage of fluorescein across the arteriole wall. Unclamping the carotid arteries led to immediate high blood flow in the arterioles, but it was not until 5 minutes later that the arterioles dilated significantly (181% ± 27%) and erythrocyte velocity in the capillaries increased significantly (460% ± 263%). Neither nonperfused capillaries nor erythrocyte capillary recruitment occurred. 7-Nitro-indazole significantly reduced the arteriole dilatation and prevented the increase in erythrocyte velocity and flux through capillaries in early reperfusion. 7-Nitro-indazole had no influence on the fluorescein leakage. The current study suggests a partial role for NO released from neurons in the postischemic microcirculatory changes and provides new findings on the timing of arteriole dilatation and blood—brain barrier opening, and on erythrocyte capillary circulation in global ischemia.
34
Park, Sang-Wook, Ki Ju Cho, Seongjun Won, and Jung Je Park. "A Case of Lobular Capillary Hemangioma at the False Vocal Cord With Intermittent Stridor." Journal of The Korean Society of Laryngology, Phoniatrics and Logopedics 32, no. 3 (December 31, 2021): 150–52. http://dx.doi.org/10.22469/jkslp.2021.32.3.150.
Abstract:
Lobular capillary hemangioma (LCH) is a type of benign vascular tumor. It arises from vascular endothelial cells and contains capillaries arranged in a lobular pattern. In the head and neck, the most common presenting location of LCH is the lips, and presentation in the larynx is very rare. LCH might not be distinct from granuloma in macroscopic views. We report a 71-year-old female with LCH of the larynx that was totally resected via laryngeal microsurgery with a CO<sub>2</sub> laser and briefly review the literature.
35
Huang, Guanghan, Jiawei Liao, Chao Fan, Shuang Liu, Wenjie Miao, Yu Zhang, Shiwo Ta, Guannan Yang, and Chengqiang Cui. "Gradient-Pattern Micro-Grooved Wicks Fabricated by the Ultraviolet Nanosecond Laser Method and Their Enhanced Capillary Performance." Micromachines 15, no. 1 (January 22, 2024): 165. http://dx.doi.org/10.3390/mi15010165.
Abstract:
Capillary-gradient wicks can achieve fast or directional liquid transport, but they face fabrication challenges by traditional methods in terms of precise patterns. Laser processing is a potential solution due to its high pattern accuracy, but there are a few studies on laser-processed capillary-gradient wicks. In this paper, capillary step-gradient micro-grooved wicks (CSMWs) were fabricated by an ultraviolet nanosecond pulsed laser, and their capillary performance was studied experimentally. The CSMWs could be divided into three regions with a decreasing capillary radius. The equilibrium rising height of the CSMWs was enhanced by 124% compared to the non-gradient parallel wick. Different from the classical Lucas–Washburn model describing a uniform non-gradient wick, secondary capillary acceleration was observed in the negative gradient direction of the CSMWs. With the increase in laser power and the decrease in scanning speed, the capillary performance was promoted, and the optimal laser processing parameters were 4 W-10 mm/s. The laser-enhanced capillary performance was attributed to the improved hydrophilicity and reduced capillary radius, which resulted from the increased surface roughness, protrusion morphology, and deep-narrow V-shaped grooves induced by the high energy density of the laser. Our study demonstrates that ultraviolet pulsed laser processing is a highly efficient and low-cost method for fabricating high-performance capillary gradient wicks.
36
Hustad, Steinar, Per Magne Ueland, and Jørn Schneede. "Quantification of Riboflavin, Flavin Mononucleotide, and Flavin Adenine Dinucleotide in Human Plasma by Capillary Electrophoresis and Laser-induced Fluorescence Detection." Clinical Chemistry 45, no. 6 (June 1, 1999): 862–68. http://dx.doi.org/10.1093/clinchem/45.6.862.
Abstract:
Abstract Background: Riboflavin is the precursor of flavin mononucleotide (FMN) and FAD, which serve as cofactors for several redox enzymes. We have developed a capillary electrophoresis method for the determination of riboflavin and its two coenzyme forms in human plasma. Methods: Trichloroacetic acid-treated plasma was subjected to solid-phase extraction on reversed-phase columns. The analytes were separated by micellar electrokinetic capillary chromatography in uncoated fused- silica capillaries filled with borate buffer containing 50 mmol/L sodium dodecyl sulfate, methanol, and N-methylformamide. Native fluorescence was monitored at 530 nm, using an argon laser operating at 488 nm as excitation source. Results: The assay was linear over a concentration range of two orders of magnitude, and the limit of detection was far below physiological concentrations for all vitamers. The within-day and between-day coefficients of variation were 4–9% and 6–12%, respectively. The reference values (median, 5–95 percentiles) obtained by analyzing plasma from 63 healthy subjects were 8.6 nmol/L (2.7–42.5 nmol/L) for riboflavin, 7.0 nmol/L (3.5–13.3 nmol/L) for FMN, and 57.9 nmol/L (44.5–78.1 nmol/L) for FAD. Conclusions: Capillary electrophoresis with laser-induced fluorescence detection allows determination of all riboflavin vitamers far below physiological concentrations. The method may become a useful tool for the assessment of riboflavin status in humans.
37
Zvorykin, Vladimir D., Sergei V. Arlantsev, Alexey V. Shutov, Nikolay N. Ustinovskii, and Polad V. Veliev. "Deep Penetration of UV Radiation into PMMA and Electron Acceleration in Long Plasma Channels Produced by 100 ns KrF Laser Pulses." Symmetry 13, no. 10 (October 6, 2021): 1883. http://dx.doi.org/10.3390/sym13101883.
Abstract:
Long (~1 mm), narrow (30−40 μm in diameter) corrugated capillary-like channels were produced in the axially symmetric 2D interaction regime of 100 ns KrF laser pulses with polymethylmethacrylate (PMMA) at intensities of up to 5 × 1012 W/cm2. The channels extended from the top of a deep (~1 mm) conical ablative crater and terminated in a 0.5 mm size crown-like pattern. The modeling experiments with preliminary drilled capillaries in PMMA targets and Monte Carlo simulations evidenced that the crown origin might be caused by high-energy (0.1–0.25 MeV) electrons, which are much higher than the electron temperature of the plasma corona ~100 eV. This indicates the presence of an unusual direct electron acceleration regime. Firstly, fast electrons are generated due to laser plasma instabilities favored by a long-length interaction of a narrow-band radiation with plasma in the crater. Then, the electrons are accelerated by an axial component of the electrical field in a plasma-filled corrugated capillary waveguide enhanced by radiation self-focusing and specular reflection at the radial plasma gradient, while channel ripples serve the slowing down of the electromagnetic wave in the phase with electrons.
38
Leu, A. J., A. Yanar, M. Geiger, U. K. Franzeck, and A. Bollinger. "Microangiopathy in Chronic Venous Insufficiency before and after Sclerotherapy and Compression Treatment: Results of a One-Year Follow-up Study." Phlebology: The Journal of Venous Disease 8, no. 3 (September 1993): 99–106. http://dx.doi.org/10.1177/026835559300800303.
Abstract:
Objective: To characterize microangiopathy in patients with chronic venous insufficiency (CVI) of a moderate to severe stage and to evaluate improvement of the microcirculatory parameters after sclerotherapy of incompetent perforators and compression therapy. Design: Fluorescence videomicroscopy (Na-fluore-scein), laser Doppler fluxmetry and tc Po2 measurements (43°C) at the medial ankle in healthy controls and patients. Laser Doppler flux and tc Po2 were recorded in supine and sitting position in order to evaluate postural vasoconstriction. The measurements were repeated 6 and 12 months after sclerotherapy of incompetent perforators (Polidocanol 40 mg/ml) and compression therapy by below-knee class II or III stockings (Sigvaris®). Setting: Department of Internal Medicine, Angiology Division, University Hospital, Zurich, Switzerland. Patients, participants: 15 healthy subjects (15 legs, mean age 53.3 years) and 15 patients with CVI of a moderate to severe stage (17 legs, mean age 56.8 years). Results: Microangiopathy in CVI is characterized by significantly enlarged, elongated and dilated capillaries with increased diameters of the pericapillary spaces (‘halos’). Single capillaries may be thrombosed. Laser Doppler flux is increased and tc Po2 is decreased. After therapy, there was a trend to decreased laser Doppler flux and an increase in tc Po2, but the differences were not statistically significant. Capillary thromboses were no longer detected. Mean halo diameters tended to decrease, but this difference was not statistically significant. Conclusions: Microangiopathy in CVI is characterized by morphological and functional changes. Beneficial changes induced by therapy develop slowly and emphasize the importance of long-lasting treatment.
39
Gorbatova, N. E., D. A. Safin, E. N. Gasanova, A. A. Sirotkin, G. P. Kuzmin, A. S. Tertychny, O. V. Tikhonevich, M. V. Remennicova, and S. A. Zolotov. "Experimental substantiation of «green» laser light application for selective photodestruction of capillary angiodysplasia of the skin." Laser Medicine 24, no. 4 (April 28, 2021): 43–53. http://dx.doi.org/10.37895/2071-8004-2020-24-4-43-53.
Abstract:
Rationale. The existing techniques for treating skin capillary angiodysplasias, including «laser» photodestruction, are not effective enough and often cause undesirable thermal damage and cicatricial deformities of the skin. Thus, the effective removal of this vascular pathology is still relevant and requires further solution.Purpose. To study the nature of thermal injuries and wound regenerative processes after «green» laser irradiation with wavelength 525 nm so as to find out if it may be used for selective photodestruction of subepithelial pathological vascular structures, including angiodysplasias of skin capillaries.Material and Methods. Scallops of alive white chickens were taken as a biological model of vascular structures for in vivo studies. An experimental solid-state laser generating «green» light with wavelength 525 nm was used. This laser light has similar peaks of the absorption coefficient of hemoglobin and oxyhemoglobin which are found in skin capillaries. Features of damage and dynamics of regenerative process in the irradiated area were studied at the model of vascular structures using findings of morphological macroscopic and histological examinations.Results. Findings of the present experimental trial have inspired that selective photodestruction of subepithelial vascular structures of scallops is possible with minimal damage to the epithelium, including growth zones. In irradiated areas, one could see whitening and smoothing of the surface due to closure of vessel lumens in the subepithelial zone and formation of collagenosis layer there, as well as epithelialization of wound surface in physiological terms without any formation of cicatricial deformation of the skin.Conclusion. The selective effect of 525 nm «green» laser light at subepithelial vascular structures with minimal skin damage has been confirmed. It opens a way to apply this light for selective photodestruction of capillary angiodysplasias of the skin with good clinical and esthetic outcomes.
40
Bollinger, Alfred, Ulrich Hoffmann, and Ulrich K. Franzeck. "Microvascular Changes in Arterial Occlusive Disease: Target for Pharmacotherapy." Vascular Medicine 1, no. 1 (February 1996): 50–54. http://dx.doi.org/10.1177/1358863x9600100109.
Abstract:
The main techniques which have been used to study skin microcirculation in patients with peripheral arterial occlusive disease include intravital microscopy with and without the use of fluorescent dyes, laser Doppler fluxmetry and transcutaneous oximetry. In patients with severe ischaemia (rest pain or incipient gangrene) the number of perfused skin capillaries is reduced. Parallel to the decreased number of microvessels containing blood, transcutaneous oxygen tension is low or even approaches the zero level. The tendency to oedema formation is documented by increased leakage of intravenously injected sodium fluorescein at the capillary apex of foot skin (‘candlelight phenomenon’). Laser Doppler flux at rest may still be within the normal range even in advanced disease, since the sample volume of these instruments also contains non-nutritive shunt vessels. However, reactive hyperaemia after arterial occlusion is decreased and delayed in peripheral ischaemia. Whereas rhythmic low-frequency vasomotion is significantly enhanced in patients with intermittent claudication, vasoparalysis with no flux fluctuations prevails in patients with critical ischaemia.
41
KITAGAWA, YONEYOSHI. "ELECTRON ACCELERATION IN A GLASS CAPILLARY AND ITS APPLICATION." International Journal of Modern Physics B 21, no. 03n04 (February 10, 2007): 540–47. http://dx.doi.org/10.1142/s0217979207042343.
Abstract:
The discussion how to accelerate electrons to GeV leads us to the concept of the capillary. The 40 TW laser with prepulses, guided into a 1 cm-long capillary has accelerated the electrons to 100 MeV. The prepulse-free PW laser was also guided into the longer capillary, which formed a 3 cm plasma channel, but the energy gain was only 40 MeV. The prepulse-free laser made it clear that the cone works as an electron seeder. Application of the capillary accelerator was finally discussed.
42
Trombetta, Amelia Chiara, Carmen Pizzorni, Barbara Ruaro, Sabrina Paolino, Alberto Sulli, Vanessa Smith, and Maurizio Cutolo. "Effects of Longterm Treatment with Bosentan and Iloprost on Nailfold Absolute Capillary Number, Fingertip Blood Perfusion, and Clinical Status in Systemic Sclerosis." Journal of Rheumatology 43, no. 11 (October 1, 2016): 2033–41. http://dx.doi.org/10.3899/jrheum.160592.
Abstract:
Objective.To quantify in patients with systemic sclerosis (SSc) the absolute nailfold capillary number/mm (the absolute number of capillaries, observable in the first row, in 1 mm per field) and fingertip blood perfusion (FBP) during longterm therapy with the endothelin receptor antagonist bosentan (BOSE) and the synthetic analog of prostacyclin PGI2 iloprost (ILO) by multiple diagnostic tools. Observed values were correlated with clinical outcomes.Methods.Thirty patients with SSc already receiving intravenous ILO (80 μg/day) for 5 continuous days (every 3 mos) were recruited in the clinic. Fifteen patients continued such treatment (ILO group), while in 15 patients BOSE (125 mg twice/day) was added (ILO + BOSE group) because of the onset of pulmonary arterial hypertension or digital ulcers (DU). The followup period was 4 years (T0–T4). Every year the following were evaluated: absolute nailfold capillary number/mm by nailfold videocapillaroscopy, FBP by laser Doppler flowmetry, DU incidence, DLCO, systolic pulmonary arterial pressure (sPAP), renal arterial resistive index, and other biomarkers. From T2 to T4, laser speckled contrast analysis was added. Nonparametric tests were used for statistical analysis.Results.Limited to the ILO + BOSE group, absolute capillary number/mm and FBP showed a progressive increase independently from other variables. In addition, during followup there was a significant reduction (80%) in the incidence of new DU, whereas DLCO and sPAP did not worsen.Conclusion.The study shows in patients with SSc with up to 4 years of combined therapy a progressive significant recovery in structure and function of microvasculature linked to improved clinical outcomes, independent of disease severity.
43
Gallaher, David L., and Mitchell E. Johnson. "Characterization of a Rugged, Open-Gap Flow Cell for Confocal Laser-Induced Fluorescence Detection in Capillary Electrophoresis." Applied Spectroscopy 52, no. 2 (February 1998): 292–97. http://dx.doi.org/10.1366/0003702981943374.
Abstract:
Construction details and performance characteristics of an open-gap flow cell for fluorescence detection in capillary electrophoresis are described. The flow cell is created by separating two pieces of capillary by a small (90 μm) gap. The gap is surrounded with buffer and grounded, and the application of electric fields to both inlet and outlet capillaries causes the material in the inlet capillary to flow across the gap. The use of a simple confocal optical arrangement for laser-induced fluorescence detection allows straightforward application of the gap flow cell to detection in capillary electrophoresis. The signal-to-noise ratio is measured to be about a factor of 2 better than that for on-column confocal detection at nanomolar concentrations over a wide range of pinhole diameters. The detection limit for fluorescein isothiocyanate is in the low picomolar range. Detection of a simple mixture of amino acids that have been derivatized with fluorescein isothiocyan ate demonstrates the stability and utility of the gap. Increased tailing is observed with the gap cell, with average asymmetry of about 1.4 near the center of the gap. Dispersion characteristics as a function of position in the gap are interpreted as dilution of the analyte as it flows across the gap. Fortunately, resolution and theoretical plates, measured by using least-squares fitting, are not significantly different from on-column separations, in spite of the tailing.
44
Nguyen, John, Nozomi Nishimura, Robert N. Fetcho, Costantino Iadecola, and Chris B. Schaffer. "Occlusion of Cortical Ascending Venules Causes Blood Flow Decreases, Reversals in Flow Direction, and Vessel Dilation in Upstream Capillaries." Journal of Cerebral Blood Flow & Metabolism 31, no. 11 (June 29, 2011): 2243–54. http://dx.doi.org/10.1038/jcbfm.2011.95.
Abstract:
The accumulation of small strokes has been linked to cognitive dysfunction. Although most animal models have focused on the impact of arteriole occlusions, clinical evidence indicates that venule occlusions may also be important. We used two-photon excited fluorescence microscopy to quantify changes in blood flow and vessel diameter in capillaries after occlusion of single ascending or surface cortical venules as a function of the connectivity between the measured capillary and the occluded venule. Clotting was induced by injuring the target vessel wall with femtosecond laser pulses. After an ascending venule (AV) occlusion, upstream capillaries showed decreases in blood flow speed, high rates of reversal in flow direction, and increases in vessel diameter. Surface venule occlusions produced similar effects, unless a collateral venule provided a new drain. Finally, we showed that AVs and penetrating arterioles have different nearest-neighbor spacing but capillaries branching from them have similar topology, which together predicted the severity and spatial extent of blood flow reduction after occlusion of either one. These results provide detailed insights into the widespread hemodynamic changes produced by cortical venule occlusions and may help elucidate the role of venule occlusions in the development of cognitive disorders and other brain diseases.
45
ANDREEV, N. E., V. E. BARANOV, B. CROS, G. MAYNARD, P. MORA, and M. E. VEYSMAN. "Laser wakefield compression and acceleration of externally injected electron bunches in guiding structures." Journal of Plasma Physics 79, no. 2 (January 3, 2013): 143–52. http://dx.doi.org/10.1017/s0022377812000736.
Abstract:
AbstractFor the considered scheme of the external electron bunch injection in front of a laser pulse, the influence of the nonlinear driving laser pulse dynamics and electron bunch self-action to the processes of electron bunch compression and acceleration in the laser wakefield is analyzed. Self-consistent modelling results confirm that the nonlinear laser pulse dynamics limits the bunch compression due to variations of the phase velocity of the wake. A growth of the injected bunch charge leads to some extent to an increase of the trapped and accelerated bunch charge and to decrease of the trapped bunch radius and emittance due to increased self-focusing bunch. The three-dimensional theoretical model is elaborated and used to describe the propagation of laser pulses in dielectric capillary waveguides under imperfect coupling and focusing conditions with broken cylindrical symmetry. The role of cone entrances to the cylindrical part of a capillary is analyzed, and it is demonstrated that matching cones can considerably increase the transmission of laser pulses through the capillary, but cannot mitigate the requirements on the precision of the laser pulse focusing into a capillary. In order to avoid a speckle structure and strong transverse gradients of the fields, which can prevent the process of regular electron bunch acceleration, one has to ensure a small laser angle of incidence into the capillary not exceeding 1 mrad.
46
Omelyanenko, K. V., A. Yu Gorshkov, A. A. Fedorovich, A. I. Korolev, V. A. Dadaeva, D. U. Akasheva, and O. M. Drapkina. "Sex features of cutaneous microvasculature in healthy working-age people." Cardiovascular Therapy and Prevention 20, no. 8 (January 8, 2022): 3111. http://dx.doi.org/10.15829/1728-8800-2021-3111.
Abstract:
Aim. To study sex characteristics of cutaneous microvascular structure and function in a cohort of healthy working-age people without cardiovascular diseases.Material and methods. The study included 35 healthy men (42±4 years) and 34 women (41 ±5 years). The cardiovascular system was assessed in all patients. The microcirculatory bed of the skin was investigated by the following non-invasive methods: 1) computerized video capillaroscopy; 2) laser Doppler flowmetry; 3) photoplethysmography.Results. According to computerized video capillaroscopy in men, compared with women, there was a smaller number of both functioning capillaries (78 vs 86 capillaries/mm2, respectively (p<0,05)) and their total number (100 vs 120 capillaries/mm2, respectively (p<0,001)). Against the background of a decrease in capillary density in men, there was a higher skin interstitial hydration — 113 vs 96 gm (p<0,005) in men than in women. At the level of precapillary arterioles, where humoral tone regulation prevails. Laser Doppler flowmetry revealed lower pulse amplitude in men than in women — 0,87 vs 1,02 pf, respectively (p<0,05), which indicates a lower arterial blood inflow to exchange microvessels. Against this background, the constrictor response of precapillary arterioles to a sympathetic nervous system stimulation in men is higher than in women — 45% vs 40%, respectively (p<0,05). At the level of large arterioles, where neural tone regulation prevails, photoplethysmography revealed lower augmentation index standardized at a heart rate in men (-4,6 vs 1,7%, respectively, p<0,05), which indicates lower rigidity of muscular vessels in men.Conclusion. In working-age healthy people, sex differences are noted at all cutaneous microvascular levels, which must be taken into account when planning studies.
47
Mazzoni, M. C., K. C. Warnke, K. E. Arfors, and T. C. Skalak. "Capillary hemodynamics in hemorrhagic shock and reperfusion: in vivo and model analysis." American Journal of Physiology-Heart and Circulatory Physiology 267, no. 5 (November 1, 1994): H1928—H1935. http://dx.doi.org/10.1152/ajpheart.1994.267.5.h1928.
Abstract:
A computer network model and in vivo measurements of microcirculatory blood flow in skeletal muscle were used to study the mechanisms responsible for low flow in hemorrhagic shock and reperfusion, with focus on the potential importance of capillary diameters and leukocyte rheology. Model flows were determined by the network pressure gradient, systemic hematocrit and leukocrit, leukocyte cytoplasmic viscosity, and vessel dimensions. After 1 h of shock (40% acute bleed) in anesthetized rabbits, pressure was reduced by 45%, hemodilution occurred, and capillary diameters decreased by 21%. The 45–50% flow reduction found experimentally in gastrocnemius muscle by laser Doppler flowmetry (LDF) and a microsphere technique matched model flow predictions with one-half of the proximal capillaries narrowed. Ringer-lactate (RL) reperfusion only partially restored control LDF flow, whereas a small-volume bolus of hypertonic saline-dextran followed by RL gave complete LDF flow recovery. The model predicted these flows for moderate hemodilution states, with the added insight that low-flow conditions are exacerbated by leukocytes only if they become activated, which is often a complication in ischemia/reperfusion.
48
Costa, G., M. P. Anania, S. Arjmand, A. Biagioni, M. Del Franco, M. Del Giorno, M. Galletti, et al. "Characterisation and optimisation of targets for plasma wakefield acceleration at SPARC_LAB." Plasma Physics and Controlled Fusion 64, no. 4 (March 3, 2022): 044012. http://dx.doi.org/10.1088/1361-6587/ac5477.
Abstract:
Abstract One of the most important features of plasma-based accelerators is their compactness because plasma modules can have dimensions of the order of mm cm − 1 , providing very high-accelerating fields up to hundreds of GV m − 1 . The main challenge regarding this type of acceleration lies in controlling and characterising the plasma itself, which then determines its synchronisation with the particle beam to be accelerated in an external injection stage in the laser wakefield acceleration (LWFA) scheme. This issue has a major influence on the quality of the accelerated bunches. In this work, a complete characterisation and optimisation of plasma targets available at the SPARC_LAB laboratories is presented. Two plasma-based devices are considered: supersonic nozzles for experiments adopting the self-injection scheme of laser wakefield acceleration and plasma capillary discharge for both particle and laser-driven experiments. In the second case, a wide range of plasma channels, gas injection geometries and discharge voltages were extensively investigated as well as studies of the plasma plumes exiting the channels, to control the plasma density ramps. Plasma density measurements were carried out for all the different designed plasma channels using interferometric methods in the case of gas jets, spectroscopic methods in the case of capillaries.
49
Zigler, A., R. W. Lee, and S. Mrowka. "Creation of X-ray laser media by high power laser heating of capillary discharge." Laser and Particle Beams 7, no. 3 (August 1989): 369–74. http://dx.doi.org/10.1017/s0263034600007321.
Abstract:
A large, high density, high temperature plasma has been produced by using a high power laser with a capillary electrical discharge. The laser beam is synchronized with the discharge to reach the plasma after it emerges several hundred microns from the capillary.
50
Duvansky, V. A., M. M. Musaev, and M. M. Gutop. "Laser technologies in the diagnostics and care of patients with decompensated forms of chronic venous insufficiency in the lower extremities." Laser Medicine 25, no. 3 (January 21, 2022): 15–20. http://dx.doi.org/10.37895/2071-8004-2021-25-3-15-20.
Abstract:
Purpose. To assess the degree of disorders in regional microcirculation in patients with decompensated forms of chronic venous insufficiency of lower extremities and potentials for their correction with low-level laser therapy (LLLT).Material and methods. The authors analyzed results of examination and treatment of 66 patients with decompensated forms of chronic venous insufficiency in their lower extremities. 34 (51.5 %) patients, in addition to traditional therapy, had laser stimulation of microcirculation. For laser irradiation, infrared laser device “Mustang” (wavelength – 0.89 μm, frequency – 80 Hz, power – 10 W, exposure – 2 min per zone) was used. In laser course, there were 10 sessions. The state of microcirculation in tissues was examined with a computerized capillaroscope, a laser analyzer of capillary blood flow and a gas analyzer.Results. Microcirculation in patients with chronic venous insufficiency C6 has its specific features which, by findings of computerized capillaroscope, are manifested with deep suppression of tissue blood flow: namely, expressed polymorphism of capillary structures, violation of sizeratio of capillary sections, increased venous section, decreased density of the capillary network by 1.8 times, increased pericapillary zone by 1.47 times , decreased speed of capillary blood flow in the arterial section by 10.5 times and in the venous section by 11.5 times.Conclusion. Patients with decompensated forms of chronic venous insufficiency in lower extremities were observed to have significant morphological and functional changes in microcirculation, including structural changes in microvessels, decreased density of capillary network, increased prevascular zone, decreased speed of capillary blood flow. As a result, these changes cause disorders in tissue trophism, progressive decrease in TcpO2 and development of trophic ulcers. Low-level laser stimulation of microcirculation in the complex treatment of patients with decompensated forms of chronic venous insufficiency activates transcapillary metabolism, helps to restore structures and functions of microvasculature by increasing the myogenic activity of smooth muscle cells of arterioles and precapillaries as well as by normalizing arterio-venous relationships what accelerates tissue granulation and ulcer epithelialization.