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Blood Flow Changes (blood + flow_change)
Selected AbstractsFunctional map and age-related differences in the human face: nonimmunologic contact urticaria induced by hexyl nicotinateCONTACT DERMATITIS, Issue 1 2006Slaheddine Marrakchi Variation in human skin reactivity to various irritants in association with age and body region has been reported. Hexyl nicotinate (HN), a lipophilic nicotinate ester, was used to induce nonimmunologic contact urticaria in human volunteers of 2 age groups: 10 young subjects [24,34 years, mean ± standard deviation (SD) 29.8 ± 3.9 years] and 10 older volunteers (66,83 years, mean ± SD 73.6 ± 17.4 years); and to define skin function and potential age-related differences in various facial areas. About 5 mM of HN in ethanol was applied to 8 locations on the face, neck, and volar forearm. A laser Doppler flowmeter was used to determine baseline blood flow and to monitor the skin blood flow changes after HN application. In the contralateral areas, stratum corneum turnover was determined using 5% dansyl chloride in petrolatum. In the young group, the perioral area exhibited the strongest reaction to HN. In the older group, the chin was the most sensitive site. In both the groups, the forearm was the least responsive. The older group demonstrated a stronger reaction than the younger group in 3 sites (forehead, cheek, and nasolabial area). Stratum corneum turnover was slower in the nasolabial area and in the forearm in both age groups, whereas the fastest was in the perioral area and the chin in the younger group and in the chin and the forehead in the older group. Compared to the older group, the younger group showed a slower stratum corneum turnover in the nose and the neck. This study demonstrates the regional and the age-related variability of the stratum corneum turnover and the skin reactions to HN. These observations may help explain some aspects of the cutaneous intolerance in skin care of the face. [source] Gingival blood flow changes following periodontal access flap surgery using laser Doppler flowmetryJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 5 2007M. Retzepi Abstract Aim: To investigate the pattern of gingival blood flow changes following periodontal access flap surgery by laser Doppler flowmetry (LDF). Material and methods: Fourteen patients with chronic periodontitis presenting upper anterior sites with pocket depth 5 mm after initial treatment were included in the study. Periodontal access flap surgery was performed on the experimental areas and LDF recordings were taken at baseline, following anaesthesia, immediately postoperatively and on days 1, 2, 3, 4, 7, 15, 30 and 60 of healing, at nine predetermined sites per flap. Results: Significant ischaemia was observed at all flap sites following anaesthesia and immediately postoperatively. At the alveolar mucosal sites, a peak increase of the gingival blood flow was observed on postoperative day 1 (p<0.001), which persisted until day 7 (p=0.012) and resolved by day 15. The mucosal sites close to the flap periphery presented higher blood perfusion compared with the sites located centrally in the flap. The microcirculatory perfusion of the buccal and palatal papillae was maximum on postoperative day 7 (p=0.013 and <0.001, respectively) and returned to baseline by day 15. Conclusion: Topographically distinct areas of the periodontal access flap consistently present different patterns of microvascular blood flow alterations during the wound-healing period. [source] Orbital blood flow velocities in patients with rheumatoid arthritisJOURNAL OF CLINICAL ULTRASOUND, Issue 7 2007Besir Erdogmus MD Abstract Purpose. To assess orbital blood flow changes in patients with rheumatoid arthritis using Doppler sonography. Patients and Methods. The study comprised 35 patients who were diagnosed with RA and were treated at the Department of Physical Therapy and Rehabilitation at Duzce Medical School. A control group consisted of 35 healthy volunteers. Color Doppler imaging was used to measure peak systolic velocity (PSV) and end diastolic velocity (EDV), from which the resistance index (RI) was calculated in the ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary arteries (PCAs). Results. In the OA, PSV, EDV, and RI were, respectively, 36.7 ± 0.6 cm/sec, 9.7 ± 0.2 cm/sec, and 0.73 in the control group versus 34.7 ± 3.0 cm/sec, 9.1 ± 1.1 cm/sec, and 0.74 in the patient group. In the CRA, they were, respectively, 11.8 ± 1.7 cm/sec, 3.6 ± 0.7 cm/sec, and 0.66 in the control group versus 11.1 ± 1.7 cm/sec, 3.4 ± 0.7 cm/sec, and 0.68 in the patient group. In the PCAs, they were, respectively, 13.2 ± 1.2 cm/sec, 4.7 ± 0.6 cm/sec, and 0.65 in the control group versus 12.4 ± 1.2 cm/sec, 4.2 ± 0.6 cm/sec, and 0.66 in the PCAs. PSV, EDV, and RI of the PCAs and OA and RI of the CRA were significantly different between patients and controls, whereas there was no difference in the serum levels of glucose, triglyceride, low-density lipoprotein cholesterol, and total cholesterol. In the patient group, there was a significant correlation between orbital blood flow and duration of disease. Conclusion. Ocular blood flow appears to be slightly lower in RA patients than in healthy controls, suggesting that RA is a systemic inflammatory disease that may also involve ocular vessels. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007 [source] On the timing characteristics of the apparent diffusion coefficient contrast in fMRIMAGNETIC RESONANCE IN MEDICINE, Issue 2 2002Stacey L. Gangstead Abstract For the past 10 years, functional MRI (fMRI) has seen rapid progress in both clinical and basic science research. Most of the imaging techniques are based on the blood oxygenation level-dependent (BOLD) contrast which arises from the field perturbation of the paramagnetic deoxyhemoglobin due to the mismatch between the local oxygen demand and delivery. Because the changes of oxygenation level take place mostly in the veins, the dominant signal sources of the BOLD signal are intra- and extravascular proton pools of the veins. Perfusion imaging methods, developed parallel to the BOLD technique, seek to quantify the blood flow and perfusion. Recently, perfusion imaging using arterial spin tagging methods have been used to study brain function by investigating the changes of the blood flow and perfusion during brain activation, thereby generating an alternative contrast mechanism to the functional brain imaging. Since most of these methods require tagging pulse and wait time for blood to be delivered to the imaged slice, the temporal resolution may not be optimal. Dynamic intravoxel incoherent motion (IVIM) weighting schemes using apparent diffusion coefficient (ADC) contrast were suggested to image the relative changes of the in-plane blood flow during brain function. In this report, it was demonstrated that, in addition to the spatial discrepancies of the activated areas, the time course based on the ADC contrast consistently precedes that from the BOLD contrast with timing offset on the order of 1 sec. Since arterial networks would have different spatial locations and preceding temporal characters, the findings in this report are indicative that the ADC contrast is sensitive to the arterial blood flow changes. Magn Reson Med 48:385,388, 2002. © 2002 Wiley-Liss, Inc. [source] Blood Flow in Snake Infrared Organs: Response-Induced Changes in Individual VesselsMICROCIRCULATION, Issue 2 2007RICHARD C. GORIS ABSTRACT Objective: In the past the microkinetics of blood flow in the infrared pit organs of pit vipers has been studied with Doppler flowmetry using various infrared stimuli such as a human hand or soldering iron at various distances, lasers of various wavelengths, etc. Quick-acting variations in blood flow were recorded, and interpreted as a cooling mechanism for avoiding afterimage in the infrared receptors. However, the Doppler measurements provided only the summation of blood flow in a number of vessels covered by the sensing probe, but did not give data on flow in individual vessels. Methods: In the present work the authors introduced into the bloodstream of Gloydius and Trimeresurus pit vipers fluorescent microspheres labeled with fluorescein isothiocyanate (FITC) contained in a solution of FITC-dextran in physiological saline. They observed the passage of the microspheres through individual pit organ vessels with a fluorescent microscope to which was attached a high-speed video camera and image intensifier. Output of the camera was recorded before, during, and after stimulus with a 810-nm diode laser. Recording was done at 250 frames/s on high-speed video apparatus and downloaded to a hard disk. Disk files were loaded into proprietary software and particles were tracked and average velocities calculated. The data were then tested for significance by ANOVA with post hoc tests. Results: A significant (p < .05) increase in blood velocity was found at the focal point of the stimulus laser, but not anywhere removed from this point. Proximal severing of the pit sensory nerves caused degeneration of the pit receptor terminals and abolished stimulus-induced blood flow changes, but did not affect normal blood flow. Conclusions: The authors conclude that the receptors themselves are directly and locally controlling the smooth muscle elements of the blood vessels, in response to heating of the receptors by infrared radiation. They speculate that the heavy vascularization constitutes a cooling system for the radiation-encoding receptors, and further that the agent of control may be a volatile neuromediator such as nitric oxide. [source] Assessment of spinal cord pathology following trauma using early changes in the spinal cord evoked potentials: A pharmacological and morphological study in the ratMUSCLE AND NERVE, Issue S11 2002Hari Shanker Sharma PhD Abstract The possibility that spinal cord pathology following trauma can be assessed with early changes in the spinal cord evoked potentials (SCEPs) was examined in a rat model. Spinal cord injury (SCI) was produced in Equithesin-anesthetized (3 ml/kg, i.p.) rats through a longitudinal incision into the right dorsal horn at the T10,11 segments. The SCEPs were recorded with epidural electrodes placed over the T9 (rostral) segment of the cord. The SCEPs consisted of a small positive amplitude and a broad and high negative amplitude (NA). SCI resulted in an instant depression of the rostral NA that lasted for 1 h. However, the latency of NA continued to increase over time. At 5 h, spinal cord blood flow declined by 30% in the T9 segment, whereas the spinal cord water content and the permeability of the blood,spinal cord barrier (BSCB) were markedly increased. Damage to the nerve cells, glial cells, and myelin was quite common in the spinal cord, as seen by light and electron microscopy. Pretreatment with p -chlorophenylalanine, indomethacin, ibuprofen, and nimodipine attenuated the SCEP changes immediately after trauma and resulted in a marked reduction in edema formation, BSCB permeability, and blood flow changes at 5 h. However, pretreatment with cyproheptadine, dexamethasone, phentolamine, and propranolol failed to attenuate the SCEP changes after SCI and did not reduce the cord pathology. These observations suggest that early changes in SCEP reflect secondary injury-induced alterations in the cord microenvironment. Obviously, these changes are crucial in determining the ultimate magnitude and severity of cord pathology. © 2002 Wiley Periodicals, Inc. Muscle Nerve Supplement 11: S83,S91, 2002 [source] Evaluation of the anti-vascular effects of combretastatin in rodent tumours by dynamic contrast enhanced MRINMR IN BIOMEDICINE, Issue 2 2002Ross J. Maxwell The anti-vascular effects of the tubulin binding agent, disodium combretastatin A-4 3- O -phosphate (CA-4-P), have been investigated in the rat P22 carcinosarcoma by measurements of radiolabelled iodoantipyrine uptake and dynamic contrast-enhanced MRI. The iodoantipyrine estimates of absolute tumour blood flow showed a reduction from 0.35 to 0.04,ml g,1 min,1 6,h after 10,mg kg,1 CA-4-P and to <0.01,ml g,1 min,1 after 100,mg kg,1. Tumour blood flow recovered to control values 24,h after 10,mg kg,1 CA-4-P, but there was no recovery by 24,h after the higher dose. Dynamic contrast-enhanced MR images were obtained at 4.7 T, following injection of 0.1,mmol kg,1 Gd-DTPA and analysed assuming a model arterial input function. A parameter, Ktrans, which is related to blood flow rate and permeability of the tumour vasculature to Gd-DTPA, was calculated from the uptake data. Ktrans showed a reduction from 0.34 to 0.11 min,1 6,h after 10,mg kg,1 CA-4-P and to 0.07 min,1 after 100,mg kg,1. Although the magnitude of changes in Ktrans was smaller than that in tumour blood flow, the time course and dose-dependency patterns were very similar. The apparent extravascular extracellular volume fraction, ,e, showed a four-fold reduction 6,h after 100,mg kg,1 CA-4-P, possibly associated with vascular shutdown within large regions of the tumour. These results suggest that Ktrans values for Gd-DTPA uptake into tumours could be a useful non-invasive indicator of blood flow changes induced by anti-vascular agents such as combretastatin. Copyright © 2002 John Wiley & Sons, Ltd. [source] Simultaneous Automatic Control of Oxygen and Carbon Dioxide Blood Gases During Cardiopulmonary BypassARTIFICIAL ORGANS, Issue 6 2010Berno J.E. Misgeld Abstract In this work an automatic control strategy is presented for the simultaneous control of oxygen and carbon dioxide blood gas partial pressures to be used during cardiopulmonary bypass surgery with heart,lung machine support. As the exchange of blood gases in the artificial extracorporeal lung is a highly nonlinear process comprising varying time delays, uncertainties, and time-varying parameters, it is currently being controlled manually by specially trained perfusionist staff. The new control strategy includes a feedback linearization routine with augmented time-delay compensation and two external linear gain-scheduled controllers, for partial oxygen and carbon dioxide pressures. The controllers were robustly tuned and tested in simulations with a detailed artificial lung (oxygenator) model in cardiopulmonary bypass conditions. Furthermore, the controllers were implemented in an ex vivo experiment using fresh porcine blood as a substitute fluid and a special deoxygenation technique to simulate a patient undergoing cardiopulmonary bypass. Both controllers showed robust stability during the experiments and a good disturbance rejection to extracorporeal blood flow changes. This automatic control strategy is proposed to improve patient's safety by fast control reference tracking and good disturbance rejection under varying conditions. [source] External cephalic version induced fetal cerebral and umbilical blood flow changes are related to the amount of pressure exertedBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 5 2004Tak Yeung Leung Objective To correlate the applied pressure during external cephalic version with the changes in fetal middle cerebral arterial and umbilical arterial flow before and after the procedure. Design A prospective observational study over a two-year period. Setting External cephalic version was performed in a university hospital. Population Sixty-nine women with singleton breech-presenting pregnancy at or above 36 weeks of gestation undergoing external cephalic version. Methods During external cephalic version, the operator wore a pair of pressure-sensing gloves which had thin piezo-resistive sensors positioned on the palmar surface. During each version procedure, real-time pressure readings were recorded from all sensors, and then analysed with a computer program. The amount of pressure applied over time was presented by pressure,time integral. The pulsatility indices of both fetal middle cerebral artery and umbilical artery before and after external cephalic version were measured. The changes of pulsatility indices of both middle cerebral artery and umbilical artery were presented as a ratio of the post-external cephalic version pulsatility indices to pre-external cephalic version pulsatility indices, denoted by middle cerebral artery pulsatility index ratio and umbilical artery pulsatility index ratio, respectively. The statistical correlation between pressure,time integral and middle cerebral artery pulsatility index ratio and umbilical artery pulsatility index ratio are analysed using Pearson's correlation test. Main outcome measures Changes in pulsatility indices of fetal middle cerebral and umbilical arteries and fetal heart rate after external cephalic version. Results The overall success rate of external cephalic version was 77%. There was a significant negative correlation between pressure,time integral and both middle cerebral artery pulsatility index ratio (P= 0.001) and umbilical artery pulsatility index ratio (P= 0.012). When women were categorised according to placental site, pressure,time integral was negatively correlated with middle cerebral artery pulsatility index ratio only when the placenta was posteriorly located (P= 0.003), and with umbilical artery pulsatility index ratio only when the placenta was laterally located (P= 0.03). Conclusions The greater the force applied during external cephalic version, the greater the reduction in pulsatility indices of middle cerebral artery and umbilical artery, indicating an increase in blood flow through these arteries. The increase in cerebral blood flow after external cephalic version is more prominent when the placenta is lying posteriorly, while the increase in umbilical flow is more prominent when the placenta is lying laterally. These findings suggest that the vascular changes probably represent a direct effect of force exerted on the fetal head and the placenta. [source] | ||||||||||