Blood Flow

During the last five years the use of acupuncture in female infertility as an adjuvant to conventional treatment in assisted reproductive technology (ART) has increased in popularity.The present paper briefly discusses clinical and experimental data on the effect of acupuncture on uterine and ovarian blood flow, as an analgesic method during ART, and on endocrine and metabolic disturbances such as

Placental blood flow was measured with the aid of radioactive microspheres, in normal (N) and manifest diabetic (MD) rats, and related to fetal body growth and incidence of congenital malformations. The total blood flow in the placentae of the MD rats was decreased to about one-half of the normal flow on gestational days 20 and 22. The placentae of the MD offspring were enlarged, whereas the fetuses in this group were smaller than normal. Thus, the placental blood flow per placental weight was drastically decreased in the MD fetuses on both days 20 and 22. In contrast, the placental blood flow per fetal weight was not different in the N and MD groups on gestational day 20 whereas it was decreased in the MD offspring on gestational day 22. Placental blood flow in the malformed fetuses of the MD group did not differ significantly from that in the nonmalformed MD fetuses.

The aim of this study was to evaluate the use of Doppler ultrasonography to monitor vascular blood flow dynamics in defined diseases of the equine digit in a noninvasive way. Doppler sonography was used to evaluate medial digital artery blood flow in eight horses with septic pododermatitis and four horses with laminitis in comparison with 10 horses of a control group. Doppler sonographic measurement and lameness examinations were performed in lame horses before treatment (day 0) and at 3, 6, and 9 days following treatment. Before treatment, blood flow velocities, arterial diameter, and flow volume were significantly higher in the lame horses, while pulsatility indices (PIs) were significantly lower (P < 0.05). Compared with the control group, there was no significant difference of resistive indices (RI) in the septic pododermatitis group, but these indices were significantly lower in the laminitis group. No significant difference between the two lame groups was recorded. After tr...

Malfunction of permanent vascular accesses remains a cause of frequent and costly morbidity in patients receiving chronic hemodialysis (CHD). Several recommendations for routine monitoring of these permanent vascular accesses for incipient failure have been proposed. In this study, multiple indicators of incipient vascular access dysfunction, including "venous" and "arterial" pressures at serial blood flows (200 ml/min, 300 ml/min, and 400 ml/min), percent urea recirculation, Doppler ultrasound, and access blood flow by ultrasound dilution technique were simultaneously evaluated in a total of 220 vascular accesses in 170 chronic hemodialysis patients in two separate study periods (6 months apart). The rate of thrombosis was determined within the subsequent 12 weeks of each study period to assess the short-term predictive power of access thrombosis. During the period of follow-up, there were 34 thrombotic events in 172 polytetrafluoroethylene (PTFE) grafts and only one thrombotic event in 48 arterio-venous fistulas (AVF). Therefore, the statistical analysis was limited to the PTFE grafts. When grafts with thromboses were compared to those without thrombosis by univariate analysis, access blood flow measured either by ultrasound dilution technique (875 +/- 426 ml/min with thrombosis vs. 1193 +/- 677 ml/min without thrombosis, P = 0.001) or by Doppler ultrasound (762 +/- 420 ml/min with thrombosis vs. 1171 +/- 657 ml/min without thrombosis, P = 0.001) were significantly different in the two groups. There was good correlation (r = 0.79, P = 0.0001) between the blood flows determined by both techniques. The grade of stenosis determined by ultrasound was also a statistically significant predictor (P = 0.02). "Venous" and "arterial" pressures were numerically similar and were not statistically different between the accesses that did and those that did not thrombose. When multivariate analysis was used, there was a significantly increased risk of thrombosis only with decreasing access blood flow determined by ultrasound dilution techniques after adjusting for other confounding variables. When the average blood flow of all grafts (1134 ml/min) is considered as the reference access blood flow (relative risk of 1.0), the relative risk of a PTFE thrombotic event within the subsequent 12 weeks was 1.23 at a blood flow 950 ml/min, 1.67 at a blood flow of 650 ml/min and to 2.39 at a blood flow of 300 ml/min. In summary, access blood flow measured by either Dilution or Doppler is a reliable indicator of subsequent short-term thrombosis risk. Other proposed methods of evaluating access dysfunction were not useful in our patients. If simple to use, cost-effective devices to measure dialysis access blood flow become readily available, the measurement of access blood flow will likely become the method of choice for screening of PTFE vascular access dysfunction in hemodialysis patients.

Analytical expressions correlating the volumetric flow rate to the inlet and outlet pressures are derived for the time-independent flow of Newtonian fluids in cylindrically-shaped elastic tubes using a one-dimensional Navier-Stokes flow model with two pressure-area constitutive relations. These expressions for elastic tubes are the equivalent of Poiseuille and Poiseuille-type expressions for rigid tubes which were previously derived for the flow of Newtonian and non-Newtonian fluids under various flow conditions. Formulae and procedures for identifying the pressure field and tube geometric profile are also presented. The results are validated by a finite element method implementation. Sensible trends in the analytical and numerical results are observed and documented.

4-Hydroxynonenal (HNE) is a major aldehydic product formed by peroxidation of omega 6-unsaturated fatty acids and is regarded as a specific marker of lipid peroxidation. In this paper we demonstrate that there is a physiological steady-state concentration of HNE in human venous blood plasma. For the quantitative determination of HNE a modified version of an existing, but tedious and time-consuming HPLC method was developed. The extraction of aldehydic hydrazones from plasma was performed using an Extrelut column and the separation step by thin-layer chromatography was replaced by column chromatography on silica gel. The concentration of HNE in human blood plasma was in the same range as the concentration that was found to inhibit the proliferation of cells of the peripheral tissues, i.e., endothelial cells and fibroblasts in vitro. In an experiment with reduced peripheral blood flow a temporary significant increase of HNE was observed during reperfusion. It was concluded that lipid ...

Ventilation at high respiratory rates is considered detrimental during CPR because it may increase intrathoracic pressure limiting venous return and forward blood flow generation. We examined whether ventilation at high, yet clinically plausible, tidal volumes could also be detrimental, and further examined effects on end-tidal pCO(2) (P(ET)CO(2)). Sixteen domestic pigs were randomized to one of four ventilatory patterns representing two levels of respiratory rate (min(-1)) and two levels of tidal volume (ml/kg); i.e., 10/6, 10/18, 33/6, and 33/18 during chest compression after 8 min of untreated VF. Data (mmHg, mean ± SD) are presented in the order listed above. Ventilation at 33/18 prompted higher airway pressures (p<0.05) and persistent expiratory airway flow (p<0.05) before breath delivery demonstrating air trapping. The right atrial pressure during chest decompression showed a statistically insignificant increase with increasing minute-volume (7 ± 4, 10±3, 12 ± 1, and 13 ...

Currently, there is a debate about which percentage of body mass loss can compromise performance and lead to complications to athletes’ health. Most of the drinking guidelines for exercise recommend replacing all the body mass lost during exercise and drinking as much as tolerable to avoid body mass loss over 2%. A greater dehydration can compromise aerobic exercise and cognitive/mental performance in warm-hot environments and increase the risk for heat stroke, heat exhaustion and cramps. A “cardiovascular model of thermoregulation” is used to explain the thermal regulation during exercise, which proposes that sweating reduces body water content, reducing blood flow and increasing the cardiovascular strain. However, this model has been criticized by many authors, who state that sweating response is regulated by neural mechanisms that are not dependant of the cardiovascular response to the exercise. The aim of this study was to review the recommendations for fluid replacement during exercise and detail the real necessity to replace all body mass lost during exercise for better performance. We searched the following electronic databases with no data limitation: national and international articles related to the subject, in the scientific portals of Capes, Scielo, PubMed, Science Direct, Highwire and randomized control trails, in English and Portuguese. The inclusion criteria was considered human studies, papers on dehydration and performance, recommendations on hydration and exercise, ingestion of electrolytic beverages in exercise and the effects of hydration status and thermoregulation. The exclusion criteria were: experimental articles and general recommendation for non athletes.

Key words: hydration, dehydration, performance, exercise, thermoregulation.

Preparations of d,l- and meso-hexamethylpropyleneamine oxime (HM-PAO) labeled with technetium-99m were added to rat brain homogenates diluted with phosphate buffer (l: 10). The conversion of d,l-HM-PAO to hydrophilic forms took place with an initial rate constant of 0.12 min−1. Incubation of the brain homogenate with 2% diethyl maleate for 5 h decreased the homogenate's measured glutathione (GSH) concentration from 160 to 16 μ M and decreased the conversion rate to 0.012 min−1. Buffered aqueous solutions of glutathione rapidly converted the HM-PAO tracers to hydrophilic forms having the same chromatographic characteristics as found in the brain homogenates. The rate constant for the conversion reaction of d,l-HM-PAO in GSH aqueous solution was 208 and 317 L/mol/min in two different assay systems and for meso-HM-PAO the values were 14.7 and 23.2 L/mol/min, respectively. Rat brain has a GSH concentration of about 2.3 m M and the conversion of the d,l-HM-PAO due to GSH alone should...

We compared a physiological model of 82Rb kinetics in the myocardium with two reduced-order models to determine their usefulness in assessing physiological parameters from dynamic PET data. A three-compartment model of 82Rb in the myocardium was used to simulate kinetic PET ROI data. Simulations were generated for eight different blood-flow rates reflecting the physiological range of interest. Two reduced-order models commonly used with myocardial PET studies were fit to the simulated data, and parameters of the reduced-order models were compared with the physiological parameters. Then all three models were fit to the simulated data with noise added. Monte Carlo simulations were used to evaluate and compare the diagnostic utility of the reduced-order models. A description length criterion was used to assess goodness of fit for each model. Finally, fits to simulated data were compared with fits to actual dynamic PET data. Fits of the reduced-order models to the three-compartment mode...