scholarly journals Impact of accumulated oxygen depletion (AOD) on measurements of oxygen tension (PO2) using phosphorescence quenching microscopy (PQM)

2008 ◽  
Vol 22 (S1) ◽  
Author(s):  
Aleksander Sergeevich Golub ◽  
Roland Nathan Pittman
Keyword(s):  
Oxygen Tension ◽  
Oxygen Depletion ◽  
Phosphorescence Quenching

Erythrocyte-associated transients in capillary Po2: an isovolemic hemodilution study in the rat spinotrapezius muscle

2007 ◽  
Vol 292 (5) ◽  
pp. H2540-H2549 ◽  
Author(s):  
Matthew C. Barker ◽  
Aleksander S. Golub ◽  
Roland N. Pittman
Keyword(s):  
Blood Flow ◽  
Oxygen Tension ◽  
Oxygen Delivery ◽  
Capillary Number ◽  
Observation Point ◽  
Isovolemic Hemodilution ◽  
Phosphorescence Quenching ◽  
Mathematical Simulations ◽  
The Impact ◽  
532 Nm

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.

Oxygen tension gradients and heterogeneity in venous microcirculation: a phosphorescence quenching study

1997 ◽  
Vol 272 (5) ◽  
pp. H2233-H2240 ◽  
Author(s):  
R. D. Shonat ◽  
P. C. Johnson
Keyword(s):  
Blood Pressure ◽  
Oxygen Tension ◽  
Systemic Blood Pressure ◽  
Systemic Blood ◽  
Microvascular Network ◽  
Waste Products ◽  
Phosphorescence Quenching ◽  
Oxygen Gradients ◽  
Weakly Dependent ◽  
Made In

Localized measurements of intravascular oxygen tension (PO2) at multiple locations in the microvascular network of the rat spinotrapezius muscle were used to study the spatial distribution of PO2 in venular structures. By use of a newly developed phosphorescence system to rapidly and repeatedly measure PO2, 538 individual measurements were made in 18 different networks during rest. Average intravascular PO2 was (in mmHg +/- SD) 33 +/- 9, 21 +/- 9, 26 +/- 10, and 33 +/- 8 in small arcade arterioles, postcapillary venules (PV), 3 degrees venules (3V), and arcade venules, respectively. The coefficient of variation (CV), a descriptive indicator of spatial heterogeneity, was correspondingly 0.28, 0.45, 0.37, and 0.23 for the different vessel groups. PO2 was found to increase significantly (P < 0.001) from PV to 3V, rising 0.009 +/- 0.002 mmHg/microns along the vessel. By linear regression, the slope of PO2 for the vessel difference group, PV-3V as a function of mean systemic blood pressure (BPm; in mmHg) was -0.09 +/- 0.04 (P < 0.05), indicating that the measured longitudinal oxygen gradients and CV are only weakly dependent on BPm. The results support the hypothesis that oxygen can diffuse across the walls of postcapillary vessels and suggest that the venular structures are not merely passive conduits for removing oxygen and waste products but may play an important role in regulating oxygen delivery.

Effect of oxygen tension on killing ofEscherichia coliby bovine polymorphonuclear neutrophil leucocytesin vitro

1995 ◽  
Vol 62 (2) ◽  
pp. 331-338 ◽  
Author(s):  
John J. Goldberg ◽  
J. Woodrow Pankey ◽  
Ioannis Politis ◽  
Boris Zavizion ◽  
A. John Bramley
Keyword(s):  
Escherichia Coli ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Tension ◽  
Oxygen Depletion ◽  
Polymorphonuclear Neutrophil ◽  
Batch Fermenter ◽  
Specific Association ◽  
Effect Of Oxygen

SUMMARYA batch fermenter modified to simulate the physical conditions of an inflamedv. uninflamed mammary gland was utilized to evaluate the effect of oxygen tension on killing ofEscherichia coliP4 by bovine polymorphonuclear neutrophil leucocytes. Leucocytosis was simulatedin vitro4 h after inoculation withEscherichia coliby adding bovine neutrophils isolated from peripheral blood to the culture medium. Experiments were conducted at 39°C in UHT treated milk. At micro-aerophilic oxygen tension (oxygen partial pressure, 3·11kPa), bacterial numbers declined during the first hour following addition of the neutrophils. Oxygen tension declined rapidly following PMN addition. Once oxygen was depleted, neutrophil activity was presumably diminished andEsch. colinumbers began to increase. Under anaerobic conditions (oxygen partial pressure, 0·17kPa), no reduction in population was observed. Photomicrographs taken at the time of neutrophil addition and at subsequent time intervals demonstrated a specific association between neutrophils and the pathogen. Subsequent lysis of neutrophils associated withEsch. coligrowth was seen coincident with oxygen depletion.

scholarly journals Microvascular oxygen tension in the rat mesentery

2008 ◽  
Vol 294 (1) ◽  
pp. H21-H28 ◽  
Author(s):  
Aleksander S. Golub ◽  
Matthew C. Barker ◽  
Roland N. Pittman
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Tension ◽  
Oxygen Delivery ◽  
Vascular Wall ◽  
Spot Size ◽  
Vessel Diameter ◽  
Primary Site ◽  
Phosphorescence Quenching ◽  
Rat Mesentery ◽  
Mesenteric Microcirculation

Longitudinal Po2 profiles in the microvasculature of the rat mesentery were studied using a novel phosphorescence quenching microscopy technique that minimizes the accumulated photoconsumption of oxygen by the method. Intravascular oxygen tension (Po2, in mmHg) and vessel diameter ( d, in μm) were measured in mesenteric microvessels ( n = 204) of seven anesthetized rats (275 g). The excitation parameters were as follows: 7 × 7-μm spot size; 410 nm laser; and 100 curves at 11 pulses/s, with pulse parameters of 2-μs duration and 80-pJ/μm2 energy density. The mean Po2 (± SE) was 65.0 ± 1.4 mmHg ( n = 78) for arterioles ( d = 18.8 ± 0.7 μm), 62.1 ± 2.0 mmHg ( n = 38) at the arteriolar end of capillaries ( d = 7.8 ± 0.3 μm), and 52.0 ± 1.0 mmHg ( n = 88) for venules ( d = 22.5 ± 1.0 μm). There was no apparent dependence of Po2 on d in arterioles and venules. There were also no significant deviations in Po2 based on d (bin width, 5 μm) from the general mean for both of these types of vessels. Results indicate that the primary site of oxygen delivery to tissue is located between the smallest arterioles and venules (change of 16.3 mmHg, P = 0.001). In conclusion, oxygen losses from mesenteric arterioles and venules are negligible, indicating low metabolic rates for both the vascular wall and the mesenteric tissue. Capillaries appear to be the primary site of oxygen delivery to the tissue in the mesenteric microcirculation. In light of the present results, previously reported data concerning oxygen consumption in the mesenteric microcirculation can be explained as artifacts of accumulated oxygen consumption due to the application of instrumentation having a large excitation area for Po2 measurements in slow moving and stationary media.

Low-temperature annealing of YBa2Cu3O7-x

1992 ◽  
Vol 50 (1) ◽  
pp. 88-89
Author(s):  
R.L. Sabatini ◽  
Yimei Zhu ◽  
Masaki Suenaga ◽  
A.R. Moodenbaugh
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Temperature ◽  
Oxygen Diffusion ◽  
Diffusion Rate ◽  
Oxygen Depletion ◽  
Low Temperature Annealing ◽  
Transmission Electron ◽  
Microstructural Effects ◽  
Oxygen Diffusion Rate

Low temperature annealing (<400°C) of YBa2Cu3O7x in a ozone containing oxygen atmosphere is sometimes carried out to oxygenate oxygen deficient thin films. Also, this technique can be used to fully oxygenate thinned TEM specimens when oxygen depletion in thin regions is suspected. However, the effects on the microstructure nor the extent of oxygenation of specimens has not been documented for specimens exposed to an ozone atmosphere. A particular concern is the fact that the ozone gas is so reactive and the oxygen diffusion rate at these temperatures is so slow that it may damage the specimen by an over-reaction. Thus we report here the results of an investigation on the microstructural effects of exposing a thinned YBa2Cu3O7-x specimen in an ozone atmosphere using transmission electron microscopy and energy loss spectroscopy techniques.

A new technique for the mapping of oxygen tension on the brain surface

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S543-S543
Author(s):  
Satoshi Kimura ◽  
Keigo Matsumoto ◽  
Yoshio Imahori ◽  
Katsuyoshi Mineura ◽  
Toshiyuki Itoh
Keyword(s):  
Oxygen Tension ◽  
New Technique ◽  
Brain Surface ◽  
A New Technique ◽  
The Brain
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