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Biomedical subjects

B A Cheney

Publications and source records attributed to B A Cheney.

9 recordsLinked to original sources
PubMed1989

Effect of diltiazem and a prostaglandin derivative (PGBx) on platelet function during long-term storage.

Calcium is an intermediate messenger between platelet stimuli and platelet response. Published studies have shown that the decreased ability of platelets to control calcium flux during long-term storage leads to platelet senility. Platelet metabolism might be more efficient during storage if pharmacologic agents that limit calcium movement were incorporated into the platelet concentrate storage solution. This hypothesis was tested by storing platelets with the calcium channel blocker, diltiazem, or with a prostaglandin B1 derivative, PGBx. During a 15-day storage period, platelets incubated with either diltiazem or PGBx showed improved function, as measured by aggregation, as compared to control platelets. The PGBx -enhanced platelet function during storage was accompanied by a significant decrease in glucose and an increase in adenosine triphospate concentrations. Platelet function after storage with PGBx improved in spite of significantly lower pH levels of the platelet concentrates at all time points tested. These studies suggest that the maintenance of calcium ion homeostasis during long-term platelet storage is important to in vitro platelet function even if the Ca2+ balance is maintained at the expense of pH and the glucose concentrations.

Blood Preservation↗
PubMed1984

Characteristics of lympho-myelopoietic stem cells isolated from canine peripheral blood.

If hematopoietic stem cells (HSC) could be separated from peripheral blood, it might be possible to harvest these stem cells for potential clinical use. By leukapheresis techniques, we harvested mononuclear cells (MNC) from peripheral blood and then placed these cells over discontinuous stractan gradients of three densities (1.077 gm/ml, 1.071 gm/ml and 1.066 gm/ml). These separated cells were submitted to colony culture to identify colony-forming-unit activity for granulocyte-macrophage (CFU-C) and T-cell lymphocyte (CFU-L) cell lines. The lightest cells (1.066) contained most of the CFU-C and no CFU-L activity. Heavier cells (greater than 1.071) contained CFU-L and very little CFU-C activity. CFU-L colonies could be distinguished from CFU-C by their density and distinct morphological appearance. In addition, the amount of CFU-C could be increased in the animal by increasing the amount of blood processed (from 3.9 +/- .76 CFU-C/10(6) MNC to 6.7 +/- .35 CFU-C/10(6) MNC). This resulted in an increase of CFU-C collected from 7.6 +/- 2.1 CFU-C/10(6) MNC after the first equivalent blood volume to 22.5 +/- 3.4 CFU-C/10(6) MNC after the third equivalent blood volume processed. These results suggest that leukapheresis and gradient density separation may be useful procedures to obtain HSC.

Animals↗
PubMed1983

Granulocyte progenitor cell (CFUC) harvest by continuous apheresis in dogs. Effects of blood volume and lithium on yields.

The ability to harvest large amounts of hematopoietic stem cells from blood would eliminate the more difficult approach of bone marrow harvest. Unfortunately, concentration of stem cells in the blood compartment is less than 1% of their concentration in bone marrow. Attempts to increase harvest of blood stem cells, as assayed by granulocyte progenitor cells (CFUC), have been only partially successful. Our study confirms previous reports that CFUC can be mobilized into the blood compartment in dogs, but this mobilization is rate-limited. Unlike platelets and granulocytes that are effectively harvested during the first blood volume processed by continuous apheresis, effective CFUC harvest begins during the second blood volume (606 +/- 97.9 CFUC/ml), peaks by the third (740 +/- 30 CFUC/ml), and remains constant through five blood volumes processed (700 +/- 272 CFUC/ml). Since blood CFUC concentration falls at the end of five blood volumes processed (40% of initial values), further continuous apheresis would not be effective. Treatment of animals with lithium did not improve CFUC harvest. These results show that apheresis procedures can be developed to a limited extent to increase the harvest of hematopoietic progenitor and stem cells.

Animals↗
PubMed1981

Buoyant density of platelets stored at room temperature as platelet concentrates.

Separation of platelets by buoyant density centrifugation was periodically performed on platelet concentrates stored up to 96 hr at room temperature. By 72 hr, platelets were much lighter, depending on pH, platelet concentration, and volume of the bag. The mean proportion of platelets in the light fraction (fraction 1) shifted from 4.3% when the concentrate was fresh to 52.2% at 72 hr and 53.6% at 96 hr. The majority of platelets had densities that ranged from 1.034 to 1.088 gm/ml after storage, whereas densities ranged from 1.054 to 1.088 gm/ml in fresh cells. With storage, the light cells became larger than when they were fresh and were mostly balloon-shaped; the heavy cells became smaller but retained their normal shape. Regression analysis showed that density distribution was highly correlated to pH. Most of the changes occurred after 12 hr; those changes that occurred during the initial 12 hr were not related to pH of the platelet concentrate. The changes were related to storage conditions and may reflect injury to the cells. The use of buoyant density separation may be a useful tool to study storage mechanisms and provide a means of separating cells modified by storage stress.

Blood Platelets↗
PubMed1981

Glycoprotein changes in fresh vs. room temperature-stored platelets and their buoyant density cohorts.

Membranes from platelets obtained from normal human volunteers were isolated for evaluation of their glycoproteins. Values were measured in fresh and stored platelet concentrates at 72 and 96 hr (22 degrees +/- 2 degrees C). Polyacrylamide gels were used to separate the membrane glycoproteins. These were identified as GPI, GPII, GPIII, GPIV, GP77, and GP44. The relative amount of GPI (155,000 daltons) was about 30% less after 72 hr storage than in fresh platelets regardless of the change in the pH of the platelet concentrate. At 96 hr, only an additional 5% loss was seen. The 72 hr value for soluble glycoprotein, glycocalicin, was only 64% of the initial value. GP77 (77,000 daltons) and GP44 (44,000 daltons) became apparent or more prominent with storage. A correlation with pH of the platelet concentrate could be demonstrated for GPI but only with those units in which the pH rose during storage. Density-separated populations of fresh and stored platelets also were studied. They were separated on arabinogalactan (Stractan II) gradients for comparative studies of membrane proteins that might be affected, since platelets become less dense with storage. There was an equal loss of GPI in all populations. However, the change was most striking in the least dense (lightest) fraction because these cells started with 20% less GPI when fresh than did heavier cells. The smallest glycoprotein, GP44, was always present in the lightest platelets after storage, whereas only 40% of the concentrates showed GP77, in small amounts, associated with heavy platelets. Alterations in the membranes of platelets stored as platelet concentrates could result in their functional impairment and loss viability.

Blood Platelets↗
PubMedDate not supplied

In vitro evaluation of platelets stored in CDP-adenine formulations.

Little information is available about the effect of adenine and added glucose on stored platelets. Two new formulations, CPDA-2 and CPDA-3, contain 34 mg adenine per 63 ml preservative and extra glucose (1.75 and 2.0 times the glucose in standard CPD). We have studied the in vitro integrity of platelet concentrates stored in CPD, CPDA-1, CPDA-2, and CPDA-3 at 22 C for 72 hours. Morphology score, pH, platelet size, population distribution parameters, and electron microscopic ultrastructure did not show any adverse effects which could be ascribed to the presence of adenine or extra glucose or both. No differences in platelet adenosine triphosphate (ATP) concentration or plasma glucose utilization during storage were found between CPD and CPDA-1 platelets. The results suggest that adenine and added glucose in these preservatives are not detrimental to platelets in vitro by the measures employed.

Adenine↗
PubMedDate not supplied

An in vivo comparison of CPD and CPDA-2 preserved platelet concentrates after an 8-hour preprocess hold of whole blood.

To see if citrate-phosphate-dextrose-adenine-two (CPDA-2) anticoagulant-preservative had an effect on the viability of platelets, we studied autologous in vivo recovery and survival in humans for platelet concentrates prepared from six units of blood drawn into CPDA-2 and compared them to six units drawn into citrate-phosphate-dextrose (CPD). These units were prepared from whole blood held at room temperature for 8 hours after collection and were then stored for 3 days at 22 +/- 2 degrees C. The recovery for platelets preserved in CPD was 39.0 +/0 4.8 percent and for platelets preserved in CPDA-2, 32.5 +/- 4.4 percent. The difference was not significant (p greater than 0.10). In order to estimate population differences, in vitro effects on in vivo viability were also evaluated. Six in vitro variables were studied but only pH at 72 hours (r = 0.77), platelet count (r = 0.64), and morphology score (r = 0.66) correlated to recovery. Only pH at 72 hours significantly influenced recovery (p = 0.007). By adjusting for individual pH differences, mean recovery for platelets stored in CPD was 37.5 percent, and for platelets stored in CPDA-2, 34.0 percent. The mean lifespan was 6.7 +/- 0.7 days for platelets preserved in CPD and 6.1 +/- 1.0 days for those preserved in CPDA-2. Although hemostatic function was not studied, these data support in vitro observations that platelets preserved with CPDA-2 are not different from platelets preserved with CPD, even after 8-hours of storage of whole blood at room temperature prior to platelet concentrate preparation.

Blood Platelets↗
PubMedDate not supplied

Glycerol-glucose cryopreservation of platelets. In vivo and in vitro observations.

Extended storage of platelets can be achieved by cryopreservation. However, most cryopreservation techniques require extensive manipulation prior to administration, limiting their practicality. A simple cryopreservative system using glycerol and glucose as cryoprotectants would eliminate the need to wash the platelets after freezing, since neither of these agents is toxic. We evaluated such a system in vivo and compared the results to 72-hour liquid-stored platelets. The percentage of in vivo recovery was significantly less (p less than 0.01) for cryopreserved (21.1 +/- 3.4% [chi +/- 1 SD]) than liquid-stored (43.8 +/- 7.4%) platelets, but those frozen-thawed cells that were viable had normal survivals (8.4 +/- 1.7 days). Liquid-stored cell appeared to be less viable (5.9 +/- 1.8 days). These results indicate that cryopreservation with the glycerol-glucose system produces significant injury to the majority of platelets and therefore, is inadequate for general blood bank use.

Blood Platelets↗