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Biomedical subjects

W A Heaton

Publications and source records attributed to W A Heaton.

At least 37 records · Page 2Linked to original sources
PubMed1992

Evaluation of posttransfusion recovery and survival of transfused red cells.

Increasing diversity of red cell preservation solutions has required more attention to the techniques of documenting the in vivo efficacy of stored red cell transfusion products. Use of double labels and survival studies will not only improve the precision of the measurement but, hopefully, will offer insight into some of the effects of the newer preservation systems. Further development of the low chloride hypotonic red cell storage solutions pioneered by Meryman may well result in red cell transfusion products that can be stored liquid in vitro for more than twice the normal in vivo lifespan. Verifying that such cells not only are recovered in the circulation but survive for the normal in vivo lifespan and function correctly will demand increasingly accurate techniques. The combination of assay precision and external imagability render radionuclide techniques the standard for verifying red cell efficacy despite the small disadvantage of the radiation absorbed dose.

Blood Preservation↗
PubMed1992

Improved maintenance of platelet in vivo viability during storage when using a synthetic medium with inhibitors.

We report on the storage of platelet concentrates and the effects on in vivo and in vitro platelet function tests of adding the platelet inhibitors prostaglandin E1 and theophylline to a plasma-free synthetic medium and storage in containers with reduced surface-to-volume ratio. Paired in vivo studies on platelets labeled with indium 111 after 14-day storage demonstrated higher recoveries (mean +/- SD) of 23% +/- 9% and longer survivals of 109 +/- 59 hours for the test group versus 8% +/- 10% and 19 +/- 22 hours, respectively (p less than 0.01), for the control group (synthetic medium with no inhibitors and use of standard containers). The improved viability was associated with a significantly lower glycolytic rate; better maintenance of other in vitro parameters including respiratory activity, adenosine triphosphate levels, hypotonic shock response, surface glycoprotein Ib (by flow cytometry); and improved preservation of morphologic integrity (p less than 0.05). In particular, a strong inverse correlation (r = -0.91) was observed between in vivo recoveries and the fraction of platelets negative for glycoprotein Ib. We conclude that avoidance of platelet activation by a combination of inhibitors, plasma removal, and reduced container surface improves platelet respiratory activity, adenosine triphosphate and glycoprotein Ib levels, and posttransfusion viability of platelet concentrates stored for 14 days.

Adenosine Triphosphate↗
PubMed1991

Extended storage of platelets in an artificial medium with the platelet activation inhibitors prostaglandin E1 and theophylline.

The addition of platelet activation inhibitors to the anticoagulant and the replacement of plasma with a fortified electrolyte medium have been shown separately in previous work to improve the storage of platelets during a 2-week period. In the present study, we have combined these strategies to investigate whether a synergistic improvement could be obtained. A total of 85 concentrates was studied with 300 nM prostaglandin E1 (PGE1) and 1.9 mM theophylline added to the whole blood, platelet-rich plasma (PRP), and/or the storage medium during the preparation of platelet concentrates. In vitro markers of platelet aggregation, respiration, and cell integrity were measured over a 20-day storage period and evaluated in an analysis of variance. We found that a single-step addition of PGE1 and theophylline to the PRP prior to centrifugation was not sufficient in terms of preventing a rapid fall in pH, rise in pO2, fall in pCO2, loss of hypotonic shock response, and loss of aggregation response, compared to the addition of the inhibitors to the storage medium used to resuspend the platelet pellet. Factorial analysis showed that a reduction in the surface-to-volume ratio of the storage container further improved the maintenance of platelet respiration and, for three in vitro markers (hypotonic shock response, released lactic dehydrogenase, and surface glycoprotein Ib levels) displayed an interactive effect with the inhibitors. The addition of protease inhibitors to the formulation of PGE1 and theophylline showed further improvement in several markers. These findings demonstrate the possibility of preserving platelets for 15-20 days with the synergistic effects of activation inhibitors and an electrolyte storage medium fortified with citrate, buffers, and dextrose.(ABSTRACT TRUNCATED AT 250 WORDS)

Alprostadil↗
PubMed1990

Development of a combined storage medium for 7-day storage of platelet concentrates and 42-day storage of red cell concentrates.

Studies were carried out to examine whether a single additive solution could support both platelet and red cell storage. An ionically balanced electrolyte solution fortified with citrate, glucose and bicarbonate was used. This solution has previously been shown to provide good platelet viability with storage for up to 7 d. Optimization studies demonstrated that with adenine added to this solution (CSM), it also allowed for satisfactory preservation of in vitro red cell parameters for up to 49 d of storage. Confirmatory paired in vivo post-transfusion studies were carried out in which platelets and red cells obtained from the same donor were processed and stored in CSM on one occasion, and in CPD-plasma (platelets) and AS-1 (red cells) on another occasion. Five paired studies were conducted with platelets stored for 5 d and red cells for 42 d; another five paired studies with platelets stored for 7 d and red cells for 49 d. Except for a slight decrease in platelet survival (P less than 0.05) with storage in CSM, there were no statistically significant differences in post-transfusion recoveries and survivals between test and control media, demonstrating that both platelets and red cells may be satisfactorily stored in a combined single additive solution.

Adult↗
PubMed1990

Platelet storage lesions in second-generation containers: correlation with in vivo behavior with storage up to 14 days.

The relationship between in vivo behavior and in vitro characteristics of 59 platelet concentrates (PC) stored for up to 14 days in a synthetic medium or in CPDA-1 plasma was systematically investigated. 25 paired studies (1 study was incomplete) were performed comparing platelets suspended either in the synthetic medium or CPDA-1 plasma with 5 days (n = 5); 7 days (n = 10); 10 days (n = 5); and 14 days (n = 5) of storage. In addition, 10 control studies were performed with freshly prepared PC (6-24 h) in CPDA-1 plasma. Both percent recovery and survival estimations showed decreases with increasing storage duration, irrespective of storage medium used. In both media, with prolonged storage, the platelet survival curves not only became shorter, but also increasingly exponential, suggesting that in vitro storage caused progressive damage to the platelets present in circulation. Survival curves of platelets suspended in synthetic medium remained more linear, indicative of less random damage during storage. Mean population lifespan (MPL) of the stored PC was determined by the area below the survival curve divided by the mean percent recovery for the fresh PC, which was 55%. MPL decreased from 4.5 days (fresh PC) to 0.4 days after 14 days of storage in plasma, with a 50% reduction (t1/2) estimated at 7.2 days of storage. MPL t1/2 for PC stored in the synthetic medium was estimated to be 8.8 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Studies with nonradioisotopic sodium chromate. I. Development of a technique for measuring red cell volume.

A nonradioisotopic method for measuring red cell volume that involves the use of 52Cr-sodium chromate as the red cell label and of graphite furnace atomic absorption analysis of chromium is described. The technique allows the labelling of 20 mL of packed red cells with 40 to 50 micrograms of sodium chromate (Na2CrO4) in 30 minutes at 22 degrees C with 94 +/- 6 percent uptake. Approximately 40 micrograms of Na2CrO4 was injected for in vivo studies. This results in posttransfusion in vivo red cell chromium levels after sample processing in the range of 1 to 7 micrograms per L, which could be quantitated accurately (coefficient of variation = 4.7%) by Zeeman electrothermal atomic absorption spectrophotometry. The labeling concentration of chromium did not cause increased hemolysis, and the labeled cells exhibited an osmotic fragility curve similar to that of unlabeled, fresh ACD red cells. Red cell glutathione peroxidase was unaffected by labeling, although glutathione reductase was reduced by approximately 13 percent (p less than 0.05). The 52Cr red cell volume-measuring method was evaluated by concurrent in vivo studies with the standard 51Cr and 125I-albumin methods for that procedure. Simultaneous measurement of red cell volumes in seven volunteers by the 51Cr, 52Cr, and 125I-albumin techniques correlated highly with each other (r greater than 0.76), with mean values of 2294 +/- 199, 2191 +/- 180, and 2243 +/- 291 mL, respectively. The standard deviations of the differences were small: 134 mL for 52Cr versus 51Cr and 183 mL for 52Cr versus 125I.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromates↗
PubMed1989

Studies with nonradioisotopic sodium chromate. II. Single- and double-label 52Cr/51Cr posttransfusion recovery estimations.

A recently developed nonradioisotopic 52Cr technique was used to measure either red cell volume or posttransfusion recovery of stored red cells. The experimental method uses Zeeman electrothermal atomic absorption spectrophotometry to measure red cell chromium. Results from the 52Cr method were compared with those from 51Cr single-label and 125I-albumin/51Cr double-label procedures using 49-day AS-1 red cell concentrates drawn and prepared according to standard procedures. In the first group of five donors, red cell volume was estimated concurrently with both 52Cr-labeled fresh red cells and 125I-albumin. The latter measured plasma volume from which red cell volume was estimated on the basis of the hematocrit (125I red cell volume). 51Cr-labeled stored red cells were transfused to measure posttransfusion recoveries. The correlation between 52Cr and 125I red cell volumes was significant (r = 0.68, p less than 0.01), and, in this group, the differences were not significant (p less than 0.05). Twenty-four-hour posttransfusion recoveries of 51Cr-labeled stored red cells averaged 66 +/- 5 percent when measured with the 125I/51Cr technique and 69 +/- 8 percent when measured with the 52Cr/51Cr method. In the second group of five donors, red cell volume was estimated by the 125I-albumin technique, and the posttransfusion recovery of stored red cells was quantitated by 51Cr- and 52Cr-labeled stored cells simultaneously. In this group, posttransfusion recoveries with 125I/51Cr averaged 73 +/- 7 percent; with 125I/52Cr, they averaged 75 +/- 10 percent. Using the single-label method of calculation, recoveries averaged 76 +/- 7 and 75 +/- 10 percent for the 51Cr and 52Cr methods, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Transfusion↗
PubMed1989

In vitro and in vivo evaluation of platelet concentrates after cotton wool filtration.

Removal of leukocytes from platelet concentrates (PC) may decrease the incidence of alloimmunization to HLA antigens on white cells and prevent or delay refractoriness. Cotton wool filtration, which effectively removes leukocytes from PC with minimal platelet loss, may cause platelet or complement activation. In this study, the effect of cotton wool filtration (Imugard IG-500) on platelet activation, in vitro function, posttransfusion survival, and complement activation was investigated. Five paired autologous in vivo percent recovery and survival studies were performed with fresh (6-8h) PC or with 5-day-stored PC prepared from CPD-anticoagulated blood and stored in PL-732(TM) containers using standard methods. In the paired design, PC from the same donor were filtered on one occasion, and not filtered on another, prior to labeling with indium-III-oxine and reinfusion. Percent recovery and survival were then determined by the standardized method. Filtration had no statistically significant effect on percent recovery on PC stored for 6-8h or for 5 days. There was, however, a slight decrease in survival hours of the filtered PC which was statistically significant at 6-8h (203 +/- 14 vs. 179 +/- 18h; p less than 0.05) but not at 5 days (166 +/- 28 vs. 132 +/- 27h; p greater than 0.05). Samples taken before and after filtration of single units (fresh and 5-day) and pooled units (3-day) for measurement of release of granular content (beta-thromboglobulin), lysis (LDH), and in vitro viability - ATP, extent of shape change with ADP, and hypotonic shock response (3-day only)-demonstrated no effect of filtration on these parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Additive solution for the suspension and storage of deglycerolized red blood cells.

The additive solution, ADSOL, was evaluated for its suitability in the extended storage of previously frozen, deglycerolized red blood cells. In vitro comparison with red cells suspended in 0.2% dextrose 0.9% saline showed that ADSOL allowed for significantly enhanced adenosine triphosphate preservation throughout the storage period (greater than 2.2 mumol/g Hb beyond 14 days) and for significantly reduced hemolysis (less than 1% beyond 14 days). After 10 days of storage in ADSOL the mean recovery after transfusion was 90% (index of therapeutic effectiveness, 77%). No bacterial contamination was observed. The results suggest that this currently approved additive solution could be used to store red cells for 14 days following thawing, thus avoiding one of the principal drawbacks of frozen red cells.

Adenine↗
PubMed1989

In vitro and in vivo comparison of platelet concentrates collected by automated versus manual apheresis.

Platelet concentrates collected by continuous flow automated apheresis (Fenwal CS-3000) were compared with those collected by manual apheresis to determine whether the prolonged centrifugation and vigorous resuspension affected platelet viability and in vitro function. Paired autologous reinfusion studies (111Indium) of 5 normal donors showed no significant differences in the mean percent recoveries (50.8 +/- 7.0% vs 53.8 +/- 4.0%) or survivals (174 +/- 23 h vs 188 +/- 10 h) for platelets collected by manual versus automated apheresis. Platelets collected by automated apheresis had a significantly higher level of beta-thromboglobulin release, but there were no significant differences between platelets collected by the two methods in regard to other in vitro parameters (ATP levels, LDH released, hypotonic shock response) believed to reflect platelet activation, injury, and malfunction. These results suggest that only slight activation of platelets takes place during automated apheresis.

Adenosine Triphosphate↗
PubMed1989

Evaluation of 99mtechnetium/51chromium post-transfusion recovery of red cells stored in saline, adenine, glucose, mannitol for 42 days.

An in vivo and in vitro study of 42-day saline, adenine, glucose, mannitol (SAGM) red cells (Terumo Corporation, Elkton, Md.) was conducted using 20 volunteers to document in vivo efficacy and analyze the validity of the 99mTc/51Cr technique. In vivo autologous post-transfusion recovery was measured by a double-label procedure involving the use of 99mTc-labeled freshly drawn red cells to quantify recipient blood volume and 51Cr to document both post-transfusion 24-hour recovery (PTR) and red cell survival. As an internal control, 5 of the 20 donors studied had red cell volumes estimated by the 125I-albumin (RISA) plasma volume technique on a separate occasion. For comparison, PTR was also calculated according to the single-label 51Cr protocol in which recipient blood volume was estimated by extrapolation from circulating 51Cr-labeled red cell activity 5-15 min after infusion. After 42 days of storage, PTR averaged 78 +/- 6% with the double-label 99mTc/51Cr technique and 81 +/- 5% with the single-label (51Cr alone), confirming a small difference between the two techniques. Correlation between the two techniques was high, r = 0.81, though the average 3% difference between them was significant (p less than 0.05). Red cell volumes of the 5 donors measured by both the 99mTc-red cell method and the 125I-albumin method exhibited excellent correlation, r = 0.96, and averaged 1,961 +/- 420 ml and 2,048 +/- 381 ml, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1988

Elevated levels of PA IgG in thrombocytopenic patients are not related to the presence of microthrombocytes or megathrombocytes.

Platelet-associated (PA) IgG levels were measured on peripheral blood samples from 63 thrombocytopenic patients with the use of fluorescein isothiocyanate (FITC)-conjugated anti-IgG antibody. Test specificity was investigated by examining the influence of variables such as the platelet count in platelet-rich plasma (PRP), platelet loss after the assay procedure, and platelet size distribution (including the percentage of microthrombocytes and megathrombocytes) on the PA IgG levels. Additionally, PA IgG levels were compared with PA albumin levels and with levels of nonspecific adherence of FITC anti-IgG by the platelets to ascertain if elevated levels were specific. Elevated PA IgG levels showed only significant correlations (P less than 0.05) with a mean platelet size below normal range and to increased PA albumin levels but not to PRP count, platelet loss after assay procedure, the percentage of microthrombocytes and megathrombocytes, and nonspecific adherence of FITC anti-IgG.

Albumins↗
PubMed1987

Improved in vivo and in vitro viability of platelet concentrates stored for seven days in a platelet additive solution.

An additive solution has been developed for storage of platelet concentrates (PC) which sustains improved in vivo and in vitro viability after 7 d of storage in second generation oxygen permeable containers. This platelet additive solution is a protein-free physiologic salt solution fortified with citrate, bicarbonate and glucose. The in vivo quality of the PC was evaluated by autologous radiolabelling with Indium-111-oxine to measure recovery and survival by multiple hit analysis. The in vitro quality was evaluated by total ATP content, hypotonic shock response and extent of shape change with ADP. Ten paired studies were performed with PC from the same donor being stored for 7 d at 22 degrees C in both CPDA-1 plasma and the additive solution. Mean recoveries and survivals were found to be substantially higher with PC stored in the additive solution than with PC stored in CPDA-1 plasma (51.0 +/- 7.8% and 144.1 +/- 15.9 h versus 36.6 +/- 10.7% and 110.4 +/- 31.6 h). The differences were statistically significant (P less than 0.001). The results of the in vitro assays described above parallelled the in vivo results, with statistically significantly superior results (P less than 0.01) for all parameters of PC stored in the additive solution. This study is the first to show that PC quality may be improved and storage extended using an additive solution.

Adenine↗
PubMed1987

Platelet storage lesion in second-generation containers: correlation with platelet ATP levels.

The nature of platelet lesion occurring with storage of platelet concentrates (PC) in second-generation containers was investigated using various storage media and storage periods up to 14 days. In CPD-plasma (control medium), the changes which occurred progressively during storage were loss of discoid shape, microscopic platelet aggregate formation, fragmentation and the appearance of disintegrated, 'balloon' forms. By day 14 less than 10% of the platelets were discoid in shape, the platelet count had decreased by 23%, and there was a 5-fold increase in the amount of lactate dehydrogenase in plasma. Associated with this was a decrease in the platelet oxygen consumption rate, D(O2), loss of cellular ATP and extent of ADP-induced shape change, and a decrease in the hypotonic shock response. These parameters decreased at a similar rate, with a 50% decrease (t1/2) at days 7-9. They correlated highly with each other during storage and also with a fall in pH. At day 14 of storage, mean pH was 6.1 +/- 0.3. To evaluate the effect of pH stabilization during storage, 4 mEq sodium bicarbonate was added to PC in CPD-plasma. Although pH maintenance was much improved, 7.2-6.6 during 14 days of storage, the same in vitro lesions developed, although more slowly. The t1/2 of the same parameters was prolonged for approximately two days. When PC were stored in a plasma-free physiologic salt solution whose salt composition was similar to CPD-plasma, the t1/2 of the parameters increased to 11-15 days of storage, although the platelets eventually developed the same in vitro lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1986

Evaluation of hemoglobin screening methods in prospective blood donors.

This study evaluates the performance characteristics of the copper sulfate screening test in routine bloodmobile operations and compares the performance of the copper sulfate test with that of a miniphotometer method of hemoglobin measurement. The copper sulfate and miniphotometer tests provide equivalent pass/fail classification of male donors with a high sensitivity and total efficiency. For female donors, both test methods show substantially lower sensitivity and total efficiency than for male donors; however, the miniphotometer is significantly more sensitive than the copper sulfate test in identifying eligible female donors. The distribution of donor hemoglobin values relative to cutoff values for acceptance may explain the male-female differences in screening test performance characteristics.

Blood Donors↗