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Biomedical subjects

W A Heaton

Publications and source records attributed to W A Heaton.

48 records · Page 3Linked to original sources
PubMed1980

Detection of accessory spleens with indium 111-labeled autologous platelets.

In two patients with recurrent immune thrombocytopenia, accessory splenic tissue was demonstrated by radionuclide imaging following administration of indium 111-labeled autologous platelets. In one of these patients, no accessory splenic tissue was seen on images obtained with technetium 99m sulfur colloid. This new technique provides a simple means for demonstrating accessory spleens and simultaneously evaluating the life-span of autologous platelets.

Adult↗
PubMed1980

Scintigraphy with 111In-labeled autologous platelets in venous thromboembolism.

Scintigraphy with 111in-labeled autologous platelets was performed in 20 patients with suspected venous thrombosis and/or pulmonary embolism. The platelets accumulated in venous thrombi in 6 or 7 patients (86%) with positive findings on impedance plethysmography or contrast venography; all 6 were receiving intravenous heparin. In 11 patients with pulmonary embolism diagnosed by ventilation--perfusion imaging or pulmonary angiography, platelet scintigraphy showed embolic uptake only in the one patient not on full-dose heparin. These findings suggest that scintigraphy with 111In-platelets is a promising noninvasive technique for detection of deep venous thrombosis. Heparin does not appear to block localization of labeled platelets in venous thrombi, but may inhibit their adherence to pulmonary emboli.

Adult↗
PubMed1980

Scintigraphic detection of carotid atherosclerosis with indium-111-labeled autologous platelets.

Using autologous platelets labeled with indium-111-oxine, we studied the localization of platelets on arterial lesions by radionuclide scintigraphy in 34 patients with suspected cerebrovascular disease. The imaging results were compared with the findings of contrast angiography in 23 patients, 16 of whom were receiving antiplatelet and/or anticoagulant drugs during the platelet imaging study. Angiography demonstrated atherosclerotic lesions at 33 sites in the extracranial arteries of 16 of these patients. There was accumulation of 111In-platelets at 20 of these sites (61%) and at three other sites without definite angiographic abnormalities. Lesions with stenoses less than 50% were slightly more frequent than those with greater stenosis (68% vs 45%). The frequency of true-positive scintigraphic results was slightly higher in patients not treated with antithrombotic agents than in those on such drugs (70% vs 57%). Our results suggest that imaging with 111In-labeled autologous platelets may be useful for evaluating the pathophysiologic characteristics of atherosclerotic lesions in patients with cerebrovascular disease.

Adult↗
PubMed1979

Indium-III: a new radionuclide label for studying human platelet kinetics.

Indium-III. when complexed with 8-hydroxyquinoline (oxine), has been employed as a radioactive platelet label for thrombus imaging in animals and man. The short half-life (2.8 d) and high yield of gamma photons of 111In make it ideal for in vitro counting and external imaging. To evaluate its suitability for studies of platelet turnover in man, platelet kinetic studies were carried out on 10 healthy volunteers using 111In-and 51Cr-platelets concurrently. For 111In labelling, platelets were harvested by differential centrifugation from 43 ml of whole blood drawn into acid-citrate dextrose (ACD) solution. The platelets were washed and suspended in a mixture of ACD and isotonic saline and then incubated with 111In-oxine, rewashed, and suspended in plasma for reinfusion. 51Cr labelling was performed using standard methods. Mean labelling efficiency was 73% with 111In and 6.5% with 51Cr. In vitro studies demonstrated minimal release, elution, and reutilization of the 111In label. There was no significant difference in the aggregation response of 111In- and 51Cr-platelets to ADP and collagen. The in vivo recovery of 111In-platelets was approximately 50% greater than that of 51Cr-platelets whereas the platelet life spans were similar. These results indicate that 111In labelled platelets may be useful for thromobokinetic studies in man. The new method offers the advantages of reduced blood requirements, higher labelling efficiency, and the ability to perform external imaging of platelet distribution in vivo.

Adult↗
PubMed1978

Scintigraphic detection of atherosclerotic lesions and venous thrombi in man by indium-111-labelled autologous platelets.

Accumulation of autologous platelets labelled with indium-111 at sites of atherosclerosis or venous thrombosis was demonstrated by scintigraphy in three patients. The lesions detected were bilateral ulcerated carotid-artery plaques, iliofemoral venous thrombosis, and renal-vein thrombosis. This technique shows promose as a non-invasive means of diagnosing focal atherosclerotic and thrombotic lesions.

Arteriosclerosis↗
PubMedDate not supplied

Effects of prolonged room temperature holding of whole blood intended for preparation of components.

Current FDA regulations require that platelet concentrates must be prepared within four hours of whole blood collection. To determine if this time period was critical for the harvesting of viable platelets and other blood components, whole blood was held at room temperature for four, six or eight hours after which various components were prepared. Our results indicate that up to eight hours storage had no detrimental effect on platelet yield, recovery in vivo or lifespan. AHF activity, supernatant hemoglobin and red blood cell ATP were also unaffected.

Adenosine Triphosphate↗
PubMedDate not supplied

Recovery, lifespan, and function of CPD-Adenine (CPDA-1) platelet concentrates stored for up to 72 hours at 4 C.

We studied the in vivo recovery, lifespan, and hemostatic effectiveness of CPDA-1 platelet concentrates stored for up to 72 hours at 4 C. A total of 120 CPDA-1 concentrates containing an average (+/- 1 S.D.) of 6.6 +/- 2.0 x 10(10) platelets were prepared. The pH of the units following storage at 4 C was 6.8 +/- 0.2; no unit had a pH below 6.3. Autologous transfusion of six normal volunteers showed that platelets stored at 4 C for 72 hours had an in vivo recovery of 40 +/- 18 per cent and a lifespan of 5.1 +/- 1.5 days. The hemostatic effectiveness of CPDA-1 platelets was determined by platelet counts and template bleeding time measurements in 10 thrombocytopenic patients. Patients receiving 48-hour-stored platelets had a four- to six-hour posttranfusion corrected platelet increment averaging 15,300 +/- 3,200/microliter which was 67 +/- 34 per cent of expected recovery. Four of the five patients transfused with this preparation showed an improved bleeding time. In contrast, three patients receiving 72-hour-stored platelets had a four- to six-hour posttransfusion increment of 5,800 +/- 2,400/microliter that was only 26 +/- 13 per cent of the expected recovery; furthermore, only one of these patients showed any correction of the bleeding time. These data indicate that CPDA-1 platelets are hemostatically effective when stored at 4 C for up to 48 hours.

Adenine↗
PubMedDate not supplied

Rejection of prospective blood donors due to systematic errors in hematocrit measurement.

Following a change from earstick to fingerstick hemoglobin estimations, donor deferrals increased from 8.8% to 13.6%. Coincident with the change to fingersticks, hematocrit measurement with miniature centrifuges was begun as the reference method to verify donor rejection by the copper sulfate test. A study of 525 donors deferred for fingerstick hematocrits showed that 46.7% were deferred inappropriately as determined by venous hematocrit measurements. The difference between fingerstick and venous hematocrits persisted even after an intensive staff inservice on technique. In further studies, no significant difference was found between venous and fingerstick hematocrits measured on the same centrifuge, but there was a significant difference between measurements on the miniature centrifuges versus a standard laboratory microhematocrit centrifuge. This small error resulted in the loss of 3.8% of presenting donors during the study period. Hematocrit measurements have now been replaced by a fingerstick cyanmethemoglobin method.

Blood Donors↗
PubMedDate not supplied

Effect of an 8-hour holding period on in vivo and in vitro properties of red cells and factor VIII content of plasma after collection in a red cell additive system.

Extension of the holding time for whole blood units from 6 to 8 hours at ambient temperature should provide enhanced flexibility in the preparation of platelet concentrates (PCs). A paired study was conducted to evaluate the characteristics of stored red cells (RBCs) and plasma prepared from whole blood collected into a red cell additive system (CPD-ADSOL) after an extended holding time. An individual donated a unit of whole blood on two occasions; 1 unit was held for 6 hours before processing and the other for 8 hours. Autologous RBC 24-hour survival levels after 42 days of storage were comparable. Laboratory A, using a 99mTc-51Cr technique, found mean survival levels of 79 percent (6-hour hold) and 78 percent (8-hour hold) (n = 8). Analysis by the single-label procedure found the mean levels to be 82 and 81 percent. Laboratory B, using an albumin 125I-51Cr technique, found mean survival levels of 74 and 72 percent (n = 10). Mean hemolysis and ATP levels were found to be comparable after 42 days of storage following 6- and 8-hour holding periods. 2,3 DPG levels were reduced to a greater degree during the longer hold. The factor VIII levels in plasma frozen for at least a month after 6- and 8-hour holding periods were comparable; thawed plasma contained mean levels of 0.77 and 0.76 units per mL (n = 21). These studies indicate that components prepared by using a CPD-ADSOL system after holding periods of 6 and 8 hours have comparable properties.

Blood↗
PubMedDate not supplied

The quality of red blood cells.

The evolving practice of medicine has required a number of changes in red cell product manufacture to ensure that the final product is more specifically tailored to the needs of the individual patient. As a result of the increasing concern over the risks of transfusion pharmaceutical standards of manufacture are now applied to blood component preparation. Studies have been undertaken to define the optimum method of blood processing, and newer technologies are emerging to allow acquisition of a more consistent dose of red cells in a fashion which may minimize the lesion of collection. Use of high efficiency 3+ generation filter technologies reduces leukokine build up during storage and improves the quality and purity of the stored blood product. The combination of new plasticizers for packaging and improved red cell additive solutions should allow the blood center to supply a more functional red cell with longer storage shelf life. Overall these developments should result in the provision of a more consistent dose of fully functional red cells to the recipient who will be less exposed to the undesirable sequelae of transfusion than previously.

Blood Preservation↗