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N McCombie

Publications and source records attributed to N McCombie.

15 recordsLinked to original sources
PubMed1998

Prevention of cytokine accumulation in platelets obtained with the COBE spectra apheresis system.

BACKGROUND AND OBJECTIVES: Febrile nonhemolytic transfusion reactions frequently accompany platelet transfusions and may be due to accumulation of cytokines mediating inflammation during storage of platelet concentrates (PCs). We wished to determine whether PCs collected using the COBE(R) SpectraTM Apheresis System (Version 4) were sufficiently leukocyte reduced (LR) to limit cytokine accumulation during storage. MATERIALS AND METHODS: Cytokine accumulation - interleukin (IL)-1beta, IL-6, IL-8, tumor necrosis factor-alpha (TNF-alpha) - and release of platelet alpha-granule - P-selectin, transforming growth factor-beta1 (TGF-beta1), platelet-derived growth factor AB (PDGF-AB), von Willebrand factor (vWf) - or dense granule (serotonin) markers were investigated during a 7-day storage period comparing apheresis-collected, LR PCs (LR PCs) and random donor platelets prepared from whole blood (WB). RESULTS: Leukocyte counts were reduced 99.95% comparing LR PCs (5.7 x 10(5)/l) and WB PCs (1.09 x 10(9)/l). Little or no accumulation of leukocyte-derived cytokines was observed in LR PCs during storage in contrast to WB PCs. A reduction in the release of platelet alpha-granule proteins, such as P-selectin, TGF-beta1 and PDGF-AB, was observed on day 0 for LR PCs compared to WB PCs with little or no difference observed from day 3 to 7. Plasma vWf levels were higher in LR PCs compared to WB PCs on days 0-7. CONCLUSION: Leukocyte levels in PCs collected with the COBE Spectra Apheresis System are sufficiently low to limit cytokine production during 7 days of storage.

Blood Preservation↗
PubMed1989

Formation of a cryogel during processing of cell-free plasma.

Automated plasmapheresis devices are being integrated into many modern plasma procurement programs. Owing to the use of a different concentration and type of anticoagulant, the recovered plasma differs in pH and citrate levels from that obtained by manual plasmapheresis or whole blood donation. Recently, fractionators noted the recovery of a sticky, gelatinous fraction (cryogel) during thawing of cell-free (CF) plasma, along with reduced recovery of factor VIII:C (FVIII:C) in the cryoprecipitate fraction. Following their manufacturing procedures, it was established that the cryogel fraction of CF plasma is enriched in FVIII:C, fibrinogen, and fibronectin, as compared to cryoprecipitate from CPDA-1 plasma. Cryogel formation was not significantly affected by pH or citrate adjustment of the recovered plasma, by the use of polycarbonate or nylon filter membranes, or by the filter wetting agent polyvinylpyrrolidone (PVP). Furthermore, passage of CPDA-1 plasma through the polycarbonate filter did not alter cryoprecipitate quality. However, cryogel formation from CF plasma was reduced significantly by 1) slow thawing at 4 degrees C rather than quick thawing at 20 and 0 or 20 and 4 degrees C, 2) the use of 1:16.6 sodium citrate rather than 1:12.5 ACD-A, or 3) the addition of intact platelets, platelet lysate, membranes, or cytosol to CF plasma before freezing. The data suggest an important and, indeed, essential role of platelet constituents in the formation of both cryoprecipitate and cryogel during the low-temperature purification of plasma proteins.

Blood Platelets↗
PubMed1989

5-day storage of single-donor platelets obtained using a blood cell separator.

Platelets were collected from normal donors via a blood cell separator (Fenwal CS-3000). Platelets were stored initially in two separate 1000-ml bags (average count per bag, 2.3 +/- 0.5 x 10(11)) in 100 ml of autologous plasma for 5 days. Little change in platelet count was noted after 5 days of storage; however, the white cell count fell from 5.1 +/- 1.7 x 10(9) at Time 0 to 3.4 +/- 2.3 x 10(9) per l at Day five. The initial lactate values were 32 +/- 11 mg per dl and rose to 165 +/- 28 mg per/dl by 5 days. Platelet aggregation was impaired both by the collection procedure and during storage: whereas the response to ADP of the donors' platelets before the procedure was 100 percent, samples taken from the product immediately after collection had only a 45 percent response, which fell to 12 percent by Day 5. Aggregation using epinephrine was similarly affected, with a 75 percent response after collection and 0 percent response by Day 5. The plasma beta-thromboglobulin (beta-TG) level was high, both after collection (5.0 micrograms/ml at Time 0) and after storage (11.0 micrograms/ml), indicating a considerable effect of collection on platelet alpha granule release. In vivo recovery of these platelets was very good at 67 +/- 6 percent, with an average survival of 7.3 +/- 1.4 days (multiple hit; n = 4).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Component Removal↗
PubMed1988

An antibody to platelet membrane antigen associated with thrombotic events in essential thrombocythemia.

A 71-year-old man with essential thrombocythemia presented with acute onset of thrombosis in his fingers. The platelet count at presentation was 752 x 10(9)/liter, and his PTT was within the normal range. Platelet aggregation was normal in response to ADP, decreased to epinephrine, and absent to collagen, with the patient receiving 1.2 g aspirin/day. Plasma vWF:Ag was 158 U/dl, VIII:C was 150 U/dl, and the vWF:Ag multimer pattern was normal. HLA antibodies were not detected in his serum, and the platelet-associated IgG was normal at 3.9 fg/platelet. Incubation of normal, unactivated platelets with the patient's plasma did not result in agglutination of the platelets. However, a serum antibody reacting against a platelet antigen with an apparent molecular weight of 45,000 could be demonstrated by Western blotting. This antibody also reacted with endothelial cells. The reactive pattern was similar to that of commercially obtained actin; the serum antibody could be removed by preincubation with actin. Platelet-plasmapheresis was carried out daily for 10 days, after which the serum still reacted weakly with the platelet antigen. By day 20, the band could still be identified on the electroblot, but 2 weeks later no band could be seen. Similar assay of sera from six other patients with myeloproliferative disorders and comparable thrombocytosis but without thrombotic manifestations did not show any such reactions. The data suggest a correlation between the presence of an antibody possibly directed against platelet and/or endothelial cell actin and the vascular events in this patient with essential thrombocythemia.

Aged↗
PubMed1988

Logistics of automated plasma collection.

Plasmapheresis is widely carried out to produce plasma for fractionation. Production of Factor VIII and albumin, two proteins in plasma, drives the plasma industry. The Canadian Red Cross would like to achieve national self-sufficiency in plasma production to meet the rising demands for these proteins in the next 4 years. In order to achieve this goal we must make efficient use of our automated plasmapheresis machines and available human resources to produce a cost-effective plasma product. An assessment was undertaken at the Ottawa Centre to evaluate the number of procedures which could be performed on each machine per day and the staff required to operate these machines safely and efficiently. Donor availability, reliability and reasons for donating plasma were recorded to determine if our population could support such an escalated programme. Donor/staff interest and acceptance of automated equipment was determined. The results showed that four automated plasmapheresis devices could be operated by one nurse and one clinic assistant processing 32 donors a day with an average time of 27 min required for a 500-ml donation of plasma. The donor population was available and extremely interested; however, the logistics of scheduling proved to be an area for concern requiring special attention.

Autoanalysis↗
PubMed1987

Registry of unrelated bone marrow donors.

Reports of successful transplantation of bone marrow obtained from unrelated donors who were histocompatibility leukocyte antigen (HLA) identical prompted the Canadian Red Cross Blood Transfusion Service in Ottawa to assess the possibility of developing a bone marrow donor registry in Canada. We sent a pamphlet that explained the program to 1568 people who had undergone apheresis and asked them to reply, stating their interest. At the same time the pamphlets and a poster were placed in the blood donor clinic. We received 1232 replies (78.6%) from the apheresis donors, 838 (68.0%) of which indicated a willingness to attend information sessions. Of the 7158 people who gave blood during the 3-month study period, 225 (3.1%) were interested. At the time this paper was written 47 information sessions had been held, and 721 people had attended, 624 (86.5%) of whom had signed a consent form. This indicates a clear interest in a bone marrow donation program. We believe that the ethical issues are overcome by requesting the donation before identification of any patient. From our experience a national registry of unrelated donors seems feasible, and steps are being taken to implement such a program.

Blood Component Removal↗
PubMed1985

Alternate dosage regimens for high molecular weight hydroxyethyl starch.

Six percent high molecular weight hydroxyethyl starch (HES) was used in the standard 500 ml dose and in various decreased doses to assess the efficacy of alternate dosage regimens for granulocyte procurement. When used in full strength, yields of 0.57 +/- .15 X 10(10) per liter of blood processed (LBP) were obtained. When HES was used on only the first three passes, the subsequent three passes, done with Anticoagulant Citrate Dextrose Solution USP Formula A (ACD-A); Fenwal Laboratories, Deerfield, IL), reduced the yield to 0.14 +/- .06 X 10(10)/LBP. Reversing this procedure gave yields of 0.06 +/- .05 X 10(10)/LBP (without HES) and 0.49 +/- 0.36 X 10(10)/LBP when HES was added during the next three passes. When the HES dose was reduced to half-strength on the second consecutive day of leukapheresis, the granulocyte yields were reduced from 0.57 +/- .15 X 10(10)/LBP to 0.42 +/- .07 X 10(10)/LBP. Use of half-strength HES on virgin donors gave yields of only 0.35 +/- .39 X 10(10)/LBP. Infusion of the entire 500 ml dose of HES 1/2 hour prior to the procedure produced low yields of 0.20 +/- .12 X 10(10)/LBP, indicating that HES must be present during the centrifugation and separation procedure in order to enhance yields. The data suggest that alternate dosage regimens of this form of HES are not advisable and that optimal yields are produced when 500 ml of the six percent solution is used during the collection procedure.

Granulocytes↗
PubMed1985

Comparative function of centrifugal apheresis devices.

The function of four apheresis devices has been evaluated to obtain comparative data on performance and safety. Granulocyte yields were highest with the CS-3000 with 1.7 X 10(10) cells, but this preparation also contained 4.5 X 10(11) platelets; plateletpheresis gave ranges of 3.4 X 10(11) to 4.5 X 10(11) cells. The amount of blood processed to obtain these yields varied greatly, ranging from 2.4 to 7 liters. Studies done on the donor return line showed no significant effects of the process. Comparative results on the efficacy of plasma exchange showed relatively little red cell contamination with any of these devices, but significant (6.9 X 10(10) platelet removal in the Fenwal bag.

Cell Separation↗
PubMedDate not supplied

A new technique for the collection of plasma: machine plasmapheresis.

The Haemonetics Model 50 permits the collection of 500 ml of plasma within an average of 30 minutes, and the donor is never disconnected from his cells. In a detailed assessment of 28 donors, we found no detrimental effect of the procedure. There was no evidence of fibrin split products or complement activation. The plasma showed good recovery of protein with slightly elevated factor VIII levels; citrate levels are only two-thirds of manual plasmapheresis values. While there was a relatively large number of platelets collected into this plasma, the platelets were small, with a mean diameter of 1.8 mu and poor response to aggregation. Therefore it would appear that this plasma should not be used to make a platelet preparation. Nonetheless, evaluation of this machine indicated that the performance parameters are acceptable and that donor acceptance is exceptional, with widespread enthusiasm for this "new" method of blood donation.

Blood Donors↗
PubMedDate not supplied

Plasma exchange in the treatment of hemolytic disease of the newborn.

Plasma exchange has become a widely used therapeutic tool in the treatment of immune-mediated disease. This technique has been applied to the treatment of gravid women whose high antibody titers and past history of stillbirths indicate a significant possibility of fetal loss due to HDN. The procedure was effective in decreasing both antibody titer and the quantity of antibody in four of five patients. In one other case, the antibody titer rose toward the end of the pregnancy; however, the quantity of anti-D remained low. The IgG:IgM ratio and the subclass specificity of IgG did not significantly change with treatment. Hematologic monitoring also indicated no adverse effects, and three of the five women delivered viable fetuses. Two of the other women produced infants only moderately affected by HDN but stillborn within days of intrauterine transfusion. The results indicate that plasma exchange is a useful therapeutic consideration in the sensitized gravid women.

Amniocentesis↗
PubMedDate not supplied

Automated platelet production during plasmapheresis.

Manual plasmapheresis is widely used to permit collection of fresh-frozen plasma with return of the red cells to the donor. However, this method is time-consuming and carries the inherent risk of returning the wrong cells to any individual donor. Automated plasmapheresis, using a specially designed discontinuous cell separator, permits the collection of 500 ml of plasma within 30 minutes without disconnecting the donor from the bag containing the donor's red cells. However, this plasma contains a small number of platelets which are not suitable for transfusion. We now report the modification of this machine to permit simultaneous collection of 3 units of platelet concentrate as well as 500 ml of plasma in less than 50 minutes. Reduction of the g force of the separator from 1200 to 650 g permits the simultaneous collection of plasma and a platelet concentrate with an average yield of 2.21 X 10(11) platelets. Platelet size distribution, in-vitro function. 51Cr survival, posttransfusion increment, and bleeding time correction are all normal. This modification has increased the flexibility of the separator and provides an instrument which can be used with a random volunteer blood donor population to generate both plasma and cells in less than 50 minutes and with increased cost-effectiveness over plasmapheresis alone.

Automation↗
PubMedDate not supplied

Alternate dosage regimens for high-molecular-weight hydroxyethyl starch.

Six percent high-molecular-weight hydroxyethyl starch (HES) was used in the standard 500-ml dose and in various decreased doses to assess the efficacy of alternate dosage regimens for granulocyte procurement. When used in full strength, yields of 0.57 +/- 0.15 X 10(10) per 1 of blood processed (LBP) were obtained. When HES was used in only the first three passes, the subsequent three passes, done with acid-citrate-dextrose, Formula-A (ACD-A, Fenwal Laboratories, Deerfield, IL), reduced the yield to 0.14 +/- 0.06 (mean +/- SD) X 10(10) per LBP. Reversing this procedure gave yields of 0.06 +/- 0.05 X 10(10) per LBP (without HES) and 0.49 +/- 0.36 X 10(10) per LBP when HES was added during the next three passes. When the HES dose was reduced to one-half strength on the second consecutive day of leukacytapheresis, the granulocyte yields were reduced from 0.57 +/- 0.15 X 10(10) per LBP to 0.42 +/- 0.07 X 10(10) per LBP. Use of one-half strength HES on first-time donors gave yields of only 0.35 +/- 0.39 X 10(10) per LBP. Infusion of the entire 500-ml dose of HES one-half hour prior to the procedure produced low yields of 0.20 +/- 0.12 X 10(10) per LBP, indicating that HES must be present during the centrifugation and separation procedure in order to enhance yields. These data suggest that alternate dosage regimens of this form of HES are not advisable and that optimal yields are produced when 500 ml of the 6 percent solution is used during the collection procedure.

Blood Specimen Collection↗
PubMedDate not supplied

Plasma collection using an automated membrane device.

A plasmapheresis device with both membrane filtration and centrifugation features was tested. The device permits the collection of 500 ml of plasma within 30 minutes; when run at a 1:12.5 ratio with acid-citrate-dextrose (ACD-A) the resultant plasma factor VIII levels were 1.05 units per ml and the albumin was 41 g per l. Free hemoglobin was not detected, and there was no evidence of fibrinopeptide A, prekallikrein, or activation of complement. The plasma had a zero hematocrit value and contained few platelets and white cells. Before and after the procedure, donors and aliquots from the return line did not show any significant effect on cell count or function. This device functioned well to collect plasma for infusion or fractionation and was accepted well by donors. A major advantage is the relatively low cost for the software package ($15.00, US, 1985), which should make plasmapheresis with this device economically feasible.

Automation↗