Biomedical subjects

S Holme

Publications and source records attributed to S Holme.

At least 19 recordsLinked to original sources

PubMed1992

Platelet microvesicles adhere to subendothelium and promote adhesion of platelets.

A role in hemostasis has been suggested for platelet membrane microvesicles (mv). The objectives of the studies reported here include functional analysis of platelet mv in models developed for study of platelet adhesion, as well as investigation of possible interactions between mv and intact platelets in these same adhesion models. Microvesicles were prepared from washed platelet concentrates by repeated freezing and thawing. Adhesion to subendothelium was measured quantitatively by radiolabelling mv with 111-In, and morphologically by scanning electron microscopy. Platelet mv adhered to subendothelium quantitatively over time. Using a modified Baumgartner chamber, we found adhesion of mv to subendothelium significantly increased with increasing shear rates. With this same model we found that prior exposure of subendothelium to mv greatly increased subsequent adhesion of platelets to the same everted vessel, compared to platelet adhesion in the absence of mv. All of these experiments were conducted with mv suspended in ACD/saline, indicating that plasma components are not essential for adhesion of mv. Our studies show that platelet mv adhere to subendothelium in much the same way as do platelets, and support the concept of a hemostatic role for mv in that they appear to increase platelet adhesion.

Animals↗

PubMed1992

[Bilateral epidural hematomas].

Bilateral epidural haematomata are rare and comprise only approximately 2% of all the intracranial haematomata. The symptomatology frequently differs from that of unilateral haematomata in that lateralisation is frequently absent. Most commonly, protracted or secondary development of clouding of consciousness is encountered. In cases of head injury, the above mentioned symptoms are indications for emergency computed tomographic (CT) scanning. When operation is performed early, the prognosis is good.

Adult↗

PubMed1992

Paired comparison of platelet concentrates prepared from platelet-rich plasma and buffy coats using a new technique with 111In and 51Cr.

Two techniques for the preparation of platelet concentrate (PC), the standard platelet-rich plasma (PRP) and buffy coat (BC) methods, were compared in nine paired studies with regard to platelet harvest, white cell (WBC) contamination, and PC quality after 5 days of 22 degrees C storage. Platelet harvest using the BC method averaged approximately 56 percent of the whole blood level (6.2 x 10(10)/concentrate), which was less than the 76 percent achieved with the PRP-PC method (8.7 x 10(10)/concentrate). An additional 5 units collected into an experimental siphon bag for BC-PC processing showed improved platelet harvest (6.7 x 10(10)/concentrate, or approx. 70% of whole blood). WBCs remaining in the BC-PC averaged 0.19 x 10(8) per unit compared to 3.6 x 10(8) per unit for PRP-PC. Buffy coat processing produced red cell (RBC) units with 50 percent of the WBC contamination of conventionally prepared units (9.8 +/- 6.2 x 10(8)/unit vs. 18.9 +/- 7.1 x 10(8)/unit). The siphon bag further reduced WBC levels in the AS-3 RBC units (6.4 +/- 3.7 x 10(8)/unit). In vitro studies performed on Days 1 and 5 after collection showed no significant differences in platelet metabolic and biologic function or cell integrity. Beta-thromboglobulin and surface glycoprotein levels, indicators of platelet activation and membrane alteration, respectively, did not differ significantly in the PRP-PC and BC-PC; nor was lactate production higher in PRP-PC, despite the substantially higher WBC counts. Autologous in vivo platelet viability determinations were performed by using concurrent transfusion of 111In-labeled freshly drawn platelets and 51Cr-labeled stored platelets.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelets↗

PubMed1992

In vitro and in vivo evaluation of cotton wool filtration of platelet concentrates obtained by automated and manual apheresis.

The effect of cotton wool filtration of apheresis platelet concentrates (PCs) on platelet viability and complement activation was evaluated by two laboratories. PCs were prepared by automated (Lab A, n = 5) or manual (Lab B, n = 5) apheresis. After storage for 1 day, the PC was filtered through cotton wool before transfusion on one occasion and, on the other occasion, filtered through a standard screen filter before transfusion to the same donor. Five paired studies were performed by each laboratory. Except for a small, but significant reduction in mean platelet size, from 7.3 +/- 1.1 to 6.6 +/- 0.9 microns 3, after cotton wool filtration, no effect of filtration on various tests of in vitro platelet function and morphologic integrity was found. As demonstrated by autologous radiolabeled studies, no effect of cotton wool filtration on platelet viability was found by Laboratory B, while Laboratory A found a slight increase in the percentage of recovery from 59 +/- 4 to 68 +/- 13 percent, and a small reduction in survival, from 8.2 +/- 0.9 to 7.7 +/- 0.5 days after cotton wool filtration (p less than 0.05). Cotton wool filtration was associated with a slight increase in C3a levels found in manual apheresis PCs. Neither laboratory found any effect of cotton wool filtration per se on the recipients' white cell (WBC) counts or C3a and C5a levels after transfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Post-transfusion recovery of function of 5-day stored platelet concentrates.

Platelets show a rapid reduction in their responsiveness to aggregating agents during storage for transfusion, but little is known about reversal of this defect in vivo after transfusion. In this study, fresh and stored platelets from the same donor (n = 12) were labelled with 111In or 51Cr, respectively, mixed, and simultaneously infused. Blood samples were taken for up to 5 d post-infusion, and the functional behaviour of the labelled platelets ex vivo was measured by retention on glass bead columns, and by whole blood aggregability to ADP, epinephrine and ristocetin. Aggregation was determined by filtering aggregated samples through a column of cotton wool to remove the aggregates, and quantitated as per cent decrease in radioactive counts. The study showed that, although infused radiolabelled 5 d stored platelets had a significantly lower aggregability towards ADP and epinephrine immediately (1 h) after infusion (32% and 29%, respectively, of fresh platelet values), a complete restoration to fresh platelet levels was found 24-72 h post-infusion, with no further change observed over the ensuing 5 d with either fresh or stored labelled platelets. A slightly (6-9%) lower adhesion to both uncoated and collagen-coated beads was found for the stored platelets throughout the 5 d period of study post-infusion. In conclusion, these studies show that, with ex vivo testing, platelets stored for 5 d quickly recovered adhesion and aggregability capabilities similar to that of fresh platelets, suggesting that the functional lesion developed during storage is quickly and completely reversed after infusion.

Adenosine Diphosphate↗

PubMed1992

Improved post-transfusion quality of density separated AS-3 red cells after extended storage.

A centrifugal method of red cell density separation was utilized for unit processing in these studies to determine the quality of the lighter fraction (neocytes) after storage for up to 42 d and to evaluate whether the heavier fraction (gerocytes) deteriorated more rapidly than neocytes during storage. Each unit was passed through a Leukotrap filter to remove white cells prior to density separation. Red cell recovery and survival were evaluated using double label technetium-99m with either chromium-51 or nonradioisotopic chromium which permitted concurrent paired analysis. In vivo neocyte red cell recovery, as tested on the same 11 donors on days 1, 7 and 42 of storage, was effectively unchanged. Recovery and survival half-life (that is, the number of days after transfusion at which half of the cells infused remain in the circulation) of 42 d stored gerocytes were significantly lower than similarly stored neocytes (75.5 +/- 7.2% and 20.1 +/- 6.5 d for gerocytes versus 84.4 +/- 4.9% and 39.0 +/- 9.0 d for neocytes). One-day stored neocytes showed a 16.5% increase in red cell availability over the combined average for 42 d stored neocytes and gerocytes. Statistically, while there were significantly higher ATP, 2,3-DPG, and lactate levels pre-storage by paired t-test for neocytes compared to gerocytes, by day 42 there were no significant differences detected between the two red cell fractions by any of the in vitro variables measured. These studies suggest that this simple separation technique for leucocyte-poor red cell units provides a neocyte population with improved viability and the potential for increased transfusion intervals in chronically transfused patients.

Blood Component Transfusion↗

PubMed1992

Effect of additive solutions on platelet biochemistry.

Use of a synthetic medium for resuspension and storage of platelets has several advantages. In addition to the opportunity to save plasma, the use of a synthetic medium offers better possibilities for obtaining platelet products by automatic component processing in a more cost-effective and convenient manner. A synthetic medium also has the potential to avoid transfusion reactions caused by noncompatible plasma proteins and to improve platelet quality, which will lessen the number of units needed in transfusion. Platelets produce a substantial amount of lactic acid by metabolism of glucose. Thus, risk of pH fall is a major problem which platelet additive solutions must address. Two approaches have been used: (1) use of a glucose-free medium, and (2) use of a glucose-containing medium with a buffer system to neutralize the production of lactic acid. Using various synthetic media described in the literature, studies described in this paper suggest that some glucose is needed in the final suspending medium in order to obtain satisfactory maintenance of platelet quality during 5 days of storage. With the presence of acetate in the additive solution, platelet respiration is increased and glycolysis substantially decreased; therefore, with 10-20% of CPD-plasma carryover, sufficient glucose may be present in the final suspending medium to last for 5 days of storage. In addition, phosphate in the additive solution markedly enhances platelet glycolysis, and inhibitors of platelet activation reduce platelet metabolic activity and improve platelet viability and function.

Acetates↗

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

Concepts about current conditions for the preparation and storage of platelets.

Substantial experimentation over the last 20 years has led to the conditions that are currently used to prepare and store platelets. Although platelet rich plasma is used in most instances to prepare platelet concentrates, there may be some benefit associated with the use of buffy coats as the source component. Extension of the maximum allowable storage time for platelets to 5 days has been possible as a result of defining the conditions which allow for the better retention of platelet properties. Storage temperature, permeability of the storage container, volume of platelet suspension, and the need to agitate platelets have been identified as key parameters that maintain platelet viability and functional properties. Storage in the 20 to 24 degrees C range prevents a reduction in posttransfusion viability that occurs when platelets are maintained at lower temperatures. Adequate influx of oxygen through container walls to support platelet metabolism and, to a lesser degree, adequate efflux of produced carbon dioxide are essential for maintaining pH levels, a key parameter that also influences posttransfusion viability. Permeability is influenced by container size and material, by use of a satisfactory volume of plasma and by agitating the container. Although platelet concentrates prepared from whole blood have been primarily used to delineate appropriate storage conditions, they also apply to platelets harvested by aphersis technology. Storage under currently used conditions, although providing products with acceptable clinical efficacy, is associated with a reduction in viability and functional characteristics. The development of storage media, specific for platelets, may minimize the occurrence of deleterious changes.

Anticoagulants↗

PubMed1991

Platelet storage in synthetic media lacking glucose and bicarbonate.

The goal of these studies was to develop a cost-effective medium for the storage at 22 +/- 2 degrees C of platelets for transfusion. Platelet concentrates were prepared from platelet-rich plasma in a standard fashion and resuspended in 55 mL of medium. Residual plasma was 14.4 +/- 4.3 percent of the final suspending solution. The use of a simple solution containing electrolytes and citrate, but no glucose or bicarbonate, was associated with a drop in pH to the range of 6.0 to 6.6, as a result of the production of lactic acid from the platelet glycogen and glucose present in residual plasma. When 25 mM (25 mmol/L) sodium phosphate was included as a buffer, the drop in pH was retarded, but the range throughout storage was still 6.5 to 6.8. Nonetheless, platelets stored for 5 days in this phosphate-containing medium showed satisfactory maintenance of many in vitro variables. However, there was a 10 to 35 percent reduction of in vivo recovery after isotopic labeling. There was no significant reduction in subsequent mean cell life. Because of the in vivo abnormalities, these media are not recommended for use at the present time. However, the results are encouraging and suggest that further research may lead to a satisfactory, cost-effective medium.

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

Storage of ADSOL-preserved red cells at 2.5 and 5.5 degrees C: comparable retention of in vitro properties.

Previous studies with CPDA-1 and Nutricel preserving solutions indicated that red cell properties were affected by small differences in storage temperature. The influence of a 3 degrees C differential on the preservation of the in vitro properties of ADSOL-preserved (AS-1) red blood cells was investigated in a paired study. AS-1 red blood cells were stored at 2.5 and 5.5 degrees C for 42 days. Extent of hemolysis, glucose consumption and pH levels were comparable at the two storage temperatures. Lactate levels were slightly, but significantly higher at 5.5 degrees C. ATP levels were slightly but significantly higher at 2.5 degrees C, only during the later part of the storage period. 2.3-DPG levels were slightly better retained at 2.5 degrees C after 7 days of storage. Holding units of whole blood for either 1 or 8 h at ambient temperature after phlebotomy prior to processing did not influence the types of temperature-dependent changes. The differences as a function of storage temperature were small and appear to be of no practical importance in connection with the storage of AS-1 red blood cells.

2,3-Diphosphoglycerate↗

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↗

PubMed1990

Platelet abnormalities in myeloproliferative disorders.

A large number of various platelet abnormalities are described in patients with MPD. These abnormalities serve diagnostic purposes only. They appear to have little or no predictive value regarding the clinical manifestations of the patients or the progress of the disease. Those platelet characteristics most consistently reported to be defective include a decrease in the platelet content of serotonin and adenine nucleotides, decreased platelet density, an abnormal ultrastructure characterized by paucity of granules and hypertrophy of the surface connecting canicular system, an altered membrane glycoprotein profile that includes reduced levels of GPIb, and reduced lipoxygenase activity and aggregation response with epinephrine. These abnormalities may originate at the megakaryocyte level. Furthermore, the released abnormal platelets may undergo modification of their functional and biochemical characteristics as a result of episodes of intravascular thrombosis or aging in circulation or as a result of the progression and treatment of the disease, thus creating the paradoxic and often conflicting relationship between the thrombotic and hemorrhagic events and the results of platelet functional tests as observed in this disorder.

Blood Platelets↗

PubMed1989

Evaluation of a new, more oxygen-permeable, polyvinylchloride container.

A new container made of polyvinylchloride (PVC) with diethylhexyl phthalate (DEHP) used as the plasticizer was subjected to in vitro and in vivo evaluation for prolonged platelet storage. As compared with the original PVC bag, this bag has increased gas permeability by its reduced film thickness, larger surface area (400 ml capacity), and more porous label. The oxygen permeability coefficient, K(O2), of the new container was measured to be 655 nmol per min per atm. On the basis of previous studies relating the K(O2) to the maximal platelet count, it was predicted that this maximal count would be in the range of 7.9 to 8.9 X 10(10) platelets. This prediction was confirmed by carrying out 58 studies measuring pH, pO2, and platelet count on platelet concentrates (PCs) stored for up to 7 days. After 5 days of storage all PCs with counts above 8.0 x 10(10) had pH less than or equal to 7.0, whereas those with counts below 8.0 x 10(10) had pH greater than or equal to 7.0. Six units (10%) with counts above 9.0 X 10(10) had pH levels of 6.5 or below. Thirteen of the PCs underwent extensive in vitro testing of platelet function during 7 days of storage. No significant differences were found in pH, ATP content, and decrease in platelet count, as compared with studies (n = 22) using PCs stored in polyolefin containers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Properties of platelet concentrates prepared after extended whole blood holding time.

Extension of the maximum holding time for whole blood collected into a CPD-ADSOL system from 6 to 8 hours at ambient temperature under conditions that cause the temperature of the blood to decrease to 20 to 24 degrees C would facilitate the preparation of platelet concentrates (PCs). In this study, the properties of CPD-PCs prepared and stored for 5 days in PL-732 containers after various initial holding periods were assessed in two laboratories, designated Laboratory A and Laboratory B. Laboratory A found higher platelet-rich plasma (PRP) volumes (276 +/- 25 vs. 249 +/- 19 mL) and platelet yields (76 +/- 18 vs. 66 +/- 18 x 10(9) platelets) with 8-hour holds (n = 10) than with 1- to 2-hour holds (n = 10), although only the difference in PRP volumes was significant (p less than 0.05). No significant difference was observed in autologous in vivo recovery (54 +/- 11 vs. 47 +/- 9%) or survival (167 +/- 37 vs. 170 +/- 25 hrs), as calculated by gamma function using 111In as radiolabel. Laboratory B also found higher PRP volumes (304 +/- 31 vs. 279 +/- 37 mL) and platelet yields with 8-hour holds (n = 12) than with a 6-hour holds (n = 10) (88 +/- 26 vs. 77 +/- 27 x 10(9) platelets). No significant differences were found in morphology score, the extent of release of beta-thromboglobulin, the discharge of lactate dehydrogenase, or hypotonic shock response.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

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↗