[show abstract][hide abstract] ABSTRACT: Platelets during storage undergo diverse alterations collectively known as the platelet storage lesion, including metabolic, morphological, functional and structural changes. Some changes correlate with activation of p38 mitogen activated protein kinase (p38 MAPK). Another MAPK, extracellular signal-related kinase (ERK), is involved in PLT activation. The aim of this study was to compare the properties of platelets stored in plasma in the presence or absence of p38 and ERK MAPK inhibitors.
A single Trima apheresis platelet unit (n = 12) was aliquoted into five CLX storage bags. Two aliquots were continuously agitated with or without MAPK inhibitors. Two aliquots were subjected to 48 hours of interruption of agitation with or without MAPK inhibitors. One aliquot contained the same amount of solvent vehicle used to deliver the inhibitor. Platelets were stored at 20-24°C for 7 days and sampled on Days 1, 4, and 7 for 18 in vitro parameters.
Inhibition of p38 MAPK by VX-702 leads to better maintenance of all platelet in vitro storage parameters including platelet mitochondrial function. Accelerated by interruption of agitation, the platelet storage lesion of units stored with VX-702 was diminished to that of platelets stored with continuous agitation. Inhibition of ERK MAPK did not ameliorate decrements in any in vitro platelet properties.
Signaling through p38 MAPK, but not ERK, is associated with platelet deterioration during storage.
PLoS ONE 01/2013; 8(8):e70732. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: BACKGROUND: Platelet (PLT) aliquots for pediatric use have been shown to retain in vitro properties when stored in gas-impermeable syringes for up to 6 hours. As an alternative, PLT aliquots can be stored for longer periods in containers used for storage of whole blood-derived PLTs. These containers are not available separate from whole blood collection sets and PLT volumes less than 35 mL either have not been evaluated or may be unsuitable for PLT storage. Gas-permeable fluoroethylene propylene (FEP) containers have been used in the storage of cell therapy preparations and are available in multiple sizes as single containers but have not been evaluated for PLT storage. STUDY DESIGN AND METHODS: A single apheresis unit was divided on Day 3 into small aliquots with volume ranging from 20 to 60 mL, transferred using a sterile connection device, and stored for an additional 2 days either in CLX (control) or in FEP containers. PLT storage properties of PLTs stored in FEP containers were compared to those stored in CLX containers. Standard PLT in vitro assays were performed (n = 6). RESULTS: PLT storage properties were either similar to those of CLX containers or differed by less than 20% excepting carbon dioxide levels, which varied less than 60%. CONCLUSION: Pediatric PLT aliquots of 20, 30, and 60 mL transferred on Day 3 into FEP cell culture containers adequately maintain PLT properties for an additional 2 days of storage.
[show abstract][hide abstract] ABSTRACT: Whole blood-derived platelets (PLTs) prepared by the PLT-rich plasma method are subjected to a recommended 1-hour rest period after the second centrifugation to avoid excessive PLT activation. Different apheresis PLT preparation methods demonstrate different levels of PLT activation and ability to form macroscopic aggregates immediately after collection. PLT collections are lost on Day 1 of storage if aggregates are not dispersed. It is possible that a rest period may help to disperse PLT aggregates. It is not established whether apheresis PLTs require a rest period before agitation and what the length of this period should be.
Apheresis PLTs (Amicus, Fenwal, Inc.) were divided into five identical aliquots. One aliquot was placed on the flatbed agitator immediately after division. The other aliquots were subjected to agitation after 1, 2, 4, and 6 hours of rest. Samples were taken on Days 1, 5, and 7 for standard PLT assays.
No differences during 7-day storage were observed in PLT content, mean PLT volume, pH levels, bicarbonate, glucose, lactate, oxygen and carbon dioxide levels, hypotonic shock response, aggregation, and activation markers in PLT aliquots subjected to different rest periods or without a rest period. In contrast, values of extent of shape change, percentage of discoid PLTs, and expression of GP1b-α were greater in aliquots subjected to different periods of rest compared to those of PLTs without a rest period.
A rest period from 1 to 6 hours may improve some but not all in vitro PLT storage parameters.
[show abstract][hide abstract] ABSTRACT: A comparative study evaluated the retention of apheresis platelet (A-PLT) in vitro properties prepared with PLT additive solution (PAS)-III or 100% plasma and stored with continuous agitation (CA) and without continuous agitation (WCA).
PLTs collected with the Amicus cell separator (Fenwal, Inc.) were utilized to prepare two matched components, each with approximately 4 × 10(11) PLTs. In the primary study, one component contained 65% PAS-III/35% plasma and the other 100% plasma. Four storage scenarios were used, one with CA and three with periods without agitation under simulated shipping conditions. In vitro assays were used early and after 5 days of storage.
pH levels after 5 days with CA were less with PAS-III components than 100% plasma components, with levels always above 6.6 in any component. With CA, a number of other variables were reduced even early during storage with PAS-III including morphology, extent of shape change, hypotonic stress response, adhesion, and aggregation. Storage WCA resulted in only a limited increase in the magnitude of the assay differences between PAS-III and 100% plasma components. Periods WCA did not reduce the pH below 6.6. The thromboelastograph variable associated with the strengthening of clots by PLTs was essentially comparable with PAS-III and plasma components throughout storage with CA or WCA.
The data indicate that a 100% plasma medium provides for better retention of specific in vitro PLT properties, with CA and WCA, although the clinical significance of these in vitro decrements due to PAS-III is unknown.
[show abstract][hide abstract] ABSTRACT: Platelet additive solutions (PASs) facilitate improved recovery of plasma and may reduce the severity and/or frequency of plasma-associated transfusion reactions. Current apheresis platelet (PLT) PAS products contain approximately 30 to 40% residual plasma. In an effort to further decrease the residual plasma, two in vitro studies were conducted with PLTs suspended in 5% plasma and a reformulated PAS-3, named PAS-5, that contains additional salts, glucose, and bicarbonate.
In Study 1, PLTs suspended in 5% plasma/95% PAS-5 were prepared directly on a separator (Amicus, Fenwal, Inc.) without additional centrifugation or washing. In Study 2, a double unit of hyperconcentrated Amicus PLTs in plasma was collected, divided, and centrifuged to prepare a control unit in 100% plasma and a paired test unit in 5% plasma/95% PAS-5. The in vitro properties of PLTs were assessed in both studies during 7-day storage at 20 to 24°C with continuous agitation.
In Study 1, PLT concentration, pH, mean PLT volume (MPV), HCO(3)(-), pCO(2), pO(2), lactate dehydrogenase, and hypotonic shock response (HSR) did not significantly change during storage. By Day 7, glucose levels and morphology scores modestly decreased (17.6 and 14.4%, respectively) and lactate levels modestly increased (to 7.2 mmol/L). In Study 2, MPV, pH, glucose, pO(2), HSR, and morphology were comparable in control and test PLTs during 7-day storage. Glucose consumption and lactate production were significantly less in test versus control PLTs (p≤0.0015). Extent of shape change and %CD62P-positive test PLTs were less than those of controls (p<0.001).
Apheresis PLTs suspended in 5% plasma/95% PAS-5 maintained in vitro properties during 7-day storage.
[show abstract][hide abstract] ABSTRACT: The gas permeability of platelet (PLT) storage bags influences the retention of in vitro PLT parameters during storage. The aim of this study was to evaluate mitochondrial function of PLTs stored in first- and second-generation bags with different gas permeabilities.
Identical whole blood-derived PLT concentrates were stored in second-generation CLX (Pall Corp.) and first-generation PL146 (Baxter Healthcare Corp.) bags (n = 12). PLTs were assayed for standard in vitro PLT assays as well as for mitochondrial membrane potential (MMP), accumulation of reactive oxygen species, Annexin V binding, mitochondrial mass, and activity of mitochondrial reduction power on Days 1, 4, 5, 6, and 7. Results were analyzed by paired t test and by multiple regression analysis.
With PLTs stored in PL146 bags that underwent large pH declines, there was greater superoxide production, greater peroxide accumulation, and greater mitochondrial membrane depolarization. Superoxide anion generation was correlated with higher levels of carbon dioxide (p = 0.0001) and lower oxygen levels (p = 0.0064; multiple regression R(2) = 0.9204). Changes in MMP were correlated with higher levels of carbon dioxide (p = 0.0288) and PLT activation (p = 0.0178; multiple regression R(2) = 0.9511).
Prolonged periods of elevated carbon dioxide levels, potentially coupled with other factors, is associated with PLT mitochondria dysfunction and poor pH control during storage.
[show abstract][hide abstract] ABSTRACT: We have previously conducted studies investigating maintenance of apheresis platelet in vitro quality measures during storage under simulated shipping conditions in which agitation was interrupted. This study examines the effect of increasing bag surface area on the preservation of in vitro platelet properties during storage with continuous agitation and with a 30 h interruption of agitation. Apheresis platelets were collected in 100% plasma with the Amicus separator to provide two identical platelet products, each with approximately 4-5 x 10(11) platelets. After collection, the volume was divided equally between 1.0 and 1.3 L PL2410 containers. In an initial study, both products were continuously agitated. In a second study, both products were subjected to a single 30-h period of interrupted agitation between Days 2 and 3 of storage by placement in a standard shipping box at room temperature. In each study, units were assayed during storage for standard in vitro platelet quality measures. Platelets stored in the 1.3 L container maintained slightly greater mean pH during 7 day storage with either continuous agitation (n=6) or with a 30-h interruption of agitation (n=12) than those of similarly treated identical platelets stored in the 1.0 L container. Most noteworthy, in experiments with products stored in the 1.0 L container in which there was a large decrease in pH to levels <6.7 or <6.3 on days 5 or 7, respectively, the pH in the matched product stored in the 1.3 L container was substantially greater (0.17+/-06 and 0.37+/-0.09 pH units greater, n=4, respectively). Other measures showed either small differences or comparability of platelet in vitro parameters with storage in the two containers after an interruption of agitation.
Transfusion and Apheresis Science 08/2010; 43(1):9-15. · 1.23 Impact Factor
[show abstract][hide abstract] ABSTRACT: Commercially available additive solutions (ASs) require 30% to 35% plasma for optimal storage of platelets (PLTs). PLTs suspended in M-sol, a bicarbonate-based experimental platelet additive solution (PAS), maintain in vitro PLT properties during storage with low levels of plasma (< or =5%).
Four different formulations of M-sol were prepared at the optimal pH (6.1): M-sol, M-sol without calcium, M-sol without citric acid, and M-sol without calcium and citric acid. Apheresis PLT units (100% plasma) were equally divided into five 50-mL aliquots in PL732 containers, centrifuged, and resuspended to prepare units suspended in the four different PASs (95%) with 5% plasma and 1 unit in 100% plasma. Units (n = 10) were stored under standard conditions and assayed for in vitro properties on Days 1, 5, and 7. The data were analyzed by analysis of variance for repeated measures (n = 10, p < 0.001).
On Day 5 of storage, PLTs suspended in the M-sol formulation containing calcium but lacking citric acid had similar pH, extent of shape change (ESC) values, and percentage of CD62-positive PLTs and greater hypotonic shock response (HSR) and percentage of discoid PLTs compared to those of PLTs suspended in 100% plasma. In contrast, PLTs suspended in the M-sol formulation lacking calcium had lesser ESC values, greater percentage of CD62-positive PLTs, and similar HSR values and percentage of discoid PLTs compared to those of PLTs suspended in 100% plasma on Day 5 (p < 0.001).
Calcium plays an important role in maintaining CD62-negative PLTs and relatively high ESC in 5% plasma. The removal of citric acid from M-sol may improve PLT storage properties with low plasma levels.
[show abstract][hide abstract] ABSTRACT: Prolonged periods without agitation produce platelet (PLT) storage lesions that result in reduced in vitro assay parameters and an increase of apoptotic markers during storage. The aim of this study was to evaluate the influence of periods without agitation on PLT mitochondrial function, blood gases, and activation.
Apheresis PLT units (n = 12) were collected using a cell separator and each was equally divided among five storage bags (50 mL of PLT suspension in 300-mL nominal volume containers). Four bags were held without agitation for 24, 48, 72, and 96 hours in a standard shipping box at room temperature and the fifth bag was continuously agitated. PLTs were assayed for standard in vitro PLT assays as well as for mitochondrial membrane potential (MMP), accumulation of reactive oxygen species, Annexin V binding, mitochondrial mass, and activity of mitochondrial reduction power (MRP) immediately after removal of units from the shipping container on Days 1, 2, 3, 4, and 7.
Increasing periods without agitation resulted in increased superoxide anion generation and PLT activation as well as reduced PLT MMP and MRP. Increasing periods without agitation resulted in increasing Annexin V binding. PLTs that had undergone periods without agitation showed increased oxygen and carbon dioxide levels immediately after storage without agitation. The superoxide anion generation was highly correlated with the loss of MMP, increasing Annexin V binding, and pH decline.
PLTs, if stored without agitation, produce a lesion that leads PLTs to apoptosis. The severity of the lesion depends on the length of the period without agitation. Prolonged periods without agitation induce formation of superoxides and depolarization of MMP along with a presentation of apoptotic markers.
[show abstract][hide abstract] ABSTRACT: Amotosalen, a psoralen, has been utilized for photochemical treatment (PCT) of apheresis platelets (PLTs) and pooled buffy coat PLTs suspended in additive solution. In the United States, the source of many PLT transfusions is from whole blood-derived PLTs prepared by the PLT-rich plasma (PRP) method. This study investigated the in vitro PLT properties of amotosalen-PCT of leukoreduced pools of PLTs prepared by the PRP method and suspended in 100 percent plasma.
On Day 1 of storage, 12 leukoreduced (n = 6) or 10 leukoreplete (n = 6) ABO-identical PLT concentrates were pooled, separated into two pools of 6 or 5 units, respectively, and leukoreduced (leukoreplete pools only). Each pool of 5 or 6 units was then photochemically treated (designated "test": amotosalen plus 3.0 J/cm(2) long-wavelength ultraviolet light followed by amotosalen/photoproduct removal) while the remaining identical pool (designated "control") was untreated. PLT in vitro assays were performed on test and control pools during 7-day storage.
PCT resulted in slightly reduced pH in test pools compared to that of matched control pools after 5 days of storage (5-unit pools: test, 6.96 +/- 0.12 vs. control, 7.15 +/- 0.09, p = 0.0033; 6-unit pools: test, 6.90 +/- 0.10 vs. control, 7.07 +/- 0.09, p < 0.0001). Test pools adequately maintained many other in vitro properties including PLT morphology, hypotonic shock response, and extent of shape change parameters during 5-day storage, which, like pH, also differed from those of controls. The pH of test and control pools declined on Day 7, with 1 of 6 test pools (either 5 or 6 units) having a pH value of less than 6.20, while all control pools had pH values of more than 6.66.
PCT of leukoreduced PLT pools of whole blood-derived PLTs in 100 percent plasma maintained adequate PLT in vitro variables through 5 days of storage.
[show abstract][hide abstract] ABSTRACT: Extensive periods without agitation can occasionally occur during platelet (PLT) shipment and can affect PLT quality during 5- to 7-day storage. The use of buffer-containing PLT additive solutions (ASs) may better preserve PLT quality during storage by maintaining PLT pH and other in vitro variables. A newly described bicarbonate-containing AS, M-sol, was compared to plasma for preservation of whole blood-derived PLT concentrates in which a 30-hour interruption of agitation was included.
ABO-identical PLT-rich plasma intermediate products were pooled in sets of four, split, and centrifuged with subsequent plasma expression (n = 12). Two units were resuspended with M-sol AS to produce a 70 percent solution/30 percent plasma PLT concentrate; 2 units were resuspended in 100 percent plasma. One M-sol resuspended unit and 1 plasma unit were held on a laboratory bench in a standard shipping box for 30 hours between Day 2 and Day 3, while the other M-sol and plasma unit were continuously agitated. Standard in vitro testing for PLT quality variables on each set of 4 units was performed during storage (n = 12).
Interrupting agitation of PLTs suspended in M-sol resulted in less of a pH decrement during storage than that of PLTs suspended in 100 percent plasma. On Days 5 and 7, the pH differences between M-sol and plasma units were 0.56 and 0.75 pH units, respectively (p < 0.0003). In addition, PLTs suspended in M-sol and subjected to an interruption of agitation had lesser Day 7 CD62+ cells, glucose utilization, and lactate production and greater hypotonic stress response, morphology, swirling, and aggregation response than those suspended in plasma (p </= 0.005).
The in vitro properties of PLTs suspended in 70 percent M-sol/30 percent plasma and subjected to a 30-hour interruption of agitation are better maintained during 7-day storage than those of matched units suspended in plasma.
[show abstract][hide abstract] ABSTRACT: Many platelet (PLT) components undergo multiple periods of shipment before transfusion. We have previously conducted studies investigating maintenance of apheresis PLT in vitro quality measures during a single 24- or 30-hour interruption of agitation, but data are not available for multiple periods without agitation.
Apheresis PLTs were collected with both the Amicus (Fenwal, Inc.) and the Trima (Gambro BCT) cell separators to provide two identical PLT products, each with approximately 4 x 10(11) to 5 x 10(11) PLTs. One product was subjected to a single contiguous 24- or 30-hour period of interrupted agitation between Days 2 and 3 of storage by placement in a standard shipping box at room temperature. The matched product was not agitated on each of 3 days (Days 0, 1, and 3) for specified intervals totaling an identical period of time.
Interrupting agitation for three periods resulted in greater maintenance of pH during storage than that observed using one contiguous period. These differences were significant for units held without agitation for 24 hours (Day 5, 0.08 pH units, p < 0.0001; Day 7, 0.10 pH units, p = 0.0059) and were also significant for units held without agitation for 30 hours (Day 5, 0.15, p < 0.0001; Day 7, 0.20, p < 0.0001). The two different interruption of agitation scenarios did not result in significant differences in the extent of shape change and hypotonic shock response variables after 5 or 7 days of storage.
Apheresis PLTs subjected to three periods without agitation maintained overall pH levels slightly greater than those of matched units subjected to one contiguous period without agitation. Other measures showed comparability of PLT in vitro variables with the two scenarios for interruption of agitation.
[show abstract][hide abstract] ABSTRACT: The activation marker CD40 ligand (CD40L) has recently been demonstrated to be released from the cytoplasm of platelets (PLTs) during storage. CD40L may be associated with some adverse transfusion reactions including febrile responses and transfusion-related acute lung injury. CD62P has been traditionally measured to assess PLT activation. This study compares the surface levels of CD40L and CD62P and accumulation of the soluble forms of these activation markers in the plasma of stored PLTs, prepared by PLT-rich plasma (PRP) or buffy coat (BC) methods and with two apheresis instruments.
Individual PLT concentrates (PCs) were prepared in 100 percent plasma from a pool of two ABO-identical whole-blood units. Apheresis PLTs (APs) were prepared in 100 percent plasma using one of two commercially available cell separators (Amicus, Baxter Healthcare; and Trima, Gambro BCT). Surface expression of CD40L and CD62P was measured by flow cytometry, and secretion of soluble CD40L (sCD40L) and soluble CD62 (sCD62) was measured by enzyme-linked immunosorbent assay during 7 days of PLT storage.
Secretion of sCD40L was greater in Amicus APs than in Trima APs during the first 3 days of storage. It was also greater in the PRP-PC preparations than in BC-PC preparations through the first day of storage. Surface expression of CD40L was low in all PLT preparations. Secretion of sCD62P was greater in Amicus APs than in Trima APs during the entire storage period and greater in PRP-PC than in BC during the first 5 days of storage. The percentage of CD62P-positive PLTs was greater in Amicus units than Trima units and greater in PRP-PC than BC-PC preparations during the first 5 and 3 days of storage, respectively.
The kinetics of the secretion of CD40L are influenced by the method used to prepare PLTs for storage. The patterns for CD40L membrane association and secretion are different than those observed for CD62P during storage.
[show abstract][hide abstract] ABSTRACT: Methods for pathogen inactivation are currently available in some European countries for treatment of plasma and platelet (PLT) components; no approved method for treatment of red cells (RBCs) or whole blood is ready for implementation. In a previous study, thiazole orange (TO), a dye commonly used to count reticulated RBCs and PLTs, exhibited potent photoactivity against human immunodeficiency virus-1 and several model viruses in RBC suspensions. The aim of this study is to further evaluate the ability of TO to inactivate pathogens by measuring its activity against the protozoa Leishmania donovani infantum and Trypanosoma cruzi.
RBC suspensions were deliberately contaminated with L. donovani infantum promastigotes or T. cruzi trypomastigotes and either maintained as an untreated control, incubated with 80 mumol per L TO in the dark, or treated with TO and light. Control and treated samples were inoculated into medium and subsequently microscopically examined for growth.
No growth was observed in samples treated with TO in the presence or absence of light, while matched control samples lacking TO and diluted up to 5 log consistently demonstrated Leishmania or T. cruzi growth (n = 3).
TO inactivated Leishmania or T. cruzi to the limit of detection in RBC suspensions without intentional illumination.
[show abstract][hide abstract] ABSTRACT: Platelet (PLT) components undergo interruption of agitation during shipment. Studies have demonstrated maintenance of PLT quality of whole blood-derived PLT concentrates during a 24-hour interruption of agitation, but data are not available for apheresis PLTs in 100 percent plasma.
Apheresis PLTs were collected with one of two commercially available separators (Amicus, Fenwal, Inc.; or Trima Accel, Gambro BCT) to provide two identical PLT products, each with approximately 3 x 10(11) to 4.5 x 10(11) PLTs. The control product was continuously agitated. The test product was subjected to a continuous 24- or 30-hour period of interrupted agitation between Day 2 and Day 3 of storage by placement in a standard shipping box at room temperature.
Interrupting agitation for 24 or 30 hours influenced in vitro PLT properties to various degrees. After 5 days of storage, pH levels were judged to be well maintained after 24 hours without agitation for PLTs collected with both separators (pH < 6.2, Trima [0/12] and Amicus [0/12]). The changes in other variables associated with the retention of postinfusion viability were also considered limited and acceptable in units subjected to a 24-hour interruption of agitation. After 7 days of storage including a 24-hour interruption of agitation, Trima PLTs better maintained PLT properties compared to Amicus PLTs. With a 30-hour period, both Trima and Amicus PLTs were deemed satisfactory for pH at 5 days, but not at 7 days (pH < 6.2: Day 5, Trima [0/23] and Amicus [1/22]; Day 7, Trima [5/23] and Amicus [4/17]).
Based on the retention of pH levels of at least 6.2, apheresis PLT quality was maintained for 5 days with a 24-hour and a 30-hour interruption of agitation.
[show abstract][hide abstract] ABSTRACT: Chagas disease, endemic in rural areas of Mexico, Central and South America, is caused by the protozoan parasite, Trypanosma cruzi, which is spread by the Reduviid bug and also by transfusion or organ transplant. Transmission of the organism from asymptomatic donors to immunocompromised recipients, leads to clinically apparent disease. With recent immigration patterns, T. cruzi is now becoming an increasing problem in non-endemic areas of North America and Europe. Blood screening tests for T. cruzi are being developed, and one test is currently licensed by the United States Food and Drug Administration and has been implemented in some US blood centers. This study alternatively investigates the potential for a novel DNA-intercalating photosensitizer, thiopyrylium (TP), to inactivate T. cruzi in red cell suspensions. With complete inactivation using 6.3 microM of TP and 1.1J/cm(2) red light treatment, results suggest that the organism is highly sensitive to photoinactivation under conditions much less stringent than those that have been previously demonstrated to maintain red cell (RBC) properties during 42 day storage.
Transfusion and Apheresis Science 09/2007; 37(1):23-5. · 1.23 Impact Factor
[show abstract][hide abstract] ABSTRACT: 2,4-Bis(4-dimethylaminophenyl)-6-alkylthiopyrylium and selenopyrylium dyes are essentially nonfluorescent (phi F < 0.001) and are poor generators of singlet oxygen in aqueous solution. However, upon complexation to calf thymus DNA, quantum yields for both fluorescence and generation of singlet oxygen increased dramatically. Irradiation of the dye-DNA complexes produced strand breaks in the DNA. The photodamage is not observed in the absence of oxygen and is suppressed by the addition of the singlet oxygen quencher imidazole. The inactivation of the pseudo-rabies virus upon treatment of oxygenated leukodepleted 20% hematocrit red blood cell suspensions with the chalcogenopyrylium dyes and light followed the same trend observed with quantum yields for the generation of singlet oxygen in the dye-DNA complexes.
The Journal of Physical Chemistry B 08/2007; 111(32):9686-92. · 3.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: A series of thio- and selenopyrylium analogues of 2,4-di(4-dimethylaminophen-yl)-6-methylthiopyrylium iodide were prepared in five steps from 4-dimethylaminophenyl-propargyl aldehyde and the corresponding lithium acetylide. When bound to DNA, all of the dyes absorb at wavelengths >600nm, which avoids the hemoglobin band I maximum at 575nm. The binding of the series of dyes to double-stranded DNA was examined spectrophotometrically and by isothermal titration calorimetry to determine binding constants, by a topoisomerase I DNA unwinding assay, by competition dialysis with [poly(dGdC)](2) and [poly(dAdT)](2), and by ethidium bromide displacement studies to examine propensities for intercalation, and by circular dichroism studies. The dyes were found to show mixed binding modes.
[show abstract][hide abstract] ABSTRACT: Recently, we have shown that thiopyrylium has robust inactivation capabilities against a broad spectrum of pathogens in the human red blood cell (RBC) suspensions while retaining key RBC in vitro properties. The 24-h recovery and survival of canine red cells were measured upon autologus reinfusion of control and phototreated units. The 24-h recovery of control and phototreated RBCs was 75.7 +/- 6.4% and 87.5 +/- 8.5%, respectively. The time for 50% survival of labelled control RBCs was similar to that of phototreated group (206 +/- 58 h vs. 255 +/- 63 h, respectively). Results suggest that thiopyrylium phototreatment does not negatively affect canine RBC in vivo recovery.