A multi-site study for detection of the factor V (Leiden) mutation from genomic DNA using a homogeneous invader microtiter plate fluorescence resonance energy transfer (FRET) assay.

The goal of this multicenter study was to evaluate the second-generation Invader technology for detecting the factor V (Leiden) mutation directly from genomic DNA of different sample types. Invader assay results were compared with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) or allele-specific PCR (AS-PCR) analysis. The Invader assay is a PCR-independent methodology that uses a microtiter plate format. In the assay, a specific upstream Invader oligonucleotide and a downstream probe hybridize in tandem to a complementary DNA template and form a partially overlapping structure. The Cleavase VIII enzyme recognizes and cuts this structure to release the 5' flap of the probe. This flap then serves as an Invader oligonucleotide to direct cleavage of a fluorescence resonance energy transfer (FRET) probe in a second invasive cleavage reaction. Cleavage of this FRET probe results in the generation of a fluorescent signal. The results of the Invader assay were 99.5% concordant with the PCR-based methods. Of the 372 samples tested once, only two gave discordant results (one from operator error and one from unknown causes), but were concordant on retesting. These results indicate that a simple microtiter plate-based Invader assay can reliably genotype clinical patient samples for the factor V (Leiden) point mutation directly from genomic DNA without prior target amplification.

A comparative study of three methods for the visualization of von Willebrand factor (vWF) multimers.

This study was performed to compare three visualization methods for the detection of vWF multimers: autoradiography (125I), electroblot with a horseradish peroxidase system (BLOT-HRP), and an avidin-biotin peroxidase system (AV-BIO). Each method was evaluated according to: 1) ability to visually detect bands and subbands thereby identifying von Willebrand's disease (vWD) subtypes and normals, 2) reagent availability, 3) cost, and 4) time requirements. Additionally, resolvability was evaluated utilizing low, intermediate, and high resolution gels prepared with both low and high gelling temperature agaroses with subsequent visualization by the three detecting systems. With intermediate resolution gels, our results showed that all three visualization methods could discern pathologic patterns from normal. In addition, the avidin-biotin peroxidase system demonstrated the best band discreteness with low resolution gels used to detect unusually high molecular weight multimers. With high resolution gels used for subtyping type II vWD, we found the internal band structure was best demonstrated using LGT agarose and the electroblot horseradish peroxidase system.

Homozygous protein S deficiency due to a one base pair deletion that leads to a stop codon in exon III of the protein S gene.

Homozygous protein S (PS) deficiency is a very rare disorder that causes purpura fulminans in affected newborns. This report describes the molecular genetic abnormality of a severe PS deficient child who developed purpura fulminans shortly after birth. The mutation was identified as a deletion of one adenine in codon 43 of exon III of the PROS 1 gene. This mutation results in a frameshift and a novel stop codon at position 45. The proband was apparently homozygous and his mother heterozygous for this mutation. The proband's father was not available for study. The single base pair deletion predicts a truncated translation product, where Lys 43 and Tyr 44 have been replaced by Asn 43 and Thr 44. This putative protein (predicted mw of 5.696 daltons) contains only the gammacarboxyglutamic acid (Gla) domain and the aromatic stack.

Efficacy of danazol in a patient with congenital protein-S deficiency: paradoxical evidence for decreased platelet activation with increased thrombin generation.

Danazol, a synthetic attenuated anabolic steroid, has been administered for 36 months to a 32 year old male with hereditary Protein S (PS) deficiency who had become non-compliant for warfarin therapy. The patient has an eleven year history of venous thrombosis. Since danazol therapy was initiated, the patient has not experienced a thrombotic event or adverse side-effects. Levels of PS, other inhibitors, fibrinolytic components, and markers for thrombin and platelet activation were measured prior and subsequent to therapy. Following danazol administration, marked and sustained increases were noted in Free Protein S, Antithrombin, and Protein C. Platelet CD62 (P-selectin) positivity which was elevated before therapy, decreased to assay threshold limits within five weeks. Both Prothrombin Fragment 1.2 and thrombin-antithrombin complexes were elevated post danazol therapy indicating continued clearance of generated thrombin. These data suggest that the protective effect provided by danazol in this patient with hereditary PS deficiency, may in large part be due to suppression of platelet activation by thrombin inhibition than simply through elevation of PS.

Rapid removal of platelets from plasma utilizing the Hepcheck heparin removal filter.

We investigated whether Hepcheck heparin removal filters could remove residual platelets from platelet-poor plasma (PPP) without compromising samples for lupus anticoagulant (LA) testing. Furthermore we assessed what effect, if any, plasma filtration has on various clotting tests that form the foundation for LA testing. Citrated blood was obtained from 35 normal donors. Two sets of citrated tubes were processed in order to obtain PPP. Citrated blood was also obtained from a single donor to check the actual amounts of platelets removed by the Hepcheck filtration device. One set of PPP samples was filtered using the Hepchek filter device and the other was not processed, i.e. unfiltered. Prothrombin time (PT), activated partial thromboplastin time (APTT), and kaolin clotting time (KCT) were performed on both unfiltered and filtered samples that were tested immediately and after freezing at -70 degrees C for 24 h. Platelet counts on the single donor's citrated plasma were dramatically reduced after filtration. PT and APTT values showed small but statistically significant differences between unfiltered and filtered plasmas whether these were fresh or frozen samples. However, these differences were not clinically significant. KCT data showed statistical and clinical differences between unfiltered and filtered plasmas whether fresh or frozen plasmas were used. In contrast, KCT values were similar if unfiltered, fresh plasmas or filtered, frozen plasmas were used. Coagulation factor assays for factors VIII, IX and X were performed on both sets of PPP samples after freezing to determine if the filtration device affected these levels and would as a result, compromise APTT based lupus testing. Factor IX levels demonstrated a loss of activity following use of the device but no change was observed in factor VIII or factor X. Von Willebrand factor antigen and function as well as multimer structure were not affected by the filtration device in 10 normal donors. Filtering plasmas of two donors with a history of an LA dramatically prolonged clotting times for APTT, Dilute Viper Venom Time, mixing studies, and STACLOT LA tests in comparison with unfiltered plasmas. The data indicate that plasma filtration using the Hepchek device does not adversely affect coagulation testing. Furthermore samples requiring testing for the lupus anticoagulant can be filtered and subsequently frozen and compare favorably with freshly processed samples.

The uptake and egress of adenine from human red blood cells in vitro.

The initial uptake of adenine from plasma by human red blood cells was measured at 0, 10, and 20 C. Initial uptake is completed in several minutes as distribution equilibrium is reached; however, total uptake requires several weeks at 4 C. Adenine inside the red blood cell was shown to egress to the plasma if the equilibrium shifted due to plasma dilution or exchange.

Effects of 4000 rad irradiation on the in vitro storage properties of packed red cells.

Immunosuppressed patients who require red cell transfusions receive irradiated (1500-3000 rad) packed red cells. These cells are irradiated immediately before infusion. If a large group of patients become immunosuppressed due to exposure to radiation or chemicals, the ability to supply large volumes of irradiated blood at the time of use might not be possible. An alternate solution to providing quantities of irradiated blood is to irradiate the units prior to storage. This study presents in vitro data comparing storage of paired packed red cell units either irradiated or not irradiated. Five units of fresh blood drawn into citrate-phosphate-dextrose-adenine (CPDA-1) were packed to a hematocrit of 75 +/- 1 percent, and then each unit was divided in two equal parts. One of each pair was irradiated (4000 rads), and both parts of each unit were stored for 35 days at 4 degrees C. Samples were analyzed every 7 days. Irradiation caused a slight drop in red cell adenosine triphosphate and 2,3 diphosphoglycerate and a slight increase in plasma hemoglobin compared to controls. Methemoglobin, pH, and glucose consumption were identical to the controls. The evidence indicates that irradiation did not cause biochemical or metabolic changes in the red cells that would lead us to suspect a difference between irradiated and nonirradiated stored red cells in function or viability. These negative findings require in vivo confirmation.

Development of an optimized additive solution containing ascorbate-2-phosphate for the preservation of red cells with retention of 2,3 diphosphoglycerate.

An additive solution containing adenine, ascorbate-2-phosphate, sodium phosphate, dextrose, and saline was developed for packed red cell preservation. The combination of all components was simultaneously optimized so that the resulting solution produced the maximum retention of both red cell adenosine triphosphate (ATP) and 2,3 diphosphoglycerate (2,3 DPG) concentrations. Fourteen nutrient combinations were tested; each combination was evaluated for 42 days of storage using cells from three donors. The nutrient combinations were chosen with the aid of a computerized experimental design process. Results of the experiments were modeled by regression analysis, and the model was optimized to produce the "best" formulation for simultaneous maintenance of ATP and 2,3 DPG. The resulting mathematically optimal formulation was tested in the laboratory using 10 units of red cells. With this solution, it was possible to store red cells for 42 days with retention of 45 to 55 percent of the initial ATP and 85 to 150 percent of the initial 2,3 DPG. Red cell lysis was low (0.8 percent), and most of the cells were biconcave discs (by scanning electron microscopy) at the end of storage. The studies were carried out in an efficient manner by using computer-optimized experimental design techniques coupled with multiple regression modeling and subsequent computer optimization of the models. This experimental approach has potential application to many current blood banking procedures. This additive solution should maintain viable red cells for 42 days. In addition, the solution will maintain red cell 2,3 DPG throughout storage.

In vivo viability studies of two additive solutions in the postthaw preservation of red cells held for 3 weeks at 4 degrees C.

An optimized additive solution was developed for the postthaw preservation of red cells that contained adenine, glucose, disodium phosphate, and citrate buffer. This solution, called AS-17, was compared to AS-3 solution in a clinical trial using 40 subjects (20 in each arm). Fresh-frozen red cells were thawed and deglycerolized after 1 to 18 months and subjected to a second period of storage in either solution for up to 3 weeks at refrigerator temperatures. Both solutions yielded red cells with 24-hour survivals in excess of 75 percent. Cells stored in AS-3 for 21 days had a mean survival of 77 +/- 8 percent and cells stored in AS-17 a mean survival of 79 +/- 11 percent. The AS-17 solution resulted in improved maintenance of pH, p50, and 2,3 DPG compared to that with AS-3, but both solutions appear adequate for 3 weeks of postthaw storage.

The in vitro evaluation of modifications in CPD-adenine anticoagulated-preserved blood at various hematocrits.

Erythrocytes stored in the new CPD-adenine anticoagulant (CPDA-1) barely met the 70 per cent 24-hour postinfusion 51Cr recoveries on day 35 when stored at hematocrit greater than or equal to 75 per cent. CPDA-1 differs from CPD in that it has 1.25 times the glucose concentration plus 17.3 mg adenine/63 ml. In an effort to improve the survivability (or viability) of red blood cells following extended storage (35+ days), two new CPD-adenine anticoagulants have been tested in vitro. CPDA-2 and CPDA-3 (both of which contain 34.6 mg/63 ml of anticoagulant or 0.50 mM adenine [final blood concentration], and either 1.75 times or 2.0 times respectively the amount of glucose used in CPD) have been tested for whole blood or red blood cell storage to 42 days. Red blood cell ATP concentrations were better maintained throughout 42 days of storage in both of these formulations than in CPDA-1 at hematocrits that ranged from 40 to 85. Other biochemical parameters (2,3-DPG, pH, plasma hemoglobin) were similar to those of blood stored in CPD or CPDA-1.

Plasma adenine and cellular ATP in red cell concentrates collected and stored in modified CPD at 4 C.

Eight units of blood were drawn into modified CPD containing 25 per cent higher glucose and 17.3 mg adenine (0.25 mM in blood). Red blood cell concentrates (RCC) were prepared to a mean hematocrit (Hct) of 70, the cells stored at 4 C, and plasma adenine and red blood cell adenosine triphosphate (ATP) were measured weekly for 42 days. The removal of plasma in the preparation of RCC reduced by 39 per cent the available adenine. As a result measurable plasma adenine was depleted by 21 days. The loss of ATP in RCC occurs at a significantly faster rate than in whole blood stored under the same conditions. When red blood cells are stored at higher HCT or for periods longer than 35 days, increased anticoagulant adenine levels are recommended.

The biochemical effects of CPDA-2-drawn red blood cells of delayed refrigeration prior to component preparation.

The effects of an 8-hour hold at 22 degrees C prior to component preparation were evaluated in a split-bag study using nine units of blood preserved in citrate-phosphate-dextrose-adenine (CPDA-2). Each unit was divided in half, platelet-rich plasma removed at 0 or 8 hours, respectively, and the half units of red blood cells stored at 4 degrees C for 42 days. The only red blood cell metabolic differences seen in the bags held 8 hours (compared to those not held) were a 21 percent rise in adenosine triphosphate, which was not significant after 14 days of storage, and a 33 percent loss of 2,3-diphosphoglycerate which resulted in a loss curve similar to that seen with acid-citrate-dextrose blood. The logistic advantages seem to warrant an 8-hour holding period for red blood cells drawn in CPDA-2.

Improved red blood cell storage using optional additive systems (OAS) containing adenine, glucose and ascorbate-2-phosphate.

Red blood cells were treated with optional additive system (OAS) solutions to provide component-specific metabolic enhancement for improved storage. Red blood cell viability, as monitored by ATP concentrations, was maintained by use of adenine and extra glucose. Red blood cell oxygen offloading characteristics were improved by maintenance of red blood cell 2,3-DPG concentrations with ascorbate-2-phosphate (AsP). The use of CPD-collected red blood cells with an OAS containing adenine, glucose, and AsP, or CPD-adenine collected red blood cells with an OAS containing AsP demonstrates the potential to store red blood cells at least 42 days and to maintain red blood cell 2,3-DPG.

Red cell ATP and 2,3-diphosphoglycerate concentrations as a function of dihydroxyacetone supplementation of CPD adenine.

Units of CPDA-1 whole blood were subdivided and each treated with additions of dihydroxyacetone (DHA) to give final concentrations from 0 to 80 mM. The 'optimum' concentration of DHA to maintain 2,3-diphosphoglycerate (2,3-DPG) with minimal loss of ATP during 42 days of storage appeared to be 30 mM of DHA. With this formulation, red cell 2,3-DPG concentrations rose to 130-140% of normal by 14 days and then decreased in a near-linear manner to 50-60% normal by 42 days, while maintaining adequate ATP levels. In addition, packed red cells were prepared form CPD fresh blood and treated with adenine, glucose, and various concentrations (0-80 mM) of DHA. The cells also responded most favorably to 30mM DHA, although the response was not as positive as whole blood. This concentration of DHA produced nearly 100% maintenance of 2,3-DPG at 14 days with subsequent fall to 30% of normal by 42 days.

Liquid storage at 4 degrees C of previously frozen red cells.

Fresh human blood was collected in citrate-phosphate-dextrose, frozen by a high-glycerol technique, and stored at -80 degrees C. The red cells were thawed, deglycerolized, and resuspended in a final wash solution, ADSOL (Fenwal Laboratories), or an additive solution (AS) containing glucose, adenine, mannitol, and phosphate. The cells were then stored at 4 to 6 degrees C for 21 days and assayed weekly for adenosine triphosphate and 2,3 diphosphoglycerate, pH, glucose use, and lysis. AS and, to a lesser extent, ADSOL produced metabolic profiles similar to or better than profiles of cells not frozen and stored in commercially available additive solutions. AS offers a potential post-thaw preservative solution for red cells that would greatly increase the flexibility and reduce the expense of using frozen blood. A sterile post-thaw storage capability will make the stockpiling of frozen red cells a practical concept for both military and civilian blood banks.

New variant of von Willebrand disease type II with markedly increased levels of von Willebrand factor antigen and dominant mode of inheritance: von Willebrand disease type IIC Miami.

A variant of von Willebrand disease (vWD) was identified in six members of a kindred spanning four generations. The proband was a 46-year-old woman with a lifelong history of bleeding, a prolonged bleeding time (> 15 minutes), markedly elevated von Willebrand factor (vWF) antigen (vWF:Ag = 2.09 U/mL), slightly reduced ristocetin cofactor activity, and a plasma vWF multimer pattern similar to that of vWD type IIC. Similar findings were observed in her three children, mother, and brother. In affected family members, platelet and plasma vWF multimer patterns were discrepant with higher molecular weight multimers observed in platelet vWF. Following a 1-Des-amino-8-D-arginine vasopressin (DDAVP) challenge, the proband failed to normalize her bleeding time even though vWF: Ag rose by 70% and higher molecular weight multimers were increased slightly. Genetic studies were consistent with autosomal dominant inheritance of a mutation within the vWF gene. By sequencing of cloned genomic DNA, mutations were excluded in exons 4, 5, 14, and 15, which encode regions of the vWF propeptide proposed to be important in multimer biosynthesis. Mutations also were excluded in exons 28 to 31, which encompass the known mutations that cause vWD types IIA, IIB, and B. This new variant of vWD, characterized by autosomal dominant inheritance, a qualitative defect that resembles vWD type IIC, and increased plasma vWF:Ag, was tentatively designated vWD type IIC Miami.

Evaluation of methemoglobin formation during the storage of various hemoglobin solutions.

Many researchers are trying to develop a blood substitute based on chemically modified human hemoglobin. In the process of making such solutions, we were faced with the problem of determining the best storage conditions to minimize oxidation of the solutions between the time of manufacture and use. Samples of stroma-free hemoglobin, purified A0 hemoglobin, and various cross-linked hemoglobins were stored for 8-12 months at +4 degrees C -20 degrees C, and -80 degrees C and were analyzed periodically for formation of methemoglobin (MetHb). Various suspending solutions were evaluated for their effects on the rate of MetHb formation, and the approximate rates of MetHb production per month were calculated. Short-term storage of hemoglobin solutions (< 14 days) can be done at +4 degrees C, but extended storage should be done at -80 degrees C with quick thawing. Salts minimize the hemoglobin oxidation during the stress of freeze-thaw operations. Storage at -20 degrees C. presents further problems and should be avoided.

Familial infantile thrombotic thrombocytopenic purpura.

PURPOSE: To further define familial infantile thrombotic thrombocytopenic purpura and clarify its pathophysiology, we describe a family with two infants presenting with this rare syndrome. RESULTS: Complete, but temporary remission followed the transfusion of whole blood in the first sibling and fresh frozen plasma (FFP) in the second. Periodic FFP transfusions have kept the surviving proband in a prolonged clinical remission. The presence of unusually large von Willebrand factor multimers was demonstrated in the proband and the processing activity of these large multimers was found to be normal. CONCLUSION: The occurrence of this rare disorder, in siblings who are products of a consanguinous union, suggests an as yet uncharacterized genetic defect.