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J D Sweeney

Publications and source records attributed to J D Sweeney.

At least 37 records · Page 2Linked to original sources
PubMed1997

The expression of p-selectin during collection, processing, and storage of platelet concentrates: relationship to loss of in vivo viability.

BACKGROUND: Recent studies suggested that platelet activation with surface expression of p-selectin on stored platelets may be related to a loss of viability. At present, there has been no thorough investigation of the extent or significance of p-selectin expression during the collection, processing, and storage of platelet concentrates (PCs) under various conditions. STUDY DESIGN AND METHODS: Platelet surface expression of p-selectin (CD62) was determined on fixed platelet samples using fluorescein-conjugated monoclonal antibodies. Platelet viability was assessed by autologous transfusion of platelets stored for 5 days and labeled with either 51Cr or 111in. RESULTS: Little (2-10%) platelet expression of p-selectin was found in whole blood and platelet-rich-plasma preparations, whereas PCs showed a substantial increase in p-selectin expression to levels of 20 to 30 percent. Both fresh PCs and those stored for 5 days, obtained with one cell separator (MCS, Haemonetics) showed substantially lower levels of p-selectin expression than PCs from two other cell separators (Spectra, COBE, and CS-3000 with TNX-6, Baxter Healthcare). Exposure of platelets to EDTA, cold, or a pH below 6.2, conditions that are known to result in the loss of viability upon transfusion, produced substantial and irreversible p-selectin expression. PCs with a pH of 6.2 to 6.8 (conditions in which no loss of viability has been demonstrated) also showed pronounced p-selectin expression, which returned to control values after incubation at 37 degrees C in plasma at pH 7.0 to 7.2. With storage under current conditions the in vivo studies (n = 61) demonstrated a rather poor correlation between p-selectin expression and the percentage of recovery (r = -0.25) but a somewhat better correlation with survival (r = -0.42). Better correlations were observed with the extent of shape change, lactate, and hypotonic shock response. CONCLUSION: These studies show that p-selectin expression on the platelet surface is a predictor of platelet viability, although the extent of shape change and the hypotonic shock response may be more sensitive.

Blood Platelets↗
PubMed1997

Addition of L-carnitine to additive solution-suspended red cells stored at 4 degrees C reduces in vitro hemolysis and improves in vivo viability.

BACKGROUND: The role of L-carnitine (LC) as the requisite carrier of long-chain fatty acids into mitochondria is well established. Human red cells (RBCs), which lack mitochondria, possess a substantial amount of LC and its esters. In addition, carnitine palmitoyl transferase, an enzyme that catalyzes the reversible transfer of the acyl moiety from acyl-coenzyme A to LC is found in RBCs. It has recently been shown that LC and carnitine palmitoyl transferase play a major role in modulating the pathway for the turnover of membrane phospholipid fatty acids in intact human RBCs, and that LC improved the membrane stability of RBCs subjected to high shear stress. RBC membrane lesions occur during storage at 4 degrees C; this study investigated whether the addition of LC (5 mM) to a standard RBC preservative solution (AS-3) affected cellular integrity with 42 days' storage. STUDY DESIGN AND METHODS: A paired (n = 10) crossover design was used for RBCs stored in AS-3 with and without LC. Both in vitro RBC properties reflective of metabolic and membrane integrity and in vivo measures of cell viability (24-hour percentage of recovery and circulating lifespan) were measured at the end of the storage. In addition, the turnover of membrane phospholipid and long-chain acylcarnitine fatty acids and the carnitine content of control and LC-stored RBCs were measured. RESULTS: It was shown that LC was irreversibly taken up by RBCs during storage, with a fourfold increase at 42 days. Furthermore, as found by the use of radiolabeled palmitate, the stored RBCs were capable of generating long-chain acylcarnitine. The uptake of LC during storage was associated with less hemolysis and higher RBC ATP levels and by a significantly greater in vivo viability for LC-stored RBCs than for control-stored RBCs: a mean 24-hour percentage of recovery of 83.9 +/- 5.0 vs. 80.1 +/- 6.0 percent and a mean lifespan of 96 +/- 11 vs. 86 +/- 14 days, respectively (p < 0.05). CONCLUSION: A beneficial effect of the addition of LC to RBCs stored at 4 degrees C was evident. This effect may be related to both biophysical and metabolic actions on the cell membrane.

Adenine↗
PubMed1997

Anti-D in a D-positive renal transplant patient.

BACKGROUND: The detection of anti-D in a D-positive renal transplant recipient is unusual and may arise by several potential mechanisms. These include passive transfer of alloantibody and the presence of autoanti-D or alloanti-D that is due to microchimerism when the allograft is from a D-negative donor. In the latter case, overt hemolysis has been seen or suspected. The occurrence of anti-D in a D-positive renal transplant recipient without hemolysis, which is most likely attributable to microchimerism, is reported. CASE REPORT: A 51-year-old group O, D-positive woman, who was serologically HLA type A1, A2; B8, B44; DR3, DR6, DR52; DQ1, DQ2, underwent the transplantation of a kidney from a cadaveric donor who was serologically HLA type A1, A2; B8, B44; DR13, DR17, DR52; DQ1, DQ2. The donor was known to be D-negative and immunized to D. No blood components or derivatives were administered at the time of organ graft. Ten weeks after the transplant, the direct antiglobulin test was positive in the recipient, and anti-D was eluted. Polymerase chain reaction amplification using primers to distinguish DR13 (donor) from DR14 alleles (recipient split of DR6) in the peripheral blood showed the recipient to be DR14. No DR13 could be detected, and thus microchimerism could not be confirmed. However, in the peripheral blood, GM and KM allotyping of the serum (GM A,F,X B,G and KM 1,3) and eluate (G1M F, KM 3) showed a pattern of allotypes most consistent with an alloantibody. Eleven months after transplantation, the graft continued to function; the direct antiglobulin test was still positive, and elution of anti-D persisted. CONCLUSION: This case of anti-D in a D-positive renal transplant recipient is attributed to microchimerism, despite the lack of confirmation by genotypic analysis of the peripheral blood. It raises the possibility that microchimerism may be a more common phenomenon in solid allograft recipients than is realized.

Female↗
PubMed1997

Decreased whole blood factor IX activity following hemodilution with hemoglobin A-zero in-vitro.

Previous studies of hemoglobin-based oxygen carriers and their effects on coagulation have shown conflicting results. This study re-examined the effect of hemoglobin solution on blood coagulation in whole blood using highly purified human hemoglobin Ao (HbAo). Citrated human whole blood samples were diluted 1:1 with HbAo (7gHb/dl) or human serum albumin (HSA; 5g/dl) as a protein control, and both activated partial thromboplastin time (aPTT) and prothrombin time (PT) were measured using a mechanically based whole blood coagulometer. Multiple runs were performed with the same volunteer donor sample. The mean aPTT time of HbAo-diluted samples (105.9 +/- 19.9 sec., n = 41) was significantly longer than the undiluted controls (46.4 +/- 5.6 sec., n = 54) or HSA-diluted blood (77.1 +/- 12.7 sec., n = 41) indicating an abnormal intrinsic coagulation pathway. There was no significant difference between the PT times of the HbAo and HSA-diluted samples. To examine the cause of the prolonged aPTT times with HbAo dilution, we performed activity assays of intrinsic factors XII, XI, IX, and VIII in a citrated human whole blood system diluted 1/5 and 1/10 with normal saline solution (NSS), and then 1:1 with either HbAo, HSA, or NSS. Only the Factor IX activity was significantly depressed by hemodilution (1/5 HbAo 50.20 +/- 8.11; HSA 61.05 +/- 6.72; NSS 74.75 +/- 9.83. 1/10 HbAo 46.50 +/- 5.57; HSA 64.97 +/- 11.01; NSS 67.92 +/- 16.03). These results suggest that in-vitro hemodilution with HbAo causes a hypocoagulatory response through interference with Factor IX function.

Blood Coagulation↗
PubMed1997

Comparison of an activated partial thromboplastin time with a Russell viper venom time test in screening for factor V(Leiden) (FVR506Q).

Factor V(Leiden) is the most common abnormality detected in patients examined because of hereditary thrombophilia. The most widely used clot-based screening test is based on the activated partial thromboplastin (aPTT) time. This test has a low sensitivity. A comparison of the aPTT-based test with a Russell viper venom time test (RVVT) was performed in matched samples. All samples were analyzed by polymerase chain reaction (PCR) for the factor V(Leiden) defect. We studied 139 samples, of which 109 were PCR-negative; 30 were PCR-positive. Using the manufacturer's suggested threshold ratio of 2, the aPTT test showed a sensitivity of 0.43, a specificity of 0.86, and a positive predictive value (PPV) of 0.97. The RVVT test had a sensitivity of 1.0, a specificity of 0.95, and a PPV of 0.91. Segregation of a subpopulation of this study population into ABO group O vs non-group O showed an effect of ABO group on the aPTT test but not on the RVVT test, consistent with an influence of factor VIII clotting (factor VIII:C) on the aPTT test. The RVVT test seems superior to the unmodified aPTT test as a screening test for factor V(Leiden).

Factor V↗
PubMed1996

Idiopathic acute transverse myelitis: MR imaging findings.

PURPOSE: To analyze the magnetic resonance (MR) imaging findings in idiopathic acute transverse myelitis (IATM) in relation to pathologic findings and MR findings in Guillain-Barré syndrome and ischemia. MATERIALS AND METHODS: The cases of 19 patients with IATM seen over a 4-year period were retrospectively reviewed. Clinical parameters and laboratory test findings were recorded for each patient independently of the MR findings. RESULTS: Ten (53%) patients experienced upper respiratory infection or vaccination within 4 weeks of symptom onset. The majority (82%) of cases occurred between December and May each year. In seven of 12 patients who underwent electromyography and nerve conduction examinations, evidence of peripheral nerve injury was seen. On T2-weighted axial images, 13 of 18 lesions were depicted with holocord abnormal signal intensity, seven (39%) had gray matter involvement similar to that seen in spinal cord ischemia, and three (16%) had isolated white matter involvement. Enhancement patterns varied. In three (17%) of the 18 lesions, enhancement in the cauda equina was similar to that seen in Guillain-Barré syndrome. CONCLUSION: IATM may be caused by a small vessel vasculopathy. MR findings in IATM also occasionally are similar to those described in Guillain-Barré syndrome and suggest a possible relationship.

Adolescent↗
PubMed1995

Influence of type of exchange fluid on survival in therapeutic apheresis for thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura (TTP) is a potentially lethal disease that may respond favorably to plasma infusion or therapeutic plasma exchange (TPE) with frozen plasma (FP) as the exchange fluid. Frozen plasma from which the cryo-precipitated fraction has been removed (cryopoor plasma, CP) has reportedly been useful in refractory cases in which a response to FP is not being observed. We report a retrospective analysis of all cases of TTP treated by TPE with either FP (1985-1989) or CP (1989-1993) as exchange fluid at a large tertiary care hospital between the years 1985 and 1993. A severity score index was compiled for each patient using the platelet count, mental status, hematocrit, and renal function at the time of diagnosis. Nineteen patients were treated with FP (group 1) and 18 patients with CP (group 2). Groups did not differ in age, gender, race, hematologic parameters, or severity scores. Patients treated with CP, however, had more plasma exchange (14 +/- 10 vs. 12 +/- 8, respectively) and more fluid exchanged than these treated with FP (50 L +/- 36 vs. 37 L +/- 40, respectively). Survival was 72% in the CP group and 47% in the FP group. Although a survival advantage for the use of CP as exchange fluid in the treatment of TTP is suggested by our observations, the retrospective nature of the study, lack of randomization, and sequential rather than concurrent use of FP and CP indicates caution in interpretation. The data do indicate, however, that use of CP is acceptable as the initial exchange fluid in TTP.

Adolescent↗
PubMed1995

Neuromuscular stimulation selectivity of multiple-contact nerve cuff electrode arrays.

The feasibility of an electrical stimulation method selectively for activating skeletal muscles innervated by a common peripheral nerve trunk has been investigated. The method utilises 'snugly' fitting nerve cuffs that incorporate an array of 12 electrodes. These electrodes have been tested as four longitudinally aligned tripoles (located 90 degrees apart on the cuff inner surface). In acute experiments on rabbit sciatic nerves, we have found that tripolar stimulation with this implant system is in general highly selective. 'Field steering,' wherein a subthreshold transverse current is used in combination with a longitudinal tripolar current, tends to increase the selectivity of stimulation. On a rabbit sciatic nerve, a combination of adjacent longitudinal tripoles of the 12 electrode array generally yields a stimulation performance similar to that which would be expected if a 24 electrode array is used. This system may find a use in functional neuromuscular stimulation applications which require highly selective control over multiple muscles.

Animals↗
PubMed1995

Pseudothrombocytopenia in plateletpheresis donors.

BACKGROUND: EDTA pseudothrombocytopenia (PTCP) is an in vitro artifact in which the anticoagulation of blood with EDTA is associated with in vitro agglutination of platelets, resulting in a spuriously low platelet count. In apheresis donors, whole-blood samples for complete blood counts are routinely drawn into tubes anti-coagulated with EDTA. STUDY DESIGN AND METHODS: Records of apheresis donors were examined to identify persons in whom the postdonation counts were less than 100 x 10(9) per L. Identified donors were studied to confirm the presence of PTCP by drawing blood samples into EDTA, heparin, and trisodium citrate for serial platelet counts at room-temperature incubation. Platelet counts in citrated plasma were measured before and after the addition of EDTA. A single HLA-matched component from an identified PTCP donor was monitored for response by corrected count increment in the recipient. RESULTS: A total of nine donations were identified, involving 2 donors from a population of 945 donors (prevalence 0.2%). On testing, both donors were confirmed to have PTCP. The addition of EDTA to citrated plasma did not affect the platelet count. Response in a recipient to an HLA-matched component showed an acceptable corrected count increment. CONCLUSION: PTCP may occur in plateletpheresis donors and result in needless medical referral or donor deferral. PTCP does not appear to alter the yield content of the component or to be passively transferred to a recipient.

Blood Donors↗
PubMed1995

At(a-) phenotype: description of a family and reduced survival of At(a+) red cells in a proposita with anti-Ata.

BACKGROUND: There is a paucity of data on the August (At) blood group antigen and clinical significance of anti-Ata. STUDY DESIGN AND METHODS: A proposita with the At(a-) phenotype was identified by the finding of anti-Ata in the cord blood eluate of her fifth live infant. Family members were studied, and a small aliquot of 51Cr-labeled At(a+) red cells was transfused to determine survival. RESULTS: There was no evidence of hemolytic disease of the newborn, as determined by the normal hemoglobin and bilirubin and normal clinical conditions. Six of seven siblings were tested, and two At(a-) female siblings were identified. In contrast to the proposita, neither sister had detectable anti-Ata in her serum, although each has had only one pregnancy. A monocyte monolayer assay performed on serum from the proposita gave a result of 20-percent hemolysis (normal, <3%), which is consistent with a clinically significant antibody. Transfusion of a small volume of allogeneic red cells that were phenotypically matched with the proposita, except for Ata, resulted in a 1-hour survival of 95 percent, but a 24-hour survival of only 18 percent, of the transfused cells. The survival pattern was exponential, which is characteristic of a non-complement-binding IgG antibody. CONCLUSION: Despite the absence of hemolytic disease of the newborn, this example of anti-Ata would appear to be a clinically significant antibody for the purposes of transfusion practice. Therefore, approaches to the management of clinical situations in which transfusion is required or likely should focus on the availability of autologous cells or frozen allogeneic At(a-) red cells.

Black People↗
PubMed1995

In vitro and in vivo effects of prestorage filtration of apheresis platelets.

BACKGROUND: The effect of prestorage filtration on the quality of apheresis platelet concentrates stored for transfusion is undetermined. STUDY DESIGN AND METHODS: Investigation of 11 plateletpheresis components used a concurrent paired-study design. On the day of collection, each component was equally divided into two suspensions; one half was filtered, and the other half was not. Each suspension was stored for 5 days. In vitro testing was performed on the day of collection (Day 0) for cell counts and on Day 5 for measurements of lactate, glucose, blood gases, pH, platelet ATP, hypotonic stress ratio, extent of shape change in response to ADP, tissue necrosis factor alpha, interleukin 8, interleukin 1 alpha, interleukin 1 beta, interleukin 6, and platelet surface glycoproteins by flow cytometry. At the end of the 5-day period, a sample was taken from each of the two suspensions, radiolabeled with either 51Cr or 111In, and transfused concurrently. Posttransfusion samples were drawn for measurements of recovery and platelet survival and for functional assessment of the ex vivo ability of the circulating radiolabeled platelets to aggregate in response to ADP. RESULTS: The apheresis component had a mean platelet yield of 3.2 +/- 0.4 x 10(11) and a white cell yield ranging from 1 x 10(5) to 1 x 10(8), with a median of 2 x 10(7). Filtration resulted in a platelet loss of approximately 10 percent and a variable 2 to 3 log10 reduction in white cell content. No significant differences between filtered and unfiltered suspensions in paired t tests that would likely have an impact on platelet quality were observed in the in vitro tests. The in vivo recovery and survival were highly similar and not statistically different in filtered and unfiltered paired suspensions: the mean difference was 1.2 +/- 4.0 percent for recovery and 7.0 +/- 15 hours for survival. The functional assessment by aggregation to ADP showed no difference between filtered and unfiltered suspensions. A small decrease in tumor necrosis factor alpha and interleukin 8 was evident in the filtered suspension as compared to levels in the unfiltered suspensions. CONCLUSION: Prestorage white cell reduction in apheresis components resulted in WBC reduction by several log10 with no evident adverse effect on platelet viability or function.

Blood Platelets↗
PubMed1995

White cell-reduced platelet concentrates prepared by in-line filtration of platelet-rich plasma.

BACKGROUND: The importance of white cell (WBC) reduction in platelet concentrates (PCs) for component quality is undetermined. STUDY DESIGN AND METHODS: Eleven paired components, each derived from one of two whole-blood units given by a single donor on the same day, were studied. One PC was WBC reduced by filtration with an in-line, integral, prototype filter, and the other was produced from unfiltered platelet-rich plasma (PRP) by a standard method. In vitro tests performed on Day 1 and Day 5 were blood gases, plasma lactate, glucose, platelet ATP, mean platelet volume, morphology score, hypotonic stress ratio, extent of shape change in response to ADP, and beta-thromboglobulin. After 5 days of storage, each component pair was labeled with 51Cr or 111In and transfused for the estimation of percent recovery and survival. RESULTS: PCs using the in-line, prototypic filter had a platelet loss of approximately 15 percent and a variable 1 to 3 log10 reduction (average, 95%) in WBC content. The variation in filter WBC removal was related to PRP WBC content and indicated that the filter did not have the capacity for a 3 to 4 log10 removal when PRP WBC content exceeded 1 x 10(8). The in vitro and in vivo measures of platelet quality showed no meaningful differences between filtered and unfiltered PCs by paired t test. The mean differences in posttransfusion percent recoveries and survivals were 0.9 +/- 2.9 percent and 4 +/- 13 hours, respectively. Additional studies were performed using a larger filter with improved capacity. Those studies (n = 18) showed a significant improvement in filtration time and platelet yield and a consistent 3 to 4 log10 reduction in WBCs. Filtration time was 6.6 +/- 2.7 minutes, total PC WBCs were 9.6 +/- 4.6 x 10(4), and total PC platelets were 7.8 +/- 1.8 x 10(10) (mean +/- SD). CONCLUSION: Prestorage filtration of PRP and the preparation of filtered platelets do not result in any significant beneficial or adverse effect on subsequent platelet quality. With the large-capacity filter, consistent WBC reduction and good platelet yields are achieved.

Blood Donors↗
PubMed1994

Storage of apheresis platelets after gamma radiation.

BACKGROUND: There are conflicting data on the effect of irradiation and subsequent storage on the quality of platelet components. STUDY DESIGN AND METHODS: The retention of platelet properties during storage of gamma-irradiated apheresis suspensions was studied in 22 apheresis components obtained on a cell separator with a specialized centrifugation chamber. Immediately after collection, each suspension was divided equally into two 1-L polyolefin containers. On Day 1 (n = 12) and Day 3 (n = 10) one of each pair of suspension containers was gamma radiated with 2500 cGy. All platelet suspensions were stored for 5 days at 20 to 24 degrees C. Samples were drawn on Day 5 from each of the 22 pairs of containers for evaluation of an array of in vitro properties. Samples were taken from 10 pairs of containers for platelet labeling with either 51Cr or 111In for subsequent transfusion and concurrent in vivo measurement of recovery and survival. Posttransfusion samples were drawn after 24 hours for ex vivo whole blood aggregation. RESULTS: Comparable in vitro and in vivo properties were measured in irradiated and control platelets, whether irradiation was performed on Day 1 or Day 3. The mean +/- 1 SD in vivo recovery and survival time for controls and platelets irradiated on Day 1 was 52 +/- 14 percent and 146 +/- 34 hours and 51 +/- 7 percent and 147 +/- 36 hours, respectively. For Day 3 irradiation, the values were 46 +/- 12 percent and 150 +/- 60 hours and 47 +/- 9 percent and 151 +/- 53 hours, respectively. A small, but measurable adverse effect of irradiation on ex vivo platelet aggregation was present. CONCLUSION: These data indicate that storage of apheresis platelets after gamma radiation is without clinically significant, demonstrably adverse effects on platelet quality.

Blood Platelets↗
PubMed1993

Age-dependent effect on the level of factor IX.

Levels of factor IX:C and factor IX:Ag were measured in 120 healthy subjects with an age range of 1 to 67 years. Levels of factor IX:C were lowest in prepubertal subjects, then reached a plateau in early adult life with a secondary increase in later adult life (> 45 years). Changes in factor IX:Ag showed a similar trend. Factor IX:Ag disproportionately increased in early adult life, however, with a less pronounced increase in later life, resulting in peaking of the ratio in early adult life. It is suggested that caution be exercised in interpreting low normal factor IX:C levels in prepubertal children, and that interpretation of ratios of antigenic to coagulant activity may need to take subject age into consideration.

Adolescent↗
PubMed1993

A theoretical analysis of the "let-go" phenomenon.

A mathematical analysis is presented that provides a theoretical explanation for the "let-go" neuromuscular stimulation phenomenon. This analysis includes consideration of electrophysiological, bioelectrical, and anthropometric factors that are involved in accidental electrical stimulation of forearm musculature during "let-go."

Adolescent↗
PubMed1992

Intraplatelet von Willebrand factor and ABO blood group.

Levels of plasma Von Willebrand Factor (vWF) are known to be influenced by ABO Blood Group but such an influence on platelet vWF is not known. Forty-three healthy donors had blood drawn for measurement of plasma and platelet vWF, both antigenic (vWF:Ag) and functional (RCo). Twenty-six were Group O and seventeen were Group A. Groups did not differ in age, platelet count, hemoglobin, white cell counts, platelet rich plasma counts nor length of in vitro storage of samples prior to assay. Plasma levels of vWF:Ag and RCo was lower in Group O as expected. Platelet RCo was lower in Group O and such a trend was present for vWF:Ag. This influence of ABO Groups on platelet vWF was modest compared to that on plasma vWF.

ABO Blood-Group System↗
PubMed1992

Effects of prestorage white cell-reduction of apheresis platelets on platelet glycoprotein Ib and von Willebrand factor.

Twenty plateletpheresis components were harvested from 11 healthy donors and stored in polyolefin bags on a horizontal flatbed agitator at 22 degrees C. After 24 hours, white cells were reduced in one aliquot by centrifugation while the other aliquot was stored unaltered. Samples were obtained aseptically from each of these platelets at intervals for up to 10 days, and measurements were made of platelet glycoprotein Ib (GPIb) by both flow cytometry and polyacrylamide gel electrophoresis, of ristocetin-induced platelet aggregation by impedance aggregometry, and of plasma and platelet von Willebrand factor (vWF) by enzyme-linked immunosorbent assay. Storage of platelets under these conditions was associated with only minor decreases in surface GPIb, intraplatelet vWF, and ristocetin-induced platelet aggregation, and no differences were observed between the white cell-reduced and nonreduced aliquots. No benefit of white cell reduction in such components before prolonged storage is evident in the vWF-platelet interaction.

Blood Component Removal↗