Platelet function abnormalities in qualified whole-blood donors: effects of medication and recent food intake.

BACKGROUND AND OBJECTIVES: Platelet function abnormalities have been reported in blood donors who have not consumed aspirin. Our objective was to identify factors other than aspirin that may contribute to impaired platelet function in qualified volunteer blood donors. MATERIALS AND METHODS: Blood samples were obtained from 24 donors following routine blood donation. Donors completed a study questionnaire that included questions about recent food consumption, medication and medical history. Platelet activation was measured using monoclonal antibodies and flow cytometry. CD62P expression and PAC-1 binding on platelets were used as indicators of platelet activation. Platelet function was measured on a platelet function analyser (PFA-100) using both collagen/epinephrine (cEPI) and collagen/ADP (cADP) cartridges. RESULTS: Fifty-four per cent of donors (13 of 24) had normal platelet function. Thirty-eight per cent (nine of 24) had prolonged cEPI closure times, of whom four (17%) had no cEPI closure (> 300 seconds). No closure was associated with aspirin use (two donors) or chocolate consumption (two donors) before donation. Two donors (8%) had either a shortened cEPI or cADP closure time. CONCLUSIONS: Platelet dysfunction in qualified blood donors is underestimated. Platelet function screening can identify donors with diet-related platelet dysfunction or with poor recollection of aspirin use.

Evaluation of a new automated quantitative d-dimer, Advanced D-Dimer, in patients suspected of venous thromboembolism.

The objective of our study was to evaluate the performance characteristics of a new automated d-dimer, the Advanced D-Dimer (Dade Behring Inc., Deerfield, IL) for use in the diagnosis of venous thromboembolism (VTE). To do this we compared the Advanced D-Dimer to existing d-dimer methods using established target cut-off values in patients suspected of VTE who were to undergo definitive radiographic studies for VTE. We studied hospitalized patients and outpatients who were suspected of having VTE and who had whole blood d-dimer performed. The patients who underwent a diagnostic study for VTE had their D-dimer results used to determine sensitivity, specificity and negative predictive values. There was relatively poor correlation between the Advanced D-Dimer and D-Dimer Gold (r = 0.63; t-test: P < 0.005) and Asserachrome D-Di (r = 0.58; t-test: P < 0.005). The Advanced D-Dimer target cutoff values for excluding VTE in hospitalized and outpatients were < or = 1800 microg/L and < or = 1500 microg/l respectively. There were 139 patients suspected with pulmonary embolism (PE) and 328 evaluated for deep vein thrombosis (DVT). There were 24 patients with PE, and 43 with DVT. The Advanced D-Dimer had comparable sensitivity, specificity and negative predictive values (96, 43, 98% for PE and 96, 48, 99% for DVT respectively) to other d-dimer methods used for that purpose. We conclude that the Advanced D-Dimer correlates relatively poorly with enzyme-linked immunosorbent assay methods. This poor correlation is likely due to incorrect reporting units and concentration. When these factors are corrected correlations improved. Compared to existing d-dimer methods used for VTE exclusion, the high sensitivity and negative predictive value would suggest that this method can be used as part of a diagnostic algorithm for the exclusion of PE and DVT.

Practical utility of the D-dimer assay for excluding thromboembolism in severely injured trauma patients.

BACKGROUND: We have advocated the use of a D-dimer assay to exclude the diagnosis of pulmonary embolism (PE) and deep venous thrombosis (DVT) in surgical and trauma patients suspected of having these diagnoses. Injury is known to increase D-dimer levels independent of thromboembolism. The purpose of this study was to assess the period after injury over which the D-dimer assay remains positive because of injury exclusive of thromboembolism. METHODS: We prospectively sampled the plasma of severely injured patients for D-dimer using an enzyme-linked immunosorbent assay method at admission; at hours 8, 16, 24, and 48; and at days 3, 4, 5, and 6. Patients were then screened for DVT with a routine duplex Doppler at day 7. Patients were followed for PE, adult respiratory distress syndrome, and disseminated intravascular coagulation. RESULTS: One hundred fifty-four patients (mean Injury Severity Score of 23) underwent a total of 1,230 D-dimer assays. Twenty-six (17%) had thromboembolism. Nine (6%) patients developed DVT, 2 (1%) developed PE, 13 (8%) developed disseminated intravascular coagulation, and 11 (7%) developed severe adult respiratory distress syndrome. None of the trauma patients with thromboembolism had a (false) negative D-dimer at or after the time of their thromboembolic complication. True-negative D-dimer results as a function of time from injury are: 0 hours, 18%; 8 hours, 16%; 16 hours, 17%; 24 hours, 22%; 48 hours, 37%; day 3, 34%; day 4, 32%; day 5, 30%; and day 6, 30%. The negative predictive value of the assay was 100%. D-dimer levels were significantly higher in those who developed a thromboembolic complication than in those who did not (independent of Injury Severity Score). CONCLUSION: These data serve to validate D-dimer as a means of excluding thromboembolism, specifically in patients with severe injury (100% negative predictive value). Before 48 hours after injury, however, the vast majority of these patients without thromboembolism had positive D-dimer assays. Because of the high false-positive rate early after severe injury, the D-dimer assay may be of little value before postinjury hour 48.

Correlation of abnormal intracranial vessel velocity, measured by transcranial Doppler ultrasonography, with abnormal conjunctival vessel velocity, measured by computer-assisted intravital microscopy, in sickle cell disease.

The Stroke Prevention Trial has confirmed that utilization of transcranial Doppler ultrasonography (TCD), which examines blood flow in large intracranial vessels, can identify children with sickle cell disease (SCD) who are at high risk of developing a premature stroke. It is not known to what extent the vasculopathy in SCD involves small vessels and whether the abnormalities, if present, correlate with large-vessel vasculopathy. Eighteen children with SCD were examined with TCD to determine middle cerebral artery (MCA) velocity and computer-assisted intravital microscopy (CAIM) to determine bulbar conjunctival vessel velocity during the same visit for vasculopathy correlation. High MCA velocity (> or = 200 cm/sec) was found by TCD in 4 patients who also showed abnormal conjunctival velocity (< 0.2 mm/sec or intermittent trickle flow) by CAIM. Three patients had conditional (> or = 170 cm/sec and < 200 cm/sec) MCA velocity: 2 showed abnormal (trickle) and 1 showed normal conjunctival velocity (1.9 mm/sec). One patient with unmeasurable MCA velocity had abnormal (trickle) conjunctival velocity. Of the remaining 10 patients who had normal MCA velocity, 2 showed abnormal (0.05 mm/sec and 0.1 mm/sec) and 8 showed normal conjunctival velocities (1.1-2.4 mm/sec). The MCA velocities correlated significantly with bulbar conjunctival flow velocities (P < or =.008, Fisher exact test). A correlation exists between MCA (large-vessel) and conjunctival (small-vessel) flow velocities. CAIM is a noninvasive quantitative technique that might contribute to the identification of SCD patients at high risk of stroke. Small-vessel vasculopathy might be an important pathological indicator and should be further explored in a large-scale study. (Blood. 2001;97:3401-3404)

Anticoagulation of children undergoing cardiopulmonary bypass is overestimated by current monitoring techniques.

HYPOTHESIS: Children who undergo cardiopulmonary bypass (CPB) are proportionally more hemodiluted than adults who undergo CPB. Current methods of monitoring high-dose heparin sulfate anticoagulation are dependent on fibrinogen level. Because of the decreased fibrinogen levels in children, current methods of monitoring heparin anticoagulation overestimate their level of anticoagulation. DESIGN: Prospective controlled trial. MAIN OUTCOME MEASURE: Production of thrombin (adequacy of anticoagulation). METHODS: Children and adults undergoing cardiac surgery who received CPB were anticoagulated in the standard fashion as directed by activated clotting time (ACT) results. Each subject had blood sampled at baseline; heparinization; start of the CPB; CPB at 30, 60, and 90 minutes; and at termination of CPB. Samples were used to assess anticoagulation with the Heparin Management Test (less dependent on fibrinogen level than ACT). We also assessed 2 subclinical markers of thrombosis, thrombin-antithrombin complexes and prothrombin fragment F1.2; a marker of procoagulant reserve, fibrinogen; the natural antithrombotic, antithrombin; and heparin concentration. RESULTS: Ten children and 10 adults completed the study. Children had lower fibrinogen levels than adults throughout CPB (P<.05). All adults had both therapeutic ACT and Heparin Management Test levels measured throughout CPB. Although children had therapeutic ACT levels, their Heparin Management Test levels were subtherapeutic while undergoing CPB. The children had significantly higher thrombin-antithrombin complexes and prothrombin fragment F1.2 than adults, indicating ongoing thrombin production (P<.01). The increases in thrombin-antithrombin complexes and prothrombin fragment F1.2 in children were inversely proportional to their weight. CONCLUSIONS: Children undergoing CPB with heparin dosing adjusted to optimize the ACT manifest inadequate anticoagulation (ongoing thrombin formation). High-dose heparin anticoagulation therapy in children undergoing CPB should be directed by tests (like the Heparin Management Test) that are less dependent on fibrinogen level than ACT.

A comparison of point-of-care instruments designed for monitoring oral anticoagulation with standard laboratory methods.

Our study compared point-of-care (POC) device monitoring with traditional clinical laboratory methods device of patients on oral anticoagulant therapy. The POC devices used in the study were Coumatrak, CoaguChek, CoaguChek Plus, Thrombolytic Assessment System (TAS) PT-One, TAS PTNC, TAS PT, Hemachron Jr. Signature, ProTime Microcoagulation System, and Medtronics ACT II. The clinical laboratory method used thromboplastins with different ISI values: Innovin and Thromboplastin C Plus (TPC). All POC INRs showed strong correlation with both laboratory methods, with correlation coefficients of >0.900. All POC methods demonstrated a significant (p <0.05) difference in INR values, except the TAS PTNC and ACT II INRs (p: 0.12 and 0.71 respectively) when compared with Innovin INRs. All POC INRs were significantly different from TPC generated INRs (p <0.05). Comparisons of the POC INRs to the group mean of the POC methods, show higher correlation (R>0.93), but there were still significant (p<0.05) differences noted between the POC group INR mean and CoaguChek Plus, ACT II, TAS PT-One, TAS PTNC, and Hemachron Jr Signature INRs. These data indicate that POC INR biases exist between laboratory methods and POC devices. Until a suitable whole blood INR standardization method is available, we conclude that clinicians using point-of-care anticoagulation monitoring should be aware of differences between POC and parent laboratory values.

Whole blood D-dimer assay: an effective noninvasive method to rule out pulmonary embolism.

BACKGROUND: The whole blood D-dimer assay has gained recognition as a noninvasive test to rule out pulmonary embolism (PE) in medical patients. METHODS: We performed a whole blood D-dimer assay in medical and surgical patients undergoing either pulmonary angiogram or pulmonary ventilation perfusion scan for suspected PE or duplex Doppler or venogram for suspected deep venous thrombosis (DVT). RESULTS: A total of 483 patients were enrolled; 16 were excluded because of an equivocal pulmonary ventilation perfusion scan. The 467 remaining patients had a mean age of 56 +/- 27 years. There were 258 women and 209 men. A total of 353 patients were admitted to a medical service and 114 to surgery/ trauma. A total of 82 patients (18%) developed thromboembolism: 20 had PE, and 62 had DVT. CONCLUSION: No surgical patient with PE or DVT (n = 27) had a negative D-dimer. A negative D-dimer result in a stable surgical patient should be considered conclusive evidence to rule out thromboembolism and, thus, negate the need for further diagnostic studies. In our surgical patients suspected of DVT or PE, had D-dimer been used, one third of the patients would have avoided an expensive or invasive diagnostic test.

A new method for measuring D-dimer using immunoturbidometry: a study of 255 patients with suspected pulmonary embolism and deep vein thrombosis.

D-Dimer testing has been suggested as a non-invasive method for the exclusion of pulmonary embolism (PE) and deep vein thrombosis (DVT). In this study, we compared a new method, the Miniquant D-dimer (Biopool International, Ventura, California, USA) to other previously validated D-dimer methods used for the purpose. Patients who were undergoing a definitive diagnostic study for thromboembolism had a blood sample drawn at that time. A whole-blood D-dimer (SimpliRed; Agen Biomedical Ltd, Brisbane, Australia) test was performed, and residual plasma was frozen and later analyzed using two enzyme-linked immunosorbent assay (ELISA) methods (D-dimer Gold; Agen, and Asserachrome D-Di; Stago International, Parsippany, New Jersey, USA) and the Miniquant D-dimer. Once all samples were analyzed, the correlation and accuracy of the Miniquant was compared with the ELISA method using Spearman's regression and Dunn's multiple paired comparison. All D-dimer methods were compared with radiographic studies. The data was analyzed collectively and segregated into in-patient (n = 112) and out-patient (n = 143) populations. The Miniquant D-dimer sensitivity, specificity and negative predictive value (NPV) for all patients were 95, 21, and 94% for DVT, and 100, 26, and 100% for PE. This new D-dimer method demonstrates acceptable sensitivity in patients with PE and DVT and, based on the high NPV of this method, it can be used for the exclusion of thromboembolism.

PFA-100 system: a new method for assessment of platelet dysfunction.

The PFA-100 system is a platelet function analyzer designed to measure platelet-related primary hemostasis. The instrument uses two disposable cartridges: a collagen/epinephrine (CEPI) and a collagen/ADP (CADP) cartridge. Previous experience has shown that CEPI cartridges detect qualitative platelet defects, including acetylsalicylic acid (ASA)-induced abnormalities, while CADP cartridges detect only thrombocytopathies and not ASA use. In this seven-center trial, 206 healthy subjects and 176 persons with various platelet-related defects, including 127 ASA users, were studied. The platelet function status was determined by a platelet function test panel. Comparisons were made as to how well the defects were identified by the PFA-100 system and by platelet aggregometry. The reference intervals for both cartridges, testing the 206 healthy subjects, were similar to values described in smaller studies in the literature [mean closure time (CT) 132 s for CEPI and 93 s for CADP]. The use of different lot numbers of cartridges or duplicate versus singleton testing revealed no differences. Compared with the platelet function status, the PFA-100 system had a clinical sensitivity of 94.9% and a specificity of 88.8%. For aggregometry, a sensitivity of 94.3% and a specificity of 88.3% were obtained. These values are based on all 382 specimens. A separate analysis of sensitivity by type of platelet defect, ASA use versus congenital thrombocytopathies, revealed for the PFA-100 system a 94.5% sensitivity in identifying ASA users and a 95.9% sensitivity in identifying the other defects. For aggregometry, the values were 100% for ASA users and 79.6% for congenital defects. Analysis of concordance between the PFA-100 system and aggregometry revealed no difference in clinical sensitivity and specificity between the systems (p > 0.9999). The overall agreement was 87.5%, with a Kappa index of 0.751. The two tests are thus equivalent in their ability to identify normal and abnormal platelet defects. Testing 126 subjects who took 325 mg ASA revealed that the PFA-100 system (CEPI) was able to detect 71.7% of ASA-induced defects with a positive predictive value of 97.8%. The overall clinical accuracy of the system, calculated from the area under the ROC curve, was 0.977. The data suggest that the PFA-100 system is highly accurate in discriminating normal from abnormal platelet function. The ease of operation of the instrument makes it a useful tool to use in screening patients for platelet-related hemostasis defects.

Solitary extramedullary plasmacytoma five years after successful cardiac transplantation: case report and review of the literature.

We document the occurrence of a solitary extramedullary plasmacytoma (SEP) in a cardiac transplant patient. The diagnosis of plasma cell malignancy was confirmed by histopathologic and immunohistochemical examination of a nodular skin lesion. A complete systemic evaluation showed no evidence of metastatic disease. The patient was treated locally with radiation therapy (RT), but disseminated multiple myeloma developed 4 months after diagnosis. A variety of tumors have been reported to develop in the cardiac or renal transplant recipient, although plasma cell malignancies are rare. To our knowledge, this is the first reported case of an SEP in an organ transplant recipient.

Treatment-related parameters predicting efficacy of Lym-1 radioimmunotherapy in patients with B-lymphocytic malignancies.

This study was designed to evaluate dosimetric, pharmacokinetic, and other treatment-related parameters as predictors of outcome in patients with advanced B-lymphocytic malignancies. Fifty-seven patients were treated with radiolabeled Lym-1 antibody in early phase trials between 1985 and 1994. Logistic regression and proportional hazards models were used to evaluate treatment parameters for their ability to predict outcome, taking into account patient risk group based on Karnofsky performance status and serum lactic dehydrogenase. The occurrence of a partial or complete response (31 of 57 patients) and development of human antimouse antibody (HAMA) predicted improved survival using a time-dependent proportional hazards model. The final multivariate model for survival with parameters significant at P

Nutritional factors required for alcoholic liver disease in rats.

Decades ago it was suggested that nutritional factors are important in the development of alcoholic liver disease (ALD). However, several models of experimental alcoholism considered that the diets fed to animals were nutritionally adequate, complete and balanced. Therefore, a concept prevailed that the effects observed were due to alcohol per se and that they occurred despite a nutritionally adequate status in the animal. Examination of various models revealed that animals were malnourished because they ingested reduced levels of macro- and micronutrients. Furthermore, they consumed only small amounts of carbohydrate and a high level of unsaturated fat for long periods during the development of ALD. Alcoholic rats show many effects of inadequate nutritional status, such as a slow growth, depressed levels of liver glycogen and pancreatic amylase, enhanced protein degradation and circulating levels of branched-chain amino acids, and increased levels of enzymes involved in gluconeogenesis and alterations in the activities of enzymes related to the metabolism of carbohydrate as compared with controls. Chronic consumption of alcohol did not result in fatty liver, high blood alcohol concentration (BAC) or other observed effects when intake of energy, carbohydrate and other nutrients was increased. Furthermore, pre-existing effects of alcohol consumption, such as fatty liver, BAC and delayed gastric emptying, were reversed in rats receiving increased energy and carbohydrate intakes while continuing alcohol ingestion. Thus, nutritional status of the animal determines the production or prevention of ALD or other effects that were considered to be due to alcohol alone.

Prognostic factors for radioimmunotherapy in patients with B-lymphocytic malignancies.

The Ann Arbor staging classification has proven less useful in nonHodgkin's lymphoma, because this malignancy is inherently a multifocal disorder. Since 1985, 57 adult patients with advanced B-lymphocytic malignancies that progressed despite standard therapy entered into one of three different therapy trials using radiolabeled Lym-1 antibody. Tumor regression in 31 (54%) of these patients fulfilled conventional requirements for an oncological response to the therapy. To define the role of radioimmunotherapy in B-lymphocytic malignancies better and to find opportunities for improving its therapeutic efficacy, the records of these patients were reviewed to assess the significance of various parameters as prognostic indicators. Twenty-one pretherapy characteristics were evaluated, including age at diagnosis, age at study entry, sex, Karnofsky performance status, prior chemotherapy and radiation therapy, interval since diagnosis, histology, constitutional B symptoms, extranodal malignancy (excluding marrow), bone marrow malignancy, tumor bulk, and circulating malignant cells; blood tests included lymphocyte, granulocyte, platelet, hematocrit, serum lactate dehydrogenase (LDH), interleukin 2 receptor, and human antimouse antibody levels. In the multivariate analysis, LDH and Karnofsky performance status were the parameters that best predicted survival, complete and partial remission, and time to progression; interleukin 2 receptor and LDH best predicted complete remission. These prognostic factors for radioimmunotherapy outcome are consistent with the pretherapy characteristics observed to be significant for chemotherapy.

Induction of malnutrition in chronic alcoholism: role of gastric emptying.

Epidemiological studies reveal that chronic alcoholics exhibiting liver disease are generally malnourished. Experimental studies unequivocally demonstrate that incidence of malnutrition cannot be avoided in animals fed liquid diets containing high concentrations of alcohol. Furthermore, ingestion of additional amounts of macronutrients by such chronically alcoholic animals prevents or regresses alcohol-induced adverse effects despite a continuous intake of high amounts of alcohol. It is thus apparent that high amounts of alcohol intake and malnutrition are necessary factors to produce adverse effects in chronic alcoholism. The mechanism by which malnutrition manifests in chronic alcoholism is, however, not clear. Recent studies have demonstrated, a) an inverse relationship between alcohol and non-alcohol energy intake and its impact on alcohol-induced effects in chronically alcoholic rats, b) a synergism between malnutrition and high doses of alcohol intake in the induction of alcoholemia, and c) that chronic alcoholemia significantly prolongs the delay in gastric emptying. Data obtained from these studies enable us to hypothesize that abnormal prolongation of gastric emptying in alcoholics with chronic alcoholemia may play a major role in the initiation of macronutrient deficiencies leading eventually to the induction of malnutrition.

Unsaturated fat and low energy intake induce whereas an increment in energy intake ameliorates fatty liver during prolonged alcohol consumption by rats.

Two groups of rats were fed liquid diets containing 35% of energy as fat and either 36 or 26% of energy as alcohol to examine the effect of fat and energy intake on alcoholic fatty liver production. After 4 wk, five rats in each group were killed for analysis of liver triglyceride concentration, and then the alcohol diets fed to remaining rats were switched. All remaining rats were killed for hepatic triglyceride determination after another 4 wk. Rats initially fed the 36% alcohol diet or those switched to this diet ingested less energy, exhibited alcoholemia and slow growth, and developed fatty livers. Rats initially fed the 26% alcohol diet or those switched to this diet ingested significantly more energy, high amounts of alcohol and fat, exhibited low alcoholemia and faster growth than when they were fed the 36% alcohol diet. Fatty liver was absent in rats fed the 26% alcohol diet but was induced when they were fed the 36% alcohol diet. Fatty liver in rats initially fed the 36% alcohol diet regressed completely when the rats were switched to the 26% alcohol diet. Additional studies employing 36% alcohol diets containing 35% of energy as fat, derived from either corn oil or olive oil, revealed that unsaturated fat and not specifically linoleate plays a role in the induction of fatty liver. Thus, nutritional factors regulate the induction or regression of fatty liver and alcoholemia in alcoholic rats.

Carbohydrate intake determines pancreatic acinar amylase activity and release despite chronic alcoholemia in rats.

Adverse effects observed in alcoholic rats are often attributed to alcohol per se. Alcoholic liver damage, however, can be avoided by modulating nutritional factors despite high blood alcohol concentrations. Hence, we examined the effect of blood alcohol concentration on pancreatic enzyme activity and release. Three liquid diets containing 36 and 18% of total energy derived from alcohol and protein, respectively, were fed. Each alcohol diet contained 11, 21 or 31% of energy from carbohydrate, and the fat concentration was appropriately adjusted. The control groups of rats (fed an isoenergetic liquid diet without alcohol) and the alcoholic groups of rats were maintained for 2 wk. The three groups of alcoholic rats consumed 13.3 +/- 2.3, 13.3 +/- 2.2 and 13.2 +/- 1.9 g/kg of alcohol daily, and their corresponding blood alcohol levels were 41.5 +/- 4.3, 55.4 +/- 8.9 and 44.6 +/- 2.2 mmol/L. Pancreatic acinar amylase activity in alcoholic rats was proportional to carbohydrate ingested, despite high blood alcohol concentrations; chymotrypsin and trypsin activities were unchanged. Acinar enzyme activities in control rats were similar. Furthermore, cholecystokinin-octapeptide-stimulated amylase release in alcoholic rats corresponded with the amylase concentration in acini, whereas stimulated trypsin output was unaltered in both control and alcoholic rats. These results demonstrate that neither alcohol ingestion nor high blood alcohol concentration affects the activities of pancreatic proteases and that the changes in the activity and release of amylase are related to the intake of carbohydrate.