Platelet kinetics in patients with idiopathic thrombocytopenic purpura and moderate thrombocytopenia

We studied ten normal subjects and 20 patients with stable, untreated idiopathic thrombocytopenic purpura (ITP) and platelet counts in the range of 35,000 to 110,000/microL. The diagnosis was made by clinical criteria. Platelet-associated IgG was increased in all nine of the nine patients studied. Autologous platelets were labeled with chromium 51 and reinfused for measurement of mean cell life and platelet production rate. Mean cell life was calculated by two methods, weighted mean and multiple hit, with excellent agreement between the two. As expected, mean cell life was significantly reduced in ITP patients as compared to the normal subjects (2.9 days v. 8.0 days, P less than .001). However, mean platelet production rates in ITP patients and normal subjects, 3.5 and 3.8 X 10(9) platelets/k/d respectively, were not significantly different. Platelet production rate was above and below the normal range (2 to 5.6 X 10(9) platelets/k/d) in two and four patients, respectively. We conclude that the rate of platelet production is not increased in most patients with ITP who have platelet counts greater than 35,000/microL. We did find that platelet size was increased in eight of the 12 patients in whom it was measured, including two of the patients with low platelet production.     

Granulocyte colony-stimulating factor administration to healthy volunteers: analysis of the immediate activating effects on circulating neutrophils

In four healthy volunteers, we analyzed in detail the immediate in vivo effects on circulating neutrophils of subcutaneous administration of 300 micrograms of granulocyte colony-stimulating factor (G-CSF). Neutrophil activation was assessed by measurement of degranulation. Mobilization of secretory vesicles was shown by a decrease in leukocyte alkaline phosphatase content of the circulating neutrophils. Furthermore, shortly postinjection, Fc gamma RIII was found to be upregulated from an intracellular pool that we identified by immunoelectron microscopy as secretory vesicles. Intravascular release of specific granules was shown by increased plasma levels of lactoferrin and by upregulation of the expression of CD66b and CD11b on circulating neutrophils. Moreover, measurement of fourfold elevated plasma levels of elastase, bound to its physiologic inhibitor alpha 1- antitrypsin, indicated mobilization of azurophil granules. However, no expression of CD63, a marker of azurophil granules, was observed on circulating neutrophils. G-CSF--induced mobilization of secretory vesicles and specific granules could be mimicked in whole blood cultures in vitro, in contrast to release of azurophil granules. Therefore, we postulate that the most activated neutrophils leave the circulation, as observed shortly postinjection, and undergo subsequent stimulation in the endothelial microenvironment, resulting in mobilization of azurophil granules. Our data demonstrate that G-CSF should be regarded as a potent immediate activator of neutrophils in vivo.     

High-dose etoposide and cyclophosphamide without bone marrow transplantation for resistant hematologic malignancy

Seventy-five patients with resistant acute leukemia or lymphoma received high-dose cyclophosphamide and etoposide to explore the activity of this combination in resistant hematologic malignancies, and to determine the maximum doses of these drugs that can be combined without bone marrow transplantation. Etoposide was administered over 29 to 69 hours by continuous infusion corresponding to total doses of 1.8 g/m2 to 4.8 g/m2. Cyclophosphamide, 50 mg/kg/d, was administered on 3 or 4 consecutive days total 150 to 200 mg/kg ideal body weight). At all dose levels myelosuppression was severe but reversible. Mucosal toxicity was dose-limiting with the maximum tolerated dose level combining etoposide 4.2 g/m2 with cyclophosphamide 200 mg/kg. Continuous etoposide infusion produced stable plasma levels that were lower than would be achieved after administration by short intravenous infusion, and this could explain our ability to escalate etoposide above the previously reported maximum tolerated dose. There were 28 complete (35%) and 12 partial (16%) responses. Median duration of complete response (CR) was 3.5 months (range 1.1 to 20+). Seventeen of 40 patients (42%) with acute myelogenous leukemia (AML) achieved CR, including 6 of 20 (30%) with high-dose cytosine arabinoside resistance. We conclude that bone marrow transplantation is not required after maximum tolerated doses of etoposide and cyclophosphamide. This regimen is active in resistant hematologic neoplasms, and the occurrence of CR in patients with high-dose cytosine arabinoside-resistant AML indicates a lack of complete cross-resistance between these regimens.     

Identification of glycoprotein Ib as a target for autoantibody in idiopathic (autoimmune) thrombocytopenic purpura

An antibody (DIL) from a patient with idiopathic thrombocytopenic purpura (ITP) was shown to have autospecificity on the basis of reactions with autologous platelets that were identical to those obtained with platelets from normal subjects. DIL antibody also reacted strongly in an immunofluorescence test with platelets from a patient with Glanzmann's thrombasthenia, but failed to react with platelets from a patient with the Bernard-Soulier syndrome who was known to be deficient in glycoprotein Ib (GPIb). Purified GPIb and control platelets, but not Bernard-Soulier platelets, inhibited the lytic activity of DIL. Using the GPIb-specific monoclonal antibody AP1 and one-dimensional rocket electrophoresis into gels containing rabbit antihuman platelet membrane antibody, it was shown that staphylococcal protein A-Sepharose beads coated with DIL antibody selectively remove GPIb from solubilized platelet preparations. By crossed immunoelectrophoresis it was found that DIL recognizes a determinant on GPIb on the membrane side of the cleavage site of the platelet calcium- activated protease (calpain). These studies provide direct evidence for binding of a platelet autoantibody to a determinant on GPIb relatively close to the site of insertion of this protein into the platelet membrane.     

Indices of body fat distribution and adiposity in Dutch children from birth to 18 years of age

Skinfold thicknesses, Quetelet index and waist-to-hip circumference ratio (WHR) were measured in 2285 Dutch children aged 0-17 years. Skinfold thicknesses, Quetelet index and WHR were significantly influenced by age. No significant differences were found between the sexes in Quetelet index. Skinfolds were generally higher in older girls compared to older boys. WHR and the trunk-to-total skinfolds percentage were used as possible indicators of body fat distribution. On average, boys had higher WHR and trunk-to-total skinfolds percentage than girls, especially in the older age groups. The WHR decreased from about 1.1 in the youngest children to about 0.8 in pubertal children. The trunk-to-total skinfolds percentage increased from about 42 per cent in both sexes at younger ages to about 60 per cent in pubertal boys and to about 52 per cent in pubertal girls. Several correlations were calculated controlled for age. Low but significant correlations were found between WHR and skinfold thicknesses or the Quetelet index. WHR was strongly inversely related to body height. In girls 58 per cent of the variation in skinfold thicknesses was associated with the Quetelet index, in boys this was 42 per cent. The prevalence of obesity in the studied population varied between 0.5 and 10 per cent according to the reference standard chosen to assess obesity. It is concluded that more research is necessary to assess whether the WHR in children is a valid indicator of body fat distribution, especially in prepubertal children. It is also concluded that more research is needed to develop a method for assessing childhood obesity in an objective way.     

Energy expenditure at rest and during activities: A comparison between young and elderly women

Energy expenditure at rest (resting metabolic rate, RMR) and during several activities was measured in 20 young (age 19–27 years) and 19 elderly (age 65–78 years) females. Fat-free mass (FFM) was estimated by means of a four compartment model which accounted for variability in water and bone mineral in the FFM. RMR was lower (P < 0.05) in the elderly (mean ± SE 3.55 ± 0.05 kJ/min) compared to the younger females (3.92 ± 0.09 kJ/min). However, after correction for differences in FFM between the groups, RMR was 3.71 ± 0.07 kJ/min and 3.77 ± 0.06 kJ/min for the elderly and young, respectively, and the difference was not significant. Energy expenditure (EE) during several activities, standing with arm movement, bicycling at 25 Watts, and walking at 3 km/h, were not different between the two groups. However, the physical activity ratios (PAR) for the activities were higher (P < 0.05) in the elderly (1.61 ± 0.03, 3.29 ± 0.07, 4.11 ± 0.16, respectively) than in the young (1.47 ± 0.03, 2.93 ± 0.05, 3.58 ± 0.14, respectively). EE due to physical activity alone (total EE minus RMR) was significantly higher for all activities in the elderly, except for walking at fixed speed of 3 km/h. After correction for the lower relative FFM in the elderly, differences between age groups disappeared. EE for walking 500 m at an individually selected speed was higher in the elderly, although they selected a lower walking speed. Differences between young and elderly decreased when step frequency was taken into account. It is concluded that EE due to physical activity in elderly women is higher than in younger females, but that the differences in EE due to physical activity are largely attributable to differences in body composition. © 1996 Wiley-Liss, Inc.     

The predictive validity of the Dutch Restrained Eating Scale

The present study aims to determine the predictive validity of the 10-item Dutch Restrained Eating Scale. The ultimate criterion of restrained eating is the degree to which an individual eats less than he or she actually would like to eat. Since a study on both actual food consumption and restriction of food intake is very complicated, if not impossible, the difference between actual and desired intake of energy was studied indirectly, that is, from estimates of deviations from the required energy intake. The relationships were studied between restrained eating scores and the magnitude of the deviation from energy requirement, and between restrained eating scores and intake of fat and sugar, because restriction in intake of these may also reflect dietary restraint. About 20% of the variance of scores on the Restrained Eating Scale could be explained from these measures of food intake, which suggests that the Dutch Restrained Eating Scale has moderate to good predictive validity.     

The Staphylococcus aureus lineage-specific markers collagen adhesin and toxic shock syndrome toxin 1 distinguish multilocus sequence typing clonal complexes within spa clonal complexes

Spa typing/based upon repeat pattern (BURP) sometimes cannot differentiate multilocus sequence typing (MLST) clonal complexes (CCs) within spa-CCs. It has been observed previously that virulence factors, such as collagen adhesin (CNA) and toxic shock syndrome toxin 1 (TSST-1), are associated with certain Staphylococcus aureus lineages. Analysis of methicillin-sensitive and methicillin-resistant S. aureus by spa typing/BURP and detection of CNA and TSST-1 observed an association between CNA and MLST CC1, 12, 22, 30, 45, 51, and 239 and between TSST-1 and MLST CC30. In spa-CC 012, associated with MLST CC7, CC15, and CC30, MLST CC30 could be distinguished from MLST CC7 and CC15 with CNA and TSST-1 as lineage-specific markers. Lineage-specific markers can overcome clustering of nonrelated MLST CCs into 1 spa-CC.