Problems with platelet counting in thrombocytopenia. A rapid manual method to measure low platelet counts.

Because most automated platelet counters cannot be relied on in thrombocytopenia, clinicians face a problem when decision making is based on platelet counts. Therefore we evaluated a visual platelet counting method from a blood smear with white blood cells (WBCs) as reference (PCW = platelet count based on WBC). Platelet counting for 74 thrombocytopenic (<120 x 10(9)/L) children was performed with PCW and with an automated counter (impedance principle); both methods were compared with evaluation by phase-contrast microscopy as the standard method. The PCW correlated well with the phase-contrast microscopy evaluation (y = -0.38 + 1.01x, r2 = 0.99). For platelet counts <20 x 10(9)/L the maximal deviation was 2 x 10(9)/L. The correlation between automated counts and the standard method was poor. The regression was y = 9.63 + 0.94x, r2 = 0.86. For platelet counts <20 x 10(9)/L the maximal deviation was 37 x 10(9)/L; on average, 7 x 10(9)/L platelets were counted in excess when compared with the standard method. PCW, in contrast to the automated impedance method, discriminated platelets from nonplatelet particles such as debris, fragments of red blood cells (hemolytic-uremic syndrome [HUS]) and of blast cells, and identified platelets of abnormal size. In addition, the appearance ofplatelets, WBCs, and RBCs gave clues to the etiology of thrombocytopenia, such as leukemia, infection, HUS, familial macrothrombocytopenia, and immune thrombocytopenia. PCW is a fast, reliable platelet counting method requiring less experience than the phase-contrast method. Visual evaluation from a stained smear clearly differentiates platelets and nonplatelet particles in contrast to most automated counters. In addition, the original smear can be preserved and reevaluated.

Acute immune thrombocytopenia (ITP) in childhood: retrospective and prospective survey in Germany.

Treatment of acute childhood immune thrombocytopenia (ITP) is controversial. For information on the present situation in Germany, a retrospective and a prospective survey were carried out. In the retrospective survey, questionnaires were sent to all German pediatric hospitals asking about local policies for handling ITP and whether in the preceding year (starting on October 1995) death or ICH had occurred; 86% answered. In the prospective survey, 94% responded to the mailings ("have you seen a case of ITP?") sent in monthly intervals between October 1, 1996 and September 30, 1997; 89% of the questionnaires were retrieved. In the retrospective survey, no deaths and no ICH were reported. If only mild bleedings, such as skin bleeds alone (or additional mild mucous membrane bleeding) were present, 20.5% (26.4%) preferred the "watchful waiting" regimen (supportive care), irrespective of the platelet count; 79.5% (73.6%) would treat if the platelet counts were <5 x 10(9)/L, 73.5% (67.9%) if < 10, 35.9% (33.6%) if < 20, and 4.2% (2.6%) if <30. Of the treaters, 50.5% would prefer immunoglobulins (Ig), 24.4% glucocorticosteroids (GC), and 20.5% GC and/or Ig. Generally, a rise in platelets, most frequently >50 x 10(9)/L was considered as therapeutic success. In the prospective survey, from the reported 323 children an annual incidence of 2.16 per 100,000 children was calculated. The incidence depended on age and gender, being highest for boys younger than 2 years with 5.8 (girls 3.42) and low with 0.44 for boys (girls 0.89) older than l4 years. About 60% of the patients had a preceding infection. Although 83% had a platelet count <20 x 10(9)/L (56% <10 x 10(9)/L), almost all (97.5%) had only mild bleeding symptoms; 2.5% had serious bleeding symptoms requiring blood transfusion or nasal packing, none had ICH, and no death was reported. The mean platelet count on admission was 11.348 (lowest count 8.253) x 10(9)/L. Sixty-one percent received Ig, 19% GC (both either alone or as first choice), 6% Ig plus GC, and 14% no treatment. Side effects were reported in 22% of the children treated with Ig. The retrospective survey mirrored the uncertainty in regard to treatment. The prospective survey provided new aspects on incidence, age, and gender distribution. Although almost all patients had only mild bleeding symptoms, most received Ig and/or GC. The decision to treat depended mainly on the platelet count. From these surveys, conclusions about the effectiveness of treatment cannot be drawn. Recommendations based primarily on platelet counts must be reconsidered.

In vivo histamine release during the first minutes after deliberate sting challenges correlates with the severity of allergic symptoms.

In this study, deliberate sting challenge was investigated as a method for estimating the severity of anaphylactic reactions in bee venom-sensitized subjects. Twenty-one patients with previous anaphylactic reactions to field bee sting were subjected to a deliberate sting challenge (n = 32). To document anaphylactic reactions, plasma histamine levels were measured before, and then 1 and 2 min after, bee sting challenge. Eleven patients were re-challenged after 3-5 weeks. On 18 occasions, sting challenges caused no systemic reactions, in seven cases reactions were mild, in five moderate and in two severe. In all children showing systemic reactions, significant increases of plasma histamine were measured after 2 min. The results correlated significantly with clinical scores but not with skin prick test or with specific immunoglobulin E (IgE) and immunoglobulin G (IgG) antibodies against bee venom. In patients developing local reactions only, no increase of plasma histamine was detected. The relative amount of released histamine correlated significantly with the severity of clinical symptoms. Significant histamine release occured during the first 2 min after sting challenge in children with subsequent systemic reactions and the severity of these subsequent anaphylactic reactions correlated with plasma histamine concentrations. The measurement of plasma histamine levels in the first minutes after challenge test may therefore be used as an objective marker of a potential systemic reaction.

Prevalence of antibodies against HEp-2 cell antigen in infants and children hospitalized with respiratory syncytial virus infection.

Infants with respiratory syncytial virus (RSV) infection were shown to have antibodies against HEp-2 cell antigen present in RSV-antigen preparation used for immunoblot analysis. The prevalence of anti HEp-2 cell antibodies was examined in infants hospitalized for RSV infection (n = 49, median age 121 days) compared to rotavirus infected children (n = 30, median age 114 days) and to healthy controls (n = 20, median age 150 days). The immunoblot analysis with RSV-infected and non-infected HEp-2 cells as antigen revealed the expected age-dependent low prevalence of G protein antibodies and clear seroconversion of N and P protein antibodies. HEp-2 antibody prevalence was higher in RSV antigen-positive infants (33/49) than in rotavirus antigen-positive (5/30) and RSV antigen-negative infants (4/20), respectively (p < 0.001). Anti HEp-2 antibodies were mostly directed against 47, 46, 33, 30 kD antigens. A multiple regression analysis found the following correlations (odds ratio; 95% confidence interval): 42 kD RSV antibodies (N protein) with pneumonia (7.58; 1.43-40), 94 kD RSV antibodies (G protein) with bronchiolitis (0.064; 0.006-0.686). This study shows repeated well-known features of humoral immunity in RSV infection. The data on anti HEp-2 antibodies point to a role for these pre-existing autoreactive antibodies in the pathogenesis of RSV infection.

MxA protein in infants and children with respiratory tract infection.

MxA protein--a stable product of cells stimulated by type I interferons--was examined prospectively for its ability to discriminate between viral and bacterial respiratory tract infections (RTIs) in 182 infants and children. The nasopharyngeal secretions (NPSs) of all of them were tested for MxA using enzyme-linked immunosorbent assay (ELISA), and the whole blood of 92. Seventy-three children undergoing elective surgery served as controls. These apparently healthy children had higher levels of serum MxA than adult controls. Using antigen detection and serology, a viral aetiology was diagnosed in 81/182 cases. The sensitivity and specificity of MxA ELISA were assessed at 92 and 76% for the blood test and at 40 and 91% for the NPS, respectively. The positive predictive value for a viral RTI was superior to a leucocyte count or C-reactive protein when determined only once.

Anaphylactic reactions to bee-sting challenges in allergic children are not modified by endogenous catecholamines.

To investigate the role of basal catecholamine levels and the response of the adrenergic system to expected bee stings, plasma catecholamines were measured before and 1 and 2 min after bee-sting challenges. Twenty-one children (aged 4-15 y) with bee-sting allergies were selected for sequential challenges to establish the need for venom immunotherapy. The time interval between the challenges varied from 2 to 6 wk. Epinephrine, norepinephrine, and dopamine plasma levels were measured using a simultaneous single-isotope radioenzymatic assay. On the first challenge, 33% of the children experienced a normal local reaction, 29% a large local reaction, and 38% a systemic reaction. On the second challenge in 18 out of 21 subjects, 67% experienced a normal normal local reaction, 22% a large local reaction, and 11% a systemic reaction. Epinephrine and norepinephrine plasma levels increased significantly on the first and second challenges. Dopamine plasma levels showed a significant increase on the first challenge only. Plasma catecholamine levels after the second challenge revealed a significant positive correlation between epinephrine increases measured 1 and 2 min after the challenge and the concomitant sting reaction. Basal epinephrine, norepinephrine, and dopamine plasma levels did not differ significantly between patients who experienced different types of sting reactions. Based on our data, we conclude that clinical reactions to in-hospital insect-sting challenges are not affected by early increases in plasma catecholamine levels produced by the expected stress situation.

Subsequent insect stings in children with hypersensitivity to Hymenoptera.

To investigate the risk of life-threatening reactions to future stings, we sequentially challenged 113 children (aged 2 to 17 years) allergic to insect stings with a sting by the relevant insect. The time interval between the challenges varied from 2 to 6 weeks. The history of the index stings was a large local reaction (LR) in 16% and a systemic reaction (SR) in 84% of the test subjects. On the first challenge, 76% had a normal LR, 11% a large LR, and 13% an SR. On the second challenge, 78% of the children had a normal LR, 5% a large LR, and 17% an SR. Thirty-nine of the untreated children were exposed to a field sting during the subsequent 3-year follow-up period. In comparison with other diagnostic evaluations such as skin-prick tests, determinations of specific IgE and IgG antibodies, and single-sting exposure, the dual sting challenge scheme appears to be the best predictor of reactions to subsequent stings. It also appears to be helpful in selecting patients with an uncertain sensitization status for venom immunotherapy.

Renal involvement in tuberous sclerosis complex: a retrospective survey.

In a retrospective survey performed in Germany and Switzerland, 207 patients (ranging in age from newborn to 70 years) were evaluated in order to establish the frequency, prognosis and diagnostic awareness of kidney involvement in the tuberous sclerosis complex. Renal manifestations were observed in 48% of patients: renal cysts (33 patients), renal angiomyolipoma (AML) (30 patients), a combination of both (8 patients), renal cell carcinoma (3 patients), life-threatening events such as haemorrhage (4 patients), hypertensive crisis (2 patients) and chronic renal failure (10 patients) were also documented. The diagnostic imaging techniques of ultrasonography, intravenous urography, computed tomography and magnetic resonance imaging (MRI) are important but do not always yield definitive information. Differentiation between AML and cysts can be achieved using special MRI techniques (RARE). The potential for renal involvement should be monitored in all patients with the tuberous sclerosis complex.

Oxygen uptake transient kinetics during constant-load exercise in children after operations of ventricular septal defect, tetralogy of Fallot, transposition of the great arteries, or tricuspid valve atresia.

Cardiovascular function accounts for endurance performance and, by a rapid increase in oxygen supply at the onset of exercise, contributes to short-lasting intensive exertion prevailing in many kinds of sports activities. This study determined the time for oxygen uptake (VO2) to reach one half of its asymptotic level above rest, and the respective oxygen deficit following the onset of a constant-load exercise corresponding to 80% to 90% of the maximal oxygen uptake (VO2max) in 35 children after surgical closure of a ventricular septal defect, after corrective surgery for tetralogy of Fallot, or after the Senning, Mustard, or Fontan procedures. In addition, VO2max and maximal blood lactate were determined. The half-time of VO2 response and oxygen deficit was lowest in patients after closure of a ventricular septal defect, whereas children had the most unfavorable VO2 transient kinetics after Fontan operation or with a transannular patch after correction of tetralogy of Fallot. A negative correlation was evaluated between half-time of VO2 response and VO2max, whereas maximal blood lactate varied independently of VO2max. It is concluded that many children with decreased VO2max after cardiac surgery also have unfavorable VO2 transient kinetics. In addition to being less qualified for endurance performance, they are also less prepared for short-lasting intensive energy expenditure. Therefore, the primary aim of training in these children is to improve the economy of motion of the respective tasks.

Oxygen deficit and blood lactate in prepubertal boys during exercise above the anaerobic threshold.

Recent studies have shown that in boys a steady-state of blood lactate is maintained at exercise levels above the anaerobic threshold. Therefore, the explanation hitherto provided for the steeper increase in blood lactate beyond the anaerobic threshold, i.e. the onset of anaerobic metabolism, needs modification. Investigations were carried out in ten boys, aged 11-12 years, during treadmill running. Maximal oxygen uptake (VO2max) and maximal blood lactate were determined during incremental exercise. Subsequently each boy performed four runs at different high constant speeds of 16 min duration, in order to determine maximal steady-state blood lactate. The underlying data also served to estimate roughly the lactate anaerobic threshold. Oxygen uptaken (VO2) was measured at 0.5 min intervals during the initial 7.5 min of each constant-speed run. Maximal steady-state blood lactate was 5.6 mmol/l corresponding to 92% of VO2max. The mean blood lactate at which the anaerobic threshold was reached or just exceeded was 2.7 mmol/l corresponding to 82% of VO2max. Oxygen transport transient kinetics were computed from the mean 0.5 min VO2-values during the constant-speed runs near the maximal steady-state blood lactate and from runs near the anaerobic threshold. Half-times of VO2 response were shorter than values previously reported for adults due to a faster increase in VO2 at the onset of exercise. Half-times increased with increasing work rates as did the oxygen deficit, due to a slower increase in VO2 along with a longer time required to attain a steady-state at higher work rates.(ABSTRACT TRUNCATED AT 250 WORDS)

[Changes in blood coagulation in treatment with ALL-BFM-90 and NHL-BFM-90 protocols]. / Gerinnungsveränderungen bei Behandlung mit den Protokollen ALL-BFM-90 und NHL-BFM-90.

1. Treatment according to the ALL/NHL-BFM 90 protocol I (induction phase) caused multiple and severe coagulation changes in all 14 patients of our study. Glucocorticoids alone made Fibrinogen drop to 148 mg/dl, AT III and Protein C rise to 136% or even 179% respectively. After day 12, immediately following the start of therapy with Coli-Asparaginase (ASP), fibrinogen continued to drop to reach its lowest average value of 46 mg/dl on day 24. Anticoagulant factors like plasminogen (lowest average value: 36%), AT III (47%) and Protein C (93%) dropped abruptly. These alterations were reversed after discontinuation of Glucocorticoids and ASP. During consolidation (protocol II) similar alterations are observed as in protocol I when Glucocorticoids are applied alone. However, after Erwinia-ASP there is no fall in AT III, plasminogen, and Protein C as is observed in protocol I with Coli-ASP. 2. Severe hemorrhages or thromboses are uncommon as compared to the degree of coagulation changes which can be regularly observed. Complications occur more often in girls. Most of them are seen during the 2nd or 3rd week of simultaneous ASP-Glucocorticoid therapy. 3. To avoid twofold alteration of hemostasis it should be considered to apply Glucocorticoids and ASP separately and to replace Coli-ASP by Erwinia-ASP. The efficacy of prophylactic replacement of decreased coagulation factors has not yet been confirmed. Immunologic and infectious side effects have to be taken into consideration. 4. More definite recommendations can be given when each suspected bleeding and/or thrombosis is confirmed by imaging procedures, when it is documented and registered, and when coagulation studies are performed during the critical phase.