Herbert A. Cooper

Risk factors for recurrent fever after the discontinuation of empiric antibiotic therapy for fever and neutropenia in pediatric patients with a malignancy or hematologic condition

We studied episodes of fever and neutropenia in children and adolescents without documented infections to determine the risk of recurrent fever after early discontinuation of empiric antibiotic therapy; 213 episodes occurred in 106 patients. All patients received empiric antibiotic therapy after cultures were obtained. Antibiotic therapy was discontinued if no infection was found, culture results were negative for 48 hours, and the patient was afebrile for 24 hours. In 83 episodes without documented infection, antibiotic therapy was stopped with absolute neutrophil counts < 0.5 x 10(9)/L (< 500/mm3); 50 episodes occurred in patients with solid tumors, leukemia in remission, and other hematologic conditions (group 1), and 33 in patients with active leukemia (group 2). Fever recurred before neutropenia resolved in 6% of group 1 and 45% of group 2 episodes; five patients in group 2 had documented infection. Recurrent fever risk correlated with absolute neutrophil count and monocyte count at the time antibiotic therapy was stopped, in both groups, as did increasing absolute neutrophil count and increasing leukocyte count in group 2. We conclude that discontinuing antibiotic therapy is safe in febrile episodes without documented infections before neutropenia resolves in patients with high potential for bone marrow recovery. The risk of recurrent fever and infection is significant for patients with neutropenia and poor marrow recovery potential.

Central venous catheter use and the risk of infection in children with acute lymphoblastic leukemia: A report from the Children's Cancer Group

PURPOSE To describe patterns of central venous catheter (CVC) use and determine the risk of infection associated with a catheter in children with acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS Children with ALL (n = 1934), participating in Childrens Cancer Group studies for good-prognosis ALL (CCG-1881) and intermediate-risk ALL (CCG-1891) were evaluated in a retrospective case-control study. The presence of a catheter and the occurrence of infectious complications were recorded after each treatment phase. RESULTS Young age and enrollment in the intermediate-risk study were associated with higher rates of catheter use. During each of the first four phases of therapy, the adjusted risk of infection was two- to fourfold higher when a catheter was in place. The proportion of patients with infection during the first four phases of therapy was 2.6 times higher with a CVC (14.4% versus 5.7%). Catheter use was associated with significantly increased hospitalization rates during induction, consolidation, and interim maintenance, but not during delayed intensification. A catheter did not significantly increase the risk of fever during neutropenia. CONCLUSION The presence of a CVC increases the risk of infection during the early phases of low-intensity therapy for ALL.

A Naturally Occurring Antibody That Inhibits Fibrin Polymerization

A 13-year-old girl with chronic aggressive hepatitis, postnecrotic cirrhosis, ulcerative colitis, and a coagulation defect acquired an antibody that specifically interfered with fibrin formation. We sought to characterize the antibody and determine the mechanism of its inhibitory activity. The patients purified fibrinogen was functionally normal; however, the antibody inhibited the self-assembly of fibrin and prolonged the clotting times of the patients plasma. This antibody, which belonged to the IgG class of immunoglobulins, acted early in the polymerization process to inhibit the association of fibrin monomers, as indicated by a prolonged lag time and a decreased slope in the polymerization curves. It did not inhibit fibrinopeptide cleavage or fibrin cross-linking. Affinity chromatography indicated that the antibody bound strongly to both fibrinogen and fibrin monomer.

The Defect in Hemophilic and von Willebrand's Disease Plasmas Studied by a Recombination Technique

Factor VIII in preparations from normal plasma is a large glycoprotein of greater than 2 million molecular weight which elutes in the exclusion volume of 4% agarose gels at an ionic strength of 0.15. Recent studies have demonstrated that the factor VIII in canine and bovine plasma is a macromolecular complex composed of a large inert carrier protein and a noncovalently bound small fragment which contains the procoagulant active site. This complex is dissociable in 0.25 M CaCl(2), and conditions for its recombination have been reported. The present study reports the dissociation characteristics of normal human factor VIII preparations in 0.25 M CaCl(2) and the ability to achieve quantitative recombination of the dissociated fragments of normal human and bovine factor VIII after the removal of Ca(2+). The recombination technique was used to characterize further the defect in hemophilia and von Willebrands disease. Void volume preparations from human hemophilia A(-), canine hemophilia A, and human von Willebrands plasma, with no factor VIII procoagulant activity, were mixed with the small active fragment prepared from the normal plasma of their respective species. Chromatography of the three mixtures in agarose gel showed that the fractions from the human hemophilic plasmas contained a molecule that bound the small active normal fragment, but neither the fractions from canine hemophilia A plasmas nor the fractions from the human von Willebrands plasmas demonstrated evidence of such material. These data suggest that there is present in human hemophilia A plasma a normal functional carrier molecule which is absent or nonfunctional in the plasma of hemophilic dogs and humans with von Willebrands disease.

Depressive symptomatology in parents of children with chronic oncologic or hematologic disease

This study identified the frequency of depressive symptomatology in parents of children who were recently diagnosed with a chronic oncologic or hematologic disorder and explored the relationship between intrusion coping, avoidance coping, parental perceptions of support, perceptions of the severity of the childs illness, and depressive symptomatology. A repeated measures design involving a convenience sample of 32 parents (23 mothers and 9 fathers) completed questionnaires within 6 months of their childs diagnosis (Time 1) and 21 parents (17 mothers and 4 fathers) who completed them a second time approximately 12 months later ( Time 2). Fourteen of the 32 parents at Time I and 7 (all mothers) of the 21 parents at Time 2 had scores indicating depressive symptomatology. No significant change in mean depression scores occurred between Time 1 and Time 2. Avoidance coping was the only variable that significantly predicted depressive symptomatology at Time 1. These findings have significance for health care p...

Parallel characterization of bovine von Willebrand protein (factor VIII-associated protein) by light scattering and SDS gel electrophoresis

Highly purified bovine von Willebrand protein (vWP) has been studied with two complementary techniques. Light scattering measurements on different samples give weight average molecular weights in the range from 7 to 13 million, radius of gyration between 75 and 140 nm and diffusion coefficient near 4.15 X 10(-8) cm2/sec. Scans after electrophoresis in sodium dodecyl sulfate on 2% agarose gels, stained with Coomassie blue, allow calculation of a mass distribution over a series of oligomers with relative size in a range from 1 to 20. The ratio of the average mol. wt. from light scattering and the average size for the observed distribution, which is the mol. wt. increment for successive vWP oligomers, has been determined and found to be 1.0 million. This implies that the molecules of vWP are oligomers of subunits themselves consisting of 4 polypeptide chains each of mol. wt. circa 250,000.

A light-scattering study of bovine factor VIII.

Classical light-scattering measurements made on bovine Factor VIII preparations, which contain a series of multimers ranging from 1 greater than 12 X 10(6) molecular weight, gave a weight average molecular weight of about 8 X 10(6) and a z-average radius of gyration of about 3000 A. Characteristic dimensions for variously shaped models were calculated.

Structure-Function of the Factor VIII Complex Studied with an Immobilized Heteroantisera to VIII:C

An antibody was raised in rabbits to the small active fragment of human factor VIII, obtained by Ca2+ dissociation of a human factor VIII preparation made from a multidonor plasma pool. After absorption, the antibody neutralized the factor VIII coagulant activity of normal human plasma, but did not precipitate with any plasma or plasma fractions or neutralize von Willebrand factor (vWF) activity as measured by ristocetin aggregation of fixed washed platelets. Immune beads were prepared by CNBr binding of the partially purified rabbit antibody to 1% agarose beads. Non‐immune beads were prepared with IgG fractions obtained from the rabbits before immunization and used throughout as a control. The amount of factor VIII coagulant activity (VIII:C) removed from plasma by immune beads was time‐dependent and proportional to the amount of beads used, but all of the VIII:C could not be readily removed. Removal of VIII:C by immune beads parallelled removal of factor VIII:antigen, but less vWF activity was removed. Immune beads could be blocked or saturated by treatment with large amounts of normal plasma, but not by von Willebrand disease plasma and only by some haemophilic plasmas.

PROTEOLYSIS OF HUMAN FIXED, WASHED PLATELETS BY GRAM‐NEGATIVE BACTERIAL METALLOPROTEASES: EFFECT ON von WILLEBRAND FACTOR‐HUMAN PLATELET INTERACTIONS*

Fixed, washed platelets (FWP) are usually stable to aggregation with von Willebrand factor (vWF) from human and certain animal plasmas over several months of storage. When one lot of FWP lost its stability in less than 1 week, studies demonstrated contamination with Serratia marcescens. Extracellular proteases produced by s. marcescens, as well as by Pseudomonas aeruginosa and Esherichia coli, were found to cause loss of FWP aggregability. Purified proteases were prepared from cell‐free culture filtrates of S. marcescens and two different strains of P. aeruginosa. They were used to study the effect on the interaction of FWP and vWF. All three purified proteases destroyed FWP aggregability in a time‐ and concentration‐dependent fashion. The protease produced by S. marcescens (SP) was found to be at least eight times more potent against FWP as a substrate than either of the two P. aeruginosa enzymes. The ability of SP to destroy FWP aggregability was prevented by EDTA and could be restored by the addition of Zn2+ in slight molar excess. When compared with trypsin and chymotrypsin, SP was found to be highly selective in digesting the FWP membrane, even at concentrations greater than that established to give a similar loss of FWP aggregability. SP does not induce aggregation of fresh, washed platelets or PRP, but renders them un‐aggregable with vWF. These proteases may be useful research tools for studying membranes and vWF‐platelet interactions.

802 VARIANT VON WILLEBRAND'S DISEASE (vWD): ABNORMALITY IN MULTIMERIC ASSEMBLY OF FACTOR VIII RELATED ANTIGEN (VIIIRAg)

Factor VIII in normal plasma is a complex of at least two molecules, VIIIRAg and VIIIC, each having distinct functional and antigenic properties. VIIIRAg normally assembles as a series of multimeric forms ranging from 1 to >20×106 daltons. We show, using a new crossed immuno-electrophoresis procedure, the importance of identifying alterations in the distribution of these multimeric forms. A normal distribution for at least 5 distinct forms of VIIIRAg was established using both pooled and individual plasmas. The slowest migrating form contained the most of the antigen while the four faster forms had progressively decreasing concentrations. Two patients presented as possible vWD variants because of prolonged bleeding times and low ristocetin cofactor activity despite normal to elevated levels of VIIIRAg. Both plasmas showed essentially complete absence of the larger multimers and an absolute increase in the concentration of the anodal forms that corresponded to the faster migrating forms in normal plasma. An additional faster migrating form was found in one of the plasmas. Patterns of cryo-supernatant and commercial FVIII preparations were similar to the variant patterns; cryoprecipitate resembled more closely the normal plasma pattern. Results suggest that some types of vWD can result from an abnormality in the ability of VIIIRAg to assemble into the larger multimeric forms and supports the hypothesis that the largest forms of VIIIRAg are necessary for normal hemostasis through participation in platelet-vessel wall interactions.