Altered glycosylation leads to Tr polyagglutination.

BACKGROUND: Polyagglutination refers to red blood cells (RBCs) that are agglutinated by a high proportion of ABO-matched adult sera but not by cord sera. Polyagglutinable RBCs have been associated with microbial infection, myeloproliferative disorders, and myelodysplasia. Lectins aid in the identification of polyagglutination. CASE STUDY: A Hispanic male infant with mild hemolytic anemia, a "Bernard-Soulier-like" syndrome, intermittent neutropenia, mitral valve regurgitation, ligament hyperlaxity, and mild mental retardation was studied. The patient's Group O RBCs were polyagglutinable; they were agglutinated by normal human sera, several lectins [including Arachis hypogea, Salvia sclarea, Salvia horminum, Glycine max, Ulex europaeus, Griffonia simplicifolia I, and Gr. simplicifolia II], and some monoclonal antibodies. His RBCs were not agglutinated by cord sera, Dolichos biflorus, or Phaseolus lunatus. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis on the RBC membranes followed by staining with periodic acid-Schiff stain showed markedly reduced staining of glycophorins A and B. Staining with Coomassie brilliant blue revealed that Band 3 has a faster mobility than normal. CONCLUSIONS: Collectively, the results suggest that the patient's RBCs have a reduction in N-acetylneuraminic acid on both N- and O-glycans, exposing, respectively, beta1,4-galactosidase and beta1,3-galactosidase. The patient likely has an altered glycosyltransferase that results in defective glycosylation in RBCs and other cell lineages. This type of polyagglutination was named Tr.

Prevalence and reversibility of lower airway obstruction in children with sickle cell disease.

OBJECTIVE: To determine the prevalence and reversibility of lower airway obstruction (LAO) in children and adolescents with hemoglobin SS sickle cell disease (HbSS SCD). STUDY DESIGN: Retrospective evaluation of lung function in a cross-section of 35 African American and 28 Hispanic children and adolescents with HbSS SCD. Lung function was evaluated with maximal respiratory flow-volume curves and body plethysmography. Each patient was assigned to 1 of 3 patterns of lung function (normal, obstructive, or restrictive). Airway hyperresponsiveness was assessed by means of a trial with bronchodilator. RESULTS: Normal pattern was detected in 57% of the patients, LAO in 35%, and restrictive lung disease in 8%. Positive response to bronchodilator was documented in 30% of those with normal pattern of lung function, 78% in those with LAO, and 67% of those with restrictive lung disease. The pattern of lung function was not associated with race or with history of vaso-occlusive crises, acute chest syndrome, reactive airways disease/asthma, or long-term transfusion therapy. CONCLUSION: Obstructive lung disease possibly precedes the development of restrictive lung disease, and airway reactivity may be part of the pathogenic mechanism.

Lung function in infants with sickle cell disease.

We performed pulmonary function testing in 20 infants (11 male and 9 female; ages 3-30 months) with sickle cell disease to assess whether abnormal lung function develops early in life. Respiratory system compliance (Crs) and resistance (Rrs) were measured by the passive occlusion technique, functional residual capacity (FRC) was measured by the nitrogen washout technique, and tidal flow-volume loops and partial expiratory flow-volume curves were obtained by the thoracoabdominal compression technique to detect airway obstruction. Patients with Hb SS (Group I, n = 12) had significantly lower hemoglobin levels and a higher (but not significant) incidence of acute chest syndrome (ACS), vasoocclusive crisis (VOC), splenic sequestration, transfusions, and history of intermittent bronchospasm compared to with patients with hemoglobinopathies Hb SC, Hb Sbt and Hb SF (Group II; n = 8). Both groups had elevated FRC, decreased maximum expiratory flows at FRC (V'max,FRC), and decreased time needed to reach peak expiratory flow (tme/tE), suggesting lower airway obstruction (LAO) and hyperinflation. Restrictive disease was found in only three patients of Group I. Our findings suggest that in sickle cell disease (especially among patients with Hb SS), abnormal lung function (predominantly LAO) may be present in early infancy. Airway reactivity may play a role in the pathogenesis, but the relation to VOC or ACS remains unclear.

Pulmonary embolism developing in patients with sickle cell disease on hypertransfusion and IV deferoxamine chelation therapy.

Pulmonary disease, including thromboembolic problems, accounts for a large portion of the morbidity of sickle cell disease. Chronic transfusion therapy is now a part of long-term treatment of sickle cell patients with stroke and chest syndrome. The resultant iron overload must be treated with chelation therapy using deferoxamine. Poor compliance with subcutaneous chelation therapy has necessitated intravenous deferoxamine treatment. We describe two patients with sickle cell disease on such a regimen, who became hypoxic as a result of pulmonary thromboembolism, secondary to venous thrombophlebitis. The thrombophlebitis and subsequent pulmonary embolism probably reflect the hypercoagulable state seen in sickle cell and are not due to the deferoxamine therapy.

Benign adenomatous kidney neoplasms in children with polycythemia: imaging findings.

PURPOSE: To correlate pathologic, computed tomographic (CT), and ultrasound (US) characteristics of nephrogenic adenofibromas and embryonal adenomas (uncommon pediatric renal tumors) in children. MATERIALS AND METHODS: Medical records and imaging and pathologic findings were reviewed in three children (aged 6 1/2, 7, and 11 years) with adenomatous renal tumors and polycythemia. Specimens were reviewed at the National Wilms Tumor Study Pathology Center (Loma Linda, Calif). RESULTS: All tumors were smaller than 3 cm in greatest dimension. They were hyperechoic on US scans and had high attenuation on unenhanced CT scans. Two patients underwent nephrectomy for initial diagnosis of Wilms tumor. The third underwent local excision. At pathologic examination, embryonal-appearing adenomatous epithelial cells were found to form tubules and papillae with abundant psammomatous calcifications. Two masses were classified as embryonal adenomas and one as nephrogenic adenofibroma. CONCLUSION: Increased attenuation on CT scans and increased echogenicity on US scans of renal adenomatous tumors are distinctive findings that may reflect the presence of tubulopapillary structures and psammomatous calcifications.

Effects of total hemoglobin and hemoglobin S concentration on cerebral blood flow during transfusion therapy to prevent stroke in sickle cell disease.

BACKGROUND: The standard treatment of stroke in sickle cell disease is chronic transfusion to maintain the fraction of abnormal hemoglobin (hemoglobin S [HbS]) below 20%. Risks associated with such transfusion can be reduced by allowing higher HbS levels, but the physiological consequences of this modification are unknown. Cerebral blood flow is elevated in sickle cell disease proportionate to the degree of anemia and is reduced by transfusion. We tested the effects of various HbS levels on cerebral blood flow during the course of transfusion therapy. CASE DESCRIPTIONS: We monitored cerebral blood flow (by the 133Xe inhalation method) in three patients whose chronic transfusion program was changed from a traditional regimen (HbS < 20%) to a moderate one, allowing HbS to rise to 45% to 50% between treatments. As expected, cerebral blood flow was higher with lower hemoglobin and higher HbS concentration. However, the HbS fraction appeared to exert a separate influence on the hyperemia, independent of total hemoglobin concentration. Furthermore, cerebral blood flow was higher during the modified regimen, despite equivalent anemia. CONCLUSIONS: These results suggest caution in adapting the modified transfusion regimen. Although HbS concentrations of 50% did not cause any frank neurological sequelae, the possible consequences of the associated hyperemia over time are unknown. We conclude that larger clinical and physiological studies of moderate transfusion regimens (allowing higher concentration of HbS) are necessary before it can become standard therapy.

Abnormal cranial magnetic resonance imaging scans in sickle-cell disease. Neurological correlates and clinical implications.

OBJECTIVE: Eight asymptomatic patients with sickle-cell disease (SCD) with magnetic resonance imaging (MRI) abnormalities consistent with cerebral infarcts (group 1) and eight asymptomatic patients with SCD with normal MRI scans (group 2) were followed up to assess the neurological correlates and the clinical outcome. DESIGN: Patients in the two cohorts underwent clinical evaluations and xenon 133 regional cerebral blood flow (rCBF) studies within 1 month of the entry MRI. This study sequence was repeated up to 5 years later. Neuropsychological studies also were performed in six group 1 patients and eight group 2 patients at the end of the study. SETTING: The patients were recruited from the Comprehensive Sickle Cell Center at Columbia University, New York, NY. PATIENTS: All patients had SCD, hemoglobin SS, and normal findings on clinical evaluation at entry. The group 1 cohort had clinically silent MRI abnormalities consistent with cerebral infarction. The group 2 cohort was age matched to group 1 and had normal MRI studies. INTERVENTIONS: None. MAIN OUTCOME MEASURE: The natural history of MRI abnormalities and the neurological correlates were assessed to determine the predictive value of subclinical MRI lesions as a risk factor for clinically apparent stroke. RESULTS: The mean duration of MRI follow-up was 3.7 years. In group 1, four patients (50%) demonstrated progressive MRI abnormalities and three patients (38%) became clinically symptomatic. In group 2, findings for all patients remained normal on clinical and radiological examination. Both groups had markedly elevated rCBF values. Individual rCBF differences correlated with the specific MRI abnormalities. The psychometric study results were similar in the two cohorts. Eighty-three percent of group 1 and 88% of group 2 patients had defective scores in one or more areas of cognitive functioning. Three patients met cognitive criteria for dementia. CONCLUSIONS: Cranial MRI abnormalities have important prognostic implications even when detected in clinically asymptomatic patients. Cognitive abnormalities exist in patients with SCD even in the absence of MRI abnormalities or clinical stroke.

Free protein S deficiency in acute ischemic stroke. A case-control study.

BACKGROUND AND PURPOSE: Deficiency of free protein S, a naturally occurring anticoagulant, may be acquired in the setting of acute illness and increasingly has become recognized as a possible stroke risk factor. We sought to determine whether free protein S deficiency is associated with acute cerebral infarction among older individuals at risk for stroke. METHODS: Free protein S was measured by Laurell rocket immunoelectrophoresis in 94 adults admitted for acute cerebral infarction and in 94 hospitalized control subjects of similar age, sex, and race. Patients with a history of cerebrovascular disease, acute thrombotic or hematologic diseases, or medical conditions known to cause free protein S deficiency were excluded from the control group. RESULTS: The percentage of patients with free protein S deficiency (< 20% normal total protein S) was similar in the case and control groups (21% versus 20%, respectively). Among all subjects, free protein S deficiency was more common in blacks than nonblacks (34% versus 13%, p = 0.001). A very low free protein S (< 15% normal total protein S) was more frequent among case patients than control subjects (11% versus 5%), but this trend failed to reach statistical significance. CONCLUSIONS: Free protein S deficiency is common among hospitalized patients, even in the absence of a recognized predisposing condition. Our findings indicate that acquired deficiency of free protein S is not a major risk factor for ischemic stroke.

An unusual complication in a gravida with factor IX deficiency: case report with review of the literature.

Factor IX deficiency (hemophilia B, Christmas disease) is an X-linked recessive coagulation disorder. It occurs in one out of every 25,000-30,000 male births and requires even rarer genetic circumstances for phenotypic expression in females. We report the occurrence of a large, late-trimester subchorionic hematoma in a gravida with factor IX deficiency and with laboratory evidence of consumptive coagulopathy during treatment. The patient was managed conservatively and had a successful outcome at term. The only four reported cases of antepartum management of factor IX deficiency in the English literature are reviewed.

Sequence of plasmin proteolysis at the NH2-terminus of the b beta-chain of human fibrinogen.

Employing high-performance liquid chromatography (HPLC), we have isolated and quantified the peptides that are released from the NH2-terminus of human fibrinogen B beta-chains by plasmin proteolysis. The peptides were identified by amino acid composition and by a radioimmunoassay developed for fibrinopeptide B detection. B beta 1-42 was the earliest fragment released during limited plasmin proteolysis. The level of this peptide reached a maximum and then began to decline during the course of the digestion. In addition, increasing levels of B beta 1-21 and of FPB followed the production of B beta 1-42. Using purified B beta 1-42 as a substrate, preferential cleavage was shown to occur at the 21-22 bond, with a minor cleavage at the 14-15 bond. Exhaustive digestion yielded two major components which were separated by HPLC: B beta 1-14 (FPB) and beta 22-42. The rate of cleavage at the 14-15 bond, which is the customary site of thrombin proteolysis, was not affected by the addition of hirudin indicating that this was not the result of trace contamination with thrombin. We have also examined plasmin proteolysis at the NH2-terminal region of the B beta-chains of a variety of fibrinogen derivatives and have found similar patterns of B beta 1-42 release. Using HPLC data, we have estimated the Km for plasmic cleavage of the beta 21-22 bond to be 1.8 X 10(-5) M and of the beta 14-15 bond to be 2.8 X 10(-5) M.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding of factors IX and IXa to cultured vascular endothelial cells.

Factor IX and its activated form IXa have been found to bind to confluent cultured bovine aortic and human umbilical vein endothelial cells. Binding of bovine factors IX and IXa to the bovine endothelial cells was saturable and specific and reached a plateau in 75 min at 4 degrees C and 30 min at 37 degrees C. Binding was half-maximal at a total factor IX or IXa concentration of 2.3 +/- 0.2 nM. At 4 degrees C, a maximum of 42 fmol of tritiated factor IX or IXa bound to 10(6) cells (an average of 20,000 molecules per cell). The binding of tritiated factor IX or IXa was inhibited by excess unlabeled factor IX or IXa but not by factor X, prothrombin, or thrombin. Competition studies indicated that factors IX and IXa interacted with the same site. Binding was reversible, with 50% of the specifically bound factor IX or IXa eluted in 40 min by a 400-fold excess of unlabeled protein. Specific binding required Ca2+ with half-maximal binding at 1.2 mM CaCl2. Factor IXa bound to the cells was tested for procoagulant activity in a clotting assay with factor IX-deficient plasma, cephalin, and CaCl2. Cell-bound factor IXa was at least 3-fold more active than was factor IXa in solution. The retention of procoagulant activity by cell surface-bound factor IXa provides a mechanism for the localization of clot-promoting activity.

The release of B beta 1-42 from fibrinogen and fibrin by plasmin.

The balance between thrombin and plasmin action has been postulated to be an important determinant of thrombosis. Measurement of plasma concentrations of fibrinopeptide A (FPA), which reflect thrombin action on the NH2-terminal end of the A alpha chain, and of B beta 1-42 (thrombin-increasable fibrinopeptide B immunoreactivity-TIFPB) which reflect plasmin action on the NH2-terminal end of the B beta chain have shown systematic changes in the relative concentrations of the two peptides in thrombotic states. This paper reports kinetic data for TIFPB release by plasmin using fibrinogen, fibrin I monomer, and fibrin I polymer as substrates. For fibrinogen and fibrin I monomer the data fit the Michaelis-Menten equation. Experiments were performed with human proteins in 0.15M Tris-buffered saline at pH 7.4 and at 37 degrees C. With fibrinogen as substrate the Km was calculated to be 0.87 microM and the Vmax 3.75 X 10(-5) M/min/unit of plasmin. With fibrin I monomer as the substrate the Km was calculated to be 1.25 microM and the Vmax 5.5 X 10(-5) M/min/unit of plasmin. With fibrin I polymer as substrate the data did not fit the Michaelis-Menten equation but there appeared to be no dramatic differences in rates from those obtained with the other two substrates. The influence of factor XIIIa-induced cross-linking of fibrin was not examined. It is concluded from these findings that fibrinogen and non-cross-linked fibrin I are equally good substrates for plasmin cleavage of the NH2-terminal end of the B beta chain.

Measurement of desarginine fibrinopeptide B in human blood.

Thrombin converts fibrinogen to fibrin in two steps. First fibrinopeptide A and fibrin I are formed and then fibrinopeptide B (B beta 1-14) and fibrin II. Since it is postulated that fibrin II is important in the genesis of thrombosis, it is of interest to measure fibrinopeptide B in peripheral blood samples. Previous difficulties in interpreting fibrinopeptide B immunoreactivity in plasma resulted from crossreaction of fibrinogen and of plasmin digest peptides B beta 1-42 and B beta 1-21 and from rapid loss of fibrinopeptide B immunoreactivity resulting from cleavage of arginine 14 by blood carboxypeptidase B. We have obviated these difficulties by removing fibrinogen from plasma by precipitation with ethanol and peptides B beta 1-21 and B beta 1-42 by adsorption on bentonite. Fibrinopeptide B is then converted to a desarginine fibrinopeptide B, which is measured in a new specific assay. Studies of the kinetics of fibrinopeptide cleavage showed that when whole blood was allowed to clot in vitro, fibrinopeptide A was cleaved more rapidly than fibrinopeptide B. In 18 patients on an acute care medical ward, desarginine fibrinopeptide B levels were lower than fibrinopeptide A levels and did not correlate with the levels of fibrinopeptide A or B beta 1-42. Desarginine fibrinopeptide B levels were less than 1 pmol/ml in all but two patients. In six patients receiving intraamniotic infusions of hypertonic saline to induce abortion, desarginine fibrinopeptide B levels increased 10-fold from the preinfusion mean level of 0.4 pmol/ml and then decreased. The pattern of changes resembled that of the fibrinopeptide A levels rather than of the B beta 1-42 levels. On the basis of these data it is suggested that plasma desarginine fibrinopeptide B levels reflect fibrin II formation in vivo.