Recombinant porcine factor VIII for high-risk surgery in paediatric congenital haemophilia A with high-titre inhibitor

INTRODUCTION

High-titre factor VIII (FVIII) inhibitors complicate peri-operative haemostasis. Recombinant porcine FVIII (r-pFVIII) may provide an alternative haemostatic agent for high-risk procedures and allow FVIII activity monitoring.

AIM

Devise an effective haemostatic plan for repair of a progressively symptomatic aortic coarctation in a 5-year-old male with immune tolerance induction (ITI) refractory high-titre FVIII inhibitors.

METHODS

Preprocedure human FVIII inhibitor titre was 58 Bethesda Units mL^-1 (BU) and cross-reacted to neutralize porcine FVIII at 30 BU. Daily ITI with plasma-derived FVIII concentrate was supplemented with anti-B-cell and anti-plasma cell immunotherapy to reduce FVIII inhibitor titres. Potential haemostatic agents were evaluated in comparative ex vivo thrombin generation assays (TGA).

RESULTS

Four weeks after immunosuppression, human and porcine inhibitor titres declined to 16 and 2 BU respectively. TGA with r-pFVIII was less robust than with activated prothrombin complex concentrate (aPCC); however, r-pFVIII was selected for cardiac surgery to secure the ability to assay FVIII levels throughout this high-bleeding risk procedure. Haemostasis with r-pFVIII was excellent; initial trough FVIII activity levels ranged from 0.81-1.17 IU mL^-1 . On postoperative day 3, peak and trough levels markedly declined suggesting a rising porcine inhibitor titre. Postprocedure prophylaxis was transitioned to aPCC, informed by TGA.

CONCLUSIONS

R-pFVIII provided effective peri-procedural haemostasis with no adverse events. Rapid neutralization of r-pFVIII after the first 60 hours, despite intensive immune suppression, accentuates the importance of careful monitoring. Use of TGA can support bypassing agent selection for convalescence. The comparative cost of r-pFVIII may limit its use to high morbidity clinical scenarios.

CSF 5-Methyltetrahydrofolate Serial Monitoring to Guide Treatment of Congenital Folate Malabsorption Due to Proton-Coupled Folate Transporter (PCFT) Deficiency

Hereditary folate malabsorption is characterized by folate deficiency with impaired folate transport into the central nervous system (CNS). This disease is characterized by megaloblastic anemia of early appearance, combined immunodeficiency, seizures, and cognitive impairment. The anemia and immunologic disease are responsive but neurological signs are refractory to folic-acid treatment. We report a 7-year-old girl who has congenital folate deficiency and SLC46A1 gene mutation who is unable to transport folate from her gut to the circulatory system and consequently from the blood to the cerebrospinal fluid (CSF). As a result she developed undetectable 5-methyltetrahydrofolate levels in her plasma and CSF and became immunocompromised and quite ill. Intramuscular treatment with 5-formyltetrahydrofolate (folinic acid) was therapeutic at her presentation and has been successful preventing other signs and symptoms of hereditary folate malabsorption even at relatively low CSF levels. Although difficult, early detection and diagnosis of cerebral folate deficiency are important because folinic acid at a pharmacologic dose may normalize outcome in PCFT gene defects, as well as bypass autoantibody-blocked folate receptors and enter the cerebrospinal fluid by way of the reduced folate carrier. This route elevates the 5-methyltetrahydrofolate level within the central nervous system and can prevent the neuropsychiatric disorder. CSF levels of 5-methyltetrahydrofolate between 18 and 46 nmol/L may be sufficient to eradicate CNS disease.

Rituximab for treatment of inhibitors in haemophilia A. A Phase II study

The development of antibodies against infused factor VIII (FVIII) in patients with haemophilia A is a serious complication leading to poorly controlled bleeding and increased morbidity. No treatment has been proven to reduce high titre antibodies in patients who fail immune tolerance induction or are not candidates for it. The Rituximab for the Treatment of Inhibitors in Congenital Hemophilia A (RICH) study was a phase II trial to assess whether rituximab can reduce anamnestic FVIII antibody (inhibitor) titres. Male subjects with severe congenital haemophilia A and an inhibitor titre ≥5 Bethesda Units/ml (BU) following a FVIII challenge infusion received rituximab 375 mg/m² weekly for weeks 1 through 4. Post-rituximab inhibitor titres were measured monthly from week 6 through week 22 to assess treatment response. Of 16 subjects who received at least one dose of rituximab, three (18.8%) met the criteria for a major response, defined as a fall in inhibitor titre to <5 BU, persisting after FVIII re-challenge. One subject had a minor response, defined as a fall in inhibitor titre to <5 BU, increasing to 5-10 BU after FVIII re-challenge, but <50% of the original peak inhibitor titre. Rituximab is useful in lowering inhibitor levels in patients, but its effect as a solo treatment strategy is modest. Future studies are indicated to determine the role of rituximab as an adjunctive therapy in immune tolerisation strategies.

The use of a single von Willebrand factor-containing, plasma-derived FVIII product in hemophilia A immune tolerance induction: the US experience

BACKGROUND

Inhibitors are a serious complication for patients with severe hemophilia A. Immune tolerance induction (ITI) is the primary method for eradicating these inhibitors. The role of type of concentrate and in particular the use of von Willebrand factor-containing, plasma-derived factor VIII (VWF/pd-FVIII) concentrate in primary or rescue ITI remains unclear.

OBJECTIVES

To report retrospective collection of data on the use of a single VWF/pd-FVIII concentrate in primary and rescue ITI.

METHODS

Retrospective chart review of hemophilia A inhibitor patients at 11 US institutions who received VWF/pd-FVIII concentrate in primary or rescue ITI.

RESULTS

Primary ITI was carried out in eight inhibitor patients with a 75% complete and partial success. Secondary ITI was carried out in 25 inhibitor patients, with 52% attaining complete or partial success.

CONCLUSIONS

This report represents the largest group of primarily pediatric, high-titer inhibitor patients treated with a single VWF/pd-FVIII concentrate. It adds retrospective data to the use of VWF-containing plasma-derived factor VIII concentrate in primary and rescue ITI, particularly in those patients with characteristics of poor response to ITI.

Quality of life in thalassemia: a comparison of SF-36 results from the thalassemia longitudinal cohort to reported literature and the US norms

Thalassemia is a chronic, inherited blood disorder, which, in its most severe form, causes life-threatening anemia. Advances in treatment have led to increased life expectancy however the need for chronic blood transfusions and chelation therapy remains a significant burden for patients. Our study compared health related quality of life (HRQOL) from the Thalassemia Clinical Research Network's (TCRNs) Thalassemia Longitudinal Cohort (TLC) study to US norms and assessed association with clinical variables. There were 264 patients over age 14 who completed the Medical Outcomes Study 36-Item Short Form Health Survey version 2 (SF36v2) baseline assessment. When compared to US norms, TLC patients had statistically significant (P < 0.05) worse HRQOL on five of the eight subscales (physical functioning, role-physical, general health, social functioning, and role-emotional) and on both summary scales (physical component summary and mental component summary). Women, older patients, and those with more disease complications and side effects from chelation reported lower HRQOL. In general, adolescents and adults with thalassemia report worse HRQOL than the US population, despite contemporary therapy. The SF-36 should become a standard instrument for assessing HRQOL in thalassemia to determine predictors of low HRQOL which may be better addressed by a multidisciplinary team.

Direct-to-consumer advertising for bleeding disorders: a content analysis and expert evaluation of advertising claims

OBJECTIVE

In the United States, the Food and Drug Administration (FDA) requires that all direct-to-consumer advertising (DTCA) contain both an accurate statement of a medication's effects ('truth') and an even-handed discussion of its benefits and risks/adverse effects ('fair balance'). DTCA for medications to treat rare diseases such as bleeding disorders is unlikely to be given high priority for FDA review.

METHODS

We reviewed all DTCA for bleeding disorder products appearing in the patient-directed magazine HemeAware from January 2004 to June 2006. We categorized the information presented in each advertisement as benefit, risk/adverse effect, or neither, and assessed the amount of text and type size devoted to each. We also assessed the readability of each type of text using the Flesch Reading Ease Score (FRES, where a score of >or=65 is considered of average readability), and assessed the accuracy of the advertising claims utilizing a panel of five bleeding disorder experts.

RESULTS

A total of 39 unique advertisements for 12 products were found. On average, approximately twice the amount of text was devoted to benefits as compared with risks/adverse effects, and the latter was more difficult to read [FRES of 32.0 for benefits vs. 20.5 for risks/adverse effects, a difference of 11.5 (95% CI: 4.5-18.5)]. Only about two-thirds of the advertising claims were considered by a majority of the experts to be based on at least low-quality evidence.

CONCLUSION

As measured by our methods, print DTCA for bleeding disorders may not reach the FDA's standards of truth and fair balance.

Rituximab for adolescents with haemophilia and high titre inhibitors

Neutralizing alloantibodies (inhibitors) to factor VIII or factor IX develop in approximately 25% of patients with haemophilia A and <3% of patients with haemophilia B treated with factor concentrate. Patients with high titre inhibitors, in whom immune tolerance therapy fails, have few treatment options. Targeted anti-B-cell therapy with rituximab (chimeric anti-CD20) has been useful in several antibody-mediated autoimmune states. Case reports of rituximab treatment in small numbers of haemophilia patients with inhibitors have been inconclusive. We describe three adolescent patients with severe haemophilia and inhibitors treated with four weekly doses of rituximab, 375 mg m(-2). Treatment with rituximab was effective in reducing the inhibitor titre in two of three patients. Rituximab may be beneficial for patients with severe haemophilia and inhibitors in whom standard therapies have failed, but larger prospective studies are required to determine safety, efficacy and predictors of success.

Deletion of SLC19A2, the high affinity thiamine transporter, causes selective inner hair cell loss and an auditory neuropathy phenotype

Mutations in the gene coding for the high-affinity thiamine transporter Slc19a2 underlie the clinical syndrome known as thiamine-responsive megaloblastic anemia (TRMA) characterized by anemia, diabetes, and sensorineural hearing loss. To create a mouse model of this disease, a mutant line was created with targeted disruption of the gene. Cochlear function is normal in these mutants when maintained on a high-thiamine diet. When challenged with a low-thiamine diet, Slc19a2-null mice showed 40-60 dB threshold elevations by auditory brainstem response (ABR), but only 10-20 dB elevation by otoacoustic emission (OAE) measures. Wild-type mice retain normal hearing on either diet. Cochlear histological analysis showed a pattern uncommon for sensorineural hearing loss: selective loss of inner hair cells after 1-2 weeks on low thiamine and significantly greater inner than outer hair cell loss after longer low-thiamine challenges. Such a pattern is consistent with the observed discrepancy between ABR and OAE threshold shifts. The possible role of thiamine transport in other reported cases of selective inner hair cell loss is considered.

Lymphoid apoptosis and myeloid hyperplasia in CCAAT displacement protein mutant mice

CCAAT displacement protein (cux/CDP) is an atypical homeodomain protein that represses expression of several developmentally regulated lymphoid and myeloid genes in vitro, including gp91-phox, immunoglobulin heavy chain, the T-cell receptor beta and gamma chains, and CD8. To determine how this activity affects cell development in vivo, a hypomorphic allele of cux/CDP was created by gene targeting. Homozygous mutant mice (cux/CDP(Delta HD/Delta HD)) demonstrated a partial neonatal lethality phenotype. Surviving animals suffered from a wasting disease, which usually resulted in death between 2 and 3 weeks of age. Analysis of T lymphopoiesis demonstrated that cux/CDP(Delta HD/Delta HD) mice had dramatically reduced thymic cellularity due to enhanced apoptosis, with a preferential loss of CD4(+)CD8(+) thymocytes. Ectopic CD25 expression was also observed in maturing thymocytes. B lymphopoiesis was also perturbed, with a 2- to 3-fold reduction in total bone marrow B-lineage cells and a preferential loss of cells in transition from pro-B/pre-BI to pre-BII stages due to enhanced apoptosis. These lymphoid abnormalities were independent of effects related to antigen receptor rearrangement. In contrast to the lymphoid demise, cux/CDP(Delta HD/Delta HD) mice demonstrated myeloid hyperplasia. Bone marrow reconstitution experiments identified that many of the hematopoietic defects were linked to microenvironmental effects, suggesting that underexpression of survival factors or overexpression of death-inducing factors accounted for the phenotypes observed. Tumor necrosis factor (TNF) levels were elevated in several tissues, especially thymus, suggesting that TNF may be a target gene for cux/CDP-mediated repression. These data suggest that cux/CDP regulates normal hematopoiesis, in part, by modulating the levels of survival and/or apoptosis factors expressed by the microenvironment.

Coagulation abnormalities in pediatric and adult patients after sclerotherapy or embolization of vascular anomalies

OBJECTIVE

The purpose of our study was to examine the coagulation status in patients with vascular anomalies who had undergone sclerotherapy or embolization.

SUBJECTS AND METHODS

Ours was a prospective pilot study of 29 patients who had undergone sclerotherapy or embolization of large vascular anomalies. Fibrinogen, platelet, and d-dimer levels and prothrombin time were obtained before, immediately after, and on the day after the procedure.

RESULTS

Five patients with venous malformations had positive d-dimer levels before the procedure. A subgroup analysis revealed a relationship between the type of agent used and the change in coagulation status. Specifically, a positive relationship was found between the use of dehydrated alcohol or sodium tetradecyl sulfate and a disruption in coagulation profiles as evidenced by a decrease in platelets and fibrinogen, an increase in prothrombin time, and a conversion from negative to positive d-dimers. In contrast, sclerotherapy or embolization with cyanoacrylic, polyvinyl alcohol foam particles, or platinum microcoils was not associated with coagulation disturbances.

CONCLUSION

The coagulation disturbances that occur in response to dehydrated alcohol or sodium tetradecyl sulfate sclerotherapy or embolization could compromise the patient's clotting ability. Patients who receive dehydrated alcohol or sodium tetradecyl sulfate during a preoperative sclerotherapy or embolization may experience coagulation disturbances that could increase the risk of bleeding, thrombosis, or hematoma. This patient population may benefit from the use of glue, foam, or coils as a substitute for dehydrated alcohol or sodium tetradecyl sulfate.

Inflammatory bowel disease associated with immune thrombocytopenic purpura in children

OBJECTIVE

Previous reports suggest an association between inflammatory bowel disease (IBD) and immune thrombocytopenic purpura (ITP) in adults. To date, only five children with both diseases have been described. The aim of the study was to describe the characteristics of children with IBD and ITP.

METHODS

Cases were obtained from the pediatric gastroenterology community by means of the pediatric gastroenterology internet bulletin board in June 1999. Eight cases were submitted from seven medical centers. Medical records were reviewed by two pediatric gastroenterologists and a pediatric hematologist.

RESULTS

The age range of the patients was 2.1 to 16.5 years, with a mean age of 9.6 +/- 5.2 years. Four children had ulcerative colitis, three had Crohn disease, and one had indeterminate colitis. All had colonic involvement of IBD. Of eight patients, three had IBD first, three had ITP first, and two had both simultaneously. At ITP diagnosis, platelet count was less than 10,000/mL in five children, 17,000/mL in one child, and 50,000 to 60,000/mL in two children. Of the three children diagnosed with ITP first, two initially had rectal bleeding at the time of ITP diagnosis. Bone marrow evaluations, performed in six of eight children, were consistent with ITP. Six of the eight children had chronic ITP, including three children who were 5 years of age or younger. Therapy for ITP included steroids (n = 6), intravenous immunoglobulin (n = 6), Rh o (D) intravenous immunoglobulin (n = 2), and splenectomy (n = 1).

CONCLUSIONS

The authors describe the largest pediatric case series of children with IBD and ITP. More than 50% of the children had the chronic form of ITP. Most patients responded to conventional therapy for ITP and IBD.

Thiamine-responsive megaloblastic anemia syndrome: a disorder of high-affinity thiamine transport

Thiamine-responsive megaloblastic anemia (TRMA) syndrome (OMIM No. 249270) comprises a distinctive triad of clinical features: megaloblastic anemia with ringed sideroblasts, diabetes mellitus, and progressive sensorineural deafness. The TRMA gene has been mapped and cloned. Designated "SLC19A2" as a member of the solute carrier gene superfamily, this gene is mutated in all TRMA kindreds studied to date. The product of the SLC19A2 gene is a membrane protein which transports thiamine (vitamin B1) with sub-micromolar affinity. Cells from TRMA patients are uniquely sensitive to thiamine depletion to the nanomolar range, while pharmacologic doses of vitamin B1 ameliorate the anemia and diabetes. Here we review the current status of studies aimed at understanding the pathophysiology of this unique transport defect.

Characterization of a murine high-affinity thiamine transporter, Slc19a2

Thiamine-responsive megaloblastic anemia with deafness and diabetes (TRMA) is a rare autosomal recessive disorder of thiamine transport. Previous studies have demonstrated that the disease is caused by mutations in the SLC19A2 gene encoding a high-affinity thiamine transporter. We hypothesize that thiamine transport, mediated by SLC19A2, plays a role in the development and or maintenance of several organ systems, in particular the erythropoietic, auditory, and glucose homeostasis systems. To investigate the transporter further, we cloned the murine Slc19a2 locus and characterized the resulting protein. Murine Slc19a2 is a 498 amino acid protein, with 12 predicted transmembrane domains. The gene spans approximately 13kb with 6 exons, structurally identical to that of the human homolog. We localized the Slc19a2 gene to mouse chromosome 1, a region syntenic to human chromosome 1q23 that contains the TRMA locus. Transient expression of Slc19a2 in HEK293T cells resulted in specific uptake of [3H] thiamine, confirming a thiamine transporter function. Western blot analysis of mouse tissues reveals a wide distribution of Slc19a2 protein. Immunohistochemistry studies indicate that Slc19a2 is expressed on the cell surface and intracellularly, and is specifically localized to a subpopulation of cells in cochlea, small intestine, and pancreas.

Mechanism of thiamine uptake by human colonocytes: studies with cultured colonic epithelial cell line NCM460

Thiamine (vitamin B(1)) is essential for normal cellular functions and growth. Mammals cannot synthesize thiamine and thus must obtain the vitamin via intestinal absorption. The intestine is exposed to a dietary thiamine source and a bacterial source in which the vitamin is synthesized by the normal microflora of the large intestine. Very little is known about thiamine uptake in the large intestine. The aim of this study was, therefore, to address this issue. Our results with human-derived colonic epithelial NCM460 cells as a model system showed thiamine uptake to be 1) temperature- and energy dependent, 2) Na(+) independent, 3) increased with increasing buffer pH from 5 to 8 and after cell acidification but inhibited by amiloride, 4) saturable as a function of concentration, 5) inhibited by thiamine structural analogs but not by unrelated organic cations, and 6) inhibited by modulators of a Ca(2+)/calmodulin-mediated pathway. NCM460 cells and native human colonic mucosa expressed the recently cloned human thiamine transporter THTR-1 (product of the SLC19A2 gene) at both mRNA and protein levels. These results demonstrate for the first time that human NCM460 colonocytes possess a specific carrier-mediated system for thiamine uptake that appears to be under the regulation of an intracellular Ca(2+)/calmodulin-mediated pathway. It is suggested that bacterially synthesized thiamine in the large intestine may contribute to thiamine nutrition of the host, especially toward cellular nutrition of the local colonocytes.

A novel mutation in the SLC19A2 gene in a Tunisian family with thiamine-responsive megaloblastic anaemia, diabetes and deafness syndrome

Thiamine-responsive megaloblastic anaemia (TRMA) syndrome with diabetes and deafness was found in two patients from a Tunisian kindred. The proband was homozygous for a novel mutation, 287delG, in the high-affinity thiamine transporter gene, SLC19A2. We demonstrated that fibroblasts from this patient exhibited defective thiamine transport. These data confirm that the SLC19A2 gene is the high-affinity thiamine carrier and that this novel mutation is responsible for TRMA syndrome.

Ticlopidine plus aspirin for coronary thrombosis in Kawasaki disease

Selective inhibitors of the adenosine 5'-diphosphate pathway of platelet activation have been used rarely in children in the United States. We report the successful use of ticlopidine, together with aspirin, in a 7-month-old infant with Kawasaki disease complicated by a thrombus in a giant coronary aneurysm that failed to resolve with thrombolytic therapy. Kawasaki disease, coronary aneurysms, antithrombotic therapy, ticlopidine, children.

Direct measurement of LDL-C in children: performance of two surfactant-based methods in a general pediatric population

OBJECTIVES

Several pediatric advisory groups have recommended selective screening for dyslipidemia in children. Low-density lipoprotein cholesterol (LDL-C) is measured clinically with the Friedewald calculation in fasting samples. Nonfasting measurement of LDL-C would be clinically useful in children.

DESIGN AND METHODS

In the present study, we examine the performance of two surfactant-based direct LDL-C assays in paired samples, fasting and nonfasting, from 100 children.

RESULTS

LDL-C in the fasting state was significantly lower with the Friedewald estimation: 2.43 +/- 0. 61 mmol/L, N-geneous (Genzyme Corp.) direct LDL-C: 2.30 +/- 0.59 mmol/L, and Roche (Roche Diagnostics) direct LDL-C: 2.32 +/- 0.57 mmol/L than with ultracentrifugation-dextran-sulfate-Mg(2+) precipitation (UC-DS): 2.47 +/- 0.64 mmol/L. Moreover, there was increased negative bias using nonfasting samples with N-geneous: 2. 25 +/- 0.56 mmol/L and Roche: 2.26 +/- 0.56 mmol/L compared with fasting UC-DS. Correlation with US-DS was highest for Friedewald (r = 0.974) and fasting N-geneous (r = 0.973), and lowest with nonfasting N-geneous (r = 0.849) and Roche in fasting (r = 0.891) and nonfasting samples (r = 0.747). The sensitivity at LDL-C concentration of 2.85 mmol/L for the two direct methods when either fasting or nonfasting samples were used, was lower than that obtained with Friedewald.

CONCLUSION

Overall, these direct LDL-C assays demonstrated limited utility in screening children but may be useful in the management of lipid disorders.

The CCAAT displacement protein/cut homeodomain protein represses osteocalcin gene transcription and forms complexes with the retinoblastoma protein-related protein p107 and cyclin A

Developmental control of bone tissue-specific genes requires positive and negative regulatory factors to accommodate physiological requirements for the expression or suppression of the encoded proteins. Osteocalcin (OC) gene transcription is restricted to the late stages of osteoblast differentiation. OC gene expression is suppressed in nonosseous cells and osteoprogenitor cells and during the early proliferative stages of bone cell differentiation. The rat OC promoter contains a homeodomain recognition motif within a highly conserved multipartite promoter element (OC box I) that contributes to tissue-specific transcription. In this study, we demonstrate that the CCAAT displacement protein (CDP), a transcription factor related to the cut homeodomain protein in Drosophila melanogaster, may regulate bone-specific gene transcription in immature proliferating osteoblasts. Using gel shift competition assays and DNase I footprinting, we show that CDP/cut recognizes two promoter elements (TATA and OC box I) of the bone-related rat OC gene. Overexpression of CDP/cut in ROS 17/2.8 osteosarcoma cells results in repression of OC promoter activity; this repression is abrogated by mutating OC box I. Gel shift immunoassays show that CDP/cut forms a proliferation-specific protein/DNA complex in conjunction with cyclin A and p107, a member of the retinoblastoma protein family of tumor suppressors. Our findings suggest that CDP/cut may represent an important component of a cell signaling mechanism that provides cross-talk between developmental and cell cycle-related transcriptional regulators to suppress bone tissue-specific genes during proliferative stages of osteoblast differentiation.

Homeoproteins CDP and SATB1 interact: potential for tissue-specific regulation

Homeoproteins are known to participate in development and cell type specification. The homeoproteins CCAAT displacement protein (CDP) and special AT-rich sequence binding protein 1 (SATB1) have been shown to bind to nuclear matrix-associated regions and to act as repressors of many cellular genes. Moreover, binding of SATB1 to the mouse mammary tumor virus (MMTV) promoter region dramatically affects the tissue-specific transcription of this retrovirus. Because protein-protein interactions are a common means of regulating homeoprotein function, we tested whether SATB1 and CDP interact in vivo and in vitro. SATB1 interacted with CDP through its DNA-binding domain, as demonstrated by glutathione S-transferase (GST) pull-down assays. GST pull-down assays also showed that CDP associated with SATB1 through three of its four DNA-binding domains (CR1, CR2, and the homeodomain). SATB1-specific antisera, but not preimmune sera, precipitated CDP from nuclear extracts, and CDP-specific antisera precipitated SATB1 from the same extracts. Far-Western blotting detected interaction of SATB1 and CDP in several different tissue extracts. Association of purified SATB1 and CDP in vitro resulted in the inability of each protein to bind to DNA in gel retardation assays. CDP overexpression in cultured T cells led to a loss of detectable SATB1 binding to the MMTV promoter region, as measured by gel shift experiments. CDP overexpression also elevated MMTV long terminal repeat reporter gene activity in transient-transfection assays, a result consistent with neutralization of the SATB1 repressor function in T cells. SATB1 is very abundant in certain tissues, particularly thymus, whereas CDP is relatively ubiquitous, except in certain terminally differentiated cell types. Because of the tissue and cell type distribution of SATB1 and CDP, we propose that the SATB1-to-CDP ratio in different tissues is a novel mechanism for homeoproteins to control gene expression and differentiation in mammals.

The gene mutated in thiamine-responsive anaemia with diabetes and deafness (TRMA) encodes a functional thiamine transporter

Thiamine-responsive megaloblastic anaemia with diabetes and deafness (TRMA; MIM 249270) is an autosomal recessive disease thought to be due to a defect in thiamine (vitamin B1) transport. Pharmacological doses of thiamine correct the anaemia, and in some cases improve the diabetes, although progressive sensorineural deafness is irreversible. Previous studies localized the TRMA gene to a 4-cM region on chromosome 1q23.3 (ref. 5), and fine-mapping has recently narrowed that region further. We have previously demonstrated that fibroblasts from people with TRMA lack high-affinity thiamine transport. Expression of a gene encoding a known yeast thiamine transporter, THI10 (refs 8-10), in TRMA mutant cells prevents apoptotic cell death in thiamine-depleted medium. On the basis of these studies, we hypothesized that a defective thiamine transporter causes TRMA. We undertook a candidate gene approach to identify putative thiamine transporters in the 1q23.3 critical region. Here we present evidence that the gene SLC19A2 (for solute carrier family 19 (thiamine transporter), member 2) encodes the first known mammalian thiamine transporter, which we designate thiamine transporter-1 (THTR-1).

Transcriptional repression of the cystic fibrosis transmembrane conductance regulator gene, mediated by CCAAT displacement protein/cut homolog, is associated with histone deacetylation

Human cystic fibrosis transmembrane conductance regulator gene (CFTR) transcription is tightly regulated by nucleotide sequences upstream of the initiator sequences. Our studies of human CFTR transcription focus on identifying transcription factors bound to an inverted CCAAT consensus or "Y-box element." The human homeodomain CCAAT displacement protein/cut homolog (CDP/cut) can bind to the Y-box element through a cut repeat and homeobox. Analysis of stably transfected cell lines with wild-type and mutant human CFTR-directed reporter genes demonstrates that human histone acetyltransferase GCN5 and transcription factor ATF-1 can potentiate CFTR transcription through the Y-box element. We have found 1) that human CDP/cut acts as a repressor of CFTR transcription through the Y-box element by competing for the sites of transactivators hGCN5 and ATF-1; 2) that the ability of CDP/cut to repress activities of hGCN5 and ATF-1 activity is contingent on the amount of CDP/cut expression; 3) that histone acetylation may have a role in the regulation of gene transcription by altering the accessibility of the CFTR Y-box for sequence-specific transcription factors; 4) that trichostatin A, an inhibitor of histone deacetylase activity, activates transcription of CFTR through the Y-box element; 5) that the inhibition of histone deacetylase activity leads to an alteration of local chromatin structure requiring an intact Y-box sequence in CFTR; 6) that immunocomplexes of CDP/cut possess an associated histone deacetylase activity; 7) that the carboxyl region of CDP/cut, responsible for the transcriptional repressor function, interacts with the histone deacetylase, HDAC1. We propose that CFTR transcription may be regulated through interactions with factors directing the modification of chromatin and requires the conservation of the inverted CCAAT (Y-box) element of the CFTR promoter.

Defective high-affinity thiamine transporter leads to cell death in thiamine-responsive megaloblastic anemia syndrome fibroblasts

We have investigated the cellular pathology of the syndrome called thiamine-responsive megaloblastic anemia (TRMA) with diabetes and deafness. Cultured diploid fibroblasts were grown in thiamine-free medium and dialyzed serum. Normal fibroblasts survived indefinitely without supplemental thiamine, whereas patient cells died in 5-14 days (mean 9.5 days), and heterozygous cells survived for more than 30 days. TRMA fibroblasts were rescued from death with 10-30 nM thiamine (in the range of normal plasma thiamine concentrations). Positive terminal deoxynucleotide transferase-mediated dUTP nick end-labeling (TUNEL) staining suggested that cell death was due to apoptosis. We assessed cellular uptake of [3H]thiamine at submicromolar concentrations. Normal fibroblasts exhibited saturable, high-affinity thiamine uptake (Km 400-550 nM; Vmax 11 pmol/min/10(6) cells) in addition to a low-affinity unsaturable component. Mutant cells lacked detectable high-affinity uptake. At 30 nM thiamine, the rate of uptake of thiamine by TRMA fibroblasts was 10-fold less than that of wild-type, and cells from obligate heterozygotes had an intermediate phenotype. Transfection of TRMA fibroblasts with the yeast thiamine transporter gene THI10 prevented cell death when cells were grown in the absence of supplemental thiamine. We therefore propose that the primary abnormality in TRMA is absence of a high-affinity thiamine transporter and that low intracellular thiamine concentrations in the mutant cells cause biochemical abnormalities that lead to apoptotic cell death.

Cux/CDP homeoprotein is a component of NF-muNR and represses the immunoglobulin heavy chain intronic enhancer by antagonizing the bright transcription activator

Nuclear matrix attachment regions (MARs) flanking the immunoglobulin heavy chain intronic enhancer (Emu) are the targets of the negative regulator, NF-muNR, found in non-B and early pre-B cells. Expression library screening with NF-muNR binding sites yielded a cDNA clone encoding an alternatively spliced form of the Cux/CDP homeodomain protein. Cux/CDP fulfills criteria required for NF-muNR identity. It is expressed in non-B and early pre-B cells but not mature B cells. It binds to NF-muNR binding sites within Emu with appropriate differential affinities. Antiserum specific for Cux/CDP recognizes a polypeptide of the predicted size in affinity-purified NF-muNR preparations and binds NF-muNR complexed with DNA. Cotransfection with Cux/CDP represses the activity of Emu via the MAR sequences in both B and non-B cells. Cux/CDP antagonizes the effects of the Bright transcription activator at both the DNA binding and functional levels. We propose that Cux/CDP regulates cell-type-restricted, differentiation stage-specific Emu enhancer activity by interfering with the function of nuclear matrix-bound transcription activators.

Update on genetic risk factors for thrombosis and atherosclerotic vascular disease

The strong familial occurrence of venous and arterial thromboembolic disease has prompted ongoing research to identify novel risk factors. Polymorphisms in the factor VII and prothrombin genes are related to increased thrombosis, but the mechanism of increased risk remains to be elucidated. Elevated levels of plasma homocysteine and of the variant lipoprotein(a) particle also contribute to increased thrombotic risk, due in part to polymorphisms in the apolipoprotein(a) gene and the gene for methylene tetrahydrofolate reductase.

Hemophilia. A new approach to an old disease

The history of hemophilia diagnosis and therapy has been a turbulent one. We are coming full circle, back to the use of genetics as the main diagnostic tool for this disease. Therapeutically, the retroviruses that ravaged one generation of hemophiliac patients now may participate in the cure for the next generation. The hemophilia community hopes that the future of hemophilia care will follow a course guided by this modified quote from James Russell Lowell: "New times demand new measures, and men [and women]. As the world advances and in time outgrows the laws that in our fathers' [and mothers'] days were the best, doubtless after us some purer scheme will be shaped out by wiser man [and women] than we, made wiser by the steady growth of truth."

Prevalence of factor V Leiden in a population of patients with congenital heart disease

PURPOSE

The incidence of thrombotic events following cardiopulmonary bypass (CPB) in patients receiving surgical repair or palliation of congenital heart defects (CHD) is as high as 16%. Protein C, an intrinsic anticoagulation protease which, when activated, breaks down factor Va of the coagulation system, aids in maintaining a normal procoagulant/anticoagulant balance. Resistance of factor Va to degradation by activated protein C occurs and predisposes to thrombotic events. The resistance of factor Va to such degradation is, in the majority of cases, due to a genetic mutation referred to as factor V Leiden (FVLeiden). The presence of FVLeiden can be diagnosed using a DNA based assay. The prevalence of FVLeiden in the with CHD has not been determined. The objective of this study was to determine the prevalence of FVLeiden in patients with CHD.

METHODS

Two hundred consecutive patients with CHD undergoing surgical repair or palliation requiring cardiopulmonary bypass were studied. Blood was taken before administration of homologous blood transfusion and assayed using a DNA based method with polymerase chain reaction amplification for the FVLeiden mutation.

RESULTS

The prevalence of FVLeiden in our study population was 9/200 (4.5%). None of these patients demonstrated thrombotic complications. However, three patients (1.5%) without the FVLeiden mutation developed postoperative thrombotic complications.

CONCLUSIONS

The prevalence of FVLeiden in patients is 4.5% that is not different from that of the population at large. There was no identifiable association with the occurrence of postoperative thrombotic events.

Refined mapping of the gene for thiamine-responsive megaloblastic anemia syndrome and evidence for genetic homogeneity

Thiamine-responsive megaloblastic anemia (TRMA, also known as Rogers syndrome, OMIM 249270) is a rare autosomal recessive disorder characterized by a triad of megaloblastic anemia, diabetes mellitus, and sensorineural deafness. Patients respond, to varying degrees, to treatment with megadoses of thiamine. We have recently shown genetic linkage of the TRMA gene to a 16-centimorgan (cM) region on 1q23.2-1q23.3 based on the analysis of four large, inbred families of Alaskan, Italian, and Israeli-Arab origin. Here we narrow the TRMA interval down to 4 cM based on genetic recombination, homozygosity mapping, and linkage disequilibrium (highest LOD score of 12.5 at D1S2799, at a recombination fraction of 0). We provide further evidence that the TRMA gene is located in this region and confirm the homogeneity of the disease. In this analysis, we genotyped seven additional families of diverse ethnic origin (Pakistani, Indian, Italian, Brazilian, and Japanese), and analyzed additional markers in two previously reported families showing evidence of linkage disequilibrium in a large area of their haplotypes. The multi-system manifestations of TRMA suggest that thiamine has a pivotal role in a multiplicity of physiological processes. Mapping the TRMA gene and understanding the molecular basis of the disease might, thus, shed light on the role of thiamine in common disorders such as deafness, anemia, and diabetes.

Combined schedule of 7-valent pneumococcal conjugate vaccine followed by 23-valent pneumococcal vaccine in children and young adults with sickle cell disease

We compared the immunogenicity of 7-valent pneumococcal-conjugate vaccine plus 23-valent pneumococcal vaccine to immunization with 23-valent vaccine only in individuals > or = 2 years of age with sickle cell disease. IgG pneumococcal antibody concentrations were higher in the combined schedule group with no increase in side effects observed after immunization with 23-valent vaccine.

Utility of direct measurement of low-density lipoprotein cholesterol in dyslipidemic pediatric patients

BACKGROUND

Low-density lipoprotein cholesterol (LDL-C) levels are the primary basis for treatment guidelines established for hyperlipidemic children and adolescents. Levels of LDL-C are commonly monitored by means of the Friedewald formula, an indirect calculation that requires an overnight fast. A new method has been developed for the direct measurement of LDL-C (DLDL-C) that does not require fasting. We evaluated the clinical utility of this method.

DESIGN

We determined LDL-C concentrations simultaneously by the DLDL-C method, Friedewald equation, and beta-quantification (reference procedure).

SETTING

Pediatric dyslipidemia clinic at Children's Hospital, Boston, Mass.

PATIENTS

Ninety-two fasting hyperlipidemic pediatric patients.

RESULTS

At the LDL-C concentration cutoffs commonly used for making therapeutic decisions, the DLDL-C method had a significant negative bias (P< or =.05) and misclassified patients into incorrect treatment groups more often than the Friedewald method. The negative predictive value for the DLDL-C method was lower than that for the Friedewald method (P< or =.05), and the cost of determining LDL-C level with the new method was 3 times greater.

CONCLUSIONS

The misclassification potential for LDL-C, and the assay costs, were greater for the DLDL-C method than for the Friedewald calculation. Despite the apparent advantages of the DLDL-C method, we conclude that for hyperlipidemic children the utility of this new method is not advantageous over the conventional Friedewald method. In some conditions, such as in diabetes or marked hypertriglyceridemia, the DLDL-C method may be useful.

Hair defects and pup loss in mice with targeted deletion of the first cut repeat domain of the Cux/CDP homeoprotein gene

CDP, a ubiquitous homeoprotein homologous to Drosophila cut, is implicated as a transcriptional repressor in several developmental systems. It contains four independent DNA binding domains: three "cut repeats" plus the homeodomain. The murine Cux/CDP gene spans more than 200 kb and is composed of at least 21 exons. We designed a targeting construct to replace the first cut repeat with a neomycin resistance cassette, introducing a nonsense mutation after position 1319 of the 4.5-kb reading frame of Cux/CDP. We expected to generate a truncated product of approximately 60 kDa with this construct, but instead we obtained mice expressing a mutant form of the protein, with an internal deletion of 246 amino acids encompassing cut repeat 1, but intact in the C-terminal region. Ribonuclease protection assays and direct sequencing of mutant cDNA obtained by RT-PCR demonstrate skipping of exons 10 and 11 in the mutant. Homozygous mutant mice, designated Cux/CDPDeltaCR1, display a phenotype characterized by curly vibrissae and wavy hair. We also observed a high degree of pup loss in litters born to mutant females, most likely on a nutritional basis. The mutant protein is present at levels slightly greater than wild-type, but exhibits the same tissue distribution as wild-type protein, and has approximately normal affinity for known target sequences (though no DNA targets identified to date require the first cut repeat for binding). These results support the hypothesis that the different DNA binding domains of the ubiquitous Cux/CDP protein are responsible for regulation of different genes in diverse tissues during development.

Localization of the gene for thiamine-responsive megaloblastic anemia syndrome, on the long arm of chromosome 1, by homozygosity mapping

Thiamine-responsive megaloblastic anemia, also known as "TRMA" or "Rogers syndrome," is an early-onset autosomal recessive disorder defined by the occurrence of megaloblastic anemia, diabetes mellitus, and sensorineural deafness, responding in varying degrees to thiamine treatment. On the basis of a linkage analysis of affected families of Alaskan and of Italian origin, we found, using homozygosity mapping, that the TRMA-syndrome gene maps to a region on chromosome 1q23.2-23.3 (maximum LOD score of 3.7 for D1S1679). By use of additional consanguineous kindreds of Israeli-Arab origin, the putative disease-gene interval also has been confirmed and narrowed, suggesting genetic homogeneity. Linkage analysis generated the highest combined LOD-score value, 8.1 at a recombination fraction of 0, with marker D1S2799. Haplotype analysis and recombination events narrowed the TRMA locus to a 16-cM region between markers D1S194 and D1S2786. Several heterozygote parents had diabetes mellitus, deafness, or megaloblastic anemia, which raised the possibility that mutations at this locus predispose carriers in general to these manifestations. Characterization of the metabolic defect of TRMA may shed light on the role of thiamine deficiency in such common diseases.

Soluble adhesion molecules in infants and children undergoing cardiopulmonary bypass

BACKGROUND

The vascular injury and tissue damage after cardiopulmonary bypass (CPB) involves leukocyte-endothelial interactions mediated by cell adhesion molecules. This study was designed to determine the time course of soluble adhesion molecule levels after CPB in infants and children and to determine whether these levels correlated with preoperative variables, intraoperative bypass management, or postoperative course.

METHODS AND RESULTS

In 56 patients undergoing CPB (median age 1.0 year, range 2 days to 19 years), plasma concentrations of soluble E-, P-, and L-selection, soluble ICAM-1, and soluble VCAM-1 were measured using sandwich enzyme-linked immunosorbent assays at the following times: at induction of anesthesia, after 15 minutes of CPB, at the end of CPB, and 1, 6, 18, and 42 hours after CPB. Preoperative, intraoperative, and postoperative data were prospectively recorded. All soluble adhesion molecule levels fell markedly at the initiation of CPB as a result of a combination of dilution and bypass circuit uptake. The time course of soluble selectins (P, E, and L), normalized to end of bypass levels, all rose significantly (P<.001) in the initial 6 hours after CPB and then returned to end bypass levels at 42 hours. Soluble ICAM-1 and VCAM rose 63% and 89% in the first 6 hours and remained elevated throughout the 42 hours. Peak soluble P-selectin levels were associated with total support time (P=.04) and preoperative cyanosis (P=.003). Soluble L-selectin levels were inversely associated with longer total support time (P=.002), longer circulatory arrest time (P=.004), longer length of intubation (P=.0009), preoperative cyanosis (P=.002), and younger age at surgery (P=.01).

CONCLUSIONS

Soluble adhesion molecules have a characteristic time course in infants and children undergoing CPB. The soluble adhesion molecule levels after CPB change most significantly in patients with the highest potential for vascular injury: younger, cyanotic patients with longer pump times and longer postoperative courses. These data may be useful in the assessment of new therapies.

CASP, a novel, highly conserved alternative-splicing product of the CDP/cut/cux gene, lacks cut-repeat and homeo DNA-binding domains, and interacts with full-length CDP in vitro

Human CDP/cut and its murine counterpart, cux1/CDP are homeodomain repressor proteins in the family of Drosophila Cut. Northern blot analysis reveals complex alternative splicing, including forms too small to encode the full 1505 amino acid protein. We have characterized a CDP/cut alternatively spliced cDNA (CASP) of 3.4 kb. Human CASP, a predicted 678 amino acid polypeptide, shares 400 amino acids with CDP, but has an alternate N terminal exon of 20 aa, and the C-terminal 258 amino acids diverge from CDP/cut entirely. As the unique C-terminus of CASP lacks the three 'cut-repeats' and homeodomain of CDP/cut, we predict it does not bind DNA. Murine CASP, 96% similar to human, shares these features. Database searches identify homologs in chicken (86% identical to human CASP) and yeast (29% identical to human). Murine CASP mRNA is ubiquitous in mouse tissues and in tissue-culture cell lines. We generated a specific antiserum against the unique C-terminus of CASP, and used this reagent to demonstrate that CASP protein is expressed as an approx. 80 kDa protein in human and murine cells. Co-translation of in vitro-translated CDP and CASP mRNA, followed by immunoprecipitation with specific anti-CASP IgG, shows that CASP polypeptide can from a complex with CDP. Studies of the intron/exon structure of the murine cux/CDP/mCASP locus (>> 100 kb) reveal that the unique 3' exons of CASP are interposed between cut-repeats 2 and 3 of the cux gene. We speculate that a primordial CASP-like gene captured a cut-repeat-homeobox gene to give rise to the eukaryotic Cut/CDP family of proteins.

Passive cigarette smoking and reduced HDL cholesterol levels in children with high-risk lipid profiles

BACKGROUND

HDL cholesterol levels are known to be lower in smokers than in nonsmokers. Previous studies have demonstrated an association of decreased HDL cholesterol with passive smoking in children but have not adjusted for potential confounding factors.

METHODS AND RESULTS

In a cross-sectional, pilot-scale study, we examined the relationship of HDL cholesterol levels to passive smoking in children and adolescents referred to a tertiary hyperlipidemia clinic. Eligibility criteria included (1) first visit to a lipid clinic, (2) LDL cholesterol >95th percentile for age or HDL cholesterol <5th percentile, (3) age between 2 and 18 years, and (4) absence of secondary causes of hyperlipidemia. Sociodemographic information, diet record, medical history, and fasting lipid profiles were obtained. Of 109 eligible patients, 103 (94%) were studied. Twenty-seven percent came from households with cigarette smokers. HDL cholesterol levels were 38.7+/-1.2 mg/dL (mean+/-SEM) in passive smokers versus 43.6+/-1.2 mg/dL in children without smoke exposure (P=.005). Smoking exposure was not significantly associated with other lipid values. The effect of smoking on HDL cholesterol was minimally affected by potential confounders. In multivariate regression adjusting for body mass index, age, sex, exercise, and dietary fat intake, passive smoking remained a significant risk factor for decreased HDL cholesterol (P=.012).

CONCLUSIONS

Mean HDL cholesterol levels are lower in dyslipidemic children from households with smokers than in those without household smoke exposure. Passive smoking may worsen the risk profile for later atherosclerosis among high-risk young persons.

Blockade of selectin-mediated leukocyte adhesion improves postischemic function in lamb hearts

BACKGROUND

Leukocyte-endothelial interactions appear to have a important role in ischemia/reperfusion injury and are mediated by specific leukocyte and endothelial adhesion molecules. The selectins are adhesion molecules found on leukocytes (L-selectin) and endothelium (P and E selectin) that bind to oligosaccharide ligands containing fucose and sialic acid to mediate leukocyte rolling on the endothelium. Fucoidin is a nontoxic sulfated fucose oligosaccharide derived from seaweed that blocks the selectins.

METHODS

We tested the effects of fucoidin in an isolated blood-perfused neonatal (age range, 3 to 7 days; mean age, 4.3 days) lamb heart model undergoing 2 hours of cold cardioplegic ischemia. In group F (n = 8) fucoidin (30 mg/L) was added at initial reperfusion. Group C (n = 9) received only cardioplegia with no reperfusion intervention. Isovolumic maximum developed pressure and the maximum positive and negative first derivatives of pressure were measured using a catheter-tip transducer in an intraventricular balloon before ischemia and at 30 minutes of reperfusion. Coronary blood flow, myocardial oxygen consumption, and white blood cell counts in the circulating blood were also measured.

RESULTS

Percent recoveries of baseline maximum developed pressure and maximum positive and negative first derivatives of pressure in group F (86% +/- 5%, 81% +/- 10%, and 74% +/- 8%, respectively; mean +/- standard deviation) were higher than in group C (77% +/- 5%, 70% +/- 9%, and 65% +/- 6%; p < 0.05). Group F postischemic coronary blood flow was greater (190% +/- 35%) than in group C (102% +/- 10%; p < 0.05). Recovery of myocardial oxygen consumption in group F (86% +/- 14%) was greater than group C (72% +/- 11%; p < 0.05). Postischemic white blood cell count in group F (88% +/- 4%) was greater than in group C (81% +/- 5%; p < 0.05).

CONCLUSIONS

Selectin blockade with fucoidin resulted in better recovery of left ventricular function, coronary blood flow, and myocardial oxygen consumption after cold ischemia, despite a higher circulating white blood cell count. These data support the hypothesis that endothelial-leukocyte interactions play an important role in ischemia/reperfusion and suggest that selectin blockade may be a useful therapeutic strategy.

CDP/cut is the DNA-binding subunit of histone gene transcription factor HiNF-D: a mechanism for gene regulation at the G1/S phase cell cycle transition point independent of transcription factor E2F

Transcription of the genes for the human histone proteins H4, H3, H2A, H2B, and H1 is activated at the G1/S phase transition of the cell cycle. We have previously shown that the promoter complex HiNF-D, which interacts with cell cycle control elements in multiple histone genes, contains the key cell cycle factors cyclin A, CDC2, and a retinoblastoma (pRB) protein-related protein. However, an intrinsic DNA-binding subunit for HiNF-D was not identified. Many genes that are up-regulated at the G1/S phase boundary are controlled by E2F, a transcription factor that associates with cyclin-, cyclin-dependent kinase-, and pRB-related proteins. Using gel-shift immunoassays, DNase I protection, and oligonucleotide competition analyses, we show that the homeodomain protein CDP/cut, not E2F, is the DNA-binding subunit of the HiNF-D complex. The HiNF-D (CDP/cut) complex with the H4 promoter is immunoreactive with antibodies against CDP/cut and pRB but not p107, whereas the CDP/cut complex with a nonhistone promoter (gp91-phox) reacts only with CDP and p107 antibodies. Thus, CDP/cut complexes at different gene promoters can associate with distinct pRB-related proteins. Transient coexpression assays show that CDP/cut modulates H4 promoter activity via the HiNF-D-binding site. Hence, DNA replication-dependent histone H4 genes are regulated by an E2F-independent mechanism involving a complex of CDP/cut with cyclin A/CDC2/ RB-related proteins.

Analytical performance and clinical utility of a direct LDL-cholesterol assay in a hyperlipidemic pediatric population

This study compares a new latex immunoseparation method for the direct determination of plasma low-density lipoprotein cholesterol (LDL-C) with the reference procedure for LDL-C (beta-quantification) in a pediatric hyperlipidemic population. The direct LDL-C assay has a mean bias of -98 mg/L in a fasting group (n = 96) of patients (mean triglycerides 1057 +/- 720 mg/L) and a bias of +177 mg/L in a nonfasting group (n = 42, mean triglycerides 4854 +/- 5457 mg/L). The mean total analytical error calculated from our data is 13.8%. The direct LDL-C assay and the commonly used Friedewald calculation respectively classified 81% and 84% of fasting patients correctly, according to the cutoffs of 1100 and 1300 mg/L for LDL-C set by the National Cholesterol Education Program for pediatric patients. Of combined fasting and nonfasting patients, 80% were correctly classified by the direct LDL-C assay. Therefore, despite several analytical shortcomings, the direct LDL-C assay may be useful in managing hyperlipidemic children without the need for a fasting specimen.

Hypoxia enhances stimulus-dependent induction of E-selectin on aortic endothelial cells

In many diseases, tissue hypoxia occurs in conjunction with other inflammatory processes. Since previous studies have demonstrated a role for leukocytes in ischemia/reperfusion injury, we hypothesized that endothelial hypoxia may "superinduce" expression of an important leukocyte adhesion molecule, E-selectin (ELAM-1, CD62E). Bovine aortic endothelial monolayers were exposed to hypoxia in the presence or absence of tumor-necrosis factor alpha (TNF-alpha) or lipopolysaccharide (LPS). Cell surface E-selectin was quantitated by whole cell ELISA or by immunoprecipitation using polyclonal anti-E-selectin sera. Endothelial mRNA levels were assessed using ribonuclease protection assays. Hypoxia alone did not induce endothelial E-selectin expression. However, enhanced induction of E-selectin was observed with the combination of hypoxia and TNF-alpha (270% increase over normoxia and TNF-alpha) or hypoxia and LPS (190% increase over normoxia and LPS). These studies revealed that a mechanism for such enhancement may be hypoxia-elicited decrements in endothelial intracellular levels of cAMP (<50% compared with normoxia). Addition of forskolin and isobutyl-methyl-xanthine during hypoxia resulted in reversal of cAMP decreases and a loss of enhanced E-selectin surface expression with the combination of TNF-alpha and hypoxia. We conclude that endothelial hypoxia may provide a novel signal for superinduction of E-selectin during states of inflammation.

ARMS test for diagnosis of factor VLeiden mutation, a common cause of inherited thrombotic tendency

We developed a simple and rapid amplification-refractory mutation system (ARMS) assay for the factor V mutation [R506Q] (factor VLeiden), which results in the autosomal dominant thrombotic tendency, resistance to activated protein C (rAPC). PCR primers within Exon 10 of the factor V gene were designed. A common upstream primer was paired with either a mutant or wild-type-specific downstream primer. The 3'-most nucleotide of the specific primers recognized either the mutant or normal allele, and the 3' penultimate nucleotide was mismatched to enhance specificity of the reaction. The assay was validated using authentic factor VLeiden DNA samples. Seven of 103 hematologically normal children (6.8%) were found to be heterozygotes. Among 27 patients studied by the rAPC assay, ARMS assay and rAPC results were concordant in 26. Among these were a 1-year-old child with a calcified clot in the inferior vena cava. Both the patient and his father were heterozygous for the mutation and both had abnormal rAPC assays. rAPC and factor VLeiden assays were discordant in a young girl with a history of stroke. Biochemical rAPC assay was abnormal, while ARMS assay revealed amplification only with wild-type primers, suggesting a non-[R506Q] mechanism for rAPC. This assay will be a valuable tool for studying subjects with thromboses and their family members.