SAFER model: Strategic allocation of fundamental epidemic resources.

BACKGROUND: To describe the Strategic Allocation of Fundamental Epidemic Resources (SAFER) model as a method to inform equitable community distribution of critical resources and testing infrastructure. METHODS: The SAFER model incorporates a four-quadrant design to categorize a given community based on two scales: testing rate and positivity rate. Three models for stratifying testing rates and positivity rates were applied to census tracts in Milwaukee County, Wisconsin: using median values (MVs), cluster-based classification and goal-oriented values (GVs). RESULTS: Each of the three approaches had its strengths. MV stratification divided the categories most evenly across geography, aiding in assessing resource distribution in a fixed resource and testing capacity environment. The cluster-based stratification resulted in a less broad distribution but likely provides a truer distribution of communities. The GVs grouping displayed the least variation across communities, yet best highlighted our areas of need. CONCLUSIONS: The SAFER model allowed the distribution of census tracts into categories to aid in informing resource and testing allocation. The MV stratification was found to be of most utility in our community for near real time resource allocation based on even distribution of census tracts. The GVs approach was found to better demonstrate areas of need.

Saving Lives with Tourniquets: A Review of Penetrating Injury Medical Examiner Cases.

Background: After numerous recent mass casualty events, civilian hemorrhage control has taken a militaristic approach with aggressive and early use of tourniquets. While military literature has demonstrated the utility of tourniquets in preventing battlefield deaths from extremity injuries, there is limited understanding of their role in civilian penetrating trauma deaths. The purpose of this study is to review medical examiner (ME) autopsy records in a defined population to determine the incidence of preventable deaths from extremity wounds amenable to tourniquet placement. Methods: This is a retrospective review of ME cases from one urban county with a descriptive analysis of the demographics, mechanisms of injuries, and causes of death of homicide cases from 2003 to 2017. Mechanism of injury and wound patterns were reviewed to determine the overall occurrence of extremity injuries and amenability of tourniquet placement. Results: A total of 1,804 homicide cases were reviewed with 1,521 (84.3%) resulting from penetrating trauma. Isolated extremity injuries were present in 22 (1.45%) of the penetrating cases, all of which were amenable to tourniquet placement. There were 409 (26.9%) concurrent extremity and central penetrating injuries. The vast majority of extremity wounds were amenable to tourniquet placement (92.1%). Extrapolating nationally to 16,187 annual penetrating injury related homicides in 2016, an estimated 235 (1.45%) isolated extremity injury related deaths could be prevented and an additional estimated 4,354 (26.9%) concurrent extremity and central injury related deaths could potentially receive enhanced care with early tourniquet placement. Conclusion: Among urban ME cases, both isolated extremity cases and concurrent extremity-central injuries exist that may be amenable to life-saving tourniquet use. Extrapolating our findings nationwide suggests that many lives could be saved with early tourniquet use. Considering these findings, tourniquet availability and early placement may have a prominent role in reducing injury deaths from penetrating trauma.

Does an individualized feedback mechanism improve quality of out-of-hospital CPR?

BACKGROUND: Despite its prevalence, survival from out-of-hospital cardiac arrest remains low. High quality CPR has been associated with improved survival in cardiac arrest patients. In early 2014, a program was initiated to provide feedback on CPR quality to prehospital providers after every treated cardiac arrest. OBJECTIVE: To assess whether individualized CPR feedback was associated with improved CPR quality measures in the prehospital setting. METHODS: This before and after retrospective review included all treated adult out-of-hospital cardiac arrest in patients in an urban community. Data was compared prior to and after the initiation of the CPR feedback program. We compared the percent of encounters reaching the system defined benchmarks as well as the average values for compression fraction, compression rate, compression depth, and pre-shock pause in the before period compared to the after period. RESULTS: There were 159 encounters in the before period and 117 in the after. Compared to the before group, the after group had higher average compression rates (111.2/min vs 113.8/min; p=0.042), increased compression depths (4.9cm vs 5.6cm; p<0.001), and increased rates of benchmark achievement for compression depth greater than 5cm (48.1% vs 72.6%; p<0.001). No significant difference was noted in pre-shock pause (21.4s vs 14.7s; p=0.068). Additionally, no difference was noted between groups for compression fraction, though goal achievement was high in both groups. CONCLUSION: We found that individual CPR feedback is associated with marginally improved quality of CPR in the prehospital setting. Further investigation with larger samples is warranted to better quantify this effect.

Familial deficiency of vitamin K-dependent clotting factors.

Combined deficiency of vitamin K-dependent clotting factors II, VII, IX and X (and proteins C, S, and Z) is usually an acquired clinical problem, often resulting from liver disease, malabsorption, or warfarin overdose. A rare inherited form of defective gamma-carboxylation resulting in early onset of bleeding was first described by McMillan and Roberts in 1966 and subsequently has been termed 'vitamin K-dependent clotting factor deficiency' (VKCFD). Biochemical and molecular studies identify two variants of this autosomal recessive disorder: VKCFD1, which is associated with point mutations in the gamma-glutamylcarboxylase gene (GGCX), and VKCFD2, which results from point mutations in the vitamin K epoxide reductase gene (VKOR). Bleeding ranges in severity from mild to severe. Therapy includes high oral doses of vitamin K for prophylaxis, usually resulting in partial correction of factor deficiency, and episodic use of plasma infusions or prothrombin complex concentrate. Recent molecular studies have the potential to further our understanding of vitamin K metabolism, gamma-carboxylation, and the functional role this post-translational modification has for other proteins. The results may also provide potential targets for molecular therapeutics and pharmacogenetics.

Association of the Lewis genotype with cardiovascular risk factors and subclinical carotid atherosclerosis: the Atherosclerosis Risk in Communities (ARIC) study.

OBJECTIVES: To evaluate the relationship of Lewis genotypes with major cardiovascular risk factors and the intima-media thickness (IMT) of carotid arteries. Lewis genotyping included four major mutations of the Lewis (FUT3) gene at nucleotide positions 59, 1067, 202 and 314. DESIGN: Two complementary population-based cross-sectional studies. SETTING: The Atherosclerosis Risk in Communities (ARIC) Study. SUBJECTS: The relationship between Lewis genotype and major cardiovascular risk factors was studied in 761 men and women aged 45-64 years without known clinical atherosclerotic disease; 577 were Caucasians and 184 were African-Americans. The association of Lewis genotype and subclinical carotid atherosclerosis was studied in 419 individuals with, and 819 controls without carotid IMT of >1.0 mm, measured by B-mode ultrasound. MAIN OUTCOME MEASURES: Mean values of cardiovascular risk factors by Lewis genotype. Lewis genotype frequencies in subclinical carotid atherosclerosis cases and controls. RESULTS: Individuals with Lewis genotypes consistent with lack of alpha(1,3/1,4)-fucosyltransferase activity (i.e. Lewis-negative genotype) had statistically significantly lower fasting glucose, factor VIIIc, von Willebrand factor and diastolic blood pressure compared with their counterparts with Lewis-positive genotypes. The distribution of Lewis genotypes and haplotypes was not significantly different between individuals with carotid IMT of >1.0 mm (cases) and their controls. The odds of carotid atherosclerosis in carriers of the Lewis-negative genotype was 1.23 (95% confidence interval 0.70-2.16) compared to individuals with Lewis-positive genotype, controlling for age, gender and race/ARIC field centre. CONCLUSION: The lack of a statistically significant association between Lewis 'genotype' and subclinical atherosclerosis in our data suggests that earlier studies reporting associations at the 'phenotypic' level may reflect aspects of the biology of the Lewis system other than an inherent genetic property.

Distribution of Lewis (FUT3)genotype and allele: frequencies in a biethnic United States population.

The objective of the study was to examine the prevalence and distribution of four major single nucleotide polymorphisms (SNPs) (T59G, T1067G, T202C, and C314T) of the Lewis ( FUT3)gene in a biethnic United States population. This population-based cross-sectional study was based on data from the Atherosclerosis Risk in Communities (ARIC) Study, which included 761 males and females aged 45-64 years, who had no known/detected clinical atherosclerotic disease (577 Caucasians, 184 African Americans). The main outcome measures were prevalence of the Lewis genotype and allele frequencies for four SNPs of the FUT3gene. The most common genotype was the "wild type" at all four nucleotide positions ( WWWW), which was found to be present in 46.9% of ARIC participants. At least one mutant allele was detected in 51.7% of Caucasians, and 56.7% of African Americans ( P=0.59). The frequencies of mutant alleles ranged from 6.3% to 18.4% at the four FUT3gene sites examined. The distribution of the Lewis genotype and allele frequencies differed significantly by ethnicity at sites 59, 202, and 314. The prevalence of the Lewis genotype suggesting a lack of alpha(1,3/1,4) fucosyltransferase activity was 11.6% in Caucasians and 9.9% in African Americans ( P=0.67). Four specific SNPs of the Lewis genotype are common in the population at large. However, these four SNPs seem to fail to explain the majority of Lewis-negative phenotype in African Americans, given that Lewis-negative genotype prevalence was about one-third of what was expected. Use of rapid DNA sequencing and simultaneous Lewis phenotype determination could avoid the problems associated with haplotype determination and Lewis genotype grouping. Further studies testing SNPs of the Lewisgene are warranted, in particular among African Americans.

Glucose-6-phosphatase mutation G188R confers an atypical glycogen storage disease type 1b phenotype.

Glycogen storage disease type 1a (GSD 1a) is caused by a deficiency in microsomal glucose-6-phosphatase (G6Pase). A variant (GSD 1b) is caused by a defect in the transport of glucose-6-phosphate (G6P) into the microsome and is associated with chronic neutropenia and neutrophil dysfunction. Mutually exclusive mutations in the G6Pase gene and the G6P transport gene establish GSD la and GSD 1b as independent molecular processes and are consistent with a multicomponent translocase catalytic model. A modified translocase/catalytic unit model based on biochemical data in a G6Pase knockout mouse has also been proposed for G6Pase catalysis. This model suggests coupling of G6Pase activity and G6P transport. A 5-mo-old girl with hypoglycemia, hepatomegaly, and lactic acidemia was diagnosed with GSD 1a. She also developed neutropenia, neutrophil dysfunction, and recurrent infections characteristic of GSD 1b. Homozygous G188R mutations of the G6Pase gene were identified, but no mutations in the G6P translocase gene were found. We have subsequently identified a sibling and two unrelated patients with similar genotypic/phenotypic characteristics. The unusual association of neutrophil abnormalities in patients with homozygous G188R mutations in the G6Pase gene supports a modified translocase/catalytic unit model.

Genetic background of Lewis negative blood group phenotype and its association with atherosclerotic disease in the NHLBI family heart study.

OBJECTIVES: To examine the prevalence of four mutations, T59G, T1067A, T202C and C314T, of the human alpha(1,3/1,4) fucosyltransferase 3 (FUT 3) gene amongst persons with Lewis negative and those with Lewis positive blood group phenotype. An additional objective was to explore the hypothesis that these mutations are associated with coronary heart disease and inflammatory reaction. DESIGN: A population-based cross-sectional study. SETTING: Analysis of samples and data from the National Heart Lung and Blood Institute Family Heart Study. SUBJECTS: All Lewis (a-b-) participants (n = 136) and a sample of Lewis positive participants (n = 136) of the Family Heart Study; all were of Caucasian ethnicity. MAIN OUTCOME MEASURES: The prevalence of examined mutations by Lewis phenotype. RESULTS: The examined mutations were common and strongly associated with the Lewis (a-b-) phenotype. Accordingly, 90-95% of Lewis (a-b-) individuals amongst Caucasians can be identified by screening for these four mutations. Exploratory analyses suggested that with the exception of T59G, all examined mutations were positively associated with prevalent coronary heart disease, although not statistically significantly, perhaps due to the small number of prevalent coronary heart disease cases. C-reactive protein tended to be higher amongst persons with a TC or CC genotype at position 202 (3.07 +/- 0.41 vs. 2.08 +/- 0.32 mg L-1, P = 0.06). CONCLUSIONS: Four specific mutations of fucosyltransferase 3 gene are responsible for the vast majority of Lewis (a-b-) phenotypes in Caucasians. These mutations are common in the population at large and may be associated with increased risk of coronary heart disease. Further studies using larger samples are warranted.

Transfection of alpha(1,3)fucosyltransferase antisense sequences impairs the proliferative and tumorigenic ability of human colon carcinoma cells.

Sialyl Lewis x and sialyl Lewis a are oncodevelopmental antigens involved in the pathogenesis of colon adenocarcinoma. Biosynthesis of these glycans is controlled by alpha(1,3/1,4)fucosyltransferases. We report the disruption of sialyl Lewis x/a biosynthesis and inhibition of colon carcinoma cell proliferation by stable transfection of antisense sequences directed at the human Lewis alpha(1,3/1,4)fucosyltransferase gene, FUT3, and the plasma alpha(1,3)fucosyltransferase gene, FUT6. COLO-205 cells expressed high levels of sialyl Lewis x/a, alpha(1,3)fucosyltransferase activity, and FUT3/6 transcripts, but COLO

A cloned CD15s-negative variant of HL60 cells is deficient in expression of FUT7 and does not adhere to cytokine-stimulated endothelial cells.

The initial steps of leukocyte adhesion depend on selectin/ligand interactions. Surface ligands on leukocytes are often modified by addition of the sialyl Lewis x (CD15s) determinant. Biosynthesis of CD15s is dependent upon alpha(2,3)sialyltransferases and alpha(1,3)fucosyltransferases. We report the isolation of an HL60 cell line variant, HL60A2, that no longer expresses CD15s. HL60A2 cells do not adhere to cytokine-stimulated endothelial cells. Enzymatic assays reveal that this cell line has normal alpha(2,3)sialyltransferase activity but is deficient in the alpha(1,3)fucosyltransferase responsible for biosynthesis of CD15s (FUT7). The fucosyltransferase that constructs the non-sialylated antigen, Lewis x (CD15), is expressed at high levels (FUT4). Transcript analyses show that FUT7 and FUT4 are inversely expressed in HL60 and variant cell lines. HL60A2 cells provide a tool to study the regulation of selectin ligands and corresponding human fucosyltransferase genes.

Expression of human alpha(1,3)fucosyltransferase antisense sequences inhibits selectin-mediated adhesion and liver metastasis of colon carcinoma cells.

The initial steps of leukocyte and tumor cell adhesion involve selectin receptor/ligand interactions. The selectin ligand components sialyl Lewis x and sialyl Lewis a are oncodevelopmental antigens involved in progression of adenocarcinoma. Interrupting biosynthesis of these surface glycans by inhibition of alpha(1,3)fucosyltransferase (FUT) gene expression is an attractive goal for functional and therapeutic studies. We report here the inhibition of E-selectin-mediated adenocarcinoma cell adhesion by stable transfection of antisense sequences directed at the human Lewis alpha(1,3/1,4)fucosyltransferase gene, FUT3. The metastatic parental cell line, HT-29LMM, expressed high levels of sialyl Lewis x, sialyl Lewis a, alpha(1,3/1,4)fucosyltransferase activity, and FUT3 transcript, but antisense transfectant cell lines did not. When injected into the spleens of nude mice, the stable antisense clones were unable to colonize the liver. These results provide target validation for inhibition of carcinoma metastasis with antisense FUT sequences and confirm the primacy of alpha(1,3)fucosyltransferases in the synthesis of selectin ligands.

Leukocyte infection by the granulocytic ehrlichiosis agent is linked to expression of a selectin ligand.

Human granulocytic ehrlichiosis (HGE) is an emerging tickborne illness caused by an intracellular bacterium that infects neutrophils. Cells susceptible to HGE express sialylated Lewis x (CD15s), a ligand for cell selectins. We demonstrate that adhesion of HGE to both HL60 cells and normal bone marrow cells directly correlates with their CD15s expression. HGE infection of HL60 cells, bone marrow progenitors, granulocytes, and monocytes was blocked by monoclonal antibodies against CD15s. However, these antibodies did not inhibit HGE binding, and anti-CD15s was capable of inhibiting the growth of HGE after its entry into the target cell. In contrast, neuraminidase treatment of HL60 cells prevented both HGE binding and infection. A cloned cell line (HL60-A2), derived from HL60 cells and resistant to HGE, was deficient in the expression of alpha-(1, 3)fucosyltransferase (Fuc-TVII), an enzyme known to be required for CD15s biosynthesis. Less than 1% of HL60-A2 cells expressed CD15s, and only these rare CD15s-expressing cells bound HGE and became infected. After transfection with Fuc-TVII, cells regained CD15s expression, as well as their ability to bind HGE and become infected. Thus, CD15s expression is highly correlated with susceptibility to HGE, and it, and/or a closely related sialylated and alpha-(1,3) fucosylated molecule, plays a key role in HGE infection, an observation that may help explain the organism's tropism for leukocytes.

Expression of human chromosome 19p alpha(1,3)-fucosyltransferase genes in normal tissues. Alternative splicing, polyadenylation, and isoforms.

The human alpha(1,3)-fucosyltransferase genes FUT3, FUT5, and FUT6 form a cluster on chromosome 19p13.3. Expression was studied using reverse transcriptase-polymerase chain reaction, rapid amplification of cDNA ends, and Northern analyses. FUT3 and FUT6 were expressed at high levels, while FUT5 expression was lower and restricted to fewer cell types. Alternatively spliced transcripts were identified for FUT3 and FUT6 in kidney, liver, and colon. A 2.37-kilobase pair (kb) FUT3 transcript, detected at high levels in kidney and colon, was absent in liver. FUT6 expression was characterized by a 3.5-kb transcript present in kidney and liver, and a 2.5-kb transcript in colon and liver. Two polyadenylation sites were shown for FUT5, but absence of consensus sequences suggests reduced efficiency for cleavage and polyadenylation. Two polyadenylation sites were also shown for FUT6, with the alternatively spliced downstream signal in tissues expressing high levels of FUT6. In these tissues, additional splicing results in isoforms with catalytic domain deletions. No detectable alpha(1,3)- or alpha(1,4)-fucosyltransferase activity was found in assays of cells transfected with FUT6 isoform cDNAs. Thus, tissue-specific post-transcriptional modifications are associated with expression patterns of FUT3, FUT5, and FUT6.

Physical maps of human alpha (1,3)fucosyltransferase genes FUT3-FUT6 on chromosomes 19p13.3 and 11q21.

Sialyl Lewis x and related fucosylated glycans are differentially expressed in human cells and form ligands for selectin adhesion receptors. alpha(1,3)Fucosyltransferases (FUTs) that complete their biosynthesis also show tissue specificity. We have established physical maps of the FUT3-6 loci to study regulation of this gene family. FUT4 has previously been localized to chromosome 11q21; FUT3, FUT6, and now FUT5 are localized to chromosome 19p13.3. Conventional and pulsed-field gel electrophoresis mapping of total genomic DNA and large genomic clones were used to generate a fine map of both loci, defining the order, orientation, and distances between FUTs. A P1 clone with all three 19p FUT genes in tandem orientation was isolated and used to study regions flanking FUT3, -5, and -6. Our studies provide preliminary information to study regulation of human FUT genes.

Molecular basis for Lewis alpha(1,3/1,4)-fucosyltransferase gene deficiency (FUT3) found in Lewis-negative Indonesian pedigrees.

The Le(a) and Le(b) human blood group antigens are synthesized in tissues producing exocrine secretions; they also circulate in plasma, where they are adsorbed by erythrocytes. They are synthesized by two fucosyltransferases, encoded by Lewis (FUT3) and secretor (FUT2) loci. This genetic model has been challenged because some erythrocyte Lewis-negative individuals express Lewis antigens in saliva. To define the molecular basis of this apparent discrepancy, we sequenced FUT3 in Lewis-negative individuals. We identified two single base pair changes. One, termed L1, yields a Leu-20-->Arg substitution in the enzyme's transmembrane domain. When expressed in COS-7 cells, enzyme substrate affinities are essentially identical to those of wild type. However, the mutant enzyme is found at substantially reduced levels in transfected cells. This suggests that the L1 mutation may alter the Golgi membrane anchoring of the enzyme. It was found alone in double dose in 10 of 30 erythrocyte Lewis-negative individuals, nine of whom express Lewis antigens in saliva. Therefore, L1 can account for erythrocyte/saliva-discrepant Lewis typing results. The L2 mutation creates an Ile-356-->Lys change in the enzyme's catalytic domain and inactivates the enzyme. It was found in double dose in 18 of 19 individuals bearing the double erythrocyte and salivary Lewis deficiency and can account for this phenotype.

Molecular basis for plasma alpha(1,3)-fucosyltransferase gene deficiency (FUT6).

While most humans express an alpha(1,3)-fucosyltransferase in plasma, 9% of individuals on the isle of Java (Indonesia) do not express this enzyme. Ninety-five percent of these plasma alpha(1,3)-fucosyltransferase-deficient individuals have Lewis negative phenotype on red cells, suggesting strong linkage disequilibrium between these two traits. To define the molecular basis for this plasma deficiency and to determine which of two candidate human alpha(1,3)-fucosyltransferase genes encode this enzyme (FUT5 and FUT6), we cloned and analyzed alleles at these two loci from an Indonesian individual deficient in plasma alpha(1,3)-fucosyltransferase activity. Single base pair changes were identified in the coding region of each gene, relative to previously published wild type alleles. These changes in turn yield three codon changes in FUT5 and three in FUT6. The codon changes in the FUT5 gene do not yield detectable diminutions in alpha(1,3)-fucosyltransferase activity when tested by expression in transfected COS-1 cells, and none of the FUT5 alleles co-segregate with plasma alpha(1,3)-fucosyltransferase deficiency in Indonesian pedigrees. By contrast, two of the codon changes in the FUT6 alleles inactivate this gene when tested by expression in transfected COS-1 cells. One of these inactivating changes is a missense mutation (Glu-247-->Lys) within the enzyme's catalytic domain. The other inactivating mutation represents a nonsense mutation (Tyr-315-->stop) that truncates the COOH terminus of the enzyme by 45 amino acids. The Glu-247-->Lys missense mutation is present in double dose in the nine plasma alpha(1,3)-fucosyltransferase-deficient individuals tested, whereas the nonsense mutation at tyrosine 315 is present in double dose in just one of these persons. These results demonstrate that the alpha(1,3)-fucosyltransferase activity in human plasma is encoded by the FUT6 gene and that the missense mutation within codon 247 of this gene is responsible for deficiency of this activity in these Indonesian families.

Molecular cloning of a fourth member of a human alpha (1,3)fucosyltransferase gene family. Multiple homologous sequences that determine expression of the Lewis x, sialyl Lewis x, and difucosyl sialyl Lewis x epitopes.

We and others have previously described the isolation of three human alpha (1,3)fucosyltransferase genes which form the basis of a nascent glycosyltransferase gene family. We now report the molecular cloning and expression of a fourth homologous human alpha (1,3)fucosyltransferase gene. When transfected into mammalian cells, this fucosyltransferase gene is capable of directing expression of the Lewis x (Gal beta 1-->4[Fuc alpha 1-->3]GlcNAc), sialyl Lewis x (NeuNAc alpha 2-->3Gal beta 1-->4 [Fuc alpha 1-->3]GlcNAc), and difucosyl sialyl Lewis x (NeuNAc alpha 2-->3Gal beta 1-->4[Fuc alpha 1-->3]GlcNAc beta 1-->3 Gal beta 1-->4[Fuc alpha 1-->3]GlcNAc) epitopes. The enzyme shares 85% amino acid sequence identity with Fuc-TIII and 89% identity with Fuc-TV but differs substantially in its acceptor substrate requirements. Polymerase chain reaction analyses demonstrate that the gene is syntenic to Fuc-TIII and Fuc-TV on chromosome 19. Southern blot analyses of human genomic DNA demonstrate that these four alpha (1,3)fucosyltransferase genes account for all DNA sequences that cross-hybridize at low stringency with the Fuc-TIII catalytic domain. Using similar methods, a catalytic domain probe from Fuc-TIV identifies a new class of DNA fragments which do not cross-hybridize with the chromosome 19 fucosyltransferase probes. These results extend the molecular definition of a family of human alpha (1,3)fucosyltransferase genes and provide tools for examining fucosyltransferase gene expression.

Isolation of a novel human alpha (1,3)fucosyltransferase gene and molecular comparison to the human Lewis blood group alpha (1,3/1,4)fucosyltransferase gene. Syntenic, homologous, nonallelic genes encoding enzymes with distinct acceptor substrate specificities.

Biochemical and genetic evidence indicates that the human genome may encode four or more distinct GDP-fucose:beta-D-N-acetylglucosaminide 3-alpha-L-fucosyltransferase (alpha(1,3)fucosyltransferase) activities. Genes encoding two of these activities have been previously isolated. These correspond to an alpha(1,3/1,4)fucosyltransferase thought to represent the human Lewis blood group locus and an alpha(1,3)fucosyltransferase expressed in the myeloid lineage. We report here the molecular cloning and expression of a third human alpha(1,3)fucosyltransferase gene, homologous to but distinct from the two previously reported human fucosyltransferase genes. When expressed in transfected mammalian cells, this gene determines expression of a fucosyltransferase capable of using N-acetyllactosamine to form the Lewis x epitope, and alpha(2,3)sialyl-N-acetyllactosamine to construct the sialyl Lewis x moiety. This enzyme shares 91% amino acid sequence identity with the human Lewis blood group alpha(1,3/1,4)fucosyltransferase, yet exhibits only trace amounts of alpha(1,4)fucosyltransferase activity. Polymerase chain reaction analyses were used to demonstrate that the gene is syntenic to the Lewis locus on chromosome 19. These analyses also excluded the possibility that this DNA segment represents an allele of the Lewis locus that encodes alpha(1,3)fucosyltransferase but not alpha(1,4)fucosyltransferase activity. These results are consistent with the hypothesis that this gene encodes the human "plasma type" alpha(1,3)fucosyltransferase, and suggest a molecular basis for a family of human alpha(1,3)fucosyltransferase genes.

Chronic active Epstein-Barr virus infection and virus-associated hemophagocytic syndrome.

We describe two unusual cases of Epstein-Barr virus infection that were complicated by the virus-associated hemophagocytic syndrome, predominantly involving the spleen. Both patients were young adult men who presented with fever, pancytopenia, and hepatosplenomegaly. Both had prompt symptomatic and hematologic improvement following splenectomy. Severe constitutional symptoms recurred in one patient 1 month after splenectomy, and he died of septicemia 2 months later. In both cases, there was prominent hemophagocytosis in the splenic red pulp. Some hemophagocytosis was also noted in the liver from the fatal case. Unexpectedly, no hemophagocytosis was detected in the bone marrow biopsy specimens or marrow aspirates obtained from these patients. The DNA hybridization studies detected Epstein-Barr virus genomes in spleen samples from both patients, and both patients had atypical patterns of serologic response to the virus, suggesting that a defective immune response may lead to an unrestrained viral proliferation. We conclude that there is an association between chronic active Epstein-Barr virus infection and the hemophagocytic syndrome, but that the tissue distribution of the hemophagocytosis may be variable.