An Alu-mediated large deletion of the FUT2 gene in individuals with the ABO-Bombay phenotype

Recently, we have found an allelic deletion of the secretor alpha(1,2)fucosyltransferase (FUT2) gene in individuals with the classical Bombay phenotype of the ABO system. The FUT2 gene consists of two exons separated by an intron that spans approximately 7 kb. The first exon is noncoding, whereas exon 2 contains the complete coding sequence. Since the 5' breakpoint of the deletion has previously been mapped to the single intron of FUT2, we have cloned the junction region of the deletion in a Bombay individual by cassette-mediated polymerase chain reaction. In addition, the region from the 3' untranslated region of FUT2 to the 3' breakpoint sequence has been amplified from a control individual. DNA sequence analysis of this region indicates that the 5' breakpoint is within a free left Alu monomer (FLAM-C) sequence that lies 1.3 kb downstream of exon 1, and that the 3' breakpoint is within a complete Alu element (AluSx) that is positioned 1.5 kb downstream of exon 2. The size of the deletion is estimated to be about 10 kb. There is a 25-bp sequence identity between the reference DNA sequences surrounding the 5' and 3' breakpoints. This demonstrates that an Alu-mediated large gene deletion generated by unequal crossover is responsible for secretor alpha(1,2)fucosyltransferase deficiency in Indian Bombay individuals.

Functional analysis of the 5'-flanking region of FTA for expression of rat GDP-L-fucose:beta-D-galactoside 2-alpha-L-fucosyltransferase

The tissue-specific and species-specific expression of the ABH antigens is well known among vertebrate species and it is regulated by the alpha(1,2)fucosyltransferase that forms the H antigen, a precursor of the A and B antigens. To investigate the mechanisms governing the tissue-specific and species-specific expression of this alpha(1,2)fucosyltransferase, we characterized the gene structure, including the promoter region, of FTA, a rat orthologous homolog of human FUT1 that encodes the H alpha(1, 2)fucosyltransferase and is responsible for the expression of the ABH antigens on human red blood cells. Northern blot and 5'-RACE analyses suggested that at least two forms of FTA mRNA (2.9 and 2.6 kb), which use alternative transcription start sites, are present in the cancer cell lines RCN-9 (rat colon cancer) and PC12 (rat pheochromocytoma), whereas only the 2.6 kb form was detected in normal colon, stomach and pancreas. Transcriptional activity of the 5'-flanking sequence, which contains three putative Sp1-binding sites, but lacks both TATA and CAAT boxes, was examined. Transient transfection experiments of promoter-reporter gene constructs showed high promoter activity in RCN-9, PC12 and human colon cancer (WiDr) cell lines, weak activity in human vascular endothelial (ECV304) cells and no activity in human erythroleukemia (HEL) cells. The results suggest that the 5'-flanking region of FTA contains a tissue-specific promoter. Deletional analysis of the 5'-flanking sequence revealed regions containing cell-type-specific positive acting element(s) and negative regulatory element(s), which are related to the promoter activity.

Allelic diversity of the human plasma alpha(1,3)fucosyltransferase gene (FUT6)

The 1080-bp coding region of the human plasma alpha(1,3)fucosyltransferase gene (FUT6) was sequenced in a total of 161 individuals (322 chromosomes) drawn from three populations, involving 56 Africans (Xhosa), 52 European-Africans of South Africa, and 53 Japanese. In addition to six reported base substitutions, eleven new base substitutions and a single base insertion were found in the coding region of the FUT6. Eleven functional and four null alleles were encountered, of which 10 alleles were novel alleles identified in this study. Two null alleles have been identified previously, whereas two novel null alleles, which contained a single base (cytosine) insertion at nucleotide 499, were found in a Xhosa population. The allelic distributions of FUT6 were different among these three populations. The heterozygosity of FUT6 was 0.860, 0.699, and 0.632, in Xhosa, European-African (South Africa), and in Japanese populations, respectively. The extensive DNA sequence diversity of the FUT6 may be suitable for application as a tool in genetic studies for modern human evolution.

Presence of H type 3/4 chains of ABO histo-blood group system in serous cells of human submandibular gland and regulation of their expression by the secretor gene (FUT2)

We have investigated by immunochemistry the distribution of H Type 3/4 chains of the ABO histo-blood group system in human submandibular gland using a monoclonal anti-H MBr1 antibody specific for H Type 3/4 chains, and have found the expression of H Type 3/4 chains was mainly in the serous cells. Serous cells from secretors were stained by MBr1 but not by anti-A and anti-B antibodies, whereas serous cells from nonsecretors exhibited a negative reaction with MBr1. Mucous cells were not stained by MBr1. Only a few striated duct cells showed a weak reaction with anti-H MBr1. These results suggested that the H Type 3/4 chains were distributed predominantly in the serous cells of the human submandibular gland and that secretor Type alpha(1,2)fucosyltransferase (Se enzyme) controlled the synthesis of H Type 3/4 chains in vivo. Saliva also contained H Type 3/4 chains, which were controlled by the secretor gene (FUT2). The differences in the distributions of H Type 1, H Type 2, and H Type 3/4 chains of the ABO histo blood group system in the submandibular gland are discussed.

Lewis (FUT3) genotypes in two different Chinese populations

The allelic frequencies of the alpha (1,3/4)fucosyltransferase gene (FUT3) in two different Chinese populations (138 individuals in Shenyang and 154 in Guangzhou) were investigated using PCR-RFLP and nucleotide sequencing methods. The common alleles in the Oriental population, Le (wild type allele), le59,508 (with the mutations at nucleotide (nt) 59T-->G and nt 508G-->A) and le59,1067 (with the mutations at nt 59T-->G and nt 1067T-->A) were encountered, and also the rare alleles, le1067 (with the mutation at nt 1067T-->A) and Le59 (with the mutation at 59T-->G), were observed in these Chinese populations. In addition, the common allele in Caucasians, le202,314 (with the mutations at nt 202T-->C and nt 314C-->T), was found in the Oriental population for the first time. The allelic frequencies of the Le, Le59, le59,508, le59,1067, le202,314, and le1067, were 0.750, 0.011, 0.145, 0.054, 0.036, and 0.004 in the Shenyang population and 0.675, 0.026, 0.14, 0.123, 0.026, and 0.010 in the Guangzhou population, respectively. The presence of the alleles containing either the 59 mutation (Le59) or the 1067 mutation (le1067) suggested that the allele le59,1067 may have originated by recombination between them.

The fusion gene at the ABO-secretor locus (FUT2): absence in Chinese populations

The fusion gene (se(fus)) is a null allele of the secretor type alpha (1, 2) fucosyltransferase gene (FUT2) and was first found in a Japanese population. It has not yet been reported in any other ethnic population. In the present study, we investigated the distribution of the fusion gene of the FUT2 locus in five populations from three ethnic groups in East Asia. The fusion gene was found in two additional Japanese populations with a high frequency (0.0551 in Okinawa and 0.0792 in Akita) and, for the first time outside Japan, in a Korean population, at a very low frequency (0.0063 in Seoul). In contrast, we found no fusion gene in two Chinese populations. These findings showed that the FUT2 fusion gene was ubiquitous in Japanese, but was rare in neighboring populations, suggesting that the FUT2 fusion gene had emerged from within the Japanese. Additionally, a new null allele with a C-to-T substitution at nucleotide 658 was found in one individual native of southern China.

Significance of each of three missense mutations, G484A, G667A, and G808A, present in an inactive allele of the human Lewis gene (FUT3) for alpha(1,3/1,4)fucosyltransferase inactivation

Recently, we found three novel missense mutations, G484A (Asp162Asn), G667A (Gly223Arg), and G808A (Val270Met), present in a Lewis-negative allele (le484,667,808) from an African (Xhosa) population. To define the relative contribution of each of the three mutations in the le484,667,808 allele for inactivation of the FUT3-encoded enzyme, we made chimeric FUT3 containing each of the three mutations. A transient expression study indicated that COS7 cells transfected with the FUT3 construct containing the G484A mutation expressed the Lewis antigen and had about 20% enzyme activity as compared with COS7 cells transfected with the wild type FUT3 allele, whereas COS7 cells transfected with the FUT3 construct containing either the G667A mutation or the G808A mutation did not express the Lewis antigen and showed no detectable alpha(1,3/1,4)fucosyltransferase activity. These results suggest that the G667A and/or the G808A missense mutations of FUT3 alleles are responsible for the inactivation of the FUT3-encoded enzyme.

Changing transcription start sites in H-type alpha(1,2)fucosyltransferase gene (FUT1) during differentiation of the human erythroid lineage

Recent studies have suggested that at least three transcription-initiation sites were present in the human H-type alpha(1,2)fucosyltransferase gene (FUT1). In the present study, we have investigated these transcription start sites of FUT1 in undifferentiated leukemic cells (K562) that have erythroid characteristics, in erythroleukemia cells (HEL), and in bone marrow cells. K562 cells used exclusively exon 1 as the start site. While HEL cells used mainly exon 2 as the start site, the major start site for bone marrow cells was within exon 7. In addition, we investigated the transcription start site(s) in vascular endothelial cells (ECV304) as an example of mature cells and found that the start site was predominantly within exon 7. The promoter activities were found in the 5' flanking regions of these three start sites after transfection of constructs with luciferase reporter gene into K562 and HEL cells. These findings suggested that the transcription start sites of FUT1 changed during differentiation of the erythroid lineage and that the tissue-specific and stage-specific expressions of the FUT1 were regulated by three distinct promoters. We also found that the 5' flanking region of exon 2 (intron 1) consisted of repetitive sequences (chromosome 19-specific 37-bp minisatellite repeats, Alu sequence and long terminal repeat) and that the start site of exon 2 was within the long terminal repeat. Thus, these repetitive sequences may play a role in the expression of the FUT1.

Extensive polymorphism of the FUT2 gene in an African (Xhosa) population of South Africa

The human secretor type alpha(1,2)fucosyltransferase gene (FUT2) polymorphism was investigated in Xhosa and Caucasian populations of South Africa by polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing. Six new base substitutions were found in the coding region of FUT2. A single base (C) deletion at nucleotide 778, which led to a frame shift and produced a stop codon at codon 275, was responsible for the enzyme inactivation. Three nonsynonymous base substitutions, A40G (lle14Val), C379T (Arg127Cys), and G481A (Asp161Asn), and two synonymous base substitutions, A375G (Glu125) and C480T (His160), were also identified in functional alleles. As a result, seven new alleles, Se40, Se481, Se40,481, Se357,480, Se357,379,480, Se375, and se357,480,778 were identified. Population studies revealed that an allele containing a nonsense mutation G428A (Trp143stop) (se428) was the common null allele in both Xhosa and Caucasian populations, whereas an allele containing a missense A385T (Ile129Phe) mutation (se357,385), which is the common null allele in Orientals, was found to be absent from both populations. The heterozygosity rates of FUT2 genotypes were as high as 0.75 in the Xhosa population and 0.65 in the Caucasian population. Therefore, the extensive polymorphism and race specificity of the FUT2 gene make it suitable for application as a new tool in genetic studies of modern human evolutionary history.

Five novel missense mutations of the Lewis gene (FUT3) in African (Xhosa) and Caucasian populations in South Africa

Five novel missense mutations, viz., C304 A, T370 G, G484 A, G667 A, and G808 A, in the Lewis gene (FUT3) were detected in African (Xhosa) and Caucasian individuals in South Africa. These single base substitutions may result in changes in amino acid residues from Gln102 to Lys in the 304 mutation, Ser124 to Ala in the 370 mutation, Asp162 to Asn in the 484 mutation, Gly223 to Arg in the 667 mutation, and Val270 to Met in the 808 mutation. Out of the five novel mutations identified in this investigation, four new alleles (le484,667, le484,667,808, Le304, and Le370) were determined in the Xhosa population and two new alleles (le202,314,484 and Le304) in the Caucasian population. The determination of alpha(1,3/1,4)fucosyltransferase activity, after transfection of plasmids containing the new alleles into COS7 cells, suggested that alleles le484,667 and le484,667,808 encoded an inactive enzyme, and that alleles Le304 and Le370 encoded a functional enzyme. In addition, we also examined the incidence of five common alleles, Le59, le59,508 le59,1067, le202,314, and le1067 in two populations by the polymerase chain reaction/restriction fragment length polymorphism method and compared differences in the allele frequencies of FUT3 among three ethnic groups (Orientals, Africans, and Caucasians).

Identification of a mutation (A1879G) of transferrin from cDNA prepared from peripheral blood cells

We have prepared a transferrin (TF) cDNA from total RNA of peripheral blood cells of an individual with a TF B variant (TF Bv) phenotype to analyze the molecular basis for the TF Bv. The TF B variant allele (TF Bv) was found to contain an A to G transition at nucleotide 1879 in the coding region that may result in substitution of glutamic acid for lysine at codon 627 located in exon 16. In addition, a transient expression study by transfection of each plasmid containing TF C1, TF C2 or TF Bv cDNA into monkey kidney (COS7) cells indicated that the products from specific TF alleles were able to be identified respective phenotypes by isoelectrofocusing electrophoresis and immunoblotting analyses. Based on this nucleotide substitution, we also established a PCR-RFLP method to detect the TF Bv allele from genomic DNA. Thus, peripheral blood cells were useful as an alternative source for preparation of cDNA from human liver for the molecular analysis of TF polymorphism.

The haptoglobin-gene deletion responsible for anhaptoglobinemia

We have found an allelic deletion of the haptoglobin (Hp) gene from an individual with anhaptoglobinemia. The Hp gene cluster consists of coding regions of the alpha chain and beta chain of the haptoglobin gene (Hp) and of the alpha chain and beta chain of the haptoglobin-related gene (Hpr), in tandem from the 5' side. Southern blot and PCR analyses have indicated that the individual with anhaptoglobinemia was homozygous for the gene deletion and that the gene deletion was included at least from the promoter region of Hp to Hpr alpha but not to Hpr beta (Hpdel). In addition, we found seven individuals with hypohaptoglobinemia in three families, and the genotypes of six of the seven individuals were found to be Hp2/Hpdel. The phenotypes and genotypes in one of these three families showed the father to be hypohaptoglobinemic (Hp2) and Hp2/Hpdel, the mother to be Hp2-1 and Hp1/Hp2, one of the two children to be hypohaptoglobinemic (Hp2) and Hp2/Hpdel, and the other child to be Hp1 and Hp1/Hpdel, showing an anomalous inheritance of Hp phenotypes in the child with Hp1. The Hp2/Hpdel individuals had an extremely low level of Hp (mean+/-SD = 0.049+/-0. 043 mg/ml; n=6), compared with the level (1.64+/-1.07 mg/ml) obtained from 52 healthy volunteers having phenotype Hp2, whereas the serum Hp level of an individual with Hp1/Hpdel was 0.50 mg/ml, which was approximately half the level of Hp in control sera from the Hp1 phenotype (1.26+/-0.33 mg/ml; n=9), showing a gene-dosage effect. The other allele (Hp2) of individuals with Hp2/Hpdel was found to have, in all exons, no mutation, by DNA sequencing. On the basis of the present study, the mechanism of anhaptoglobinemia and the mechanism of anomalous inheritance of Hp phenotypes were well explained. However, the mechanism of hypohaptoglobinemia remains unknown.

Missense mutation of FUT1 and deletion of FUT2 are responsible for Indian Bombay phenotype of ABO blood group system

The Bombay phenotype fails to express the ABH antigens of ABO blood group system on red blood cells and in secretions because of a lack in activities of the H gene (FUT1)- and Secretor gene (FUT2)-encoded alpha (1,2)fucosyltransferases. In this study, we have examined the FUT1 and the FUT2 from three unrelated Indian individuals with the Bombay phenotype. These three individuals were found to be homozygous for a T725G mutation in the coding region of the FUT1, which inactivated the enzyme activity. In addition, we did not detect any hybridized band corresponding to the FUT2 by Southern blot analysis using the catalytic domain of the FUT2 as a probe, indicating that the three individuals were homozygous for a gene deletion in the FUT2. These results suggest that the T725G mutation of FUT1 and the gene deletion of FUT2 are responsible for the classical Indian Bombay phenotype.

Structure and expression of the gene encoding secretor-type galactoside 2-alpha-L-fucosyltransferase (FUT2)

The expression and secretion of ABO antigens in epithelial cells of glands are controlled by secretor-type alpha (1,2)fucosyltransferase activity. We have examined the expression of the secretor-type alpha(1,2)fucosyltransferase gene (FUT2) and a pseudogene of FUT2 (Sec1) in several tumor cell lines by northern blot and/or reverse-transcription-PCR (RT-PCR) analyses. Transcripts of FUT2 were found in total RNA from ovarian, gastric and colonic cancer cell lines but not from six leukemic cell lines, including erythroleukemic HEL cells, by RT-PCR. On the other hand, RT-PCR indicated that Sec1 was expressed in all these tumor cells, including all hematopoietic cells studied. Northern blot analysis indicated that FUT2 transcripts with a similar size (3.3 kb) were expressed in cancer cell lines. Rapid amplification of cDNA ends suggested that the entire FUT2 cDNA is 3.1-kb long and has two Alu repetitive elements in its 3' untranslated region, including an inverted repeat. The mRNA, therefore, may form a large stem-and-loop structure (1.2 kb). Each stem contains about 300 bases, the loop contains 640 bases, and the percentage of complementary nucleotide sequences in the stem region is 85%. The presence of a large stem-and-loop structure in the 3' untranslated region may regulate the level of the FUT2 transcript by affecting the stability of the mRNA.

Structure and expression of H-type GDP-L-fucose:beta-D-galactoside 2-alpha-L-fucosyltransferase gene (FUT1). Two transcription start sites and alternative splicing generate several forms of FUT1 mRNA

The expression of the ABO antigens on erythrocyte membranes is regulated by H gene (FUT1)-encoded alpha(1,2)fucosyltransferase activity. We have examined the expression of the FUT1 in several tumor cell lines, including erythroid lineage and normal bone marrow cells, by Northern blot and/or reverse transcription-polymerase chain reaction (RT-PCR) analyses. RT-PCR indicated that bone marrow cells, erythroleukemic cells (HEL), and highly undifferentiated leukemic cells (K562) that have erythroid characteristics expressed the FUT1 mRNA while four leukemic cell lines did not. The FUT1 mRNA was also demonstrated in gastric, colonic, and ovarian (MCAS) cancer cell lines by RT-PCR. Northern blot analysis indicated that a 4. 0-kilobase FUT1 transcript was expressed in some of these tumor cell lines. Rapid amplification of 5' cDNA end (RACE) analysis suggested that the FUT1 transcript had several forms generated by two distinct transcription start sites and alternative splicing. The results of RT-PCR using specific primers for each starting exon suggested that two transcription initiation sites (exon 1A and exon 2A) of the FUT1 were identified in gastric cancer cells and in ovarian cancer cells. Only exon 1A was identified as a transcription start site in another gastric cancer cell line, two colonic cancer cell lines, and in K562 cells, whereas only exon 2A was identified in HEL cells and in bone marrow cells. These two transcription start sites were located 1.8 kilobases apart. Therefore, two distinct promoters appeared to be present in the FUT1. The distinct promoters of the FUT1 and alternative splicing of the FUT1 mRNA may be associated with time- and tissue-specific expression of the FUT1.

Two missense mutations of H type alpha(1,2)fucosyltransferase gene (FUT1) responsible for para-Bombay phenotype

BACKGROUND AND OBJECTIVES

Rare individuals (Bombay and para-Bombay phenotypes) fail to express the A, B and H antigens on erythrocyte membranes because of a lack in the H gene (FUT1)-encoded alpha(1,2)fucosyltransferase activity. In this study, we have found a para-Bombay individual (Bmh) who expressed B and H antigens in saliva but not on red blood cells. The FUT1 alleles of this person contained two single base changes (T460C and G1042A) in the coding region relative to the wild type allele. These substitutions may result in changes in two amino acid residues (Y154H and E348K).

MATERIALS AND METHODS

Since the T460C and G1042A mutations destroy endonuclease RsaI and AvaI sites, respectively, we tested for these mutations using PCR-RFLP.

RESULTS

Our findings indicated that this para-Bombay person was homozygous for the T460C and G1042A mutations, and that neither of these mutations was found in 136 randomly selected Japanese individuals. The measurement of the alpha(1,2)fucosyltransferase activity after transient expression of the FUT1 alleles in COS-7 cells indicated that the H-deficient allele-encoded enzyme had no detectable activity. Moreover, transfection by chimera FUT1 allele contains only the T460C mutation, or only the G1042A mutation, and yielded 1.0 or 9.3%, respectively, of the activities compared to transfection by the wild type allele.

CONCLUSIONS

These results suggest that the two mutations in combination are responsible for the inactivation of the FUT1-encoded enzyme activity.

PCR analysis of Lewis-negative gene mutations and the distribution of Lewis alleles in a Japanese population

Three mutations in the Lewis-negative gene, T59G, G508A and T1067A, have been detected by means of a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 149 unrelated Japanese individuals. We found three common Lewis alleles-Le (without the T59G, G508A, and T1067A mutations), le1 (with the T59G and G508A mutations), and le2 (with the T59G and T1067A mutations) in a Japanese population. In addition, we also found one rare Lewis-negative allele, le3 (only with the T1067A mutation). The allele frequencies of Le, le1, le2, and le3 were 0.607, 0.275, 0.114, and 0.003, respectively. Our results were in accordance with those expected by the Hardy-Weinberg equilibrium. Some statistical parameters of forensic interest were also calculated.

Molecular basis for secretor type alpha(1,2)-fucosyltransferase gene deficiency in a Japanese population: a fusion gene generated by unequal crossover responsible for the enzyme deficiency

About 20%-25% of Caucasian individuals are nonsecretors who fail to express soluble A, B, H, and Lewis b histo-blood group antigens in secretory organs and secretory fluids because of the absence of the Secretor gene (FUT2)-encoded alpha(1,2)-fucosyltransferase (Se enzyme) activity. Recently, the FUT2 and a pseudogene have been isolated, and an Se enzyme-deficient allele (se) caused by a nonsense mutation (G428A, se1) in Caucasians has also been reported. Although we were unable to find the se1 allele, we have found a missense mutation (A385T, se2) and two nonsense mutations (C571T, se3 and C628T, se4) in the Japanese Se enzyme-deficient alleles. In addition, we have found a fusion gene, which consisted of the 5'-region of the pseudogene and the 3'-region of the functional FUT2, as a Se enzyme-deficient allele (se5). The DNA sequence analysis of the fusion gene indicated that the crossover region corresponded to regions between bases 253 and 313 of the pseudogene and between bases 211 and 271 of the FUT2. This finding suggested that the fusion gene was generated by homologous but unequal crossover. A population study on 141 randomly selected Japanese has indicated that the se2 is a common Se enzyme-deficient allele in the Japanese population. The results suggest that Se enzyme-deficient alleles are race specific.

Rapid decline of residual renal function in patients on automated peritoneal dialysis

OBJECTIVE

To determine the effect of peritoneal dialysis modalities such as nightly intermittent peritoneal dialysis (NIPD), continuous cyclic peritoneal dialysis (CCPD), and continuous ambulatory peritoneal dialysis (CAPD) on residual renal function.

DESIGN

A six-month prospective, nonrandomized comparison study.

SETTING

Outpatient CAPD unit of a university hospital.

PARTICIPANTS

Eighteen end-stage renal disease patients treated by peritoneal dialysis (8 by NIPD, 5 by CCPD, and 5 by CAPD).

INTERVENTIONS

Samples from the total dialysate, blood, and 24-hour urine collection were obtained monthly.

MEASUREMENTS

Urea, creatinine, and beta2-microglobulin concentrations were measured. Renal and peritoneal clearances of each substance and KT/V urea were calculated. Residual renal function (RRF) was estimated by renal creatinine clearance (RCcr).

RESULTS

No significant differences in age, sex, and primary renal disease among the three groups were noted. In all groups, anemic and hypertensive states were controlled identically, and mean weekly total (renal + peritoneal) KT/V urea (over 2.1/wk) and total creatinine clearance (over 60 L/wk/1.73 m2) were maintained during the whole experimental period. Starting mean RCcr was near 4.0 mL/min/1.73 m2 in all groups. Thereafter, a rapid and significant decline in RRF was demonstrated on NIPD and CCPD. The declining rates of RCcr values at 6 months after starting NIPD and CCPD were -0.29 and -0.34 mL/min/month, respectively, which were much greater than those of CAPD (+0.01 mL/min/month).

CONCLUSION

Because of a possibly characteristic progressive loss of RRF in automated peritoneal dialysis (APD), strict regular assessment of RRF should be performed from the start of APD.

A dialysis patient with systemic calciphylaxis exhibiting rapidly progressive visceral ischemia and acral gangrene

Systemic calciphylaxis is a rare, poorly understood syndrome of progressive peripheral ischemic necrosis and medial arterial calcification in patients with end-stage renal disease. We report a patient with this syndrome which developed following corticosteroid administration and who ultimately required amputation of the four extremities. Furthermore, cerebral, myocardial, splenic, and intestinal infarctions also developed in parallel with the increment of visceral arterial calcification. No evidence of noticeable hyperparathyroidism or elevation of serum calcium-phosphate product was observed. We speculated that, in addition to diabetes mellitus and chronic renal failure while undergoing dialysis therapy, the administration of corticosteroids might act synergistically to cause calciphylaxis.

Establishment and characterization of immortalized human coronary endothelial cells

We established an immortalized cell line from endothelial cells derived from a human coronary artery, isolated at autopsy from 76-year-old male, by transfecting the cells with origin-minus simian virus 40 DNA. These cells showed SV40 T antigen in the nuclei and Ulex europaeus I agglutinin and factor VIII-related antigen, as endothelial cell markers, in their cytoplasm. This cell line synthesized prostacyclin, tissue-type plasminogen activator (tPA), and plasminogen activator inhibitor-1 (PAI-1) as well as produced the proform of matrix metalloproteinase 1, which was activated by cultivating the cells with plasminogen. These findings reveal that this immortalized endothelial cell line retains characteristics of human coronary endothelial cells, indicating that this cell line is useful for studying atherogenesis of the coronary artery.

Detection of T to G mutation at position 59 in the Lewis gene by mismatch polymerase chain reaction

Recently, we discovered the missense mutations of T to G at position 59 and of G to A at position 508 in one of the Lewis-negative (le) genes (Koda et al. 1993). In the present study, we report a method to detect the mutation at position 59 using mismatch PCR amplification and endonuclease MspI digestion. For this mutation, we found that 7 out of 12 Lewis-negative, and none of 15 Lewis-positive individuals were homozygous, while 4 out of 12 Lewis-negative, and 4 out of 15 Lewis-positive individuals were heterozygous. These results indicate that the mutation at position 59 is a common mutation in the le genes.

Hydrolysis of S-2-aminoethylcysteinyl peptide bond by Achromobacter protease I

The substrate specificity of Achromobacter protease I (API) was examined for S-2-aminoethyl(AE)cysteinyl bonds in Bz-AEC-OMe/OEt, Bz-AEC-NH2, and AE-insulin B chain. The protease hydrolyzed all of the tested AE-cysteinyl bonds at the same rate as that of lysyl bonds. Kinetic parameters were estimated for this hydrolysis reaction.