Human noroviruses recognize sialyl Lewis x neoglycoprotein

The carbohydrate binding characteristics of a norovirus GII.3 (Chron1) and a GII.4 (Dijon) strain were investigated using virus-like particles (VLPs) and saliva samples from 81 individuals genotyped for FUT2 (secretor) and FUT3 (Lewis) and phenotyped for ABO and Lewis blood groups. The two VLPs showed a typical secretor-gene-dependent binding and bound significantly stronger to saliva from A, B, and AB than from O individuals (P < 0.0001 and P < 0.001) but did not bind to any samples from secretor-negative individuals. The GII.3 strain showed larger interindividual variation and bound stronger to saliva from B than from A(2) secretors (P < 0.01). When assaying for binding to neoglycoproteins, the GII.3 and GII.4 strains were compared with the Norwalk GI.1 prototype strain. Although all three strains bound to Lewis b (and H type 1 chain) glycoconjugates, only the two GII strains showed an additional binding to sialyl Lewis x. This novel binding was specific since the VLPs did not bind to structural analogs, e.g., Lewis x or sialyl Lewis a, but only to sialyl Lewis x, sialyl diLewis x and sialylated type 2 chain conjugates. In inhibition experiments, the sialyl Lewis x conjugate was the most potent inhibitor. The minimal requirement for this potential receptor structure is Neu5Ac alpha 3Gal beta 4(Fuc alpha 3)GlcNAc beta 3Gal beta- where Fuc is not absolutely necessary for binding. Our study shows that some human norovirus GII strains have at least two binding specificities: one secretor-gene-dependent related to alpha1,2-fucosylated carbohydrates and another related to alpha2,3-sialylated carbohydrates of the type 2 chain, e.g., sialyl Lewis x.

Different affinity of galectins for human serum glycoproteins: galectin-3 binds many protease inhibitors and acute phase proteins

Here we report the first survey of galectins binding to glycoproteins of human serum. Serum was subjected to affinity chromatography using immobilized galectins, and the bound glycoproteins were analyzed by electrophoresis, Western blotting, and mass spectrometry. Galectins-3, -8, and -9 bound a much broader range of ligands in serum than previously known, galectin-1 bound less, and galectins-2, -4, and -7 bound only traces or no serum ligands. Galectin-3 bound most major glycoproteins, including alpha-2-macroglobulin and acute phase proteins such as haptoglobin. It bound only a selected minor fraction of transferrin, and bound none or little of IgG. Galectins-8 and -9 bound a similar range of glycoproteins as galectin-3, but in lower amounts, and galectin-8 had a relative preference for IgA. Galectin-1 bound mainly a fraction of alpha-2-macroglobulin and only traces of other glycoproteins. The binding of galectin-3 to serum glycoproteins requires affinity for LacNAc, since a mutant (R186S), which has lost this affinity, did not bind any serum glycoproteins. The average affinity of galectin-3 for serum glycoproteins was estimated to correspond to K(d) approximately 1-5 muM by modeling of the affinity chromatography and a fluorescence anisotropy assay. Since galectins are expressed on endothelial cells and other cells exposed to serum components, this report gives new insight into function of galectins and the role of their different fine specificity giving differential binding to the serum glycoproteins.

Major ampullate spidroins from Euprosthenops australis: multiplicity at protein, mRNA and gene levels

Spider dragline silk possesses extraordinary mechanical properties. It consists of large fibrous proteins called spidroins that display modular structures. It is known to consist of two proteins: the major ampullate spidroin (MaSp) 1 and MaSp2. This study analyses MaSp sequences from the nursery-web spider Euprosthenops australis. We have identified a previously uncharacterized MaSp2 sequence and a new MaSp-like spidroin, which display distinct homogenous submotifs within their respective Gly-rich repeats. Furthermore, a group of MaSp1 cDNA clones show unexpected heterogeneity. Genomic PCR identified several MaSp1 gene variants within individual spiders, which suggests the presence of a gene cluster in E. australis. Finally, the evolution of spidroin genes is discussed in relation to phylogenetic analysis of nonrepetitive C-terminal domains from diverse species.

Host genetic resistance to symptomatic norovirus (GGII.4) infections in Denmark

A total of 61 individuals involved in five norovirus outbreaks in Denmark were genotyped at nucleotides 428 and 571 of the FUT2 gene, determining secretor status, i.e., the presence of ABH antigens in secretions and on mucosa. A strong correlation (P = 0.003) was found between the secretor phenotype and symptomatic disease, extending previous knowledge and confirming that nonsense mutations in the FUT2 gene provide protection against symptomatic norovirus (GGII.4) infections.

Virus-induced transcriptional activation of host FUT genes associated with neo-expression of Ley in cytomegalovirus-infected and sialyl-Lex in varicella-zoster virus-infected diploid human cells

Cell surface carbohydrate structures including sialyl-Lewis X (sLe(x)) and Lewis Y (Le(y)) are important ligands in normal and malignant tissues. The aim here was to determine the possible influence on the expression of such antigens by two viruses varicella-zoster virus (VZV) and cytomegalovirus (CMV) involved in persistent infections of humans. We found that infection of human diploid fibroblasts with both viruses resulted in transcriptional activation of several fucosyltransferase (FUT) genes that were either dormant or expressed at low levels in uninfected cells. Both viruses induced FUT3, FUT5, and FUT6, encoding alpha1,3- and/or alpha1,4-specific fucosyltransferases. CMV, but not VZV, induced transcription of FUT1 (encoding an alpha1,2-specific fucosyltransferase), FUT7, and FUT9. The changes in transcription of FUT genes were expectedly associated with expression of Le(y) in CMV-infected cells and sLe(x) in the VZV-infected fibroblasts although no expression of these antigens was observed in uninfected cells. One major explanation for this difference between CMV- and VZV-infected cells was that CMV, but not VZV, induced expression of FUT1, necessary for Le(y) expression. The induced carbohydrate antigens in CMV- and VZV-infected cells could be of significance for virus spread and possible escape from immune responses.

A homozygous nonsense mutation (428G-->A) in the human secretor (FUT2) gene provides resistance to symptomatic norovirus (GGII) infections

Noroviruses (formerly Norwalk-like viruses) are a major cause of acute gastroenteritis worldwide and are associated with a significant number of nosocomial and food-borne outbreaks. In this study we show that the human secretor FUT2 gene, which codes for an alpha(1,2)-fucosyltransferase synthesizing the H-type 1 antigen in saliva and mucosa, is associated with susceptibility to norovirus infections. Allelic polymorphism characterization at nucleotide 428 for symptomatic (n = 53) and asymptomatic (n = 62) individuals associated with nosocomial and sporadic norovirus outbreaks revealed that homozygous nonsense mutation (428G-->A) in FUT2 segregated with complete resistance for the disease. Of all symptomatic individuals, 49% were homozygous (SeSe) and 51% heterozygous (Sese428) secretors, and none were secretor negative (se428se428), in contrast to 20% nonsecretors (se428se428) among Swedish blood donors (n = 104) (P < 0.0002) and 29% for asymptomatic individuals associated with nosocomial outbreaks (P < 0.00001). Furthermore, saliva from secretor-positive and symptomatic patients but not from secretor-negative and asymptomatic individuals bound the norovirus strain responsible for that particular outbreak. This is the first report showing that the FUT2 nonsecretor (se428se428) genotype is associated with resistance to nosocomial and sporadic outbreaks with norovirus.

Characterization of EBV-transformed B-cells established from an individual homozygously mutated (G329A) in the FUT7 alpha1,3-fucosyltransferase gene

The alpha1,3-fucosyltransferase VII (Fuc-TVII) is involved in the biosynthesis of E- and P-selectin ligands such as sialyl Lewis x (SLe(x)) on human leukocytes. Recently, individuals were characterized carrying a missense mutation (G329A; Arg110-Gln) in the FUT7 gene encoding this enzyme. The mutated FUT7 construct produced a Fuc-TVII enzyme with impaired activity compared with the wildtype enzyme. Polymorphonuclear granulocytes from an individual carrying this mutation homozygously also showed a reduced expression of SLe(x). In the present study, we have established Epstein-Barr virus-transformed B-cell lines from this individual (SIGN) and from an individual not carrying the mutation (IWO). The cell lines were confirmed to be of B-cell origin by flow cytometry analysis. IWO cells interacted with E-selectin in an in vitro flow chamber analysis whereas SIGN cell did not. However, when SIGN cell was transiently transfected with wildtype FUT7 cDNA, interaction with E-selectin could be restored. Cell surface expression of the SLe(x)-related epitopes recognized by antibodies CSLEX-1, KM-93 and HECA-452 was elevated on IWO cells compared with that on SIGN cells, consistent with a role of these antigens in E-selectin recognition. These cell lines will be useful in further characterization of E-selectin ligands and encourage further studies on the consequences of the FUT7-G329A mutation in vivo.

Real time PCR for monitoring regulation of host gene expression in herpes simplex virus type 1-infected human diploid cells

Herpes simplex virus type 1 (HSV-1) induces prominent shifts in the rates of transcription of host cellular genes of relevance for the outcome of the viral infection. The quantitative analysis of transcription may be obscured by virus-induced alterations in the levels of RNA encoded by cellular housekeeping genes that are used commonly for normalisation of real time reverse transcription PCR (RT-qPCR). In the present study, we analysed beta-actin, GAPDH and 18S rRNA for their usefulness in normalisation of RT-qPCR analysis of the transcription of the HSV-1 gamma gB-1 gene and FUT5, a cellular gene induced by viral infection. The transcription of these genes was monitored in a TaqMan-based real time RT-PCR system over a 24h interval of virus infection of human embryonic lung fibroblasts. The levels of gB-1 and FUT5 RNA were normalised via difference in the threshold cycle (deltaC(t)) values relative to each and one of the housekeeping genes or calculated in relation to the number of infected cells without any further normalisation. The levels of RNA encoded by beta-actin or GAPDH were found to vary by several orders of magnitude during HSV-1 infection, introducing large errors in the estimation of the gB-1 and FUT5 RNA levels. In contrast, the variation of C(t) values for 18S rRNA was less than one cycle during 24h period of HSV-1 infection. The FUT5 and gB-1 RNA figures obtained by DeltaC(t) normalisation relative 18S rRNA were identical to those calculated in relation to the number of infected cells. These data recommend 18S rRNA for normalisation in HSV-1-infected human cells but discourage the use of beta-actin and GAPDH RNA for this purpose. By applying these procedures, it was shown that the transcription of FUT5 was increased by 50-fold 5-24h after HSV-1 infection and 200-fold by the inhibition of viral DNA replication in HSV-infected cells.

Evolution of human calicivirus RNA in vivo: accumulation of mutations in the protruding P2 domain of the capsid leads to structural changes and possibly a new phenotype

In the present study we report on evolution of calicivirus RNA from a patient with chronic diarrhea (i.e., lasting >2 years) and viral shedding. Partial sequencing of open reading frame 1 (ORF1) from 12 consecutive isolates revealed shedding of a genogroup II virus with relatively few nucleotide changes during a 1-year period. The entire capsid gene (ORF2) was also sequenced from the same isolates and found to contain 1,647 nucleotides encoding a protein of 548 amino acids with similarities to the Arg320 and Mx strains. Comparative sequence analysis of ORF2 revealed 32 amino acid changes during the year. It was notable that the vast majority of the cumulative amino acid changes (8 of 11) appeared within residues 279 to 405 located within the hypervariable domain (P2) of the capsid protein and hence were subject to immune pressure. An interesting and novel observation was that the accumulated amino acid changes in the P2 domain resulted in predicted structural changes, including disappearance of a helix structure, and thus a possible emergence of a new phenotype. FUT2 gene polymorphism characterization revealed that the patient is heterozygous at nucleotide 428 and thus Secretor(+), a finding in accordance with the hypothesis of FUT2 gene polymorphism and calicivirus susceptibility. To our knowledge, this is the first report of RNA evolution of calicivirus in a single individual, and our data suggest an immunity-driven mechanism for viral evolution. We also report on chronic virus excretion, immunoglobulin treatment, and modification of clinical symptoms; our observations from these studies, together with the FUT2 gene characterization, may lead to a better understanding of calicivirus pathogenesis.

Pharmacokinetics and anticoagulant effect of the direct thrombin inhibitor melagatran following subcutaneous administration to healthy young men

The pharmacokinetic dose linearity and reproducibility, the effects on ex-vivo coagulation time assays and bleeding time, and tolerability of the direct thrombin inhibitor melagatran following subcutaneous (s.c.) dosing were investigated in two open-label studies in healthy males: (i). a dose-escalation study in which subjects received single s.c. doses of melagatran (0.1-5 mg); and (ii). a repeated-dosing study in which 3 mg s.c. melagatran was administered at 12-h intervals for 4 days. In both studies, melagatran was rapidly absorbed with maximum plasma concentrations (C(max)) observed about 0.5 h post dosing. The half-life of melagatran was about 2 h. The area under the melagatran plasma concentration versus time curve increased linearly with dose. No time dependency in the area under the curve or Cmax was observed over 4 days of twice-daily dosing. The variability in pharmacokinetic parameters was low and the bioavailability of melagatran appeared to be complete. There was a steep and linear prolongation of thrombin time, a non-linear prolongation of both activated partial thromboplastin time and activated coagulation time, and a decrease in prothrombin complex activity with increasing melagatran plasma concentration. Only moderate increases in capillary bleeding time were observed with s.c. doses up to 5 mg melagatran. Melagatran was well tolerated after s.c. injection, with good local tolerability at the injection site.

Quantitative analysis of desmethylselegiline, methamphetamine, and amphetamine in hair and plasma from Parkinson patients on long-term selegiline medication

Hair and plasma from patients on long-term selegiline medication were analyzed to evaluate the relationships between plasma and hair melanin concentrations and the incorporation of the selegiline metabolites methamphetamine and amphetamine in hair, and to evaluate hair analyses for determining compliance in medication. Analyses were performed on both the whole hairs, as well as pigmented and non-pigmented hairs from gray-haired patients. Melanin was quantitated by spectrophotometry, and metabolites were quantitated by gas chromatography-mass spectrometry. Concentrations in pigmented and non-pigmented hairs differed significantly for both methamphetamine (p < 0.01) and amphetamine (p < 0.02), with mean concentration ratios being 3.69 +/- 1.88 and 2.95 +/- 1.16 for methamphetamine and amphetamine, respectively. Segmental analysis indicated that some patients had not been compliant with medication. We concluded that the incorporation of methamphetamine and amphetamine into hair of single individuals shows a preference for pigmented hairs over white hairs and that segmental analysis of hair may be useful when measuring compliance with medication.

Identification of seven new 2,3-sialyltransferase III, ST3Gal III, transcripts from human foetal brain

We have recently cloned and sequenced 19 human ST3Gal III gene isotranscripts from peripheral blood leukocytes and identified very complex patterns of isotranscripts of this gene in neuronal tissues. We have now cloned and sequenced additionally seven new isotranscripts from foetal brain. These novel isotranscripts showed losses of complete exons along the whole length of the coding sequence. None of the new isotranscripts coded for proteins with the two (L- and S-) sialylmotifs intact. One of the isotranscripts belonged to the isoform ST3Gal III -B, five to the ST3Gal III -C isoform and one to ST3Gal III -D isoform of isotranscripts, which lacks exon 3, exons 3 and 4 and exon 4 respectively. Two of the C series isotranscripts, ST3Gal III C4 and C11 had both lost exons 12 and 13 containing the S-motif but had otherwise the L- and the VS-motifs intact. Three isotranscripts, ST3Gal III C5, C12 and D5, were similar in the 3'-end coding for an identical amino acid sequence unrelated to the original enzyme. Isotranscripts ST3Gal III C9 and B10 were distinctly different from all other forms identified so far. The splice variants reported here are unlikely to express enzymatic activities but may other biological functions.

Polymorphonuclear leukocytes from individuals carrying the G329A mutation in the alpha 1,3-fucosyltransferase VII gene (FUT7) roll on E- and P-selectins

We recently identified several individuals carrying a missense mutation (G329A; Arg(110)-Gln) in the FUT7 gene encoding fucosyltransferase VII. This enzyme is involved in the biosynthesis of the sialyl Lewis x (Le(x)) epitope on human leukocytes, which has been identified as an important component of leukocyte ligands for E- and P-selectin. No enzyme activity was measurable in expression studies in COS-7 cells using the mutated FUT7 construct. One of the identified individuals carried this mutation homozygously. Flow cytometry analysis of polymorphonuclear leukocytes (PMN) from this individual showed a nearly complete absence of staining with mAbs directed against sialyl Le(x) and a diminished staining with an E-selectin IgG chimera. However, staining with P-selectin IgG chimera and Abs directed against P-selectin glycoprotein ligand-1 was not affected by the mutation. PMN from the homozygously mutated individual was further analyzed in an in vitro flow chamber assay. The number of rolling PMN and the rolling velocities on both E- and P-selectin were in the range of PMN from nonmutated individuals. FUT4 and FUT7 mRNA was quantified in PMN isolated from individuals carrying the FUT7 mutation. It was found that PMN from both FUT7 homozygously and heterozygously mutated individuals exhibited an elevated expression of FUT4 mRNA compared with PMN from FUT7 nonmutated individuals. The elevated expression of fucosyltransferase IV was reflected as an increased expression of the Le(x) and CD65s Ags on PMN from these individuals. The significance of the mutation was supported by transfection of BJAB cells.

Pharmacokinetics, pharmacodynamics and clinical effects of the oral direct thrombin inhibitor ximelagatran in acute treatment of patients with pulmonary embolism and deep vein thrombosis

INTRODUCTION

Ximelagatran is a novel, oral direct thrombin inhibitor that is currently being investigated for the prophylaxis and treatment of thromboembolic events. This study evaluated the pharmacokinetics, pharmacodynamics, and clinical effects of melagatran, the active form of ximelagatran, in patients with both deep vein thrombosis (DVT) and pulmonary embolism (PE).

MATERIALS AND METHODS

In this open-label study, 12 patients received a fixed dose of 48 mg oral ximelagatran twice daily for 6-9 days. Plasma samples were collected for determination of melagatran concentrations and scintigraphic changes and adverse events were recorded.

RESULTS

Peak plasma concentrations of melagatran were attained approximately 2 h after administration of ximelagatran. Melagatran plasma concentration profiles were similar on Days 1, 2, and 6-9. Plasma activated partial thromboplastin time increased following administration of ximelagatran and reached a peak that was approximately twofold higher than the predose activated partial thromboplastin time and correlated with melagatran plasma concentrations (R(2) = 0.69). All but one patient (with malignancy) showed regressed or unchanged lung scintigraphic findings, and six of these demonstrated no, or only minor, perfusion defects at central evaluation after 6-9 days of ximelagatran treatment. Clinical symptoms, including chest pain, dyspnoea, cough, and oedema, and pain in the affected leg, were improved. Ximelagatran was well tolerated with no deaths or severe bleeding events reported during treatment.

CONCLUSION

Treatment with a fixed dose of oral ximelagatran, used without routine coagulation monitoring, showed reproducible pharmacokinetics and pharmacodynamics with a rapid onset of action and promising clinical results in patients with pulmonary embolism.

Factor V Leiden (G1691A) and prothrombin gene G20210A mutations as potential risk factors for venous thromboembolism after total hip or total knee replacement surgery

Patients (n = 1600) from 12 European countries, scheduled for elective orthopaedic hip or knee surgery, were screened for Factor V Leiden and prothrombin gene G20210A mutations, found in 5.5% and 2.9% of the populations, respectively. All patients underwent prophylactic treatment with one of four doses of melagatran and ximelagatran or dalteparin, starting pre-operatively. Bilateral ascending venography was performed on study day 8-11. The patients were subsequently treated according to local routines and followed for 4-6 weeks postoperatively. The composite endpoint of screened deep vein thrombosis (DVT) and symptomatic pulmonary embolism (PE) during prophylaxis did not differ significantly between patients with or without these mutations. Symptomatic venous thromboembolism (VTE) during prophylaxis and follow-up (1.9%) was significantly over-represented among patients with the prothrombin gene G20210A mutation (p = 0.0002). A tendency towards increased risk of VTE was found with the Factor V Leiden mutation (p = 0.09). PE were few, but significantly over-represented in both the Factor V Leiden and prothrombin gene G20210A mutated patients (p = 0.03 and p = 0.05, respectively). However, since 90% of the patients with these genetic risk factors will not suffer a VTE event, a general pre-operative genotyping is, in our opinion, of questionable value.

Cloning and sequencing of nineteen transcript isoforms of the human alpha2,3-sialyltransferase gene, ST3Gal III; its genomic organisation and expression in human tissues

The recruitment of human peripheral blood leukocytes (PBL) to sites of infection and inflammation requires the surface expression of Sialyl Lewis x glycoconjugates (SLe(x)) on white blood cells and their interaction with E- and P-selectins on activated endothelial cells. E-selectin has additionally been shown to interact with the sialyl Lewis a (SLe(a)) epitope. Human ST3Gal III codes for an alpha2,3-sialyltransferase involved in the biosynthesis of both SLe(a) and SLe(x) epitopes, although the latter with a lower efficiency. We have cloned and sequenced human ST3Gal III gene transcripts from human peripheral blood leukocytes, covering the coding region of this gene. Within our clones we isolated 19 different transcripts with a wide variety of deletions from 45 to 896 nucleotides, and insertions of 26 to 173 nucleotides. Among the insertions we identified two new exons (E3, E6). In order to map and characterise the ST3Gal III gene we used the GenBank database and "computer-cloned" and characterised the genomic organisation of the ST3Gal III gene. The coding sequences of the ST3Gal III gene stretch over a gene sequence of approximately 223 Kb comprised of 15 exons. RT-PCR and laser-induced fluorescent capillary electrophoresis (LIF-CE) were used to examine the expression of this gene in twenty-one human tissues, which showed a highly specific tissue expression pattern. Neural and muscular tissues showed the most complex patterns and were distinctly different from all other tissues examined.

Characterization of galactosyl glycerolipids in the HT29 human colon carcinoma cell line

Glycoglycerolipids constitute a family of glycolipids with apparently very restricted expression in human tissues. They have previously been detected only in the testis and the nervous system. In the present study, two glycoglycerolipids were isolated from the HT29 human colon carcinoma cell line. The glycoglycerolipids were structurally characterized as a monogalactosylglycerolipid (1-O-alkyl-2-O-acyl-3-O-(beta-galactosyl)-sn-glycerol) and a digalactosylglycerolipid (1-O-alkyl-2-O-acyl-3-O-(beta-galactosyl(1-4)alpha-galactosyl)-sn-glycerol) using NMR and mass spectrometry. This digalactosylglycerolipid has not previously been structurally characterized. When HT29 cells were allowed to differentiate into more enterocyte-like cells by culture in glucose-free medium, expression of both of these glycoglycerolipids was greatly diminished. The presence of glycoglycerolipids in a human colon carcinoma cell line indicates that expression of this family of glycolipids may not be as restricted as previously thought. Instead this class of glycolipids may serve as differentiation antigens in various normal tissues and in tumor development. The Galalpha1-4Gal epitope was previously identified as a receptor for bacterial adhesins and toxins. The finding that this epitope is also linked to a glycerolipid moiety opens up new possible roles for this carbohydrate receptor in intracellular signaling.

Determination of Lewis FUT3 gene mutations by PCR using sequence-specific primers enables efficient genotyping of clinical samples

We have developed a polymerase chain reaction method using sequence-specific primers (PCR-SSP) for rapid and correct genotyping of the common Lewis (FUT3) gene mutations 59T>G, 202T>C, 314C>T, 508G>A, and 1067T>A. The PCR-SSP method was validated on 20 healthy blood donors and 16 non-insulin-dependent diabetic patients. All individuals were in parallel genotyped by our established polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. The FUT3 genotypes, determined with the PCR-SSP method, were in complete accordance with the results of the PCR-RFLP reference method. The PCR-SSP method could also be adapted to assign the presence of a specific mutation to the respective FUT3 alleles. We found the method to be reliable, rapid and cheap with no requirements for restriction enzyme processing.

Incorporation of selegiline metabolites into hair after oral selegiline intake

We have previously shown that melanin in human hair has a great impact on the incorporation of codeine into hair. The present study on 10 subjects was performed to investigate whether or not these findings could also be extrapolated to other therapeutic drugs. We chose selegiline because it metabolizes to two commonly abused central stimulants, methamphetamine and amphetamine. The results would therefore also be of interest when studying the intake of such drugs and their incorporation into human hair. Selegiline and metabolites were determined by gas chromatography-mass spectrometry, total melanin by spectrophotometry, and pyrrole-tricarboxylic acid by high-performance liquid chromatography with ultraviolet detection. Our results show strong positive exponential relationships (y = e(x)) between melanin and the metabolites, which for methamphetamine improved by normalizing for plasma area under the curve. We conclude that the major metabolites of selegiline can be detected in hair up to four weeks after a single oral dose and that the incorporation closely relates to the melanin contents.

Identification of nine alternatively spliced alpha2,3-sialyltransferase, ST3Gal IV, transcripts and analysis of their expression by RT-PCR and laser-induced fluorescent capillary electrophoresis (LIF-CE) in twenty-one human tissues

In order to characterise the candidate alpha2,3-sialyltransferases necessary for biosynthesis of the selectin ligand SLe(x) and related antigens we have cloned and sequenced, from peripheral blood leukocytes of single individuals, various transcripts from the human ST3Gal III, IV and VI genes. Our clones have revealed a considerable heterogeneity in transcript isoforms. Among our ST3Gal IV clones we isolated nine alternatively spliced transcripts covering the coding region of the human ST3Gal IV gene (A1, A1 - 12, A1 + 18, A2, A2 - 12, A2 + 18, B, B - 12 and B + 18). Five of these isotranscripts A1 - 12, A1 + 18, A2 - 12, A2 + 18 and B + 18 have not been described before. In order to investigate if the alternatively spliced isotranscripts were specific for human PBL, we analysed the expression by RT-PCR and laser-induced fluorescent capillary electrophoresis (LIF-CE) in twenty other human tissues. We found a tissue specific expression of ST3Gal IV A1, A1 - 12, A1 + 18, A2, A2 - 12, A2 + 18 and B + 18 as well as a general expression of ST3Gal IV B and B - 12 isotranscripts in all tissues examined.

Identification of a missense mutation (G329A;Arg(110)--> GLN) in the human FUT7 gene

The human FUT7 gene codes for the alpha1,3-fucosyltransferase VII (Fuc-TVII), which is involved in the biosynthesis of the sialyl Lewis x (SLe(x)) epitope on human leukocytes. The FUT7 gene has so far been considered to be monomorphic. Neutrophils isolated from patients with ulcerative colitis were examined for apparent alterations in protein glycosylation patterns by Western blot analysis using monoclonal antibodies directed against SLe(x) and SLe(x)-related epitopes. One individual showed lower levels of SLe(x) expression and an elevated expression of CD65s compared to controls. The coding regions of the FUT7 gene from this individual were cloned, and a G329A point mutation (Arg(110) --> Gln) was found in one allele, whereas the other FUT7 allele was wild type. No Fuc-TVII enzyme activity was detected in COS-7 cells transiently transfected with the mutated FUT7 construct. The FUT7 Arg(110) is conserved in all previously cloned vertebrate alpha 1,3-fucosyltransferases. Polymerase chain reaction followed by restriction enzyme cleavage was used to screen 364 unselected Caucasians for the G329A mutation, and a frequency of < or =1% for this mutation was found (3 heterozygotes). Genetic characterization of the family members of one of the additional heterozygotes identified one individual carrying the G329A mutation in both FUT7 alleles. Peripheral blood neutrophils of this homozygously mutated individual showed a lowered expression of SLe(x) and an elevated expression of CD65s when analyzed by Western blot and flow cytometry. The homozygous individual was diagnosed with ulcer disease, non-insulin-dependent diabetes, osteoporosis, spondyloarthrosis, and Sjögren's syndrome but had no history of recurrent bacterial infections or leukocytosis.

Identification of two functionally deficient plasma alpha 3-fucosyltransferase (FUT6) alleles

One Indonesian individual without detectable plasma alpha3-fucosyltransferase activity was identified with three point mutations, 730C>G (L244V), 907C>G (R303G), and 370C>T (P124S), in the coding region of one FUT6 allele. Another individual, expressing weak plasma alpha3-fucosyltransferase activity, had the 907C>G together with the 370C>T mutation, but did not have the 730C>G mutation. PCR-RFLP analyses of complete families confirmed the segregation of these alleles and illustrated the existence and inheritance of the [370C>T; 907C>G] mutated allele in three additional families. Altogether, this allele was found heterozygously in nine Indonesian and two Swedish individuals, all with detectable plasma alpha3-fucosyltransferase activities. The FUT6 allele with the three mutations (370C>T; 730C>G; 907C>G) was identified heterozygously in only two Indonesian individuals, both having the inactivating 739G>A mutation in the other allele and both lacking plasma alpha3-fucosyltransferase activity. Enzyme studies made on transiently transfected COS-7 cells demonstrated that the combination of the 370C>T, 730C>G and 907C>G mutations decreased the V(max) by more than 80%, but caused no obvious change of the apparent K(m) values for GDP-fucose and Gal-N-acetyllactosamine. In comparison, chimeric constructs with the isolated 730C>G or 907C>G mutations decreased the V(max) values by about two thirds and one third, respectively.

Interaction of the antitumor compound cryptophycin-52 with tubulin

Cryptophycin-52 (LY355703) is currently undergoing clinical evaluation for cancer chemotherapy. It is a potent suppressor of microtubule dynamics in vitro, and low picomolar concentrations appear to inhibit cancer cell proliferation at mitosis by stabilizing spindle microtubules. In the present study, using [(3)H]cryptophycin-52, we found that the compound bound to tubulin at a single high-affinity site [apparent K(a) (3.6 +/- 1) x 10(6) L/mol, 34 degrees C]. The binding of cryptophycin-52 to tubulin was rapid, not appreciably temperature-dependent, and very poorly reversible. However, we could remove [(3)H]cryptophycin-52 from [(3)H]cryptophycin-52-tubulin complex by denaturing the complex with either urea treatment or boiling. These data suggest that the binding of cryptophycin-52 to tubulin is not covalent. A van't Hoff plot of the binding data indicated that the binding of cryptophycin-52 to tubulin is primarily entropy-driven with a minimum enthalpy contribution. In addition, cryptophycin-52 perturbed the far-ultraviolet circular dichroic spectrum of tubulin and it inhibited the colchicine-induced guanosine triphosphatase activity of tubulin, indicating that its binding to tubulin induces a conformational change in the tubulin. Competition experiments with vinblastine suggest that the binding site for crytophycin-52 may overlap with the vinblastine binding site.