PubMed Health⌕ Search

Biomedical subjects

T de Vries

Publications and source records attributed to T de Vries.

At least 19 recordsLinked to original sources
PubMed2001

Plant members of the alpha1-->3/4-fucosyltransferase gene family encode an alpha1-->4-fucosyltransferase, potentially involved in Lewis(a) biosynthesis, and two core alpha1-->3-fucosyltransferases.

Three putative alpha1-->3/4-fucosyltransferase (alpha1-->3/4-FucT) genes have been detected in the Arabidopsis thaliana genome. The products of two of these genes have been identified in vivo as core alpha1-->3-FucTs involved in N-glycosylation. An orthologue of the third gene was isolated from a Beta vulgaris cDNA library. The encoded enzyme efficiently fucosylates Galbeta1-->3GlcNAcbeta1-->3Galbeta1-->4Glc. Analysis of the product by 400 MHz (1)H-nuclear magnetic resonance spectroscopy showed that the product is alpha1-->4-fucosylated at the N-acetylglucosamine residue. In vitro, the recombinant B. vulgaris alpha1-->4-FucT acts efficiently only on neutral type 1 chain-based glycan structures. In plants the enzyme is expected to be involved in Lewis(a) formation on N-linked glycans.

Acetylglucosamine↗
PubMed2001

Fucosyltransferases: structure/function studies.

Alpha3-fucosyltransferases (alpha3-FucTs) catalyze the final step in the synthesis of a range of important glycoconjugates that function in cell adhesion and lymphocyte recirculation. Six members of this family of enzymes have been cloned from the human genome, and their expression pattern has been shown to be highly regulated. Each enzyme has a unique acceptor substrate binding pattern, and each generates a unique range of fucosylated products. Results from a range of studies have provided information on amino acids in the FucT sequence that contribute to the differential acceptor specificity for the FucTs, and to the binding of the nucleotide sugar donor GDP-fucose. These results, in conjunction with results obtained from the analysis of the disulfide bond pattern, have provided useful clues about the spatial distribution of amino acids that influence or directly contribute to substrate binding. This information is reviewed here, and a molecular fold prediction is presented which has been constructed based on the available information and current modeling methodology.

Chromosome Mapping↗
PubMed2001

Neighboring cysteine residues in human fucosyltransferase VII are engaged in disulfide bridges, forming small loop structures.

Among alpha 3-fucosyltransferases (alpha3-FucTs) from most species, four cysteine residues appear to be highly conserved. Two of these cysteines are located at the N-terminus and two at the C-terminus of the catalytic domain. FucT VII possesses two additional cysteines in close proximity to each other located in the middle of the catalytic domain. We identified the disulfide bridges in a recombinant, soluble form of human FucT VII. Potential free cysteines were modified with a biotinylated alkylating reagent, disulfide bonds were reduced and alkylated with iodoacetamide, and the protein was digested with either trypsin or chymotrypsin, before characterization by high-performance liquid chromatography/electrospray ionization mass spectrometry. More than 98% of the amino acid sequence for the truncated enzyme (beginning at amino acid 53) was verified. Mass spectrometry analysis also demonstrated that both potential N-linked sites are occupied. All six cysteines in the FucT VII sequence were shown to be disulfide-linked. The pairing of the cysteines was determined by proteolytic cleavage of nonreduced protein and subsequent analysis by mass spectrometry. The results demonstrated that Cys(68)-Cys(76), Cys(211)-Cys(214), and Cys(318)-Cys(321) are disulfide-linked. We have used this information, together with a method of fold recognition and homology modeling, using the (alpha/beta)(8)-barrel fold of Escherichia coli dihydrodipicolinate synthase as a template to propose a model for FucT VII.

Amino Acid Sequence↗
PubMed2001

Production of soluble human alpha3-fucosyltransferase (FucT VII) by membrane targeting and in vivo proteolysis.

The rational design of fucosyltransferase (FucT VII) inhibitors as potential medication in the treatment of rheumatoid arthritis requires the three-dimensional structure of this member of the glycosyltransferase family. Structure determination by X-ray diffraction analysis needs purified, soluble enzyme protein. For this purpose we developed a novel method for the high-yield production of soluble FucT VII by in vivo proteolysis. To obtain a soluble form of FucT VII a mammalian expression construct was made encoding an N-terminal portion of FucT VI (amino acids 1-63) fused with the stem region and catalytic domain of FucT VII (amino acids 39-342). Chinese hamster ovary cells stably transfected with this construct produced FucT activity in the supernatant, which has the same catalytic properties as wild-type FucT VII. This soluble form of FucT VII can be obtained in high amounts (1 mg/L) and can be efficiently purified by GDP-hexanolamine affinity chromatography. In conclusion, it was demonstrated that the intrinsic properties of FucT VII could be transferred to secreted FucT VII constructs, which may open possibilities for production of soluble forms of other members of the glycosyltransferase family as well.

Amino Acid Sequence↗
PubMed1998

Are pretransplant psychological variables related to survival after bone marrow transplantation? A prospective study of 123 consecutive patients.

Few studies have investigated relationships between psychological variables and survival after bone marrow transplantation (BMT). There is some evidence that psychological variables play a role in the course of cancer, and also after BMT. The present study focused on relationships between psychological variables and survival after BMT, in addition to prognostic disease, treatment, and demographic variables. In a consecutive sample of 123 patients undergoing BMT between 1987 and 1992, psychological variables were assessed before BMT. None of the psychological variables was univariately related to survival when entered into a Cox proportional hazards model as continuous variables. When divided into four groups of equal size, based on the 25th, 50th, and 75th percentiles, low self-esteem tended to be related to shorter survival. In multivariate analyses, none of the psychosocial variables measured before BMT was significant. Our data do not support the view that psychological variables influence survival after BMT.

Adolescent↗
PubMed1998

Reliability of reverse transcription-polymerase chain reaction (RT-PCR)-based assays for the detection of circulating tumour cells: a quality-assurance initiative of the EORTC Melanoma Cooperative Group.

Reverse transcription-polymerase chain reaction (RT-PCR)-based assays detecting occult neoplastic cells are increasingly being used for the study of tumour dissemination and minimal residual disease. However, different methods are employed by various research groups and the results are heterogenous. We prospectively assessed the results from nine laboratories performing tyrosinase RT-PCR assays for the detection of melanoma cells on a series of blind samples. After complete analysis, the results were compared for sensitivity and specificity. All laboratories reported correct results for cDNA standards. Five laboratories attained acceptable specificity and a sensitivity detecting 10 cells in 10 ml of whole blood. Four laboratories had unacceptable specificity and/or sensitivity. This blind study highlights the difficulty of RT-PCR data interpretation and the need for quality assurance between laboratories. Measures to increase the reliability of RT-PCR assays are proposed, which have to be prospectively evaluated in future studies.

DNA, Neoplasm↗
PubMed1998

Acceptor specificity of the human leukocyte alpha3 fucosyltransferase: role of FucT-VII in the generation of selectin ligands.

The alpha3 fucosyltransferase, FucT-VII, is one of the key glycosyltransferases involved in the biosynthesis of the sialyl Lewis X (sLex) antigen on human leukocytes. The sialyl Lewis X antigen (NeuAcalpha(2-3)Galbeta(1-4)[Fucalpha(1-3)]GlcNAc-R) is an essential component of the recruitment of leukocytes to sites of inflammation, mediating the primary interaction between circulating leukocytes and activated endothelium. In order to characterize the enzymatic properties of the leukocyte alpha3 fucosyltransferase FucT-VII, the enzyme has been expressed in Trichoplusia ni insect cells. The enzyme is capable of synthesizing both sLexand sialyl-dimeric-Lexstructures in vitro , from 3'-sialyl-lacNAc and VIM-2 structures, respectively, with only low levels of fucose transfer observed to neutral or 3'-sulfated acceptors. Studies using fucosylated NeuAcalpha(2-3)-(Galbeta(1-4)GlcNAc)3-Me acceptors demonstrate that FucT-VII is able to synthesize both di-fucosylated and tri-fucosylated structures from mono-fucosylated precursors, but preferentially fucosylates the distal GlcNAc within a polylactosamine chain. Furthermore, the rate of fucosylation of the internal GlcNAc residues is reduced once fucose has been added to the distal GlcNAc. These results indicate that FucT-VII is capable of generating complex selectin ligands, in vitro , however the order of fucose addition to the lactosamine chain affects the rate of selectin ligand synthesis.

Animals↗
PubMed1995

Acceptor specificity of different length constructs of human recombinant alpha 1,3/4-fucosyltransferases. Replacement of the stem region and the transmembrane domain of fucosyltransferase V by protein A results in an enzyme with GDP-fucose hydrolyzing activity.

The acceptor specificity of recombinant full-length, membrane-bound fucosyltransferases, expressed in COS-7 cells, and soluble, protein-A chimeric forms of alpha 1,3-fucosyltransferase (Fuc-T) III, Fuc-TIV, and Fuc-TV was analyzed toward a broad panel of oligosaccharide, glycolipid, and glycoprotein substrates. Our results on the full-length enzymes confirm and extend previous studies. However, chimeric Fuc-Ts showed increased activity toward glycoproteins, whereas chimeric Fuc-TIII and Fuc-TV had a decreased activity with glycosphingolipids, compared to the full-length enzymes. Unexpectedly, chimeric Fuc-TV exhibited a GDP-fucose hydrolyzing activity. In substrates with multiple acceptor sites, the preferred site of fucosylation was identified. Fuc-TIII and Fuc-TV catalyzed fucose transfer exclusively to OH-3 of glucose in lacto-N-neotetraose and lacto-N-tetraose, respectively, as was demonstrated by 1H NMR spectroscopy. Thin layer chromatography immunostaining revealed that FucT-IV preferred the distal GlcNAc residue in nLc6Cer, whereas Fuc-TV preferred the proximal Gl-cNAc residue. Incubation of Fuc-TIV or Fuc-TV with VI3NeuAcnLc6Cer resulted in products with the sialyl-LewisX epitope as well as the VIM-2 structure. To identify polar groups on acceptors that function in enzyme binding, deoxygenated substrate analogs were tested as acceptors. All three Fuc-Ts had an absolute requirement for a hydroxyl at C-6 of galactose in addition to the accepting hydroxyl at C-3 or C-4 of GlcNAc.

Animals↗
PubMed1994

Biosynthesis of sialyl-oligomeric-Lewisx and VIM-2 epitopes: site specificity of human milk fucosyltransferase.

In a previous study we have established the order of fucosylation of a trimer of Gal beta 1-->4GlcNAc (LacNAc) linked to a synthetic hydrophobic aglycon, (LacNAc)3-[(trifluoroacetamido)phenyl]ethyl, by a partially purified alpha 3-fucosyltransferase preparation from normal human milk [De Vries, Th., Norberg, T., Lönn, H., & van den Eijnden, D. H. (1993) Eur. J. Biochem. 216, 769-777]. Using the same fucosyltransferase preparation, we have now studied the fucosylation of the oligosaccharide NeuAc alpha 2-->3(LacNAc)3-Me. This compound was generated from the asialo analogue by use of an alpha 3-sialyltransferase preparation from human placenta. The location of the fucose residues in the monofucosylated and difucosylated intermediate products was determined by analyzing digests obtained after endo-beta-galactosidase treatment using HPLC on amino-bonded silica. In addition, the fucosylated NeuAc alpha 2-->3(LacNAc)3-Me structures were characterized by high-pH anion-exchange chromatography with pulsed amperometric detection and were identified by 400-MHz 1H-NMR spectroscopy. Intermediate products included oligosaccharides that contained the VIM-2, sialyl-LewisX, and sialyl-dimeric-LewisX epitopes. The final product was identified as the sialyl-trimeric-LewisX oligosaccharide. Kinetic analysis of the fucosylation reaction indicated that there is a significant difference in the rate of transfer of the first, second, and third fucose residues onto the acceptor molecule. Transfer of the first fucose occurred to either of the three GlcNAc residues in NeuAc alpha 2-->3(LacNAc)3-Me with only a modest preference for the proximal and medial residues. A similar slight preference for these GlcNAc residues was found for the attachment of the second fucose residue.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate Conformation↗
PubMed1994

Expression of fucosylated antigens and alpha 1,3 fucosyltransferases in human leukaemia cell lines.

The expression of alpha 1,3 fucosylated type 2 antigens is generally thought to be restricted to myeloid cells among normal human haemopoietic tissue. The distribution of three fucosylated antigens [Lewis X (Le(x)), sialyl Lewis X (sLex) and VIM2] was investigated among nine human leukaemia cell lines by fluorescence activated cell sorting (FACS) analysis. As expected, all myeloid cell lines were positively stained by antibodies against these three fucosylated antigens. Unexpectedly, two T-lymphocytic cell lines (CCRF-CEM and MOLT4) were found to express Le(x) and VIM2, and the plasma, B-cell line, RPMI 8226, expressed all three fucosylated antigens. Enzymatic and RNA analyses [Northern blot and reverse transcription polymerase chain reaction (RT-PCR)] were used to evaluate possible control points in the biosynthetic pathway for Le(x) and sLex. beta 1,4 Galactosyltransferase (beta 1,4GalT, an enzyme involved in the synthesis of the core oligosaccharide of the three fucosylated antigens) activity and the corresponding mRNA were found in all of the leukaemia cell lines, regardless of whether or not they expressed the fucosylated antigens. In contrast, alpha 1,3 fucosyltransferase (GDP-fucose:beta-D-N-acetylglucosaminide 3-alpha-L-fucosyltransferase; alpha 1,3FT) activity and the corresponding mRNA were found only in those cell lines expressing fucosylated antigens. Based on RNA analysis, acceptor specificity and N-ethylmaleimide inhibition studies, it was concluded that all of the cell lines expressing fucosylated antigens contained alpha 1,3FTIV (myeloid alpha 1,3FT). This appeared to be the major alpha 1,3FT in the myeloid and T-lymphocytic cell lines. Interestingly, even though both types of cell lines expressed the same alpha 1,3FT, only the myeloid cell lines expressed sLex, whereas all of the myeloid and T-lymphocytic cell lines expressed a structural analogue of sLex (i.e. VIM2). In contrast to the myeloid and T-cell lines, RPMI 8226 cells contained more than one fucosyltransferase activity. Acceptor specificity analysis demonstrated that this cell line contains alpha 1,3 and alpha 1,4FTs. Among the fucosyltransferases expressed by RPMI 8226, alpha 1,3FTIV accounted for only a small amount of the total activity. The results of this study demonstrate that fucosylated antigens, which are generally considered to be myeloid specific antigens, are also expressed by lymphocytic leukaemia cell lines, and that the types of fucosylated antigens and fucosyltransferases expressed in these cell lines vary.

Antigens, Neoplasm↗
PubMed1993

Efficient enzymatic synthesis of the sialyl-Lewisx tetrasaccharide. A ligand for selectin-type adhesion molecules.

Sialyl-Lewisx (NeuAc alpha 2-->3Gal beta 1-->4[Fuc alpha 1-->3]GlcNAc] has been identified as a ligand for E-selectin, P-selectin and recently also for L-selectin. We have synthesized the sialyl-Lewisx tetrasaccharide by total enzymatic synthesis from N-acetyllactosamine using a placental alpha 2-->3-sialyltransferase specific for type-2 chain acceptors, followed by a cloned human alpha 1-->3-fucosyltransferase (FucTV, the 'plasma-type' enzyme). This procedure resulted in the tetrasaccharide in a 61% overall yield.

Amino Sugars↗
PubMed1993

The use of human milk fucosyltransferase in the synthesis of tumor-associated trimeric X determinants.

We have studied the fucosylation of a chemically synthesized trimer of N-acetyllactosamine [(LacNAc)3-EtPhNHCOCF3] with a fucosyltransferase preparation from normal human milk, which utilizes both type-1 and type-2 structures, whether sialylated or not. When fucose residues were added enzymically to the (LacNAc)3-EtPhNHCOCF3 hexasaccharide, mono-, di-, or trifucosylated oligosaccharide species were formed, containing the Lewisx determinant (Gal beta 1-->4[Fuc alpha 1-->3]Glc-NAc beta 1-->3). With excess GDP-fucose and prolonged reaction times, the trifucosylated product was formed in almost quantitative yield. Kinetic analysis of the fucosylation reaction indicated that there is a significant difference in the rate of transfer of the first, second and third fucose residues onto the acceptor molecule. The location of the fucose residues in the monofucosylated and difucosylated intermediate products was assessed by analyzing the digests obtained after endo-beta-galactosidase treatment by HPLC and reverse-phase chromatography. In addition, the fucosylated (LacNAc)3-EtPhNHCOCF3 structures were characterized by HPLC and were identified by 400-MHz 1H-NMR spectroscopy. There is a highly preferred order in which the fucosyl residues are attached to (LacN-Ac)3-EtPhNHCOCF3. In the major pathway, the first two fucose residues are transferred with equal preference to the medial (GN3) and proximal (GN1) GlcNAc residues, whereas the third fucose is attached to the distal (GN5) GlcNAc residue. These results are of relevance in understanding the role of alpha-3-fucosyltransferase in the biosynthesis of Lewisx-related cell-surface carbohydrate structures, that function as ligands for selectin-type cell-adhesion molecules and may play a role in the invasion and metastasis of several carcinoma.

Amino Sugars↗
PubMed1993

Phosphorylation of surface E-selectin and the effect of soluble ligand (sialyl Lewisx) on the half-life of E-selectin.

E-selectin (ELAM-1) is an adhesion molecule for leukocytes that is transiently expressed on endothelial cells. Following cell surface expression of E-selectin on human umbilical vein endothelial cells (HUVEC) stimulated with tumor necrosis factor, the induced E-selectin molecules are rapidly degraded. The kinetics of turnover of surface disposed E-selectin were investigated. The rapid disappearance of surface E-selectin is temperature dependent and sensitive to the lysosomotropic agent chloroquine. The half-life of E-selectin is not affected by inclusion of soluble sialyl Lewis x (sLex) ligands in the medium. Surface E-selectin is phosphorylated on one or more serine residues, but this modification is not obviously related to internalization.

Cell Adhesion Molecules↗
PubMed1993

A feasibility study on weight reduction in obese postmenopausal breast cancer patients.

An attempt was made to undertake a randomized clinical trial of weight reduction in obese postmenopausal breast cancer patients as an adjuvant to primary surgical and radiotherapeutic treatment. The rationale was to improve prognosis which has been shown to be worse in the obese (probably because of its effect on extra-ovarian oestrogen production). Difficulties in recruiting a sufficient number of patients and the introduction of tamoxifen as anti-oestrogenic adjuvant therapy led to the decision to modify the aim of the study by limiting it to a feasibility study in 102 patients. In three hospitals in The Netherlands and in two hospitals in Poznan, Poland these patients were randomized in intervention and control groups according to a 3:2 ratio. Weight reduction in the intervention group was achieved by dietary means, ie caloric restriction was adapted to personal needs and behaviour of the patients. After 1 year a median weight loss of 6 kg was reached in both countries. In the Netherlands further follow-up indicated that this result could be maintained for another 2 years.

Aged↗
PubMed1992

Occurrence and specificities of alpha 3-fucosyltransferases.

The Le(x) (CD15) carbohydrate antigen and sialylated and oligomeric derivatives thereof have been implicated in cell adhesion processes. Expression of these antigens is developmentally regulated and (re)occurrence of several members of this group has been reported in malignant transformation of cells. Studies on the enzymology and genetics of alpha 3-fucosyltransferases, glycosyltransferases that play a key role in the biosynthesis of these antigens, would yield insight in the regulation of expression of these carbohydrate structures. In this paper the existing literature on these enzymes is reviewed and placed in the context of cell adhesion and malignancy.

Animals↗