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T Kristensen

Publications and source records attributed to T Kristensen.

At least 37 records · Page 2Linked to original sources
PubMed2000

Structure of the human oxytocinase/insulin-regulated aminopeptidase gene and localization to chromosome 5q21.

The human oxytocinase/insulin-regulated aminopeptidase (OTase/IRAP) is a 1024 amino acid type II integral membrane protein that is expressed mainly in fat, muscle and placenta tissues. It has been thought to be involved mainly in the control of onset of labour but recently rat OTase/IRAP was shown to participate in the regulation of glucose transporter isoform 4 vesicle trafficking in adipocytes as well. To approach an understanding of OTase/IRAP gene regulation the organization of the human gene was determined. Accordingly, three overlapping genomic clones were isolated and characterized. The human OTase/IRAP gene (OTASE) was found to span approximately 75 kb containing 18 exons and 17 introns. The gluzincin aminopeptidase motif: GAMEN-(31 amino acids)-HELAH-(18 amino acids)-E associated with Zn2+-binding, substrate binding and catalysis is encoded by exons 6 and 7. A major and a minor transcriptional initiation site in OTASE were identified by primer extension 514 bp and 551 bp, respectively, upstream of the translation start codon. Chloroamphenicol acetyltransferase-reporter assays revealed a functional CpG-rich promoter/enhancer region located between nucleotide -621 and the major transcriptional initiation site. Human OTASE was assigned to chromosome 5 by hybridization to genomic DNA from characterized somatic cell hybrids. Finally, the OTASE and the human aminopeptidase A gene were subchromosomally localized to 5q21 and 4q25, respectively, by in situ hybridization.

Amino Acid Sequence↗
PubMed1999

Expression of major histocompatibility complex antigens and induction of human T-lymphocyte proliferation by astrocytes and macrophages from porcine fetal brain.

Porcine fetal brain cells are of potential use as donor cells for transplantation therapies of neurodegenerative diseases in humans. Our aim was to determine the immunestimulatory properties of astrocytes and macrophages from porcine fetal brain in vitro. By flow cytometry, freshly isolated porcine fetal brain cells were nonautofluorescent, while primary cultures of these cells, prepared to favor growth of astrocytes and macrophages/microglia, consisted of both an autofluorescent and a nonautofluorescent cell population. The cultured autofluorescent cells had qualities typical of macrophages: CD18 (beta(2) integrin subunit) expression, high granularity, and phagocytic activity. The cultured nonautofluorescent cells stained positive for the astrocyte marker glial fibrillary acidic protein and CD56 (NCAM isoform). While freshly isolated porcine fetal brain cells expressed very low levels of major histocompatibility complex (MHC) class I and no MHC class II antigens, primary culture of these cells resulted in upregulation of MHC class I antigens on astrocytes and macrophages and MHC class II antigens on a subpopulation of the macrophages. Single-cell suspensions prepared from the primary cultures were flow sorted into astrocyte and macrophage populations on the basis of cell granularity and autofluorescence or on the basis of CD56 expression. Pure suspensions (>98%) of astrocytes induced a low proliferative response in human T lymphocytes, as determined by [(3)H]thymidine incorporation after 4 days of coculture. A suspension of 91% macrophages was a strong inducer of human T-cell proliferation, even stronger than allogeneic mononuclear blood cells. For neural xenotransplantation, our findings suggest that depletion of macrophages from the donor-cell suspensions may enhance graft survival by reducing cell-mediated rejection.

Animals↗
PubMed1999

Characterisation of tumour infiltrating lymphocytes and correlations with immunological surface molecules in colorectal cancer.

Using flow cytometry, we studied the phenotype of tumour infiltrating lymphocytes (TILs) in 41 enzymatically dissociated colorectal cancers and compared this to the expression of HLA class I and II and CD80 on tumour cells. We studied the possible enzymatic damage to various surface markers after enzymatic dissociation. The reproducibility of flow cytometric determinations obtained from TILs was good (kappa value: 0.79). The median CD4+/CD8+ ratio was 2.2. Approximately 43-45% (median of cells in each tumour) of both the CD4(+)- and the CD8(+)-TILs expressed HLA class II; 14.2% of the CD4(+)-TILs expressed CD25 and none of the CD8(+)-TILs expressed CD25. CD3-/CD16+/CD56(+)-TILs were very infrequent. Expression of HLA class II did not correlate with any lymphocyte surface markers. Since TILs are "turned off" rather than stimulated when tumour cells express HLA class II but not CD80, the lack of correlations could be due to anergy.

Adult↗
PubMed1999

Structure of the human beta2-glycoprotein I (apolipoprotein H) gene.

The gene encoding the human plasma protein beta2-glycoprotein I or apolipoprotein H was cloned and its structure determined. The gene which consists of eight exons was shown to span 18 kb and was localized to chromosome 17q23-24. The transcriptional initiation site was assigned to a position 31 bp upstream of the start codon. Several consensus sequence elements relevant for regulation of transcription in liver were seen in the 5'-upstream region of the gene. Exon 1 contains the 5'-UTR together with the signal peptide coding sequences. Short consensus repeats (SCRs) 1, 3, 4, and 5 are encoded by single exons each while SCR2 is encoded by two exons. Exon 8 comprises the region encoding the C-terminal end of beta2-glycoprotein I (from His-310), the stop codon and the 3'-UTR.

Amino Acid Sequence↗
PubMed1998

Inhibition of lipid peroxidation mediated by indolizines.

Esters, ethers, carbonates and carbamates of 1-indolizinols and azaindolizinols exhibit a profound inhibition of lipid peroxidation in vitro. The antioxidants were prepared by cyclization of pyridines and diazines with diphenylcyclopropenone followed by introduction of the O-substituent.

Antioxidants↗
PubMed1998

Flow cytometric investigation of immune-response-related surface molecules on human colorectal cancers.

Our purpose was to clarify whether human colorectal cancer cells are equipped to present tumour-associated-antigens to the immune system, and whether this ability correlates with lymphoid infiltration, the Dukes' stage and Jass classification. Enzymatically dissociated tumour cells from 70 different colorectal cancers were monitored by multiparameter flow cytometry. Gating on EP4+ cells, the expression of the surface molecules HLA class I, HLA class II, CD80 (B7-1), CD54 (ICAM-I) and CD58 (LFA-3) was evaluated. In 60 of 70 tumours, all tumour cells expressed HLA class I, in 10 tumours 15-96% of the tumour cells expressed HLA class I. In 1 tumour, all tumour cells expressed HLA class II, in 67 tumours some expressed HLA class II, in 2 tumours none expressed HLA class II. Expression of CD58 was heterogeneous, and there was no or only sparse expression of CD80 and CD54. Expression of the HLA class I molecules, but not the class II, was correlated with lymphoid infiltration and the Jass classification. Expression of these surface molecules was not correlated with the Dukes' stage. The tumour cells were generally equipped to present antigens to the effector arm of the immune system since HLA class I is expressed, but the tumour cells were not optimal in stimulating an immune response, since HLA class II and CD58 were only marginally expressed and CD80 and CD54 were absent.

Adult↗
PubMed1998

Cloning, sequence analysis and expression in E. coli of the DNA polymerase I gene from Chloroflexus aurantiacus, a green nonsulfur eubacterium.

We have cloned and sequenced the polA gene from Chloroflexus aurantiacus, a green nonsulfur eubacterium, and expressed the recombinant protein in Escherichia coli. One open reading frame encodes a protein with 942 amino acids showing 38% identity with DNA polymerase I from E. coli. Sequence alignments with other members of DNA polymerase family A and analysis of the separate domains show that the central 3'-5' exonuclease domain is 30% identical to the corresponding E. coli domain and that three sequence motifs associated with 3'-5' exonuclease activity are conserved. Also, a protein fraction from E. coli expressing the Chloroflexus polymerase contains a thermostable 3'-5' exonucleolytic activity, indicating that this activity is present in the enzyme, in agreement with the sequence analysis. The N-terminal 5'-3' exonuclease domain and the C-terminal polymerase domain show 31 and 46% identity, respectively, with the corresponding E. coli domains and all sequence motifs associated with these two enzymatic activities also are conserved. Since several DNA polymerase I enzymes lack the proofreading activity associated with the central domain it has been suggested that the ancestral polA gene contained only the two more conserved N- and C-terminal domains and that the proofreading 3'-5' exonuclease domain was introduced later in those eubacterial branches that have this activity. Our data indicate a different scenario where the ancestral polA gene contained both the exonucleolytic activities in addition to the polymerase activity and where several eubacterial branches lost the polymerase-associated proofreading activity during evolution.

Amino Acid Sequence↗
PubMed1998

From serological to computer cross-matching in nine hospitals.

In 1991 it was decided to reorganise the transfusion service of the County of Funen. The aims were to standardise and improve the quality of blood components, laboratory procedures and the transfusion service and to reduce the number of outdated blood units. Part of the efficiency gains was reinvested in a dedicated computer system making it possible--among other things--to change the cross-match procedures from serological to computer cross-matching according to the ABCD-concept. This communication describes how this transition was performed in terms of laboratory techniques, education of personnel as well as implementation of the computer system and indicates the results obtained. The Funen Transfusion Service has by now performed more than 100.000 red cell transfusions based on ABCD-cross-matching and has not encountered any problems. Major results are the significant reductions of cross-match procedures, blood grouping as well as the number of outdated blood components.

Blood Banks↗
PubMed1998

A comparison of flow cytometry and immunohistochemistry in human colorectal cancers.

In human colorectal cancer it has been reported that some tumours lack the HLA-ABC antigens. This has been interpreted as reflecting tumour escape from the immune system. Earlier data have been obtained by immunohistochemistry. In this study, we compared the expression of HLA-ABC, HLA-DR, CD80 (B7-1) and CD54 (ICAM-1) in 20 tumours using both a conventional immunohistochemistry two-layer technique and multiparameter flow cytometry, gating on an epithelial cell marker. Colorectal cancer tissue used in flow cytometry was dissociated with collagenase, deoxyribonuclease and hyaluronidase. The intensity of expression of HLA-ABC, HLA-DR and CD80 was unaffected by the enzymes, but CD54 was decreased by 30%. The reproducibility of flow cytometry was good. Microscopy of sections revealed that about 5% of each tumour sample consisted of normal epithelium, but even after correction for this, flow cytometry was superior to immunohistochemistry in 33 out of 80 cases, and showed that tumours described as HLA-ABC negative by immunohistochemistry were in fact weakly positive for HLA-ABC. We conclude that flow cytometry and immunohistochemistry are complementary, and that flow cytometry is superior to immunohistochemistry for detecting antigens/epitopes present in low amounts.

Aged↗
PubMed1998

High-throughput screening for known mutations by automated analysis of single sequencing reactions.

This work shows that single sequencing reactions analyzed on an automated DNA sequencer can be an efficient way of screening PCR products for known mutations. We have analyzed a mutation in exon 10 of the human aromatase gene and show that an unambiguous genotype could be elucidated in more than 90% of the analyzed samples. Compared to analysis by full sequencing, 4 times more samples can be analyzed per gel, so that the sample capacity of the gel is approaching that of alternative gel-based methods for genotype analysis. Unlike many of these, the method offers direct identification of the variant sequence position and on-line analysis without the need of post-electrophoretic processing of the gel.

Aromatase↗
PubMed1997

The complete amino acid sequence of human placental oxytocinase.

The complete amino acid sequence of human placental oxytocinase (placental leucine aminopeptidase) has been determined by cDNA cloning and sequencing. Oxytocinase is a type II integral membrane protein of 1025 amino acid residues, consisting of an acidic intracellular region of 110 amino acids followed by a hydrophobic transmembrane segment of 22 residues and 893 extracellular residues containing the characteristic Zn2+ coordination sequence element His-Glu-Xaa-Xaa-His-(18 residues)-Glu found in gluzincins. Two sets of cDNA clones with different 5'-ends were isolated and suggested to represent different spliced products of 3.6 kb (mature mRNA) and 12 kb, respectively. Oxytocinase mRNA is present in large amounts in placenta, heart and skeletal muscle and in small amounts in brain, kidney, liver and pancreas. A conserved sequence element, the GAMEN motif, which distinguishes the aminopeptidase family among gluzincins from other gluzincins, has been identified.

Amino Acid Sequence↗
PubMed1997

[Transfusion service of the county of Funen. Organizational and economical aspects of restructuring].

The reorganization of the transfusion service in the County of Funen during the period from 1990 to 1996 is described. The professional responsibility for the transfusion service was delegated to the county's only department with specialists in transfusion medicine. The responsibility for economy and personnel remained decentralized. Standard operation procedures for collection and production of blood components and for blood group serology were standardized resulting in higher quality. The number of collections were reduced from 47,000 to 35,000 in spite of an unchanged number of transfused units (approx. 31,000 per year). The outdating was reduced from 35 to 2%. A computer system was implemented resulting in rationalized flow of work and the introduction of a computer crossmatch. From 1997, when the computer system will have been paid for, the county and the university hospital will gain DKK 1.6 million and DKK 2.0 million per year respectively as a result of the reorganization.

Blood Banks↗
PubMed1997

Molecular basis of the apolipoprotein H (beta 2-glycoprotein I) protein polymorphism.

Apolipoprotein H (apoH, protein; APOH, gene) is considered to be an essential cofactor for the binding of certain antiphospholipid autoantibodies to anionic phospholipids. APOH exhibits a genetically determined structural polymorphism due to the presence of three common alleles (APOH*1, APOH*2 and APOH*3) detectable by isoelectric focusing (IEF) and immunoblotting. The APOH*3 allele can be further characterized into two subtypes, APOH*3w and APOH*3B, based upon its reactivity with monoclonal antibody 3D11. In this study we have determined the molecular basis of the APOH protein polymorphism and its distribution in three large U.S. population samples comprising 661 non-Hispanic whites, 444 Hispanics and 422 blacks. By direct DNA sequencing of PCR amplified fragments corresponding to the eight APOH exons, we identified two missense mutations that correspond to the APOH*1 and APOH*3w alleles. A missense mutation (G-->A) in exon 3, which alters amino acid Ser to Asn at codon 88 and creates a restriction site for TSP509 I, was present in all APOH*1 allele carriers. A second missense mutation (G-->C) at codon 316 in exon 8, which replaces amino acid Trp with Ser and creates a restriction site for BSTBI, was present in all APOH*3w carriers. The distribution of the Ser 88 Asn and Trp 316 Ser mutations was significantly different between the three racial groups. The frequency of the Asn-88 allele was 0.011, 0.043, and 0.056 in blacks. Hispanics and non-Hispanic whites, respectively. While the Ser-316 allele was observed sporadically in blacks (0.008), it was present at a polymorphic frequency in Hispanics (0.027) and non-Hispanic whites (0.059). The identification of the molecular basis of the APOH protein polymorphism will help to elucidate the structural-functional relationship of apoH in the production of antiphospholipid autoantibodies.

Alleles↗
PubMed1997

Detection of irregular red cell antibodies: more than 3 years of experience with a gel technique and pooled screening cells.

BACKGROUND AND OBJECTIVES: The purpose of this study was to evaluate more than 3 years of experience with a gel technique in combination with pooled screening cells for the detection of irregular red cell antibodies. MATERIALS AND METHODS: Conventional serologic methods were used for blood typing, antibody screening and cross-matching until the end of 1992. We introduced the gel technique as a routine assay for antibody detection and identification in 1993. RESULTS: After the tube technique had been abandoned, the number of false-positive antibody screening tests was reduced by 71%, positive antibody screening tests by 33%, enzyme agglutination by 100% and rouleaux reactions and cold-reacting antibodies by more than 50%. There was a 40% increase in first-time detection of clinically relevant antibodies. We saw no increase in delayed haemolytic transfusion reactions. CONCLUSIONS: For the detection of irregular red cell antibodies, pooled screening cells in combination with a gel technique are at least as efficient and safe as a conventional tube technique with unpooled test cells.

Blood Grouping and Crossmatching↗
PubMed1997

Direct cytotoxic response of human lymphocytes to porcine PHA-lymphoblasts and lymphocytes.

Transplantation of cells and organs from pigs to human beings offers potential treatment for medical conditions such as diabetes, kidney and heart failure, and Parkinson's disease. When the antibody-mediated hyperacute rejection barrier is overcome, a xenograft may not be treated as an allograft by the human immune system. Without prior culture with porcine cells, human lymphocytes are cytotoxic to some porcine cells. Our aim was to functionally characterize this direct cytotoxic response to porcine PHA-lymphoblasts and lymphocytes. Peripheral blood mononuclear cells from seven of eight human beings were cytotoxic to porcine PHA-lymphoblasts in bulk chromium-release assays, but not to the porcine lymphocytes from which the PHA-lymphoblasts were derived. The NK cell-sensitive cell line K562 only partly blocked the response to the PHA-lymphoblasts. IL-2-expanded clones of human lymphocytes were able to discriminate between PHA-lymphoblasts from two pigs and unable to lyse K562. When using IL-2 to make the anti-porcine cells proliferate under limiting dilution conditions, the proliferation and/or function of these cells did not conform to single-hit kinetics. All the observations from experiments with cells in bulk cultures and as short-term clones suggest that the direct cytotoxic response of human lymphocytes to porcine cells is heterogeneous and composed of a small population of in vivo-activated T cells as well as NK cells.

Animals↗
PubMed1997

Estimation of body weight from body size measurements and body condition scores in dairy cows.

The objective of this study was to evaluate the use of hip height and width, body condition score, and relevant demographic information to predict body weight (BW) of dairy cows. Seven regression models were developed from data from 972 observations of 554 cows. Parity, hip height, hip width, and body condition score were consistently associated with BW. The coefficients of multiple determination varied from 80 to 89%. The number of significant terms and the parameter estimates of the models differed markedly among groups of cows. Apparently, these differences were due to breed and feeding regimen. Results from this study indicate that a reliable model for estimating BW of very different dairy cows maintained in a wide range of environments can be developed using body condition score, demographic information, and measurements of hip height and hip width. However, for management purposes, substantial improvements can be obtained by developing models that are specific to a given site.

Animals↗
PubMed1996

[Rational transfusion therapy. A study of transfusion practice and possibilities of optimization in elective coronary bypass surgery].

The objective of the study was to evaluate the effect of intervention on physicians' transfusion behavior in elective coronary artery bypass grafting (CABG). We analyzed transfusion data on 176 patients who underwent primary elective CABG during two periods, either before (phase one, n = 102) or after (phase two, n = 74) intervention. The intervention was based on cooperation with the involved department of cardiac surgery, interviews of the surgeons and anaesthesiologists ordering blood, and concurrent audit of transfusion practice using a blood order form. The proportion af patients receiving allogenic transfusions decreased from 90% in phase one to 58% in phase two and the total use of blood components was reduced from an average of 6.3 units/patient to 2.7 units/patient, p < 0.01. Indications for transfusion documented in the medical record increased from 19% in phase one to 63% in phase two. It is concluded that intervention on physicians' transfusion behavior can improve the transfusion therapy in patients who undergo elective CABG.

Adult↗