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T Hansen

Publications and source records attributed to T Hansen.

At least 199 records · Page 11Linked to original sources
PubMed1993

T cells specific for viral antigens presented by HLA-Dw4 recognize DR13 on allogeneic cells: a possible mechanism for induction of rejection.

Alloreactivity probably involves T cell recognition of peptides bound to allogeneic HLA molecules. In order to study whether T cells recognizing common viral antigens presented by self HLA molecules also recognize some allogeneic HLA molecules we generated T lymphocyte clones (TLC) specific for herpes simplex virus (HSV) antigen. Two TLC were found which recognized HSV presented by self Dw4, but which also respond to DR13 on allogeneic cells in the absence of HSV. The response against DR13 could be inhibited by preincubating the allogeneic cells with tetanus toxoid, but not with other protein antigens tested. The difference between Dw4 (encoded by DRB1*0401) and DR13 (encoded by DRB1*1302) mainly involves amino acid residues assumed to be of importance for peptide binding, and not residues putatively interacting with the T cell receptor. Thus, the results suggest that T cells recognizing a virally-derived peptide presented by self Dw4 molecules may also recognize a different peptide presented by allogeneic DR13 molecules. Our findings indicate that some rejection episodes may be induced and effected by T cells activated by viral peptides presented by self HLA molecules.

Amino Acid Sequence↗
PubMed1993

Expression of insulin receptor spliced variants and their functional correlates in muscle from patients with non-insulin-dependent diabetes mellitus.

Due to alternative splicing of exon 11 of the receptor gene, the human insulin receptor exists in two forms, that have distinct tissue-specific expression and are functionally different. Needle biopsies obtained from vastus lateralis muscle from 20 patients with noninsulin-dependent diabetes mellitus (NIDDM) and 20 normal control subjects were analyzed for the relative expression of insulin receptor mRNA variants in a novel assay using fluorescence-labeled primers and subsequent analysis on an automated DNA sequencer. In subgroups of patients and control subjects, insulin binding and tyrosine kinase activity were examined in wheat germ agglutinin-purified insulin receptors isolated from muscle biopsies. Moreover, insulin-stimulated glucose disposal was studied by means of the euglycemic hyperinsulinemic clamp technique. No difference in the relative expression of spliced variants of the insulin receptor mRNA was observed (control subjects, 71.4 +/- 1.3% insulin receptor mRNA with exon 11; NIDDM patients, 71.5 +/- 1.3% insulin receptor mRNA with exon 11). No significant interrelationships were demonstrated among the relative expression of insulin receptor mRNA variants, insulin binding, and tyrosine kinase activity toward the exogenous substrate poly(Glu-Tyr(4:1)). Furthermore, no significant relationship was demonstrated between the glucose disposal rate and the relative expression of insulin receptor splice variants. In conclusion, in skeletal muscle from both normal control subjects and NIDDM patients, the proportion of insulin receptor mRNA with exon 11 is about 70%. In addition, no significant correlations exist among insulin binding, insulin receptor tyrosine kinase activity, glucose disposal rate, and expression of alternative spliced insulin receptors in human skeletal muscle.

Adult↗
PubMed1993

Effect of wheat fibre supplements on duodenal ulcer recurrence.

In the present study the prophylactic effect of concentrated wheat fibre on duodenal ulcer recurrence was evaluated. Eleven grams of fibre (Fiberform) or placebo was added to an ordinary Norwegian diet for 1 year after endoscopic healing of duodenal ulcer. The ulcer recurrence rates were 84% (31 of 37 patients) in the fibre-supplemented group and 85% (30 of 36 patients) in the placebo group (NS). The effect on ulcer symptoms was similar in both groups. Side effects were infrequently seen. A concentrated wheat fibre supplement seems to have no preventive effect when given to duodenal ulcer patients living on a traditional Norwegian diet.

Adult↗
PubMed1993

Correlation between insulin receptor occupancy and tyrosine kinase activity at low insulin concentrations and effect of major histocompatibility complex class I-derived peptide.

In rat adipocytes, insulin dose-response curves were determined for the following effects in the same cells under the same conditions: glucose uptake, binding to insulin receptors (IR), IR autophosphorylation in vivo and in vitro, IR tyrosine kinase activity and insulin-stimulated phosphatidylinositol (PI) kinase. All the EC50 values were essentially the same (mean +/- S.E.M. was 7 +/- 1 nM), except for glucose uptake, which was 170 pM. Using an improved method, we were able to measure PI kinase activity at picomolar concentrations of insulin (> 30 pM) corresponding to the EC50 for glucose uptake. These experiments showed that insulin-stimulated increase in glucose uptake was associated with an increase in antiphosphotyrosine antibody precipitable PI kinase activity, consistent with the view that IR tyrosine kinase activity may be involved in insulin-mediated signaling of glucose uptake. Small peptides (17-25 residues long) derived from major histocompatibility complex class I have previously been shown to inhibit IR internalization without any effect on the affinity of insulin to the receptor. It is now shown that the peptide-mediated inhibition of internalization, which doubles the number of insulin-occupied receptors at an insulin concentration of 70 pM, also results in a corresponding enhancement of PI kinase activity and glucose uptake. Thus, the receptors arrested on the cell surface by the peptide are biologically active.

1-Phosphatidylinositol 4-Kinase↗
PubMed1993

Oxygen status determined by the photo-electric method--a circular finger-probe constructed for detection of blood oxygen content, blood flow and vascular density.

Three factors are the major determinants of tissue oxygenation: blood oxygen content, blood flow and vascular density. Blood oxygen content can be measured in vitro by haemoximetry or in vivo by oximetry. The blood flow and the vascular density may be estimated by a further development of pulse oximetry, based on the photo-electric method separating the signal into an AC and DC-part. A circular finger-probe was constructed to analyse the propagation of light through blood perfused tissue by the photo-electric method. The AC and DC-signals were compared at different positions around the finger. The detectors were placed at -45 degrees, 45 degrees, 90 degrees, 180 degrees and 215 degrees in relation to the light source. The preliminary results have shown that it is possible to record AC and DC-signals from the different angles. The size and configuration of the AC-signals are very similar but the levels of the DC-signals decrease with the distance between source and detector. It is our suggestion that blood flow can be estimated from the area of the AC-signal and the vascular density from the relationship between the DC-levels at different positions.

Blood Circulation↗
PubMed1992

[Patient information prior to sterilization].

The law in Denmark prescribes that the patient and the general practitioner to whom the patient directs his or her request for sterilization are obliged to confirm by their signatures that the patient has received information about sterilization, its risk and consequences. We asked 97 men and 96 women, if they had received this information prior to their sterilization. They were also asked about their knowledge about sterilization. 54% of the women and 35% of the men indicated that they had not received information. Only few of these wished further information by the hospital doctor. Knowledge about sterilization was good. It is concluded that the information to the patient prior to sterilization is far from optimal. The patients' signature confirming verbal information is not a sufficient safeguard. We recommend, among other things, that the patient should receive written information and that both the general practitioner and the hospital responsible for the operation should ensure that optimal information is received by the patient.

Denmark↗
PubMed1992

T-cell receptor beta usage by 35 different antigen-specific T-cell clones restricted by HLA-Dw4 or -Dw14.1.

We studied whether antigen-specific T cells being restricted by the very similar HLA-Dw4 and/or -Dw14.1 molecules might demonstrate homogeneities in parts of their TCR. TCCs were generated from three individuals who were all HLA-Dw4/Dw14.1 heterozygous. Thirty-five TCCs specific for PPD or TT and restricted by HLA-Dw4 and/or -Dw14.1 were selected for TCR beta gene sequencing. We found that 19 different V beta genes from 13 V beta families were expressed by these TCCs. Thus, it seems that many different TCRV beta genes may be used by TCCs restricted by these HLA molecules. For PPD-specific TCCs, a possible biased usage of V beta 8, as well as possible preferential usage of a CDR3 motif, were found.

Amino Acid Sequence↗
PubMed1992

T cell receptor usage by HLA-DQw8-specific T cell clones.

To investigate whether T cells recognizing the same HLA molecule may demonstrate homology in parts of their TCR, five different HLA-DQw8-specific T lymphocyte clones (TLC) were studied. The TCR alpha and -beta genes of four alloreactive, HLA-DQw8-specific and one antigen-specific TLC were sequenced. All TLC used different V alpha and V beta genes. However, four of the TLC shared a certain CDR1 beta motif and all five used either J beta 2.3 or -2.5. In addition, two used the same J alpha. The results indicate a possible preferential usage of certain TCR structures by T cells specific for DQw8.

Amino Acid Sequence↗
PubMed1992

Coding region polymorphisms of human T-cell receptor V beta 6.9 and V beta 21.4.

Two new TCRV beta coding region polymorphisms were identified: V beta 6.9a/b and V beta 21.4a/b. In both cases, a single nucleotide difference gives rise to an amino acid exchange. Genomic typing by the PCR/sequence-specific oligonucleotide probing technique was performed to study a possible contribution of these two new polymorphisms in susceptibility to autoimmune diseases. However, there was no association with insulin-dependent diabetes mellitus, rheumatoid arthritis, juvenile rheumatoid arthritis, multiple sclerosis, myasthenia gravis or coeliac disease. On the other hand, significant differences were found between Caucasoid and Oriental populations in frequencies of the V beta 6.9 and V beta 21.4 alleles.

Alleles↗
PubMed1991

Identification of the 1H-NMR spectra of complex oligosaccharides with artificial neural networks.

Artificial networks can be used to identify hydrogen nuclear magnetic resonance (1H-NMR) spectra of complex oligosaccharides. Feed-forward neural networks with back-propagation of errors can distinguish between spectra of oligosaccharides that differ by only one glycosyl residue in twenty. The artificial neural networks use features of the strongly overlapping region of the spectra (hump region) as well as features of the resolved regions of the spectra (structural reporter groups) to recognize spectra and efficiently recognized 1H-NMR spectra even when the spectra were perturbed by minor variations in their chemical shifts. Identification of spectra by neural network-based pattern recognition techniques required less than 0.1 second. It is anticipated that artificial neural networks can be used to identify the structures of any complex carbohydrate that has been previously characterized and for which a 1H-NMR spectrum is available.

Artificial Intelligence↗
PubMed1991

Epitope mapping of human monoclonal antibodies to HLA-B27 by using natural and mutated antigenic variants.

The epitopes defined by three human monoclonal antibodies (mAbs) (Tr3B6, TrCG10, TrBH12) against HLA-B27 have been mapped by flow cytometry. For this purpose we used murine transfected cells expressing at their surface hybrid antigens between HLA-B7 and -B27 and, in addition, Epstein-Barr virus cell lines expressing the six HLA-B27 alleles B*2701 to B*2706. The results indicated that the mAbs are domain specific. TrBH12 recognizes the first external (alpha-1) domain. Residues critical for the TrBH12 epitope are located in the alpha-1 helix and include the polypeptide stretch 63-76 plus a critical amino acid at position 77. Tr3B6 binds the second external (alpha-2) domain, and one mutation (VAL152----GLU152) destroyed its epitope. TrCG10 also binds the alpha-2 domain.

Alleles↗
PubMed1991

Partial DNA sequences derived from two previously unknown HLA class I genes.

Genomic DNA of HLA class I gene segments was amplified by the polymerase chain reaction (PCR). The amplified 0.8 kb gene segment encompassed sequences corresponding to an exon 2 (alpha 1 domain), an intron 2 and an exon 3 (alpha 2 domain). The PCR product was cloned in M13 and sequenced. Two previously unknown sequences were found. One of them (DAN2) had an open reading frame and intact intron splice sites, but we did not find evidence for transcription. Best homology (87.5%) was found with HLA-BeWo C.1, a recently described HLA-C gene. The other sequence (DAN4) is derived from a pseudogene, because the putative 3' splice site of intron 2 was changed from AG to ATG and the sequence corresponding to exon 3 had a shift in reading frame resulting in a stop codon.

Amino Acid Sequence↗
PubMed1991

Sequences of four previously undescribed human T-cell receptor beta chain variable genes.

T-cell receptor beta chain mRNA from 4 human T-lymphocyte clones was reverse transcribed, amplified by PCR, cloned in M13 and sequenced. Four hitherto undescribed variable genes were found. One of them (V beta-IW22) showed the highest homology (74.5%) to V beta 1. Two others (V beta-IW6 and V beta-IW10) belonged to the recently described V beta 21 family. The last gene (V beta-VW114) belonged to the V beta 9 family. However, the latter gene a is pseudogene because of an in-frame stop codon.

Amino Acid Sequence↗
PubMed1991

Particular HLA-DQ alpha beta heterodimer associated with IDDM susceptibility in both DR4-DQw4 Japanese and DR4-DQw8/DRw8-DQw4 whites.

Insulin-dependent diabetes mellitus (IDDM) susceptibility is associated with the DR4-DQw4 haplotype in Japanese and the DR4-DQw8/-Drw8-DQw4 genotype (among others) in whites. We investigated whether these Japanese and white individuals encode the same or a similar DQ alpha beta heterodimer, which may be an IDDM-susceptibility molecule in both populations. First, we carried out genomic DQA1 and DQB1 typing with sequence-specific oligonucleotide probes. The results revealed that Japanese DR4-DQw4 and white DR4-DQw8/DRw8-DQw4 IDDM patients carried the DQA1*0301 allele and the DQB1*0401 or DQB1*0402 allele, either in the cis (Japanese DR4-DQw4 individuals) or trans (white DR4-DQw8/DRw8-DQw4 individuals) position. Because the DQB1*0401 and DQB1*0402 alleles differ only at residue 23, these DQB1 genes are very similar. We next tested cells from these individuals with a particular DQ-specific T-lymphocyte clone, HH58. The clone was only restimulated with cells from Japanese individuals who carried the DQA1*0301 and DQB1*0401 alleles in the cis position or white individuals who carried the DQA1*0301 and DQB1*0402 alleles in the trans position. Thus, particular cis- or trans-encoded DQ alpha beta heterodimers, which in both cases are recognized by T lymphocytes, may confer susceptibility to IDDM in both ethnic groups.

Alleles↗