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Biomedical subjects

H Knudsen

Publications and source records attributed to H Knudsen.

At least 19 recordsLinked to original sources
PubMed2004

Stopping power in insulators and metals without charge exchange.

The slowing-down process of pointlike charged particles in matter has been investigated by measuring the stopping power for antiprotons in materials of qualitatively very different nature. Whereas the velocity-proportional stopping power observed for metal-like targets such as aluminum over a wide energy range of 1-50 keV is in agreement with expectations, it is surprising that the same velocity dependence is seen for a large band-gap insulator such as LiF. The validity of these observations is supported by several measurements with protons and several checks of the target properties. The observations call for both a qualitative explanation and a quantitative theoretical model.

Journal Article↗
PubMed2002

Food safety on the slaughterline: inspection of pig heads.

This paper summarises information on the current inspection procedures for pig heads on the slaughterline and their impact on food safety, and considers the implications for food safety of certain lesions. It is argued that although a modified slaughter and inspection technique would decrease the contamination of the carcase with pathogenic microorganisms, leaving lesions in the head undiscovered would be of little or no importance either for human health or for the overall supervision of animal health.

Abattoirs↗
PubMed2002

Antiproton stopping at low energies: confirmation of velocity-proportional stopping power.

The stopping power for antiprotons in various solid targets has been measured in the low-energy range of 1-100 keV. In agreement with most models, in particular free-electron gas models, the stopping power is found to be proportional to the projectile velocity below the stopping-power maximum. Although a stopping power proportional to velocity has also been observed for protons, the interpretation of such measurements is difficult due to the presence of charge exchange processes. Hence, the present measurements constitute the first unambiguous support for a velocity-proportional stopping power due to target excitations by a pointlike projectile.

Journal Article↗
PubMed2002

Electromagnetically induced nuclear-charge pickup observed in ultrarelativistic Pb collisions.

A strong increase of inclusive nuclear-charge pickup cross sections, forming 83Bi from 158A GeV 82Pb ions, is observed in comparison to similar measurements at 10.6A GeV. From the dependence of these cross sections on target atomic number, this increase is attributed to the electromagnetic process of pion production by equivalent photons. The observed cross sections can be reproduced quantitatively using the recently developed RELDIS code.

Journal Article↗
PubMed2002

A case of lymphoblastoid natural killer (NK)-cell lymphoma: association with the NK-cell receptor complex CD94/NKG2 and TP53 intragenic deletion.

The clinical, histological, phenotypic and genotypic features of a lymphoblastoid natural killer (NK)-cell lymphoma presenting in the skin in a young caucasian woman are described. The disease behaved aggressively, but long-lasting remission was obtained by combination chemotherapy followed by autologous bone marrow transplantation. The blastoid cells were positive for terminal deoxynucleotidyl transferase, CD34, CD56 and CD4. Furthermore, the NK-cell receptor complex CD94/NKG2 was strongly expressed, as shown by examination with reverse transcription-polymerase chain reaction. The T-cell receptor (TCR)-gamma genes were in germline, and with the exception of CD4 all T-cell antigens were negative, including CD3, TCR-beta, TCR-delta, TIA-1, granzyme B and perforin. Epstein-Barr virus was negative, and no expression was seen of myeloid cell-associated markers. Molecular analysis showed no abnormalities of the CDKN2A (p16), CDKN2B (p15) or TNFRSF6 (Fas) genes. By contrast, a 34-bp deletion in exon 7 of the TP53 (p53) gene was detected. It is suggested that lymphoblastoid NK-cell lymphoma, which is a rare but distinctive disease, originates from NK cell precursors and may be associated with and possibly caused by alterations in the TP53 gene. Experience is too limited to warrant therapeutic suggestions. However, stem cell transplantation may be a useful option in younger patients.

Adult↗
PubMed2001

Expanded bed adsorption in the purification of monoclonal antibodies: a comparison of process alternatives.

Expanded bed adsorption (EBA) was examined as the initial capture/purification step in the purification of monoclonal antibodies from Chinese hamster ovary (CHO) cultures. Two process alternatives each using EBA were compared to a conventional Protein A process without EBA. One alternative used Protein A affinity EBA followed by packed-bed cation and anion-exchange steps. The other alternative used cation-exchange EBA as the capture step followed by packed-bed Protein A and anion-exchange steps. The process using Protein A EBA produced comparable purity (host cell protein, DNA, Protein A, antibody aggregate) to the conventional process. However, the Protein A EBA column showed a significant decrease in dynamic capacity with a limited number of cycles. The process using cation EBA achieved comparable levels of host cell proteins (HCP) and DNA but not antibody aggregate or leached Protein A compared to the conventional process.

Adsorption↗
PubMed1997

CD34+ megakaryoblastic leukaemic cells are CD38-, but CD61+ and glycophorin A+: improved criteria for diagnosis of AML-M7?

The aim of this flow cytometry study in acute megakaryoblastic leukaemia (AML-M7) was to describe the membrane phenotype of CD34+ progenitor subsets and compare these with the phenotypes expressed by other AML FAB types. Following conventional histopathological diagnosis mononuclear cells from bone marrow and blood were examined in seven patients with AML-M7 and compared with results from 26 sequential patients with AML-M0 to AML-M6. The CD34+ subsets in AML-M7 patients differed from that of patients with AML-M0 to AML-M6 as the CD34+ CD61+ and the CD34+ Glycophorin A+ subsets were median 31% and 20%, respectively, compared to 4% and 2% in the AML-M0 to AML-M6 (P = 0.0005). Only 1% of the CD34+ progenitors were CD34+ CD38+ in AML-M7 compared to 72% in other AML subtypes (P < 0.000). These findings suggest that the CD34+ cell compartment in AML-M7 consists of early lineage-specific progenitors. In conclusion, flow cytometry analysis of CD34+ subsets may improve the diagnostic safety in AML-M7 and consequently the prognostic significance of immunophenotyping in acute leukaemia.

Adult↗
PubMed1997

Application of peptide nucleic acid in cancer therapy.

Peptide nucleic acid (PNA) is a DNA mimic with a pseudopeptide backbone composed of aminoethyl glycine units. Several features of PNA, such as superior hybridization affinities to RNA and DNA, high biological stability, and convenient solid-phase synthesis, make it a promising candidate for use as a gene targeting drug. Here we review the chemical and biological properties of PNA in relation to its potential as an anti-cancer drug.

Animals↗
PubMed1996

Antisense properties of duplex- and triplex-forming PNAs.

The potential of peptide nucleic acids (PNAs) as specific inhibitors of translation has been studied. PNAs with a mixed purine/pyrimidine sequence form duplexes, while homopyrimidine PNAs form (PNA)2/RNA triplexes with complementary sequences on RNA. We show here that neither of these PNA/RNA structures are substrates for RNase H. Translation experiments in cell-free extracts showed that a 15mer duplex-forming PNA blocked translation in a dose-dependent manner when the target was 5'-proximal to the AUG start codon on the RNA, whereas similar 10-, 15- or 20mer PNAs had no effect when targeted towards sequences in the coding region. Triplex-forming 10mer PNAs were efficient and specific antisense agents with a target overlapping the AUG start codon and caused arrest of ribosome elongation with a target positioned in the coding region of the mRNA. Furthermore, translation could be blocked with a 6mer bisPNA or with a clamp PNA, forming partly a triplex, partly a duplex, with its target sequence in the coding region of the mRNA.

Base Sequence↗
PubMed1995

Short-term in vivo priming of bone marrow haematopoiesis with rhG-CSF, rhGM-CSF or rhIL-3 before marrow harvest expands myelopoiesis but does not improve engraftment capability.

In an attempt to optimize bone marrow grafts for autologous transplantation 37 sequential patients suffering from various haematological diseases were treated with either recombinant human granulocyte colony-stimulating factor (rhG-CSF) (n = 23) or granulocyte-macrophage CSF (rhGM-CSF) (n = 8) for 5 days or interleukin 3 (rhIL-3) (n = 6) for 10 days before marrow harvest. All patients were in marrow remission at study entry. In contrast to rhIL-3, the administration of rhG-CSF or rhGM-CSF caused a significant (P < 0.01) increase in blood absolute neutrophil count. An increased marrow cellularity and a rise in the myeloid:-erythroid ratio was seen in the majority of patients during therapy, and in the rhIL-3 treated group a rise in the number of megakaryocytes and increased marrow fibrosis was seen in most patients. Moreover, a median of 2-, 5- and 10-fold increase in myeloid progenitors was the result of short-term administration of rhIL-3, rhGM-CSF and rhG-CSF, respectively. However, transplantation performed with primed expanded marrow grafts did not significantly reduce the time to myeloid regeneration when compared to historical controls. In conclusion, the results demonstrate that short-term priming with haematopoietic cytokines before autologous bone marrow stem cell harvest is a safe procedure which effectively expands marrow haematopoisis without enhanced engraftment capability.

Adolescent↗
PubMed1994

A common response element mediates differential effects of phorbol esters and forskolin on type-1 plasminogen activator inhibitor gene expression in human breast carcinoma cells.

We have characterized regulation of type-1 plasminogen activator inhibitor (PAI-1) gene expression by phorbol 12-myristate 13-acetate (PMA) and the cAMP-inducing agent forskolin in the human breast carcinoma cell line MCF-7. PMA caused a strong induction of PAI-1, while forskolin suppressed the PMA response. Transfection experiments with fusion genes showed that sequences mediating PMA induction as well as forskolin suppression were present between base pairs -100 and -30 of the 5'-flanking region of the PAI-1 gene. The region was found to contain two Sp1 binding sites. A proximal sequence in the region, TGAGTTCA (P box), with sequence similarity to phorbol ester response elements (TRE) as well as to cAMP response elements (CRE), bound a low-abundance, as yet unidentified nuclear protein in MCF-7 cells. This sequence had a higher affinity to purified c-jun homodimer than to c-jun/c-fos heterodimer in MCF-7 nuclear extracts; it had no affinity to the proteins binding to CRE consensus sequences in these extracts. A distal TRE-like sequence, TGAGTGG (D box), had a weak affinity to c-jun/c-fos heterodimer and c-jun homodimer; binding of proteins to this sequence was facilitated by binding of proteins to the P box. Both the P box and the D box were necessary for PMA responsiveness, suggesting a cooperativity between the two binding sites. A mutation of the P box removing the CRE similarity abolished the forskolin suppression of the PMA response. We propose that the protein kinase C and the protein kinase A signal-transduction pathways, with opposite effects on PAI-1 gene expression converge by modulating differently P-box-binding proteins.

Base Sequence↗
PubMed1993

[Multiple personality--a phenomenon also in Norway?].

Dissociative disorders are little known and seldom referred to in the Norwegian medical literature. Our paper describes signs and criteria for multiple personality and dissociative syndromes, and reviews the recent literature. Three cases are briefly presented.

Adult↗