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Biomedical subjects

J Clausen

Publications and source records attributed to J Clausen.

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

Endogenous retroviruses and multiple sclerosis.

Endogenous retroviruses are normal constituents in vertebrate genomes. They have been associated with various diseases of presumed autoimmune etiology. However, conclusive evidence of their significance as susceptibility factors in these diseases is still lacking. In our laboratory we have focused attention upon endogenous retroviruses as candidate genes in multiple sclerosis. In this communication we describe general properties of endogenous retroviruses and we present observations from some of our studies.

Endogenous Retroviruses↗
PubMed1999

The major selenium-containing protein in human peripheral granulocytes.

Previously, a selenium-containing protein with subunit molecular weight of 15 kDa was found in peripheral human granulocytes. In continuation of this work, the present communication accounts for purification, identification, and characterization of this major selenium-containing protein. The protein was purified on a heparin-Sepharose column followed by Sephacryl S-200 column chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis visualized two bands with subunit molecular weights around 15 kDa. o-Phthaldialdehyde precolumn derivatization and reverse-phase high-performance liquid chromatography showed that the protein contains selenocysteine or selenocystine residues. High-performance gel filtration and isoelectric focusing revealed that the protein had an apparent molecular weight of 32 kDa and a pI value of 7.9. The addition of the protein synthesis inhibitor puromycin to the cell culture medium decreased the 15-kDa protein synthesis. These data suggest that the major selenium-containing protein in peripheral human granulocytes might be a protein with two subunits around 15 kDa. Enzyme studies showed that the protein had peroxidase activity assayed with H2O2 as a substrate and O-dianisidine as a hydrogen donor. This enzymatic activity competed with glutathione peroxidase on the consumption of H2O2, leading to an "inhibiton" of glutathione peroxidase (GSH-Px) activity. Sodium azide could eliminate the inhibition of the protein to GSH-Px. All of the above results implicated that the protein might be a H2O2-dependent selenium containing peroxidase different from GSH-Px. Therefore, the biological function of the protein could be related to eliminating H2O2 generated in the respiratory burst reaction of granulocytes, thus protecting these cells from oxidative damage during phagocytosis.

Blood Proteins↗
PubMed1999

Thioredoxin reductase is one of the selenoproteins in both promyelocytic and granulocytic HL-60 cells.

Human leukemia promyelocytic HL-60 cells differentiate into granulocytes when cultured with 1.25% dimethyl sulfoxide for 3 d. The radioactive Na2 75SeO3 incorporation and the amount of total proteins were interrelated in both promyelocytic and granulocytic HL-60. Promyelocytic cells had four times higher 75Se incorporation and 34% more protein synthesis than the granulocytic cells on the fifth culturing day. The enzyme activities of glutathione peroxidase (GSH-Px, E.C. 1.11.1.9) and thioredoxin reductase (TrxR, E.C. 1.6.4.5) in both types of cells increased significantly and approached steady stage on the third day. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (PAGE) analysis and autoradiography of the proteins from the cells revealed three proteins with molecular weights of 57, 28, and 21 kDa, respectively. These three 75Se-labeled proteins were present in both types of cells. The proteins from HL-60 cells were separated by DEAE-Sepharose and 2'5'-ADP-Sepharose columns. The purified 57-kDa protein had TrxR activity of 0.744 micromol 5'-thionitrobenzoic acid (TNB) formed/min/mg protein and two isoelectric points at pH 5.9 and 6.0. These results suggest that TrxR is one of the selenoproteins in both promyelocytic and granulocytic HL-60 cells.

Autoradiography↗
PubMed1999

A pilot study of expiratory flow limitation and lung volume reduction surgery.

STUDY OBJECTIVES: To examine the relationships between changes in expiratory flow limitation (FL) during anesthesia and postoperative responses to lung volume reduction surgery (LVRS). DESIGN: Prospective consecutive case comparison. SETTING: University medical center. PATIENTS: Eight patients with severe emphysema. INTERVENTIONS: General anesthesia with muscle paralysis and thoracic epidural analgesia were provided for LVRS via median sternotomy. MEASUREMENTS: FEV(1), functional residual capacity (FRC), and total lung capacity (TLC) were measured preoperatively and 3 months postoperatively. Tidal volume (VT) flow/volume (F/V) curves were obtained with a Pitot-type spirometer. VT, expiratory flow rate at 0. 25 x VT (V'VT,25% ), and peak expiratory flow rate (V'VT,MAX) were obtained from VT F/V curves to derive V'VT,25%/V'VT,MAX ratio as a measure of FL. RESULTS: Closed chest VT F/V curves during anesthesia pre-LVRS showed four patients with FL (group A) whose V'VT,25%/V'VT, MAX ratio was 0.38 +/- 0.06 (mean +/- SD) and four patients without FL (group B) whose V'VT,25%/V'VT,MAX ratio was 0.82 +/- 0.06 (p = 0. 0001). Closed chest post-LVRS V'VT,25%/V'VT,MAX ratio during anesthesia increased by 0.48 +/- 0.08 in group A, compared with a 0. 19 +/- 0.16 reduction in group B (p = 0.0001). Preoperative FEV(1) was 0.57 +/- 0.10 L for group A vs 0.82 +/- 0.13 L for group B (p = 0.02). Postoperative FEV(1) increased by 67 +/- 40% for group A (p = 0.03) vs 29 +/- 21% for group B (not significant). FRC decreased by 33 +/- 3% for group A vs 17 +/- 5% for group B (p = 0.0007), and FRC/TLC decreased by 0.14 +/- 0.05 for group A vs 0.01 +/- 0.07 for group B (p = 0.026). Post-LVRS V'VT,25%/V'VT,MAX ratio change during anesthesia correlated with postoperative reduction in FRC (r(2) = 0. 89, p = 0.0004) and FRC/TLC (r(2) = 0.52, p = 0.045). CONCLUSION: Post-LVRS change in V'VT,25%/V'VT,MAX ratio during anesthesia showed a linear relationship with 3-month postoperative improvement in dynamic hyperinflation. Thus, V'VT,25%/V'VT,MAX ratio may help provide valuable insights into the interactions between chest wall recoil, dynamic hyperinflation, and VT flow rates in patients with severe COPD and LVRS.

Aged↗
PubMed1999

A novel haplotype of the endogenous retrovirus, HRES-1, in patients with multiple sclerosis and healthy individuals.

In this study we searched for genetic variation in a segment of the human endogenous retrovirus, HRES-1, which encodes a potential autoantigen of 28 kDa. The purpose was to further investigate a possible association between this endogenous retrovirus and multiple sclerosis (MS). Fragments amplified from the HRES-1 region in question were subjected to single strand conformational analysis (SSCP analysis) and sequencing if the SSCP migration pattern suggested presence of polymorphisms. Using this approach a synonymous G --> C substitution, creating an NciI site, was found. Our sequence data also revealed an additional nucleotide in the region encoding the 28-kDa protein, i.e. a nucleotide not present in the first published sequence. This finding has implications for future studies of the 28-kDa HRES-1 protein since the additional nucleotide changes the reading frame of this protein. The detection of the Nci polymorphism allowed us to define a novel haplotype of HRES-1 distinct from the three previously known HRES-1 haplotypes. On comparison of the distribution of these four haplotypes in MS patients and healthy individuals we found a statistically significant difference (P = 0.03) but the contribution from the novel haplotype to this was modest.

Alleles↗
PubMed1998

Incidence and outcome of hepatic veno-occlusive disease after blood or marrow transplantation: a prospective cohort study of the European Group for Blood and Marrow Transplantation. European Group for Blood and Marrow Transplantation Chronic Leukemia Working Party.

To determine the incidence and outcome of hepatic veno-occlusive disease (VOD) after blood or marrow transplantation (BMT), we prospectively evaluated all consecutive patients receiving a BMT during a 6-month period in participating EBMT centers. All of them were evaluated for occurrence of VOD according to previously defined clinical criteria. The clinical course, outcome, value of prophylactic and therapeutic interventions, and the influence of previously described risk factors were analyzed. During the study period, 1,652 BMT were performed in 73 centers. VOD was diagnosed in 87 patients (5.3%; 95% confidence interval [CI], 4.2% to 6.4%). Fifty-six of 631 allogeneic BMT (8.9%) and 31 of 1,010 autologous BMT (3.1%) developed this complication (P <.0001). VOD was classified as mild in 7 (8%), moderate in 56 (64.4%), and severe in 24 (27.6%) cases. Sixteen patients died of VOD (corresponding to 1% of the whole series, 18.4% of VOD patients, and 66.7% of severe VOD). The use of unfractionated heparin did not significantly decrease the incidence of VOD. Independent variables associated with an increased risk of VOD were allogeneic BMT (relative risk [RR], 2.8; P <.001), pre-BMT elevation of serum aspartate aminotransferase (RR, 2.4; P =.001), high-dose cytoreductive therapy (RR, 2.3; P =.003), Karnofsky performance score less than 90% (RR, 2.7; P =.006), and prior abdominal radiation (RR, 2.9; P =.03). In conclusion, this prospective study shows that (1) the incidence of VOD is lower than that reported in smaller studies from single centers, (2) about one fourth of cases of VOD progress to severe disease, (3) main risk factors have a major impact on incidence of VOD, and (4) the use of prophylactic unfractionated heparin does not seem to reduce the incidence of VOD.

Adult↗
PubMed1998

The effects of hypoxia and sleep apnea on isoproterenol sensitivity.

STUDY OBJECTIVES: To determine the effects of both apnea and hypoxia on beta-adrenergic receptor sensitivity. DESIGN: Cross-sectional study. SETTING: A clinical research center. PATIENTS: Forty-five normotensive and hypertensive sleep apnea patients (respiratory disturbance index >20) and non-apneic controls. MEASUREMENTS AND RESULTS: The chronotropic 25 dose (CD25), an in vivo measure of beta-adrenergic receptor sensitivity derived from the heart rate response to a graded infusion of isoproterenol, was determined while subjects breathed either a normoxic (21% O2, 79% N2) or a hypoxic (15% O2, 85% N2) gas mixture. Under normoxic conditions, apnea patients showed a significantly higher CD25 (lower beta-adrenergic receptor sensitivity) as compared to controls (5.9 microg, SD=2.1 versus 4.6 microg, SD=1.2, respectively; p=0.018). In response to hypoxia, apnea patients showed no change in CD25, while controls showed a significant increase in CD25 (beta-adrenergic receptor desensitization) (p=0.002), to a value comparable to the apneics' (5.6 microg, SD=2.0). CONCLUSION: The in vivo finding of reduced beta-adrenergic receptor sensitivity in sleep apnea patients is consistent with previous in vitro assessments of the beta-adrenergic receptor. The finding that apnea patients do not respond to hypoxia with a further receptor desensitization suggests that sleep apnea patients may have reached a threshold effect of hypoxia on the beta-adrenergic receptor. These findings may be relevant to the greater incidence of hypertension seen in patients with sleep apnea syndrome.

Adrenergic beta-Agonists↗
PubMed1998

Different selenium-containing proteins in the extracellular and intracellular media of leucocytes cultivated in vitro.

The purpose of this communication is to elucidate if selenium plays a role in the function of granulocytes and lymphocytes. Thus, the incorporation of selenium in proteins from granulocytes and lymphocytes cultured with 1 microCi/mL radioactive Na2(75)SeO3 was studied. The protein peaks containing 75Se from two columns of Heparin Sepharose CL-6B and Sephacryl S-200 HR were separated further by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The results showed that the incorporation of 75Se into granulocytes was about six times higher than that of lymphocytes during a 96-h cultivation, however, the GSH-Px activity in granulocytes did not change significantly. On the other hand, the GSH-Px activity of lymphocytes rose significantly after three days cultivation. These data indicated that the main chemical form of selenium in granulocytes was not GSH-Px. Results from SDS-PAGE revealed a strongly 75Se-labeled protein band with subunit molecular weight of 15 kDa in the supernatant of granulocyte homogenate. However, the main chemical forms of selenium in the culture media of granulocytes and lymphocytes were found to be selenoprotein P. The different forms of selenium-containing proteins in the intracellular and extracellular media of granulocytes indicated the different functions of these proteins.

Cells, Cultured↗
PubMed1998

Large number of polymorphic nucleotides and a termination codon in the env gene of the endogenous human retrovirus ERV3.

The terminal portion of the pol gene and the entire env gene of the human endogenous retrovirus ERV3 was screened for polymorphic nucleotides. For this purpose fragments amplified from the desired regions of ERV3 were subjected to single strand conformational analysis (SSCP analysis). Using this approach, we detected 13 polymorphic nucleotides, namely four in the pol gene and nine in the env gene. Three of the nucleotide substitutions were synonymous (not affecting the amino acid code). One of the non-synonymous nucleotide substitutions changed an arginine codon to a termination codon. The alleles at the different polymorphic sites could be arranged into five ERV3 haplotypes, two of which were new. To evaluate the possible significance of the termination codon, which precludes expression of a putative immunoregulatory factor, we examined samples of DNA from patients with multiple sclerosis, a demyelinating disease of presumed autoimmune etiology. We did not find an association between the ERV3 allele with the termination codon and this disease. Perhaps the presence of a stop codon combined with the high number of non-synonymous nucleotide substitutions in the reading frame of the env gene reflects absence of selective constraints during evolution. Obviously, our findings contradict the assumption that the reading frame of the ERV3 env gene has been conserved throughout evolution.

Codon, Terminator↗
PubMed1998

Pathophysiology of changes in absolute lung volumes.

Changes in absolute lung volumes are common in lung disease and result in significant impacts on gas exchange, respiratory muscle function, the sensation of dyspnoea, and limitations to maximal exercise. Though our knowledge regarding the magnitude and determinants of changes in lung volumes in health and disease has increased in the past 20 years, a number of important questions remain unanswered. Consideration of the limitations of specific methods for measuring lung volumes is essential when analysing published studies regarding absolute lung volumes in infants, children and adults. Though functional residual capacity is most commonly measured in children and adults with the subject awake and at rest, increasingly attention is being directed to making these measurements under clinically more relevant conditions (e.g. during exercise, sleep, anesthesia, or mechanical ventilation). The relationships between dynamic changes in functional residual capacity, flow limitation during tidal breaths, sensation of dyspnoea and exercise limitation are important to understand, and are the focus of current and future research. Improved understanding of these relationships may lead to improvements in therapy of patients with acute and chronic lung disease and are likely to be particularly important for evaluating the efficacy of and optimal patient selection for new modes of therapy, such as lung volume reduction surgery.

Adolescent↗
PubMed1998

Factors in human serum interfere with the measurement of advanced glycation endproducts.

Advanced glycation endproducts (AGEs) have been implicated in the pathophysiology of coronary heart disease in ageing, diabetes and renal disease. Competitive enzyme-linked immunosorbent assays (ELISAs) have been developed to measure these compounds in serum, but as recognition of AGEs is both carrier protein- and antibody-dependent standardisation is problematic. We report here on another barrier to standardization, as yet unrecognised. During the development of an AGE ELISA, we found that serum samples did not dilute in parallel to AGE standards or each other. This finding was confirmed by recovery studies that showed over-recovery of AGEs at high serum concentrations, but under-recovery at high dilutions of serum in assay buffer. We developed an inhibition assay to detect factors in serum capable of interacting directly with AGEs immobilised on microtitre plates. Binding of these factors prevented recognition of AGEs by a CML monoclonal antibody and a polyclonal anti-AGE antibody, and was neither sugar- nor carrier protein-dependent. We detected the presence of this factor in all human sera tested and also in foetal calf serum. Pre-incubation of sera with AGEs or heat-treatment at 56 degrees C for 30 min. significantly reduced this binding. We are currently investigating the nature of this factor and the possibility that it may be complement. The effect of this factor on immunoassays for AGEs can only be detected by performing parallelism and recovery studies and we suggest the use of the method referred to in this paper to aid interpretation of parallelism data.

Antibodies↗
PubMed1997

Selective immunoaffinity-based enrichment of CD34+ cells transduced with retroviral vectors containing an intracytoplasmatically truncated version of the human low-affinity nerve growth factor receptor (deltaLNGFR) gene.

Human hematopoietic stem cells remain one of the most promising target cells for gene therapeutic approaches to treat malignant and nonmalignant diseases. To rapidly characterize transduced cells and to isolate these from residual nontransduced, but biologically equivalent, cells, we have used a Moloney murine leukemia virus (Mo-MuLV)-based retroviral vector containing the intracytoplasmatically truncated human low-affinity nerve growth factor receptor (deltaLNGFR) cDNA as a marker gene. Supernatant transduction of CD34+ cells (mean purity 97%) in fibronectin-coated tissue culture flasks resulted in 5.5-45% (mean 26%) transduced cells expressing deltaLNGFR (LNGFR+ cells). After transduction, more than 65% of the transduced cells remained CD34+. Compared with control (mock- and nontransduced) CD34+ cells, transduction did not decrease the cloning efficiency of CD34+ cells. Immunomagnetic selection of the transduced cells with a monoclonal anti-LNGFR antibody resulted in >90% LNGFR+ cells. Further phenotypic characterization of these highly enriched LNGFR+ cells indicated that the majority co-expressed the CD34 and CD38 antigens. These results show that transduced cells expressing an ectopic cell-surface protein can be rapidly and conveniently quantitated and characterized by fluorescence-activated cell sorting (FACS) analysis and fast and efficiently enriched by immunoadhesion using magnetic beads. The use of cell-surface reporters should facilitate optimization of methods of gene transfer into more primitive hematopoietic progenitors.

Animals↗
PubMed1997

Effects of dietary broccoli on human drug metabolising activity.

Eighteen volunteers received 500 g fresh broccoli every day for 12 days after a 6-day period of standard diet. The activity of CYP1A2, CYP2E1 and the estrone 2 and 16alpha-hydroxylation were determined prior to and after the broccoli diet. The average activity of CYP1A2 and the average 2/16alpha-hydroxyestrone ratio were increased 19% (P < 0.0005) and 29.5% (P < 0.05), respectively; however, no effects were observed on the CYP2E1 activity.

Anticarcinogenic Agents↗
PubMed1997

Long-term follow-up of leukaemia patients after related cryopreserved allogeneic bone marrow transplantation.

We have previously shown that allogeneic bone marrow transplantation (BMT) with cryopreserved donor marrow cells can be used without prolonging the engraftment time or interfering with the reconstitution of haemopoiesis. In this report we extend our initial observations of the first 40 patients who underwent allogeneic bone marrow transplantation from related donors with cryopreserved donor bone marrow for haematological malignancies, including the long-term follow-up data of the previously reported patients. The outcome of these patients was compared with that of 40 related BMT recipients receiving fresh donor bone marrow (historic control group). Time until engraftment of all patients receiving cryopreserved bone marrow was not different from the control group (ANC > 0.5 x 10(9)/l 17d (range 11-24 d) versus 17.5 d (range 10-28 d): platelets > 20 x 10(9)/l 21 d (range 11-85 d) versus 22 d (range 13-69 d), respectively). There was the same incidence of acute and chronic GvHD in patients receiving either cryopreserved bone marrow or fresh bone marrow (acute GvHD > or = II 61% v 60% and chronic GvHD 56% v 52%, respectively). Chimaerism studies showed no difference between the patient groups. Furthermore, the two groups did not differ in day 100 survival (82% v 72%). With a median follow-up of 520 d (range 47-1365 d) and 1289 d (range 48-1849 d), 60% of the patients receiving cryopreserved and 53% of the patients receiving fresh allogeneic donor bone marrow, respectively, are alive. We conclude that cryopreservation of allogeneic related donor bone marrow does not adversely affect engraftment, does not decrease the incidence of severe acute GvHD, and does not seem to affect the day 100 survival or long-term haemopoiesis.

Adolescent↗
PubMed1997

Possible involvement of endogenous retroviruses in the development of autoimmune disorders, especially multiple sclerosis.

Endogenous retroviruses are normal elements in vertebrate genomes. Many aspects concerning these genomic elements are still uncertain. In mice some endogenous retroviral sequences seem to be involved in the regulation of immune responses and there is even evidence that a retroviral element is responsible for the development of an autoimmune disease in a mouse strain. Whether endogenous retroviruses also contribute to the development of autoimmune diseases in humans is not known, but it is an interesting possibility. Below we briefly review endogenous retroviruses as potential etiological factors in autoimmunity and we discuss a possible association between MS and endogenous retroviruses on the basis of results from our laboratory.

Animals↗
PubMed1997

Expression of endogenous retroviruses in blood mononuclear cells and brain tissue from multiple sclerosis patients.

OBJECTIVES: To compare the expression of endogenous retroviruses in MS patients and controls. MATERIAL AND METHODS: Peripheral blood mononuclear cells were obtained from 22 MS patients, a corresponding number of matched healthy donors and five patients with other central nervous system disease. Also brain specimens from MS patients and controls were obtained. Transcripts of various endogenous retroviruses in these samples were detected by RNA-PCR. RESULTS: Several endogenous retroviral sequences were transcribed in peripheral blood mononuclear cells and brain tissue from MS patients as well as controls. A composite transcript of an endogenous retrovirus and a zinc finger sequence was more frequently found in healthy donors than in MS patients. CONCLUSION: Some endogenous retroviruses are normally transcribed in white blood cells and brain tissue. The significance of those findings, which concerned the composite transcripts of the zinc finger sequence and its associated endogenous retrovirus is uncertain.

Adult↗