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Johnson-Léger C, Christensen J, Klaus GG. CD28 co-stimulation stabilizes the expression of the CD40 ligand on T cells. Int Immunol 1998; 10:1083-91. [PMID: 9723694 DOI: 10.1093/intimm/10.8.1083] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The ligand for CD40 (CD40L) is a protein which is expressed on CD4 T cells following their activation: CD40-CD40L interactions are absolutely required for the induction of T cell-dependent antibody responses, yet little is known about the mechanisms whereby CD40L+ primary T cells activate naive B cells, since the protein is only transiently expressed and is rapidly down-regulated following T cell-B cell contact. We show here, using a variety of assays, that co-stimulation of primary murine T cells via CD3 and CD28 stabilizes the expression of the CD40L protein. Firstly, T cells stimulated in this manner express higher levels of CD40L when activated in the presence of B cells, compared to CD3-activated T cells. Secondly, the CD40L expressed on CD28-co-stimulated T cells is more resistant to B cell-induced down-regulation. Finally, CD3/CD28-preactivated, rested T cells re-express higher levels of CD40L more rapidly following re-stimulation via CD3 than T cells preactivated via CD3 alone. CD3/CD28-preactivated T cells, but not CD3-activated cells, are competent to induce DNA synthesis in naive B cells, and this requires re-stimulation via CD3 and prolonged ligation of CD40. These data therefore reinforce the concept that naive T cells need to be activated initially by cognate interaction with B7-bearing antigen-presenting cells (such as dendritic cells), before becoming competent helper effector cells capable of driving B cells into proliferation via a CD40-dependent pathway.
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Aasted B, Alexandersen S, Christensen J. Vaccination with Aleutian mink disease parvovirus (AMDV) capsid proteins enhances disease, while vaccination with the major non-structural AMDV protein causes partial protection from disease. Vaccine 1998; 16:1158-65. [PMID: 9682374 DOI: 10.1016/s0264-410x(98)80114-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Vaccination studies were performed with partially purified recombinant AMDV VP1/2 capsids as well as with the major AMDV non-structural protein (NS1). All vaccine constructs induced an antibody response, but did not prevent infection upon challenge with AMDV. The severity of Aleutian disease (AD) was judged by the serum gammaglobulin level, the quantity of peripheral blood CD8 lymphocytes, antibody titers to VP1/2 and NS1 proteins and mink death rates. The VP1/2 vaccine constructs enhanced the disease process with drastic death rates for the vaccinated mink. On the contrary, the NS1 vaccine constructs resulted in milder AD than seen in the non-vaccinated mink.
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203
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Carstensen B, Christensen J. Herd size and sero-prevalence of Salmonella enterica in Danish swine herds: a random-effects model for register data. Prev Vet Med 1998; 34:191-203. [PMID: 9604267 DOI: 10.1016/s0167-5877(97)00072-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The association between herd size and sero-prevalence of Salmonella was assessed in a random-effects model with herd size, county and date of slaughter as fixed effects. A total of 510,915 meat-juice samples from 14,593 herds located in 13 counties in Denmark was included in the study. A random-effects model was developed from separate models for smaller strata of data from herds with approximately equal sizes. The combined model was analysed and the results reported. Herd size was positively associated with the sero-prevalence of Salmonella enterica, but the size of the association was biologically of little importance, because the within-herd and the between-herd variations were relatively large in comparison. The relative magnitudes of the variance components indicated that factors associated with both the herd level and the pig level could be important in the prediction of seroprevalence of S. enterica.
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204
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Christensen J, Lund K. [Education--much needed discussion]. SYGEPLEJERSKEN 1998; 98:30-1, 35. [PMID: 9528607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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205
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Christensen J, Parks L, McNutt R, LeBlanc G. Reversal of multidrug resistance by derivatives of acrivastine. Oncol Rep 1997; 4:1353-60. [DOI: 10.3892/or.4.6.1353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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207
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Christensen J, Svensmark B. Evaluation of producer-recorded causes of preweaning mortality in Danish sow herds. Prev Vet Med 1997; 32:155-64. [PMID: 9443324 DOI: 10.1016/s0167-5877(96)01147-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The validity of producer-recorded preweaning mortality causes was evaluated in 31 Danish sow herds. For 1206 piglets producer-recorded preweaning mortality cause was compared with post-mortem diagnosis. The predominant preweaning mortality causes at post-mortem were injury (trauma, lain on, and savaged), miscellaneous (unknown, starvation, illthrift, euthanasia, and low viability), and diarrhoea, with 391, 219, and 119 recordings, respectively. The sensitivity of producer-recorded preweaning mortality causes was generally low, and further analyses showed that the probability of being born alive and the probability of being given 'a producer diagnosis other than unknown' were associated with the herd and that a correct producer-recorded mortality cause relative to the post-mortem diagnosis depended on the mortality cause. Rare mortality causes with primarily internal signs tended to be misclassified. The producers often gave 'a diagnosis other than unknown' to pigs with a weight at death under 0.75 kg and it was often correct. To pigs with a weight at death over 1.75 kg, they rarely gave 'a diagnosis other than unknown', but when they did it was often correct.
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208
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Christensen J. Pediatric traumatic brain injury rehabilitation: challenges in care delivery. NeuroRehabilitation 1997. [DOI: 10.1016/s1053-8135(97)00020-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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209
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Christensen J, Cotmore SF, Tattersall P. Parvovirus initiation factor PIF: a novel human DNA-binding factor which coordinately recognizes two ACGT motifs. J Virol 1997; 71:5733-41. [PMID: 9223459 PMCID: PMC191825 DOI: 10.1128/jvi.71.8.5733-5741.1997] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A novel human site-specific DNA-binding factor has been partially purified from extracts of HeLa S3 cells. This factor, designated PIF, for parvovirus initiation factor, binds to the minimal origin of DNA replication at the 3' end of the minute virus of mice (MVM) genome and functions as an essential cofactor in the replication initiation process. Here we show that PIF is required for the viral replicator protein NS1 to nick and become covalently attached to a specific site in the origin sequence in a reaction which requires ATP hydrolysis. DNase I and copper ortho-phenanthroline degradation of the PIF-DNA complexes showed that PIF protects a stretch of some 20 nucleotides, covering the entire region in the minimal left-end origin not already known to be occupied by NS1. Methylation and carboxy-ethylation interference analysis identified two ACGT motifs, spaced by five nucleotides, as the sequences responsible for this binding. A series of mutant oligonucleotides was then used as competitive inhibitors in gel mobility shift assays to confirm that PIF recognizes both of these ACGT sequences and to demonstrate that the two motifs comprise a single binding site rather than two separate sites. Competitive inhibition of the origin nicking assay, using the same group of oligonucleotides, confirmed that the same cellular factor is responsible for both mobility shift and nicking activities. UV cross-linking and relative mobility assays suggest that PIF binds DNA as a heterodimer or higher-order multimer with subunits in the 80- to 100-kDa range.
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Jørgensen P, Bennedsen B, Christensen J, Hyllested A. Acute and transient psychotic disorder: a 1-year follow-up study. Acta Psychiatr Scand 1997; 96:150-4. [PMID: 9272200 DOI: 10.1111/j.1600-0447.1997.tb09920.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A study sample consisting of 51 patients suffering from acute and transient psychotic disorder (ATPD) (ICD-10) on initial examination was evaluated at 1-year follow-up. The findings show a diagnostic change in half of the patients (48%), most often to schizophrenia (15%) and affective disorder (28%). From index admission to follow-up, patients with an unchanged diagnosis of ATPD manage fairly well with regard to psychosocial functioning, and no deteriorating development is observed. In the majority of cases no personality disorder (PD) (ICD-10, 54%; DSM-IV, 71%) is apparent, and the ATPD is not related to any specific PD. With regard to diagnostic stability, no significant demographic, social or clinical predictors were found. The findings highlight the need for validation of the concept of ATPD, and point to the fact that brief psychotic episodes with an acute onset may be an early manifestation of severe mental disorder (schizophrenia and affective disorder).
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Bager F, Madsen M, Christensen J, Aarestrup FM. Avoparcin used as a growth promoter is associated with the occurrence of vancomycin-resistant Enterococcus faecium on Danish poultry and pig farms. Prev Vet Med 1997; 31:95-112. [PMID: 9234429 DOI: 10.1016/s0167-5877(96)01119-1] [Citation(s) in RCA: 293] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We determined the association between the use of the glycopeptide antibiotic avoparcin as a growth promoter and the occurrence of Enterococcus faecium (VREF) with high-level resistance to vancomycin (MIC > or = 64 micrograms ml-1) on poultry and pig farms. The investigations were conducted as retrospective cohort studies, where groups of farms exposed or not exposed to avoparcin between September 1994 and April 1995 were compared. In poultry, the association between the use of avoparcin and the occurrence of VREF was confounded by the use of broad-spectrum antibiotics, and the adjusted relative risk was 2.9 (1.4-5.9). In pigs, the association had a similar magnitude with a non-adjusted relative risk of 3.3 (0.9-12.3). The similar findings in the two studies provide evidence in favour of a causal association between the use of avoparcin and the occurrence of VREF on farms, and suggest that food animals constitute a potential reservoir of infection for VREF in humans.
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Cullen JJ, Herrmann BM, Thomas RM, Fang S, Murray JA, Ledlow A, Christensen J, Conklin JL. The role of antioxidant enzymes in the control of opossum sphincter of Oddi motility. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 272:G1050-6. [PMID: 9176213 DOI: 10.1152/ajpgi.1997.272.5.g1050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Superoxide rapidly oxidizes nitric oxide (NO) to form peroxynitrite, thus terminating the biological activity of NO. The aims of our study were to determine if superoxide alters the motor function of the sphincter of Oddi and to localize the antioxidant enzymes in the sphincter of Oddi. Immunostaining was performed and enzyme activities were measured in the sphincter of Oddi. In physiological experiments, force-displacement transducers recorded tension in the spontaneously contracting sphincter of Oddi and after electrical field stimulation (EFS) of precontracted sphincter of Oddi. Superoxide was generated by the addition of xanthine with xanthine oxidase, superoxide radicals were scavenged by the addition of superoxide dismutase (SOD), and catalase or SOD was inhibited by diethyldithiocarbamic acid. Immunostaining demonstrated SOD and catalase immunoreactivity in ganglia situated at the serosal surface of the circular muscle. Total SOD activity was 202 +/- 12 U/mg. Generation of superoxide or inhibition of SOD increased the contractile frequency and decreased relaxation after EFS. We conclude that superoxide alters sphincter of Oddi motor function, and the presence of superoxide scavenging enzymes in enteric plexuses suggests that they may regulate sphincter of Oddi neuromuscular function by clearing endogenous superoxide.
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Christensen J, Cotmore SF, Tattersall P. A novel cellular site-specific DNA-binding protein cooperates with the viral NS1 polypeptide to initiate parvovirus DNA replication. J Virol 1997; 71:1405-16. [PMID: 8995666 PMCID: PMC191197 DOI: 10.1128/jvi.71.2.1405-1416.1997] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Replication of linear single-stranded parvovirus DNA proceeds by a rolling-hairpin mechanism which generates long, palindromic, duplex concatamers. Processing to monomer length requires initiation from origins of DNA replication located at the 3' and 5' ends of each embedded monomer, reactions which can be recapitulated in vitro for minute virus of mice (MVM). To determine which cellular proteins were essential for replication from these origins, S100 extracts from 293S cells were fractionated on phosphocellulose. When recombined, these fractions were able to support replication in vitro, dependent on the viral initiator protein NS1, using plasmid forms of the 5' origin or the minimal 3' origin as templates. Fraction P-cell 1 contains two factors, replication protein A (RPA) and proliferating-cell nuclear antigen (PCNA), known to be essential for simian virus 40 replication in vitro. When P-cell 1 was replaced with purified recombinant RPA and PCNA, NS1-mediated MVM replication initiated from the 5' origin but not from the 3' origin. The 3' origin is a 50-bp sequence containing three distinct recognition elements, an NS1 binding site, a site at which NS1 nicks the DNA to generate the priming 3' OH, and a region containing a consensus activated transcription factor (ATF) binding site. To identify the missing factor(s) for 3' origin replication, P-cell 1 was fractionated by further chromatography and active fractions were identified by their ability to complement RPA, PCNA, and P-cell 2 for NS1-mediated, origin-specific replication. Gel shift and UV cross-linking analysis of the replication-competent fractions revealed a novel 110-kDa sequence-specific DNA binding protein which recognized the consensus ATF binding site region of the origin and which we have termed parvovirus initiation factor, or PIF. Binding of PIF appears to activate the endonuclease function of NS1, allowing efficient and specific nicking of the 3' minimal origin under stringent conditions in vitro.
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214
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White JC, Rosson C, Christensen J, Hart R, Levinson W. Wrapping things up: a qualitative analysis of the closing moments of the medical visit. PATIENT EDUCATION AND COUNSELING 1997; 30:155-165. [PMID: 9128617 DOI: 10.1016/s0738-3991(96)00962-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The purpose of this preliminary study is to develop an operational definition of the closure phase of the medical visit. A listening group developed a definition of closure by consensus based on audiotaped data from 22 office visits to physicians. The group noted new problems in closure not previously raised. Closure was defined as the final phase of the medical visit in which the doctor and patient shift perspective to the future, finalize plans, and say goodbye. Two distinct organizational frameworks of closure are outlined. Thirty-six percent of closures were interrupted in some way. New problems occurred in 23% of visits, even those with open-ended beginnings and early physician requests for all patient concerns. Doctors' communication involved expression of emotion, patient education, clarification, summary, and parting comments. Patient communication included expression of emotion, information sharing, and parting comments. Doctors' communication skills for closure are proposed. Closure is a distinctive phase of the visit with an organizational framework and specific tasks. The frequency of new problems in closure suggests that physicians may have the potential to improve their effectiveness.
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215
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Rudolph CD, Hyman PE, Altschuler SM, Christensen J, Colletti RB, Cucchiara S, Di Lorenzo C, Flores AF, Hillemeier AC, McCallum RW, Vanderhoof JA. Diagnosis and treatment of chronic intestinal pseudo-obstruction in children: report of consensus workshop. J Pediatr Gastroenterol Nutr 1997; 24:102-12. [PMID: 9093995 DOI: 10.1097/00005176-199701000-00021] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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216
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Kendrick KM, Guevara-Guzman R, de la Riva C, Christensen J, Ostergaard K, Emson PC. NMDA and kainate-evoked release of nitric oxide and classical transmitters in the rat striatum: in vivo evidence that nitric oxide may play a neuroprotective role. Eur J Neurosci 1996; 8:2619-34. [PMID: 8996812 DOI: 10.1111/j.1460-9568.1996.tb01557.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The effects of N-methyl-D-aspartate (NMDA), kainate, S-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and KCl on striatal nitric oxide (NO), acetylcholine (ACh), dopamine (DA), serotonin (5-HT), aspartate (ASP), glutamate (GLU) and gamma-aminobutyric acid (GABA) release were measured in anaesthetized rats in vivo by microdialysis and in vitro in organotypic slice cultures. Local NMDA (1-100 microM) infusion by retrodialysis dose-dependently increased levels of classical transmitters, NO2-, NO3-, citrulline and arginine at similar thresholds (10 microM). Similar patterns of NMDA-evoked (50 microM) release were seen in striatal cultures. NMDA-evoked changes were all calcium-dependent and blocked by NMDA (APV or MK-801) but not AMPA/kainate (DNQX) receptor antagonists, excepting DA which could be prevented by both. In vivo, kainate increased NO2-, NO3-, CIT and ARG levels at 50 and 100 microM but was less potent than NMDA. Kainate also evoked significant ACh, DA and GLU release dose-dependently starting at 1-10 microM whereas 5-HT, ASP and GABA required 50 or 100 microM doses. Kainate effects were inhibited by DNQX, but not by APV, and were calcium-dependent, AMPA failed to alter NO2-, NO3-, CIT or ARG levels at 50 or 100 microM doses but dose-dependently increased ACh and DA. Similar results were seen with kainate (50 microM) and AMPA (50 microM) in vitro. KCl evoked NO2-, NO3-, CIT and ARG release as well as that of the classical transmitters in vivo and in vitro. In vivo administration of the NO synthase inhibitor L-nitroarginine (L-NARG; 100 microM) significantly reduced NO2-, NO3- and CIT levels and prevented NMDA, kainate or KCl-evoked increases. It also potentiated ACh, ASP, GLU and GABA release and reduced that of DA in response to 50 microM NMDA whereas treatment with an NO-donor (SNAP; 10 microM) significantly reduced evoked ACh, ASP and GLU release. The NO synthase inhibitor L-NARG potentiated kainate-evoked ACh release and reduced that of DA, although less potently than NMDA, but it had no effect on KCl-evoked transmitter release. Overall, these results show that both NMDA and kainate increase striatal NO release at similar dose-thresholds as for classical transmitter release suggesting that NO is dynamically released under physiological and not just pathological conditions. Reductions of striatal NO levels also potentiates calcium-dependent transmitter release in response to NMDA and, to a lesser extent, kainate, whereas increasing them reduces it. This is consistent with a role for NO as a neuroprotective agent in this region acting to desensitize NMDA receptors.
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Jørgensen P, Bennedsen B, Christensen J, Hyllested A. Acute and transient psychotic disorder: comorbidity with personality disorder. Acta Psychiatr Scand 1996; 94:460-4. [PMID: 9021000 DOI: 10.1111/j.1600-0447.1996.tb09891.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A study sample of 51 patients with acute and transient psychotic disorder (ATPD) (ICD-10) is presented. The findings suggest that, in hospital settings, ATPD is a non-frequent condition with onset in early adult life and most often associated with female sex, good premorbid social functioning and no or minor/moderate psychosocial stressors. The DSM-IV criteria distribute the patients into three diagnostic categories: schizophreniform disorder (41%), brief psychotic disorder (33%) and psychotic disorder not otherwise classified (25%). A high prevalence (63%) of personality disorders (PD) is revealed after recovery from the psychotic episode. The ATPD is not related to any specific PD, and in a substantial minority (37%) of cases no PD is found. The unspecified category is by far the most frequent PD in patients with ATPD. The sample will be followed up and reassessed.
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218
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Najakshin AM, Belousov ES, Christensen J, Storgaard T, Aasted B, Taranin AV. Structure of mink immunoglobulin gamma chain cDNA. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 1996; 20:231-240. [PMID: 8915626 DOI: 10.1016/0145-305x(96)00019-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Two cDNA clones, encoding mink Ig gamma chains were characterized. The pIGG47 clone contains a part of the leader segment, VDJ and C regions, and pIGG14 contains a part of the J and a complete C region. The clones differ by only four nucleotides in the C region, and they most probably represent allelic variants of the same gene. The V gene segment of pIGG47 was found to be highly similar to human VHIII subgroup sequences; there was 86-87% similarity for the whole V gene segment and 91% for the VHIII specific regions (codons 65-87). Southern blot analysis demonstrated that a high proportion of mink VH genes is VHIII related. The V gene segment used as a probe revealed 19-23 bands in mink DNA under stringent conditions. This is in agreement with our previous data showing that a high proportion of mink Ig contains an 'alternative' binding site for protein A, a feature common to VHIII-related molecules. According to Southern blot analysis there may be 5-7 C gamma genes at the mink IgH locus.
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219
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Rao SS, Gregersen H, Hayek B, Summers RW, Christensen J. Unexplained chest pain: the hypersensitive, hyperreactive, and poorly compliant esophagus. Ann Intern Med 1996; 124:950-8. [PMID: 8624062 DOI: 10.7326/0003-4819-124-11-199606010-00002] [Citation(s) in RCA: 141] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
OBJECTIVE To determine whether neuromuscular dysfunction of the esophagus causes chest pain in patients in whom no disease is found on cardiac work-up, upper gastrointestinal endoscopy, esophageal manometry, and 24-hour pH studies. DESIGN Prospective study. SETTING Tertiary referral center. PATIENTS 24 consecutive patients and 12 healthy controls. MEASUREMENTS A new technique, impedance planimetry, was used to measure the sensory, motor, and biomechanical properties of the human esophagus. The impendance planimeter, which consists of a probe with four ring electrodes, three pressure sensors, and a balloon, simultaneously measures intraluminal pressure and cross-sectional areas. This allows calculation of the biomechanical variables of the esophageal wall. RESULTS Stepwise balloon distentions from 5 to 50 cm H2O induced a first sensation at a mean pressure (+/- SD) of 15 +/- 9 cm H2O in patients and 30 +/- 11 cm H2O in controls (P < 0.001). Moderate discomfort and pain were reported by 20 of 24 patients (83%) at 26 +/- 9 cm H2O and at 36 +/- 9 cm H2O, respectively, but by none of the controls (P < 0.001). Typical chest pain was reproduced in 20 of 24 patients (83%). In patients, the reactivity of the esophagus to balloon distention was greater (P = 0.01), the pressure elastic modulus was higher (P = 0.02), and the tension-strain association showed that the esophageal wall was less distensible (P = 0.02). Distention excited tertiary contractions and secondary peristalsis at a lower threshold of pressure (P = 0.05) and with a higher motility index in patients than in controls (P = 0.04). CONCLUSION In patients with chest pain and normal cardiac and esophageal evaluations, impedance planimetry of the esophagus reproduces pain and is associated with a 50% lower sensory threshold for pain, a 50% lower threshold for reactive contractions, and reduced esophageal compliance.
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220
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Christensen J. Reflections on doing and writing interpretive research. Contemp Nurse 1996; 5:48-53. [PMID: 8716846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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221
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Knudsen DU, Nielsen SM, Hariri J, Christensen J, Kristensen S. Ultrasonographically guided fine-needle aspiration biopsy of intrathoracic tumors. Acta Radiol 1996; 37:327-31. [PMID: 8845263 DOI: 10.1177/02841851960371p169] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PURPOSE Evaluation of diagnostic accuracy and complication frequency at ultrasonographically guided fine-needle aspiration biopsy of intrathoracic tumors. MATERIAL AND METHODS A total of 134 ultrasonographically guided percutaneous fine-needle aspiration biopsies were performed on 128 patients with intrathoracic tumors abutting on the pleura. A cytologic diagnosis was obtained in 119 patients (93%). RESULTS In 83 patients, cytologic malignancy was found; in 34, benignity; and in 2, cellular atypia. A total of 117 diagnoses were correct and 2 diagnoses were false-positive. A malignancy subtyping based on the cytologic aspirates was made in 80 patients. In 40 (93%) of 43 histologically proven subtypes, the subtyping was correct. The complication frequency in terms of pneumothorax was 3.7%. CONCLUSION Ultrasonographically guided percutaneous fine-needle aspiration biopsy is a safe and reliable method of establishing the cytologic diagnosis of intrathoracic tumors.
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222
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Baggesen D, Wegener H, Bager F, Stege H, Christensen J. Herd prevalence of Salmonella enterica infections in Danish slaughter pigs determined by microbiological testing. Prev Vet Med 1996. [DOI: 10.1016/0167-5877(95)00563-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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223
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Christensen J. The influence of selected litter and herd factors on treatments for lameness in suckling piglets from 35 Danish herds. Prev Vet Med 1996. [DOI: 10.1016/0167-5877(95)00523-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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224
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Engelward BP, Dreslin A, Christensen J, Huszar D, Kurahara C, Samson L. Repair-deficient 3-methyladenine DNA glycosylase homozygous mutant mouse cells have increased sensitivity to alkylation-induced chromosome damage and cell killing. EMBO J 1996. [DOI: 10.1002/j.1460-2075.1996.tb00429.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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225
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Engelward BP, Dreslin A, Christensen J, Huszar D, Kurahara C, Samson L. Repair-deficient 3-methyladenine DNA glycosylase homozygous mutant mouse cells have increased sensitivity to alkylation-induced chromosome damage and cell killing. EMBO J 1996; 15:945-52. [PMID: 8631315 PMCID: PMC450292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
In Escherichia coli, the repair of 3-methyladenine (3MeA) DNA lesions prevents alkylation-induced cell death because unrepaired 3MeA blocks DNA replication. Whether this lesion is cytotoxic to mammalian cells has been difficult to establish in the absence of 3MeA repair-deficient cell lines. We previously isolated and characterized a mouse 3MeA DNA glycosylase cDNA (Aag) that provides resistance to killing by alkylating agents in E. coli. To determine the in vivo role of Aag, we cloned a large fragment of the Aag gene and used it to create Aag-deficient mouse cells by targeted homologous recombination. Aag null cells have no detectable Aag transcripts or 3MeA DNA glycosylase activity. The loss of Aag renders cells significantly more sensitive to methyl methanesulfonate-induced chromosome damage, and to cell killing induced by two methylating agents, one of which produces almost exclusively 3MeAs. Aag null embryonic stem cells become sensitive to two cancer chemotherapeutic alkylating agents, namely 1,3-bis(2-chloroethyl)-1-nitrosourea and mitomycin C, indicating that Aag status is an important determinant of cellular resistance to these agents. We conclude that this mammalian 3MeA DNA glycosylase plays a pivotal role in preventing alkylation-induced chromosome damage and cytotoxicity.
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