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J Petersen

Publications and source records attributed to J Petersen.

At least 91 records · Page 5Linked to original sources
PubMed1998

F-actin distribution and function during sexual differentiation in Schizosaccharomyces pombe.

Sexual differentiation in Schizosaccharomyces pombe is induced from the G1 phase of the cell cycle by nitrogen starvation and the presence of mating pheromones. We describe the distribution of F-actin during sexual differentiation. Cortical F-actin dots have previously been shown to be restricted to one end of the rod shaped cell during the G1 phase of the cell cycle. Within half an hour of nitrogen starvation the distribution of cortical F-actin dots switched from being monopolar to bipolar. This was then reversed as the F-actin cytoskeleton repolarized so that cortical F-actin dots accumulated towards the projection tip at one end of the cell. Following cell fusion, F-actin dots were randomly scattered during the horsetail movement that precedes meiosis I and remained scattered until prometaphase or metaphase of meiosis II, when they concentrated around the nucleus. F-actin was seen on the lagging face of the nuclei which faced the partner nucleus during anaphase B of meiosis II. Early on in this anaphase F-actin was also seen on the opposite side of the nucleus, near the spindle pole body. F-actin accumulated within the spores in the mature ascus. Treatment with the actin depolymerising drug Latrunculin A showed that F-actin is required for cell fusion and spore formation. Latrunculin A treatment extended all stages from karyogamy to meiosis I. The S. pombe homologue of the actin binding protein profilin, Cdc3, was shown to be required for conjugation. Cdc3 co-localized with the formin related molecule Fus1 at the projection tip. The polarization of F-actin cortical dots to the projection tip was unaffected in the cdc3.124 mutant, but cdc3.124 mutant cells were unable to break down the cell walls between the two cells following agglutination.

Actin Cytoskeleton↗
PubMed1998

Anti-neutrophil cytoplasm autoantibodies (ANCA). The need for specific and sensitive assays.

Anti-neutrophil cytoplasm antibodies (ANCA) are a group of autoantibodies primarily associated with systemic vasculitis. Hitherto, the method of choice for ANCA detection has been indirect immunofluorescence (IIF). By this method two major patterns can be seen: a cytoplasmic pattern (cANCA) or a perinuclear pattern (pANCA). The cANCA pattern is most often caused by antibodies directed against proteinase-3 (PR3) and in rare cases it is caused by anti-myeloperoixdase (MPO) antibodies. The pANCA pattern can de caused by antibodies directed against a large group of proteins i.e. MPO, lactofenin and bactericidal/permeability-increasing protein. Often there is a discrepancy between the results obtained by IIF and those reported from the use of assays with purified antigens. This causes confusion. Until now only anti-PR3 and anti-MPO have been found of any clinical value. Therefore, it would be more proper to use assays with these highly purified antigens instead of an unspecific method like IIF.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1998

CC chemokine receptor 5 polymorphism in rheumatoid arthritis.

OBJECTIVE: Some chemokine receptors have been shown to be co-receptors for human immunodeficiency virus (HIV-1). A 32 base pair deletion allele in the CC chemokine receptor 5 gene (CCR5 delta32 allele) affects both transmission of HIV-1 and acquired immunodeficiency syndrome (AIDS)-free survival. Chemokines are suggested to be critical for establishment of inflammatory processes in autoimmune diseases such as rheumatoid arthritis (RA). We hypothesized that the defective allele may modulate the inflammatory process in RA. METHODS: Using polymerase chain reaction methods, we investigated the significance of the CCR5 delta32 allele in 163 Danish patients with RA and monitored clinical and paraclinical variables. RESULTS: The gene frequency of the CCR5 delta32 allele (0.10) did not deviate significantly from healthy controls and from that reported in healthy Caucasian populations, nor did the distribution deviate from the Hardy-Weinberg predictions (131 wild type, 30 heterozygous, 2 homozygous for the deletion allele; p = 0.85). However, a significantly increased proportion of those carrying the deletion allele were negative for IgM rheumatoid factor (RF) compared to those homozygous for the normal allele (29 vs 9%; p = 0.007). The proportion of CCR5 delta32 allele carriers with swollen joints was decreased compared to those homozygous for the normal allele (35 vs 58%, respectively; p = 0.03), as was the duration of morning stiffness (median 0 vs 60 min, respectively; p = 0.0002). CONCLUSION: The CCR5 delta32 allele seems to have some influence on RA variables including RF, which suggests that inhibition of chemokine receptors might be a potential target for disease modifying therapy in RA.

Adult↗
PubMed1997

A cholera toxoid-insulin conjugate as an oral vaccine against spontaneous autoimmune diabetes.

Mucosally induced immunological tolerance is an attractive strategy for preventing or treating illnesses resulting from untoward inflammatory immune reactions against self- or non-self-antigens. Oral administration of relevant autoantigens and allergens has been reported to delay or suppress onset of clinical disease in a number of experimental autoimmune and allergic disorders. However, the approach often requires repeated feeding of large amounts of tolerogens over long periods and is only partly effective in animals already systemically sensitized to the ingested antigen such as in animals already harboring autoreactive T cells, and thus presumably also in humans with an autoimmune disease. We have recently shown that oral administration of microgram amounts of antigen coupled to cholera toxin B subunit (CTB), can effectively suppress systemic T cell reactivity in naive as well as in immune animals. We now report that feeding small amounts (2-20 microg) of human insulin conjugated to CTB can effectively suppress beta cell destruction and clinical diabetes in adult nonobese diabetic (NOD) mice. The protective effect could be transferred by T cells from CTB-insulin-treated animals and was associated with reduced lesions of insulitis. Furthermore, adoptive co-transfer experiments involving injection of Thy-1,2 recipients with diabetogenic T cells from syngeneic mice and T cells from congenic Thy-1,1 mice fed with CTB-insulin demonstrated a selective recruitment of Thy-1,1 donor cells in the peripancreatic lymph nodes concomitant with reduced islet cell infiltration. These results suggest that protection against autoimmune diabetes can be achieved by feeding minute amounts of a pancreas islet cell autoantigen linked to CTB and appears to involve the selective migration and retention of protective T cells into lymphoid tissues draining the site of organ injury.

Administration, Oral↗
PubMed1997

Histologic/histochemical grading system for osteoarthritic articular cartilage: reproducibility and validity.

OBJECTIVE: To evaluate the reproducibility and validity of the histologic/histochemical grading system (HHGS) for osteoarthritis (OA) developed by Mankin and coworkers. METHODS: Sections of human articular cartilage from macroscopically normal and osteoarthritic femoral heads were graded by the HHGS (0-14 scale) twice by 3 observers, and intra- and interobserver reproducibility was determined. RESULTS: The exact intra- and interobserver reproducibilities ranged from 22% to 33% and from 13% to 25%, respectively. Intra- and interobserver variation ranged from -7 to 5. Although scores were generally higher in cartilage from osteoarthritic joints as compared with cartilage from normal joints, the difference reached statistical significance for only 2 observers. Additionally, the average scores from all observers were within the definitive range for OA (>5) in 30% of sections from normal joints, and in only 47% of sections from OA joints. CONCLUSION: The results indicate that the reproducibility and the validity of the HHGS are inadequate, and an improved histopathologic grading system for OA is needed.

Adult↗
PubMed1997

A longitudinal study of pulmonary function in Danish patients with systemic sclerosis.

OBJECTIVE: To determine the types, prevalence and development of respiratory abnormalities in patients with systemic sclerosis (SSc), and to correlate the results with clinical and serological findings. METHODS: 176 patients with SSc observed longitudinally were retrospectively included in the study. The change per year of vital capacity (VC), forced expiratory volume in one second/vital capacity (FEV1/VC), diffusing capacity (DLco) and diffusing constant (Kco) of carbon monoxide from the first till the latest pulmonary function test were correlated to clinical and serological findings, including anti-centromere, anti-Scl-70, and antinucleolar antibodies. RESULTS: An isolated reduction of DLco was seen in 47% and a restrictive ventilatory pattern in 25% of the patients. Restrictive ventilatory pattern correlated to pulmonary fibrosis, dyspnoea, a low prevalence (13%) of anti-centromere antibodies and a high prevalence of anti-Scl-70 antibodies (36%). Progression of DLco reduction was related to long disease duration, presence of anti-centromere antibodies and absence of treatment with penicillamine. CONCLUSION: Pulmonary involvement is common in patients with SSc. The occurrence of different serological abnormalities in patients with restrictive disease and in patients with progressive isolated reduction of DLco, suggests that the two types of pulmonary damage may have different pathogeneses rather than being different stages in the progression of pulmonary damage.

Adult↗
PubMed1997

CD44 expression is up-regulated in the deep zone of osteoarthritic cartilage from human femoral heads.

AIMS: The objective of this study was to detail the topographical and zonal distribution of the cell adhesion molecule CD44 in normal and osteoarthritic cartilage. METHODS AND RESULTS: Immunohistochemistry utilizing well characterized anti-CD44 antibodies (clones A3D8, Bric 235, 2C5) was performed on cryostat and paraffin sections of human articular cartilage from macroscopically normal (n = 18) and osteoarthritic (n = 11) femoral heads. Samples for cryostat sections were obtained from 12 topographically different sites. Sections were divided into zones (superficial, middle, deep) and the CD44 staining scored. Chondrocytes in normal articular cartilage and cartilage from osteoarthritic femoral heads stained positive for CD44 in both cryostat and paraffin sections. Normal cartilage showed a significant decrease in CD44 staining in the deep zone as compared to the superficial zone (P < 0.05). However, cryostat sections of residual cartilage from osteoarthritic femoral heads showed increased CD44 staining in the deep zone as compared to normal articular cartilage. The CD44 staining showed no topographical variation in either the normal cartilage or the osteoarthritic residual cartilage. CONCLUSIONS: CD44 expression displays a distinct zonal variation in normal articular cartilage which is lost in osteoarthritic cartilage due to an up-regulated expression in the deep zone. CD44 expression does not exhibit topographical variation.

Aged↗
PubMed1997

[Accidental macular injuries caused by the neodymium:YAG laser].

BACKGROUND: The number of laser-users is steadily increasing. This implies an increasing risk of laser accidents with injuries especially of the posterior eye segment. PATIENTS AND METHODS: Two engineers accidentally suffered severe macular injuries caused by Neodym: YAG-lasers with 1064 and 1064/532/355 nm wavelength, respectively. In both cases very high energies were used. One patient looked directly at the laser beam, while in the other case the laser light was reflected from a detector. RESULTS: Depending on the emitted laser energy serious foveal destruction of retinal and chorioideal tissue, surrounding retinal edema and vitreous hemorrhage occurred, resulting in immediate reduction of visual acuity to 0.125 and 1/24 in 1 m, resp., and central scotoma. The most important damage mechanisms are plasma formation and expansion, emission of acoustic transients and cavitation with jet formation. Subsequently, macular scars evolved which were responsible for the limited increase of visual acuity up to 0.32, resp, 0.16 and remaining absolute central scotoma. CONCLUSION: Since there is no effective therapy, attention must be paid to preventive aspects. Improved information and awareness concerning the serious functional consequences of macular injuries is necessary, especially for non-medical users. Due to distinctive technical conditions (experimental arrangement with unprotected laser beam, comparatively high laser energy, prevailing parallel laser radiation), this circle of laser-users has a high risk of accident. A proper opportunity for an improved education are workshops for laser safety precautions.

Accidents, Occupational↗
PubMed1997

Increase in the frequency of hepadnavirus DNA integrations by oxidative DNA damage and inhibition of DNA repair.

Persistent hepadnavirus infection leads to oxidative stress and DNA damage through increased production of toxic oxygen radicals. In addition, hepadnaviral DNA integrations into chromosomal DNA can promote the process of hepatocarcinogenesis (M. Feitelson, Clin. Microbiol. Rev. 5:275-301, 1992). While previous studies have identified preferred integration sites in hepadnaviral genomes and suggested integration mechanisms (M. A. Buendia, Adv. Cancer Res. 59:167-226, 1992; C. E. Rogler, Curr. Top. Microbiol. Immunol. 168:103-141, 1991; C. Shih et al., J. Virol. 61:3491-3498, 1987), very little is known about the effects of agents which damage chromosomal DNA on the frequency of hepadnaviral DNA integrations. Using a recently developed subcloning approach to detect stable new integrations of duck hepatitis B virus (DHBV) (S. S. Gong, A. D. Jensen, and C. E. Rogler, J. Virol. 70:2000-2007, 1996), we tested the effects of increased chromosomal DNA damage induced by H2O2, or of the disturbance in DNA repair due to the inhibition of poly(ADP-ribose) polymerase (PARP), on the frequency of DHBV DNA integrations. Subclones of LMH-D21-6 cells, which replicate DHBV, were grown in the presence of various H2O2 concentrations and exhibited up to a threefold increase in viral DNA integration frequency in a dose-dependent manner. Moreover, inhibition of PARP, which plays a role in cellular responses to DNA breakage, by 3-aminobenzamide (3-AB) resulted in a sevenfold increase in the total number of new DHBV DNA integrations into host chromosomal DNA. Removal of either H2O2 or 3-AB from the culture medium in a subsequent cycle of subcloning was accompanied by a reversion back towards the original lower frequency of stable DHBV DNA integrations for LMH-D21-6 cells. These data support the hypothesis that DNA damage sites can serve as sites for hepadnaviral DNA integration, and that increasing the number of DNA damage sites dramatically increases viral integration frequency.

Animals↗
PubMed1996

CO2 angiography--a technique for vascular imaging in renal allograft dysfunction.

Use of iodinated contrast for vascular imaging can be associated with nephrotoxicity and hypersensitivity reactions. Renal injury following conventional angiography is more likely to manifest in the setting of preexisting renal dysfunction. In the setting of suboptimal renal allograft function, these considerations are particularly relevant. Recently, CO2 has received attention as a nontoxic, injectable, rapidly absorbed gas that is a cost-effective alternative to standard contrast agents in high-risk patients, such as renal transplant recipients. We report the clinical course of a patient with transplant renal artery stenosis and a serum creatinine of 2.8 mg/dl who has successfully undergone angiography and percutaneous transluminal angioplasty using CO2 as the sole contrast agent. This case illustrates the potential use for CO2 as a contrast agent for vascular imaging in patients with suboptimal renal function who require definitive vascular imaging or therapy.

Adult↗
PubMed1996

Binding of the oxidized, reduced, and radical flavin species to chorismate synthase. An investigation by spectrophotometry, fluorimetry, and electron paramagnetic resonance and electron nuclear double resonance spectroscopy.

Chorismate synthase (EC 4.6.1.4) binds oxidized riboflavin-5'-phosphate mononucleotide (FMN) with a KD of 30 microM at 25 degrees C, but in the presence of 5-enolpyruvylshikimate-3-phosphate (EPSP), the KD decreases to ca. 20 nM. Similar effects occur with the substrate analogue (6R)-6-fluoro-EPSP (KD = 36 nM) and chorismate (KD = 540 nM). Fluorescence of oxidized FMN is slightly quenched in the presence of chorismate synthase. Addition of EPSP or the (6R)-6-fluoro analogue causes a shift of the fluorescence from 520 to 495 nm. Chorismate causes no shift in, but a quenching of, the fluorescence emission maximum. In the presence of EPSP, (6R)-6-fluoro-EPSP, or chorismate, the neutral flavinsemiquinone is generated. The electron paramagnetic resonance (EPR) line width of the flavin radical is indicative of a neutral flavinsemiquinone. Frozen solution electron nuclear double resonance (ENDOR) of the radical with (6R)-6-fluoro-EPSP shows a number of proton ENDOR line pairs. The largest splitting is assigned to a hyperfine coupling to the methyl group beta-protons at position 8 of the isoalloxazine ring. The hyperfine-coupling (hfc) components have values of A perpendicular = 8.07 MHz and A parallel = 9.60 MHz, giving Aiso of 8.58 MHz, consistent with a neutral semiquinone form. The isotropic hfc coupling of the 8-methyl protons with (6R)-6-fluoro-EPSP decreases by about 0.5 MHz when chorismate is bound, indicating that the spin density distribution within the isoalloxazine ring system depends critically on the nature of the ligand. The redox potential of FMN in the presence of chorismate synthase was 95 mV more positive than that of free FMN (at pH 7.0), equivalent to a 1660-fold tighter binding of reduced FMN. The pH dependence of the redox potential of chorismate synthase-bound FMN exhibits a slope of -30 mV per pH unit between pH 6 and 9, indicating that the two-electron reduction of the flavin is associated with the uptake of one proton; this, and the UV-visible spectrum, is consistent with the reduced flavin being bound to chorismate synthase in its monoanionic form.

Electron Spin Resonance Spectroscopy↗
PubMed1996

Digital pulse plethysmography as a non-invasive method for predicting drug-induced changes in left ventricular preload.

OBJECTIVE: Changes in the contour of the plethysmographically recorded digital pulse curve after nitrate ingestion are well known, but it has not been fully established whether these changes reflect nitrate action on left ventricular (LV) preload or afterload. Therefore, we compared the pulse wave contour after administration of equieffective doses of nitroglycerin and nifedipine. METHODS: In 20 patients with coronary artery disease we measured aortic blood pressure curve in the aorta ascendens, digital volume pulse curve with a photoelectric pulse pickup, Riva Rocci blood pressure and heart rate after administration of either 0.8 mg nitroglycerin or 10 mg nifedipine. RESULTS: Peak plasma concentrations of nitroglycerin and nifedipine were achieved 5 min and 20 min after ingestion of the drugs. Systolic aortic blood pressure decreased after both nitroglycerin and nifedipine to 19.4 mmHg, but diastolic blood pressure decreased only after nifedipine by 10.5 mmHg (P < 0.05). Riva Rocci blood pressures showed a similar time course. Heart rate increased from 67.4 to 70.9 beats.min-1 after nitroglycerin and from 58.9 to 69.4 beats.min-1 after nifedipine. The calculated a/b ratio of the aortic pressure curve increased after both medications (nitroglycerin, from 1.66 to 1.99; nifedipine, from 1.66 to 1.93) and its time course mimicked that of the systolic blood pressure. The a/b ratio of the digital pulse curve did not change after nifedipine, but showed a pronounced rise after nitroglycerin from 1.29 to 1.84. With regard to pharmacological actions, nitroglycerin causes a reduction in LV preload and afterload, whereas nifedipine has only LV-afterload-reducing activity. CONCLUSION: We conclude, that the reduction in afterload did not cause the typical changes in wave contour of the peripheral pulse curve which occur with organic nitrates. Most likely changes in the a/b ratio reflect changes in LV preload.

Adult↗
PubMed1996

Complexes between proteinase 3, alpha 1-antitrypsin and proteinase 3 anti-neutrophil cytoplasm autoantibodies: a comparison between alpha 1-antitrypsin PiZ allele carriers and non-carriers with Wegener's granulomatosis.

To test the hypothesis that anti-neutrophil cytoplasm autoantibodies (ANCAs) interfere with the functions of proteinase 3 (PR3) (the Wegener autoantigen) and alpha 1-antitrypsin (alpha 1AT), complexes of PR3/alpha 1 AT and PR3/PR3-ANCA-IgG were assayed Plasma samples were obtained from 44 patients with Wegener's granulomatosis (WG): 34 had active disease (88% ANCA positive) whereas 10 patients were in remission (20% ANCA positive). Plasma samples from 14 of the patients with active disease were also available at the time of remission. The complexes of PR3/alpha 1 AT and PR3/PR3-ANCA-IgG were detected by capture enzyme-linked immunoassays (ELISAs) alpha 1 AT deficiency was evaluated by determining PiZ alleles by ELISA. Eight (18%) of the patients were PiZ positive. The frequency of this alpha 1-antitrypsin phenotype in the Scandinavian population is 4.7% (P < 0.001). The median PR3/alpha 1AT complex level in the PiZ-positive group with active disease (n = 5) was similar to the level in the PiZ-negative group with active disease. During remission the median level for the PR3/alpha 1AT complex was significantly higher than in the acute group (P < 0.001) including both PiZ-positive and PiZ-negative patients. No difference between PiZ positivity and PiZ negativity could be found in the remission group. PR3/PR3-ANCA-IgG complexes were found in patients with acute disease as well as in patients in remission, in almost equal frequency. This complex was also present in 13/18 ANCA-negative samples from patients in remission. Finally, purified IgG fractions from WG patients were examined for their capacity to inhibit binding between PR3 and alpha 1AT. An effect on the binding between PR3 and alpha 1AT by PR3-ANCA could not be demonstrated. Thus, our results do not support the hypothesis that PR3-ANCA interferes with the binding between PR3 and alpha 1AT. However, the high prevalence of the PiZ alleles among WG patients suggests that an imbalance between proteinases and alpha 1AT may be of importance in this disease. The clinical usefulness of both the PR3/alpha 1AT and the PR3/PR3-ANCA-IgG complexes and the possible influence on ANCA detection need to be examined in prospective longitudinal studies.

Acute Disease↗
PubMed1996

Reduction of extraneural scarring by ADCON-T/N after surgical intervention.

The effects of ADCON-T/N (Gliatech, Inc., Cleveland, OH), a carbohydrate polymer gel, on peripheral nerve scarring and regeneration were studied in rodents undergoing three types of surgical intervention. Procedure I involved external neurolysis of the sciatic nerve from surrounding tissues and separation of its tibial and peroneal components. Procedure II involved the addition of an abrasive injury. Procedure III involved transection and suture anastomosis of the tibial component. ADCON-T/N or a control gel was locally applied in a blind fashion. Additional animals received no gel, as a further control. Animals underwent second operations 4 weeks after Procedures I and II and 6 weeks after Procedure III. The surgical sites were evaluated using a numerical grading scheme to assess wound healing, sciatic nerve adherence to surrounding tissues, and separability of its tibial and peroneal components. Animals receiving ADCON-T/N demonstrated reduced nerve adherence to surrounding tissues and enhanced separability of the tibial and peroneal components, compared with animals receiving control gel or no gel. Quantitative histological analysis revealed a statistically significant reduction in the amount of dense scar tissue surrounding nerves treated with ADCON-T/N. No evidence of nerve toxicity caused by ADCON-T/N was noted. Counts of regenerating myelinated axons in animals undergoing nerve transection and suture repair did not statistically differ in treated and untreated animals. In conclusion, ADCON-T/N seems to be both safe and effective in reducing extraneural scar formation after peripheral nerve surgery and local trauma.

Animals↗