Determination of gelatinase-A (MMP-2) activity using a novel immunocapture assay.
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Amino Acid Sequence↗
Biomedical subjects
H Visser
Publications and source records attributed to H Visser.
HLA-DQ-associated predisposition to and dominant HLA-DR-associated protection against rheumatoid arthritis.
We have recently proposed a new hypothesis to explain the association of Human Leukocyte Antigen (HLA) with rheumatoid arthritis (RA) predisposition. In this model, which challenges the Shared Epitope (SE) hypothesis, HLA-DQ predisposes while HLA-DR protects. In the present study, we have compared these two models in an Early Arthritis Clinic started in 1993 in the Department of Rheumatology at the Leiden University Medical Centre. Out of 524 patients who enrolled this programme in the period 1993-1998 and completed the one year follow-up, 155 have been classified as RA. These patients along with 306 consecutive cadaveric renal organ donors have been typed for HLA-DR and -DQ. The distributions of predisposing DR alleles according to SE, and predisposing DQ and protective DR according to our model were analysed. We found that two doses of predisposing DQ alleles strongly predisposed to RA, even in individuals with a single dose of SE while DRB1 alleles carrying the motif DERAA confered a dominant protection in DQ5-positive individuals. We conclude that the present findings are consistent with our previously described model of HLA and RA association. Using this new model, we have been able to characterise two novel groups of individuals on the basis of their HLA typing: one strongly predisposed to RA and one protected. Knowing the mechanism of HLA-related dominant natural protection may help in designing novel treatment modalities for RA.
Alleles↗
[Dental CT: image quality and radiation exposure in relation to scan parameters].
PURPOSE: To develop a scan protocol for dental-CT which guarantees good image quality at the lowest possible radiation dose. METHODS: In an experimental investigation Dental-CT (HSA, GE, Milwaukee, USA) of the mandible of two human skeletons positioned in a water tank were performed in order to define the most advantageous scan protocol. Tube currents ranged from 40 to 200 mA and the scan technique was modified (axial mode or helical mode with pitches of 1 to 3 and corresponding increments of 0.4 to 1.0 mm). 39 patients underwent a dental-CT with decreased current (80 mA) in the helical scan mode (pitch 2, slice thickness 1 mm). Dose measurements were performed for two different scan protocols (A: axial, 130 mAs, B: helical, 80 mA, pitch 2). RESULTS: The preliminary investigations of image quality showed only a minor effect of the applied current. For the helical scan mode, pitches of more than 2 impaired image quality. A low increment had no advantages. There were no disadvantages in clinical practice using protocol B with decreased tube current. Absorbed radiation dose of dental CT performed with protocol B was decreased to one third in comparison to protocol A. CONCLUSIONS: A scan protocol with a low tube current (e.g., 80 mA, for a rotation time of 1 s) and a helical scan mode (e.g., for a slice thickness of 1 mm with a pitch of 2 and an increment of 1 mm) is recommended for performing dental-CT.
Adult↗
Isolation and characterization of the epoxide hydrolase-encoding gene from Xanthophyllomyces dendrorhous.
The epoxide hydrolase (EH)-encoding gene (EPH1) from the basidiomycetous yeast Xanthophyllomyces dendrorhous was isolated. The genomic sequence has a 1,236-bp open reading frame which is interrupted by eight introns that encode a 411-amino-acid polypeptide with a calculated molecular mass of 46.2 kDa. The amino acid sequence is similar to that of microsomal EH and belongs to the alpha/beta hydrolase fold family. The EPH1 gene was not essential for growth of X. dendrorhous in rich medium under laboratory conditions. The Eph1-encoding cDNA was functionally expressed in Escherichia coli. A sixfold increase in specific activity was observed when we used resting cells rather than X. dendrorhous. The epoxides 1,2-epoxyhexane and 1-methylcyclohexene oxide were substrates for both native and recombinant Eph1. Isolation and characterization of the X. dendrorhous EH-encoding gene are essential steps in developing a yeast EH-based epoxide biotransformation system.
Amino Acid Sequence↗
[Thrombocytopenia caused by gold fillings?].
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Dental Restoration, Permanent↗
A novel and simple immunocapture assay for determination of gelatinase-B (MMP-9) activities in biological fluids: saliva from patients with Sjögren's syndrome contain increased latent and active gelatinase-B levels.
Here we describe a new principle for accessing the activity of the different members of the human matrix-metalloproteinases (MMPs) by a colorimetric assay. Using protein engineering, a modified pro-urokinase was made in which the activation sequence, normally recognized by plasmin (ProArgPheLys/IleIleGlyGly), was replaced by a sequence that is specifically recognized by MMPs (ArgProLeuGly/IleIleGlyGly). The active urokinase resulting from the activation of this modified pro-urokinase by MMPs can be measured directly using a chromogenic peptide substrate for urokinase. The assay has been made specific for MMP-9 using an MMP-9 specific monoclonal antibody. Using this antibody MMP-9 is captured from biological fluids or tissue culture media, and MMP-activity of both active and latent MMP-9 can be analysed. We determined the gelatinase-B (MMP-9) activity present in saliva from patients with Sjögren's syndrome. Using a general gelatinase assay with radioactively-labeled gelatinated collagen it was observed that gelatinase activity was slightly, though not significantly, increased in patients: general gelatinase activity in patients versus healthy controls: 17.0 +/- 4.9 vs 12.2 +/- 2.5 x 10(4) cpm/ml (p > 0.05, and 44.0 (4.0 vs 36.1 +/- 1.9 x 10(4) cpm/ml (p > 0.05), for active and latent gelatinase, respectively. However, using the immunocapture activity assay (using modified urokinase) specifically MMP-9 activity was measured, which was significantly increased in saliva from patients compared to healthy controls: MMP-9 (already active): patients 8.9 +/- 2.5 U/mg, controls 1.0 +/- 0.5 U/mg (p = 0.002); latent plus active MMP-9: patients 53.1 +/- 9.8 U/mg, controls 16.5 +/- 2.6 U/mg (p = 0.01). This assay, measuring MMP-9 activity using modified pro-urokinase as a substrate can easily be adapted for the specific detection of the various members of the MMP-family or other difficult to measure proteases, in a format that can be used for high throughput screening of compounds or samples.
Animals↗
Diagnosis and course of early-onset arthritis: results of a special early arthritis clinic compared to routine patient care.
OBJECTIVE: Early arthritis patients referred to an Early Arthritis Clinic (EAC) (n = 233) were compared to 241 patients from the routine out-patient clinic with respect to lag time between the onset of symptoms and the visit to the rheumatologist, clinical presentation and the consistency of the diagnosis after 1 yr. RESULTS: The reduction in median lag time for the EAC patients was at least 3 months. An insidious onset of symptoms was found more often in the rheumatoid arthritis (RA) patients in the routine clinic. In 70% of all cases, a diagnosis could be made after 2 weeks and, if the clinical diagnosis was definite RA, this hardly changed during the following year. Early erosions were seen in 25% of RA patients and were associated with a positive rheumatoid factor (OR 2.08, 95% CI 0.95 4.59). CONCLUSION: An early diagnosis of RA at the EAC is possible and reliable; the high frequency of erosions illustrates the need for early treatment.
Adolescent↗
Inhibition of MMP synthesis by doxycycline and chemically modified tetracyclines (CMTs) in human endothelial cells.
Doxycycline is a commonly used broad-spectrum antibiotic. Recently, it has been shown that it also inhibits the activity of mammalian collagenases and gelatinases, an activity unrelated to its antimicrobial efficacy. In this study, we show that doxycycline not only inhibits MMP-8 and MMP-9 (gelatinase B) activity, but also the synthesis of MMPs in human endothelial cells. Doxycycline (50 microM) completely inhibited the phorbol-12-myristate-13-acetate (PMA)-mediated induction of MMP-8 and MMP-9, as measured by Western blotting and gelatin zymography, respectively. The inhibition was also observed at the mRNA level. No effect was observed on the expression of MMP-2 and of the MMP inhibitors TIMP-1 and TIMP-2. Chemically modified tetracyclines (CMTs) showed an inhibition similar to that of doxycycline, albeit less efficient. These observations demonstrate that endothelial cells display a specific regulation of MMPs, which may have implications for the pharmaceutical interaction in angiogenesis and angiogenesis-related diseases.
Anti-Bacterial Agents↗
Disposition of hospital assets: the legal issues.
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Canada↗
International migration scenarios for the European Economic Area.
"This article describes the assumptions on international migration underlying the new population scenarios for countries of the European Economic Area. Three scenarios will be presented. The Baseline scenario describes a situation in which observed developments are continued. In the High scenario net migration is assumed to increase in the short run. In the long run this will provoke a political reaction, resulting in a significant reduction in the influx of migrants. In the Low scenario it is assumed that current net migration figures of the EEA will be halved in the next decade."
Demography↗
Effect of the economy on international migration flows.
"This article examines the relationship between economic growth and international migration. On the basis of regression analysis of immigration into the Netherlands it may be concluded that a rise in unemployment in the Netherlands has a negative influence on immigration. A rise in unemployment in the country of origin of migrants has a positive effect on the migration to the Netherlands."
Demography↗
Routine measurement of IgM, IgG, IgA rheumatoid factors.
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Arthritis↗
Matrix metalloproteinase-8 is expressed in rheumatoid synovial fibroblasts and endothelial cells. Regulation by tumor necrosis factor-alpha and doxycycline.
Neutrophil collagenase (matrix metalloproteinase-8 or MMP-8) is regarded as being synthesized exclusively by polymorphonuclear neutrophils (PMN). However, in vivo MMP-8 expression was observed in mononuclear fibroblast-like cells in the rheumatoid synovial membrane. In addition, we detected MMP-8 mRNA expression in cultured rheumatoid synovial fibroblasts and human endothelial cells. Up-regulation of MMP-8 was observed after treatment of the cells with either tumor necrosis factor-alpha (10 ng/ml) or phorbol 12-myristate 13-acetate (10 nM). Western analysis showed a similar regulation at the protein level. The size of secreted MMP-8 was 50 kDa, which is about 30 kDa smaller than MMP-8 from PMN. Conditioned media from rheumatoid synovial fibroblasts contained both type I and II collagen degrading activity. However, degradation of type II collagen, but not that of type I collagen, was completely inhibited by 50 microM doxycycline, suggesting specific MMP-8 activity. In addition, doxycycline down-regulated MMP-8 induction, at both the mRNA and protein levels. Thus MMP-8 exerts markedly wider expression in human cells than had been thought previously, implying that PMN are not the only source of cartilage degrading activity at arthritic sites. The inhibition of both MMP-8 activity and synthesis by doxycycline provides an incentive for further studies on the clinical effects of doxycycline in the treatment of rheumatoid arthritis.
Arthritis, Rheumatoid↗
Effect of photoperiod on body mass, and daily energy intake and energy expenditure in young rats.
In this experiment we investigate the effect of photoperiod on locomotor activity, body mass, food intake, growth efficiency (relationship between body mass change and food intake), energy expenditure, and body composition in growing Wistar rats. Two groups of animals were subjected to either a long, LD 18:6 (n = 8) or short photoperiod, LD 6:18 (n = 7), during a period of 190 days after weaning. Activity, body mass, food intake, and energy expenditure were measured during the study, as well as body composition at the end of the experiment. We show that growing rats exposed to short photoperiod (a) have a lower rate of weight gain, (b) have similar energy intakes, (c) have lower growth efficiency, (d) have lower daily energy expenditure and resting metabolic rate, and (e) gain less lean body mass than those exposed to long photoperiods. We suggest that the distribution of energy expenditure and food intake over the total 24-h cycle may be responsible for the differences in body weight gain between the two photoperiods.
Age Factors↗
Can dentists recognize manipulated digital radiographs?
OBJECTIVES: To determine the ability of dentists to recognize digitally manipulated radiographs. METHODS: A poster was presented at the Annual Meeting of the German Society for Periodontology displaying the intra-oral radiographs of 12 different patients. Half of the radiographs were subjected to digital manipulation to add or remove specific features. Dentists were asked to identify these radiographs by means of a questionnaire. RESULTS: Thirty-nine dentists submitted usable questionnaires. Statistical evaluation revealed a distribution of hits similar to the random distribution. None of the dentists detected all the six manipulated radiographs; three dentists had five correct, but there were five with only one. An authentic radiograph scored highest as a manipulation. CONCLUSIONS: Image manipulations which alter the diagnostic content of a radiograph are unlikely to be detected by dentists. Digital radiography requires additional measures for data protection.
Clinical Competence↗
Free gingival grafts using a CO2 laser: results of a clinical study.
Free gingival grafts are a reliable method for treatment of gingival recessions: An autograft is taken from the palate as replacement for the lost keratinized gingiva. A technique using the CO2 laser and results from a clinical study are presented. The receptor beds for 23 free gingival grafts were prepared with a CO2 laser. After a trapezoid incision in the epithelium, the connective tissue fibers were cut parallel to the periosteum avoiding coagulation of this delicate tissue. The grafts from the palate were taken conventionally. In all cases wound healing and incorporation of the grafts were good; no delay could be seen. Controls after 1 year revealed good results of the treatment. The CO2 laser can be useful for the free gingival graft procedure. Good hemostasis and low mechanical stress of the receptor bed can be achieved without affecting wound healing or incorporation of the delicate free gingival grafts.
Carbon Dioxide↗
Diagnostic and prognostic characteristics of the enzyme linked immunosorbent rheumatoid factor assays in rheumatoid arthritis.
OBJECTIVE: To determine the diagnostic and prognostic test qualities of the enzyme linked immunosorbent assays (ELISA) for rheumatoid factor isotypes in rheumatoid arthritis (RA), and to compare them with the latex fixation test. METHODS: Rheumatoid factor tests were performed in 1988 consecutive new rheumatology outpatients within two months after their first visit to the outpatient clinic of the Department of Rheumatology of Leiden University hospital. The sensitivity, specificity, accuracy, and predictive values of the tests in discriminating RA from non-rheumatoid arthritis and erosive from non-erosive disease after two years of follow up were determined and presented as receiver operating characteristic curves and post-test probability curves. RESULTS: The sensitivity of the ELISA for IgG, IgA, and IgM rheumatoid factor for RA versus all controls at optimal cut off titres was 72%, 44%, and 69%, respectively; the specificity was 52%, 84%, and 86%. For the latex fixation test the sensitivity was 66% and the specificity 91%. The post-test probability of RA, at a clinical prevalence rate of 12%, given a positive test result in the ELISAs for IgG, IgA, and IgM rheumatoid factor and the latex fixation test, was 17%, 27%, 40%, and 49%, respectively; with negative test results the probability was 7%, 8%, 5%, and 5%, respectively. The specificity of all tests in discriminating erosive from non-erosive RA at two years was low: 41%, 44%, 47%, and 58% for the ELISAs for IgG, IgA, and IgM rheumatoid factor and the latex fixation test, respectively. CONCLUSION: The ELISAs for IgG and IgA rheumatoid factor are of no significance in diagnosing RA and in the prediction of erosive disease. The ELISA for IgM rheumatoid factor is a reasonable alternative for the latex fixation test when age and gender are taken in to consideration. The specificity of all rheumatoid factor tests in discriminating erosive from non-erosive RA is low.
Adolescent↗
[Migration in the countries of the European Economic Area].
"During the last decade the number of migrants entering the European Economic Area has increased considerably. The governments in many countries have responded to this increase by implementing restrictive immigration policies. Most countries forecast a decline in net migration." Information is provided on push and pull factors, net migration, asylum applications, and forecasts are made for the years 2000 to 2010. (SUMMARY IN ENG)
Demography↗